The Best Absorbents for Spill Cleanup And Control
There are so many types and quality of absorbents on the market, that companies may find themselves inundated with high priced products that do not address their specific industry or requirement. Finding the right absorbents for the right applications is an ongoing challenge for companies who require effective products to control spills and storm water issues.
The best solutions for environmental compliance issues require that companies have adequate inventory of these products that effectively address the environmental compliance challenges for spills and cleanup.
Absorbents are a small segment of the spill containment products that are designed to address environmental issues. Absorbents represent a cost effective way to manage and control liquid spills, leaks and fast cleanup.
Absorbent pads are designed for specific applications and can also enhance the cleanliness of a workplace environment. A variety of absorbent pads are available that fits a specific type and size of spill.
Some of the Absorbent Product available includes:
Universal Gray Absorbent Pads (Most Popular) hide grunge with their gray color will foster longer use. These absorbent pads were made to absorb both oil and water based fluids. Maintenance repair shops, manufacturing facilities, municipalities and many more users have made our universal absorbent pads our best seller.
Oil Only White Absorbent Pads (Repels Water) absorb oil on water or for outside applications. These absorbent pads were made to absorb oil and repel water-based fluids.
Oil Only White Absorbent Pads are used successfully in the following industries:
*Marine industry
*Petroleum industry
*Outside facilities
Hazmat Yellow Chemical Absorbent Pads (For Aggressive Fluids) are designed to absorb aggressive or unknown fluids. These absorbent pads are a caution yellow color for safety and bring awareness to individuals who might wander into a dangerous spill area.
Industries that use these types of Absorbent Pads include:
*Chemical industry
*Manufacturing facilities
HAZMAT absorbent pads are a critical component of their spill control program
Universal Spill Cleanup Absorbent Pads absorbs oil, oil-based products, and water (all liquids). These pads are made of polypropylene. Absorbent pads clean up messy drips, leaks and over spray of fluids quickly. One pad absorbs approximately a ½ quart of oil, and pads can withstand hot oil up to 210°F.
Some of the applications for this product are:
*Placement under vehicles
*Under machines
*Under equipment
*Placed in the bilge of boats
This product helps in absorbing spills and can be used as well to wipe oily hands and clean oily tools.
Static Resistant Oil Only Pads and Rolls are used around flammable liquids and where static electricity poses a hazard. These pads are suitable for arctic and desert climates. Static resistant pads are great for diesel fuels. These pads repel water-based liquids. They are sold by the case or roll.
Absorbent universal socks are the best choice for industrial applications. These general purpose Absorbent socks absorb both oil and water base liquids and drips.
Easy to mold and shape around leaky equipment and machinery. Universal absorbent socks are primarily effective for oils, coolants, solvents and water. These absorbent socks absorb 1 gallon of liquid per sock (4 ft. size). These socks are used to absorb leaks and drips around the bases of machinery.
Multi-functional water absorbent in Anhui. (New Products).
Located in Fuyang City, anhui Province, Guomao Biochemical Products Plant has put on stream a kind of multi-functional water absorbent made of macromolecular materials, which has powerful water-absorbing capacity and high expansion ratio with no pollution, no poisonous and harmless to human being.
The absorbent can absorb water weighting from several hundred to near one thousand times than itself while it can be degraded naturally. This absorbent has a lot of applications such a s in agriculture and live-stock farming industry, forestry, .
Absorbent articles comprising surface cross-linked superabsorbent polymer particles made by a method using vacuum ultraviolet radiation
[0002] Superabsorbent polymers (SAPs) are well known in the art. They are commonly applied in absorbent articles, such as diapers, training pants, adult incontinence products and feminine care products to increase the absorbent capacity of such products while reducing their overall bulk. SAPs are capable of absorbing and retaining amounts of aqueous fluids equivalent to many times their own weight.
[0003] Commercial production of SAPs began in Japan in 1978. The early superabsorbent was a cross-linked starch-g-polyacrylate. Partially neutralized polyacrylic acid eventually replaced earlier superabsorbents in the commercial production of SAPs, and has become the primary polymer in SAPs. SAPs are often applied in form of small particles. They generally consist of a partially neutralized lightly cross-linked polymer network, which is hydrophilic and permits swelling of the network once submerged in water or an aqueous solution such as physiological saline. The cross-links between the polymer chains assure that the SAP does not dissolve in water.
[0004] After absorption of an aqueous solution, swollen SAP particles become very soft and deform easily. Upon deformation the void spaces between the SAP particles are blocked, which drastically increases the flow resistance for liquids. This is generally referred to as “gel-blocking”. In gel blocking situations liquid can move through the swollen SAP particles only by diffusion, which is much slower than flow in the interstices between the SAP particles.
[0005] One commonly applied way to reduce gel blocking is to make the particles stiffer, which enables the swollen SAP particles to retain their original shape thus creating or maintaining void spaces between the particles. A well-known method to increase stiffness is to cross-link the carboxyl groups exposed on the surface of the SAP particles. This method is commonly referred to as surface cross-linking.
[0006] The art refers, for example, to surface cross-linked and surfactant coated absorbent resin particles and a method of their preparation. The surface cross-linking agent can be a polyhydroxyl compound comprising at least two hydroxyl groups, which react with the carboxyl groups on the surface of the SAP particles. In some art, surface cross-linking is carried out at temperatures of 150.degree. C. or above.
[0007] A water-soluble peroxide radical initiator as surface cross-linking agent is also known. An aqueous solution containing the surface cross-linking agent is applied on the surface of the polymer. The surface cross-linking reaction is achieved by heating to a temperature such that the peroxide radical initiator is decomposed while the polymer is not decomposed.
[0008] More recently the use of an oxetane compound and/or an imidazolidinone compound for use as surface cross-linking agent has been disclosed. The surface cross-linking reaction can be carried out under heat, wherein the temperature is preferably in the range of 60.degree. C. to 250.degree. C. Alternatively, the surface cross-linking reaction can also be achieved by a photo-irradiation treatment, preferably using ultraviolet rays.
[0009] In general, the surface cross-linking agent is applied onto the surface of the SAP particles. Therefore, the reaction preferably takes place on the surface of the SAP particles, which results in improved cross-linking on the surface of the particles while not substantially affecting the core of the particles. Hence, the SAP particles become stiffer and gel-blocking is reduced.
[0010] A drawback of the commercial surface cross-linking process described above is, that it takes relatively long, commonly at least about 30 min. However, the more time is required for the surface cross-linking process, the more surface cross-linking agent will penetrate into the SAP particles, resulting in increased cross-linking inside the particles, which has a negative impact on the capacity of the SAP particles. Therefore, it is desirable to have short process times for surface cross-linking. Furthermore, short process times are also desirable with respect to an overall economic SAP particle manufacturing process.
[0011] Another drawback of common surface cross-linking processes is, that they take place only under relatively high temperatures, often around 150.degree. C. or above. At these temperatures, not only the surface cross-linker reacts with the carboxyl groups of the polymer, but also other reactions are activated, such as anhydride-formation of neighbored carboxyl groups within or between the polymer chains, and dimer cleavage of acrylic acid dimers incorporated in the SAP particles. Those side reactions also affect the core, decreasing the capacity of the SAP particles. In addition, exposure to elevated temperatures can lead to color degradation of the SAP particles. Therefore, these side reactions are generally undesirable.
[0012] SAPs known in the art are typically partially neutralized, for example, with sodium hydroxide. However, neutralization has to be carefully balanced with the need for surface cross-linking: The surface cross-linking agents known in the art react with free carboxyl groups comprised by the polymer chains at relatively high speed but react with a neutralized carboxyl groups only very slowly. Thus, given carboxyl groups can either be applied for surface cross-linking or for neutralization, but not for both. Surface cross-linking agents known in the art preferably react with the chemical group carboxyl groups, they do not react with aliphatic groups.
[0013] In the process of making SAP particles, neutralization of free carboxyl groups typically comes first, before surface cross-linking takes place. Indeed, the neutralization step is often carried out in the very beginning of the process, before the monomers are polymerized and cross-linked to form the SAP. Such a process is named “pre-neutralization process”. Alternatively, the SAP can be neutralized during polymerization or after polymerization (”post-neutralization”). Furthermore, a combination of these alternatives is also possible.
[0014] The overall number of free carboxyl groups on the outer surface of the SAP particles is limited by the foregoing neutralization but it is believed that the free carboxyl groups are also not homogeneously distributed. Hence, it is currently difficult to obtain SAP particles with evenly distributed surface cross-linking. On the contrary, often SAP particles have regions of rather dense surface cross-linking, for example, with a relatively high number of surface cross-links, and regions of sparsely surface cross-linking. This inhomogeneity has a negative impact on the desired overall stiffness of the SAP particles.
[0015] In one embodiment, a method of making SAP particles with evenly distributed, homogenous surface cross-linking is provided.
[0016] Moreover, it is difficult to obtain SAP particles having both, sufficient stiffness to avoid gel blocking (sometimes referred to as “gel strength”) and sufficient swelling capacity (sometimes referred to as “gel volume”). Typically, increasing the gel strength of the SAP particles has a negative impact on the gel volume and vice versa.
[0017] In another embodiment, the surface cross-links are restricted to the very surface of the SAP particles in order to minimize the decrease in capacity. Thus, the core of the SAP particles should not be considerably affected and the additional cross-links introduced in the core should be kept to a minimum.
[0018] In another embodiment, a method of surface cross-linking SAP particles is provided, which can be carried out quickly to increase the efficiency of the method.
[0019] In another embodiment, a method of surface cross-linking SAP particles is provided, which can be carried out at moderate temperatures in order to reduce undesired side reactions, such as anhydride-formation and dimer cleavage.
SUMMARY OF THE INVENTION
[0020] In one embodiment, a method of surface cross-linking superabsorbent polymer particles is provided, said method comprising the steps of: [0021] a) providing superabsorbent polymer particles; [0022] b) providing a reactor comprising a drum; [0023] c) feeding the superabsorbent polymer particles into said drum; [0024] d) moving the superabsorbent polymer particles in the drum by rotating the drum around its longitudinal axis; [0025] e) the superabsorbent polymer particles are irradiated by the irradiation source) as the particles are moved within the drum; and [0026] f) collecting the superabsorbent polymer particles leaving the drum. The drum has a longitudinal axis and further has a cross-section. An irradiation source is provided such that the radiation emitted by the irradiation source is able to reach superabsorbent polymer particles within the drum and the irradiation source is able to emit UV radiation of a wavelength between about 100 nm and about 200 nm.
Air diaphragm pumps prove reliability.
Experience at Akzo Nobel led to the specification of over 100 Verder air diaphragm pumps for their new plant: 2.5 years later they are still maintenance free.
Akzo Nobel Inks use over one hundred Verderair air diaphragm pumps at their new ink production facility in Manchester. These pumps have been in continuous operation since they were installed two and half years ago and remain maintenance free. Staff at the plant have commented on the excellent performance of the units and are impressed with the level of technical support they have received from Verder.
Pumps in the same range were used at the Akzo Nobel previous site and performed so well that they were specified for the new plant.
They perform a variety of dosing and bulk transfer duties and handle solvents, process fluids and printing inks of varying viscosity.
VA40 pumps (1.5″) in Aluminium service the tank farm while VA25’s (1″) in Polypropylene are incorporated in the ink machines.
The pumps are ideally suited to conveying the flammable liquids used at the plant, as they are seal-less, leak-proof and present no electrical hazard.
In addition to the fixed units installed at the site, Akzo also make use of trolley-mounted pumps to off-load product from tankers.
With their efficient, low leakage air valves, these pumps have demonstrated the cost savings that Verderair products can achieve through reduced air consumption and a high displacement rate per stroke.
By standardising on these pumps, Akzo will benefit from lower life cycle costs.
The VA25, 40 and 50 models share a common air valve that requires no lubrication, comprises just nine parts and can be serviced without disconnecting the pump.
Other makes of air diaphragm pump typically use air valves that are specific to one pump size, feature many more parts and need servicing more regularly.
Popular options on gas analyser reduced in price
The new MX2100S multi-gas analyser from Cambridge Sensotec has been introduced for detection of a choice of the most popular gases: O2 - H2S - CO - Explosives - at a reduced cost
Cambridge Sensotec and Oldham Gas Detection announce a new version of the exisiting MX2100 multi-gas analyser. The new MX2100S is distinguished by its red colour and is identical to the MX2100: apart from the choice of gases. The MX2100S offers a choice of the most popular four gases needing measurement: O2 - H2S - CO - Explosives.
The customer can choose any combination of these four gases and select between 2 and 4 gases.
There is a new fixed price structure.
* MX2100S fitted with all four cells GBP500.
* MX2100S fitted with any three of the cells GBP464.
* MX2100S fitted with any two of the cells GBP428.
The price includes a complete unit with NiMH batteries, vibrator alarm plus charger pack.
These reduced list prices represent considerable savings over the existing MX2100 unit if purchased in the same configuration.
The MX2100 is still available, and is suitable for detection of a wider range of gases.
For further details please contact Cambridge Sensotec.
Multiple chemical sensitivity sufferer requests help
My daughter, 24, is dying and no one is able to help us. I had never heard of MCS until a few weeks ago, when my sister in Florida emailed me to say she had read something about MCS, that it sounded like Kim, my daughter, and I should check it out.
My daughter’s problems started over a dozen years ago, and have steadily evolved. Her first “episode” is of unknown origin. My husband and I came home after an evening out, and checked on Kim in bed. She looked like she had been beaten up. Her face was swollen and bruised and almost unrecognizable. We still have no idea what caused this. Seemed to be allergies. Over the next few years she would have repeated swellings in her face for seemingly no reason. The swelling would be so extreme that small blood vessels burst, resulting in bruising. She began to see an allergist for testing and subsequently shots. Mold, dust, etc, etc. High school was especially rough. One day the swelling started in school, and a counselor thought we were abusing Kim. Despite Kim’s protests that she was fine before she got to school, the counselor called the authorities. They wouldn’t believe that we had not harmed Kim, and sent someone over to visit us at home. The man was skeptical, despite our explanations and Kim’s. I finally ran my finger over the top of the hutch, rubbed the dust under Kim’s nose, and told him to watch. He said he’d never seen anything like that in his life–in front of his eyes Kim’s face began to swell and bruise. Her chin was always the most affected, and her lips. The rest of high school passed similarly; there was remodeling being done and the smell of the paint bothered her. This was also during the time that the local dump fumes were being carried into the building and the town was in an uproar. The dump was later capped and closed, but not before we had to remove Kim from school on a permanent basis and home school her for her senior year.
Over the next few years, after completing her allergy shots, the swelling and bruising ceased. Kim developed asthma instead. We could not figure out why, nor was there any rhyme or reason to her attacks. Exercise doesn’t affect her as one would expect, and she can just be sitting somewhere and suddenly have an attack. Doctors have tried to blame it on our pets, but we point out that she’s best at home. The animals are not affecting her. During one period of disability from work she spent a couple of months at home, exclusively surrounded by animals. She was fine until the day she left the house to go to the doctor for an appointment.
The past three years have been a nightmare, and getting progressively worse. I’m afraid she is going to die because no one understands or can help her.
She works for a supermarket chain, mid-management. She went months with no problems, then was moved to another store. Episode after episode followed–mostly just asthma attacks. It was decided that the ventilation system in the store might be harboring something that bothered her, so they cleaned it. She was fine after that. Kim was transferred to another store, and had more problems. The asthma attacks became worse, and Kim was taken out of the store a couple of dozen times via ambulance. She started to notice that the attacks were brought on by smells. Perfumes are the worst. Paint and just about anything else can trigger this as well.
Kim has been on so many medications for so long I don’t see how her system can take much more. This past December, during another hospitalization, she was on massive doses of IV steroids. After two weeks she was unable to walk. The doctors wanted to put her into a nursing home for rehab. I refused, and drove her to the Mayo Clinic in Florida, hoping to get her accepted as a patient. She was, but has yet to return. I knew it was the steroids that caused the muscle weakness; I was right. Getting her off the steroids saved her mobility.
She has had many close calls. She’ll leave work ok, and start to feel “funny” on the way home. She’s been stopped numerous times by law enforcement for erratic driving and ended up in the hospital. Her one goal during an attack is to get home. That’s where she feels safe. Luckily she’s never had an accident so far, but I’m sure the day will come. When she’s at the height of an attack she’s disoriented and confused.
Kim had a baby in July. During the pregnancy she had a few episodes, but stayed home for the most part. Now she’s back to work, and getting worse. Three weeks ago we went out to dinner, and a man had chest pains. The ambulance came and took him away, but not before he had vomited. The cleaning solution that the staff used to clean up caused Kim to have an attack. I could see she wasn’t going to last long, so we finished up dinner. We tried to get Kim outside to a car to take her to the hospital, and she collapsed. My husband and sister-in-law stabilized her while I called for an ambulance. (My husband and I are EMT’s, my sister-in-law is a Paramedic). Vital signs were not good, and she wasn’t moving any air. She was confused and disoriented. She got to the hospital, was kept for a few hours while she was observed, and released. She did have one more incident while at the hospital, which was triggered by the cleaning cart outside the door. Oxygen, breathing treatments, steroids. The usual.
Two weeks ago she called me from her car. She had been to an appointment with the baby, and the lady had perfume on. Kim was trying to get home. She assured me she could make it; she was two miles from the house at the most. I called home to alert my son (14) to look for her, and headed home. It took me 15 minutes to get home–no Kim. We managed to get her on her cell phone. She was lost. We told her to pull over and park. It was another 15 minutes before we found her. My husband called the police to help find her. We found her a few miles from home on a road that is not on the way home by any stretch of the imagination, parked as she had been instructed. She had no idea where she was or how she got there. I called the police to update them and order an ambulance. Kim was incoherent for the most part. Totally out of it. One of the officers had oxygen, so we hooked her up to that while we waited for the ambulance. When the ambulance arrived there was no time to wait for a paramedic intercept, they basically loaded her and went straight to the hospital. At the hospital Kim failed all the questions. Wrong birthdate, wrong day of the week, and so on. She kept insisting she was late for school. After some breathing treatments, IV steroids, and oxygen she was ok to return home.
Yesterday we received a phone call from her manager at work. He used her cell phone to contact us. He had found Kim wandering around, dazed and confused and wheezing. He admitted it seemed as though she was high on drugs, but he knows her condition and knew that wasn’t the case. He had called an ambulance. He told me when she was lying down, before the ambulance came, that her eyes rolled back in her head and she passed out for a few moments. According to the paramedic, her pulse was up, respirations were up, audible wheezing, blood sugar 64, and the scariest–pulse ox of 74. That’s darn close to dead. Kim was again very confused and incoherent during most of the long ambulance ride, but somewhat more “normal” by the time she got to the hospital. While at the hospital the lady in the next cubicle sprayed perfume. Kim was later admitted, and remains there. She’s on oxygen, breathing treatments, and IV steroids again. They’re saying she’s anemic. No surprise. And a bunch of other things. But I think they’re missing the whole concept here. “MCS” is a “figment of our imagination.” The pulmonologist who has been treating her for two years doesn’t seem to take this seriously. He thinks steroids are the answer. Steroids and drugs. Those will kill her themselves. To keep her breathing she requires massive doses of too many things.
She’s getting progressively worse. The memory goes. No rational thoughts during an attack. “I’m late for work. I’m late for school. I need to call my Mommy.” And so on. She has a baby to support, yet allowing her to work or drive is dangerous. She doesn’t recognize her own mother, me. (She still lives with us) The incidents are coming more often and are more severe each time. She’s going to die if we can’t find someone to help us!
What can I do, where can I go? HELP!
Heidi Evans
Evans Group at Keller Williams
275 Greenwood Avenue
Bethel, Connecticut 06801 USA
203-744-7355
www.ctrealtor.net
Nitrogen unbound: new reaction breaks strong chemical link - Science news: this week
For almost a century, industrial chemists have had to rely on hellishly high temperatures and gas pressures to cleave the tenacious chemical bond that holds together each two-atom nitrogen molecule. That done, chemists can use the nitrogen from the atmosphere to make fertilizers, explosives, and other modern products. Now, researchers have devised a way to split nitrogen molecules under milder conditions within liquids, a step that may inaugurate a variety of energy-efficient techniques for creating nitrogen-bearing substances.
The triple bond between a nitrogen molecule’s atoms is one of the strongest chemical attractions around. In nature, only the megavoltage of a lightning bolt and the potent enzymes in some soil bacteria and fungi can split nitrogen molecules, says chemist Paul J. Chirik of Cornell University.
It was early in the last century that the German chemists Fritz Haber and Carl Bosch invented and developed an economic method for splitting nitrogen molecules, a feat for which they each received a Nobel prize. Today, manufacturers use the Haber-Bosch process to generate more than 100 million tons of ammonia annually for the chemical and fertilizer industries.
Chemists have long sought substitutes for the Haber-Bosch process, which works most efficiently at temperatures between 400[degrees]C and 500[degrees]C and at pressures around 400 times that of the atmosphere at sea level. Chirik and his colleagues now propose one less-extreme alternative.
The key to the new reaction is a subtle modification to a zirconium-bearing substance that includes two copies of a bulky chemical group–called a methylated eyelopentadienyl–that’s based on a five-atom ring of carbon. With a methyl group, or [CH.sub.3], attached to every carbon atom in these rings, the molecules are so large that they can attach to only one end of a nitrogen molecule.
Chirik and his colleagues found that when one methyl group was removed from each ring, the complex was just the right size to snuggle up to both atoms in a nitrogen molecule and give an electron to each atom. This double donation, which can take place in an organic solvent at 100[degrees]C and atmospheric pressure, disrupts the triple bond. Further reactions in the same solution then finish the job of splitting the nitrogen molecules and adding hydrogen atoms to make ammonia. Chirik’s team reports its feat in the Feb. 5 Nature.
The relative ease and possible energy efficiency of the new nitrogen-splitting technique may still not be enough to displace the Haber-Bosch process, says Michael D. Fryzuk, a chemist at the University of British Columbia in Vancouver. Many companies have large investments tied up in equipment to carry out that operation.
Chirik agrees but notes that the new, liquid-based technique may enable researchers to develop energy-efficient methods for making nitrogen-containing ingredients that go into pharmaceuticals, dyes, and other industrial chemicals.
Chemical Demilitarization: Public Policy Aspects
Chemical Demilitarization: Public Policy Aspects, Al Mauroni, Praeger Pulishers, April 2003.
The U.S. Army has a long history in chemical demilitarization, dating back to the activities of the Chemical Warfare Service in World War I. Though the practices have changed over the decades, they were always in keeping with the practices of industry at the time.
Al Mauroni’s discourse on chemical demilitarization is limited to the U.S. Army Chemical Corps’s experience with incineration (from the 1970s to the present). His main focus is on how a straightforward endeavor ended up as a hotly debated $24-billion, 25-year project and ultimately what lessons chemical soldiers may gain from this experience.
The book is replete with references to public laws and is one of the most detailed accounts of U.S. chemical-demilitarization activities. Mr. Mauroni sees the evolution of the demilitarization program as three distinct bands: Army-funded to destroy “leakers,” Department of Defense (DOD)-funded to destroy obsolete chemical weapons to make room for binary weapons, and the current program to destroy all chemical weapons to meet U.S. disarmament treaty obligations.
His accounts are highly detailed and show a program embroiled with political conflicts. It is also a testament to the responsiveness of the U.S. Army to communities and groups. His analysis is critical of the political machinery at work on national projects and the inability of the Chemical Corps to affect public policy.
The book concludes that the policy lessons from the chemical demilitarization program are educational to other chemical- and biological-related issues (such as the anthrax vaccination program). A cultural change within the Army and greater teamwork within DOD is recommended.
Chemical Demilitarization is a valuable historical study and a must-read reference on the subject. It is also invaluable for understanding public-policy processes that affect the Chemical Corps
Keep out: certain chemical preservatives are unwelcome contaminants in the mulch and wood fuel markets
Markets for recycled construction and demolition (C&D) wood include mulch or wood fuel. Both options minimize landfill disposal and serve as substitutes for new wood materials.
However, the presence of preservatives within C&D scrap wood greatly degrades the quality and thereby limits the potential of this valuable material.
PROBLEM PRESERVATIVES. Preservatives are added to wood intended for outdoor applications (e.g. fences, decks, docks, etc.) to provide protection against fungi and termites. Treated wood can also be used indoors in areas where the wood is in contact with the foundation of a building or in high termite hazard areas. The amount of chemical added to wood varies depending upon its intended use. The amount added, or “retention level,” is described in pounds of chemical added per cubic foot of wood (PCF).
Preservative-treated wood can be broadly separated into two general categories–oil-borne preservatives and waterborne preservatives. Oil-borne preservatives use an oil or organic solvent as the carrier during the pressure treatment process, whereas waterborne preservatives are dissolved in water that then serves as the carrier.
Oil-borne preservatives, such as creosote and pentachlorophenol, are traditionally used for heavy-duty industrial applications, such as utility poles and railroad ties. Because of their large dimensions, wood treated with oil-borne preservatives can be readily identified and removed from the recycling stream.
Waterborne preservatives, on the other hand, are used to treat not only industrial products but also to treat products used in residential areas, such as lumber, timbers and plywood. As a result, this portion of treated wood can be easily commingled during disposal with wood that is untreated. One primary challenge when recycling C&D wood is thus identifying and sorting out preservative-treated lumber, timbers and plywood.
Currently, several different types of preservatives are used for treating lumber, timber and plywood. The most common of these preservatives include CCA, which contains chromium, copper and arsenic; ACQ, which contains copper; CBA, which contains copper and boron; ACZA, which contains copper, zinc and arsenic; and borate-treated wood, which contains boron. Among the elements within the common wood preservatives, arsenic is characterized by the strictest regulatory standards, chromium and copper are the next strictest, followed by boron and zinc.
For example, soil clean-up target levels (SCTL, which are typically used as a guideline to determine if a recycled material can be land applied, such as in the case of mulch) are generally lowest for arsenic by roughly a factor of 100 relative to that for copper.
If the goal is to meet Florida SCTL residential guidelines for land application of recycled materials, the amount of arsenic-treated wood (either as CCA or ACZA) that can be commingled with untreated wood must be less than 0.05 percent, which is less than 1 pound of arsenic-treated wood per ton of wood processed.
For copper-treated wood (either as ACQ or CBA) the guidelines are less strict, permitting for up to 2 percent to 3 percent non-arsenical copper-treated wood, or between 45 to 60 pounds of copper-treated wood per ton of wood processed. Because of the high SCTLs for boron, there are no limits on the amount of boron-treated wood.
Because of the strict regulatory levels for arsenic, compliance with the regulatory guidelines is difficult. We estimate that at the Florida recycling facilities we have observed since 1996, the amount of arsenic-treated wood in incoming loads ranges from 6 percent to 30 percent.
Identifying arsenic-treated wood is not always easy. This dilemma has led wood recyclers to ask, “How can C&D wood be recycled while minimizing contamination from preservative-treated wood?”
This question is being addressed through a governmental, university and industry collaborative effort funded through the Florida Department of Environmental Protection (FDEP) Innovative Recycling Grants Program. The fund recipient was the town of Medley in Dade County, Fla. Medley has facilitated the cooperation of University of Miami and University of Florida researchers to work with Florida Wood Recycling to document the efficiency of different sorting methods to identify treated wood within C&D scrap wood.
THE SORTING SOLUTION. This study has documented that a multi-tiered approach is best for identifying preservative-treated wood debris. The first line of defense is to inspect loads as they enter the facility.
Florida Wood Recycling, a mid-sized recycling facility located in Medley, accepts yard debris and source separated C&D wood (C&D wood that has not been commingled to a great extent with other components of C&D debris). As part of this stud> the facility has initiated the processing of commingled C&D debris containing wood (a.k.a. commingled C&D wood).
For the source-separated C&D wood, Florida Wood Recycling inspects each load as it enters the facility. Inspection has been based upon visual identification and knowledge concerning the origin of the wood. Visual identification relied upon many different factors, including looking at the load to evaluate if it contains remnants of an exterior structure, such as portions of a fence or a dock, indicating it likely contains treated wood.
Other criteria include observing the general dimensions and color of the wood and looking for end tags. Wood characterized by very large dimensions had likely been used for industrial applications and are almost exclusively treated and should not be recycled as mulch. Examples include railroad ties that are 8 inches by 8 inches by 3 feet or more and utility poles (typically 1 foot in diameter or more).
In some cases, landscape timbers that are also typically treated can be identified by their shape, which in many cases is characterized by rounded edges for decorative purposes.
End tags provide another important clue as to whether or not wood within a load is treated. End tags typically list the type of chemical contained in the wood.
In some cases a load containing treated wood can be identified by observing the color of the wood, which, if not treated, typically has a light yellow hue. If treated with a copper containing preservative (e.g. ACQ, CBA, CCA, and ACZA) the wood would be characterized by an olive color that is faint for lower retention level wood and very distinct for wood treated at high retention levels.
If the wood is incised, it is also treated. Incising is a process by which uniform cuts are made in the wood to improve the penetration of the preservative during treatment. Incising is typically used for denser wood species, such as Douglas Fir, which is primarily used in the Western United States.
Close observation of incoming loads of source-separated wood has resulted in notably “clean” wood at Florida Wood Recycling. Of 10 tons of wood sorted, only 100 pounds (0.5 percent) was treated. This fraction of treated wood is considered to be exceptionally good quality at the first line of defense. After the initial inspection at Florida Wood Recycling, the wood is further evaluated once it is unloaded, after it has been moved to the mulch supply pile and once it is on its way to be chipped.
The study has also shown it is much more difficult to control the quality of the incoming scrap wood stream if the wood is commingled with other C&D material, such as concrete, drywall, tile and the like. Commingled C&D loads at Florida Wood Recycling are first inspected upon arrival and the wood is then sorted out using a picking line.
Of nine tons of wood inspected from the picking line, almost 1,400 pounds (or 8 percent) was treated. Of the 1,400 pounds, about 10 percent was treated with creosote, 67 percent was treated with CCA, and 23 percent was treated with copper-based alternatives. The net fraction treated with CCA was 5 percent. Although some plywood was observed to have been CCA-treated, the vast majority of the CCA-treated wood was in the form of lumber and timbers.
TOOLS OF THE TRADE. Because of the difficulty of visually inspecting commingled C&D materials for the presence of CCA-treated wood, removal of arsenic-treated wood at C&D recycling facilities accepting commingled C&D debris will thus depend more heavily upon “back-end” inspection–inspection after the wood is sorted out on a picking line.
However, visually identifying preservative treatment for wood sorted on a picking line is much more difficult than for source-separated C&D scrap wood. The difficulties are two-fold.
Produced-water chemical treatments enable environmental compliance: many chemical types can produce similar results
There are numerous misconceptions regarding the chemical treatment of oilfield produced water. This article helps overcome these by providing a general understanding of specialty chemical usage and by reviewing the chemistry of produced water. It discusses the chemicals used to modify these chemistries to overcome common oil production problems. Specific attention is given to emulsion-breaking, water-clarifying chemistries, the methods used to determine treat-water chemistries and trends in the produced water treatment.
INTRODUCTION
Oilfield specialty chemical companies treat produced water and often must overcome a negative reputation to demonstrate their value as a technical service provider. Most chemical companies aggravate this negative view by clouding their work in jargon and subterfuge in an attempt to prevent their competition from profiting from a technical advantage.
This article presents an overview of produced-water chemical treatment, while protecting intellectual property, and represents the authors’ views. As in all fields of chemistry, there are different data interpretations and many theories for the chemical mechanisms. The authors seeks to generate discussion of these mechanisms, and a more favorable understanding of the difficulties in designing effective chemical treatment programs. The article is limited to crude oil production chemistries after well completion.
There are three basic classes of chemistry used in the oil field: solids control, corrosion control, and demulsification/ clarification. For ease of presentation, these are discussed individually. Each class of chemistry, and the subclasses, has an effect on all the other programs. A single chemical can have effects in more than one class, and those effects can be positive or negative
SOLIDS CONTROL
Solid control chemistries include scale inhibitors, paraffin inhibitors and dispersants, asphaltene inhibitors and dispersants, hydrate inhibitors, biocides in certain applications, clarifiers in certain applications, sand dispersants and wetting agents. This chemical class includes those used in “flow assurance.” They are divided into four types:
1. Those that chelate, or sequester, the component molecules prior to nucleation
2. Those that modify crystal growth
3. Those that prevent nucleation
4. Those that disperse solids and prevent them from accumulating.
Chelation. Chelation is reserved for scale inhibition. It is described by an equilibrium reaction between a metal ion and a complexing agent. Chelation reactions form more than one bond between the metal and a molecule of the complexing agent. Chelation results in a ring structure incorporating the metal ion. The typical chelating chemistry is shown in Fig. 1, ethylenediaminetetraacetic acid (EDTA). (1)
[FIGURE 1 OMITTED]
Crystal growth modification and nucleation prevention. Crystal growth modification is a threshold process, whereby a small number of growth inhibitor molecules can slow or prevent the growth of a number of crystals. Crystal growth inhibitors exploit the ability of certain molecules to replace a densely packed lattice of a crystal with a molecule that prevents close association. This is a heterogeneous effect, i.e. it affects the ions or molecules as they adhere to the lattice structure. Nucleation inhibition, on the other hand, results from a homogenous threshold effect at the beginning of crystal growth, as in Fig. 2. (2)
[FIGURE 2 OMITTED]
Many papers attempt to determine the effect of various chemistry types on scale deposition, and debate the method of effect. (3) Chemistries are either oligomers of phosphonates or low molecular weight, free radical addition polymers. Although specific chemistries are subject to IP constraints, a Google search delivered the following structures from the Web page of Heriot-Watt University in Great Britain. (4) Typical chemistries are phosphonates, and polymers, Figs. 3 and 4.
[FIGURES 3-4 OMITTED]
It is generally accepted that phosphonates function by crystal growth modification and require a slightly higher dosage, but are more forgiving in application, while polymers can function either way, but require significantly more care in application. These result in more failures in polymer programs, but a lower cost, if ideally applied.
Another application of crystal modification and nucleation inhibition for solids control is for the prevention of gas hydrate blockages. Kinetic hydrate inhibitors (KHI) prevent or delay crystal nucleation, and are effective with or without an oil phase. Anti-agglomerate hydrate inhibitors (AAHI) are crystal modifiers, and are effective in an oil phase. Both types of inhibitors are low-dosage hydrate inhibitors. (5) The KHI’s are polymers such as poly(N-vinylcaprolactum), Fig. 5. The AAHIs are quaternary ammonium or phosphonium salts, Fig. 6. (6)
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Paraffins are aliphatic hydrocarbon waxes present in most crude oils. These will precipitate from a crude oil and deposit in production risers, subsea tiebacks, or any other production tubular or transportation pipeline where the temperature falls below the wax appearance temperature of the crude. Paraffin inhibitors function by interfering with the bonding of aliphatic wax molecules to each other. They are generally branched chain type polymers, Fig. 7. (7)
[FIGURE 7 OMITTED]
Asphaltenes are a solubility class within crude oil that are soluble in aromatics, but insoluble in aliphatics. They are considered large aromatic agglomerates composed of heterocyclic rings. Asphaltenes are thought to be held in solution by naturally occurring petroleum resins that adhere to the outer surface of the asphaltene agglomerate. Asphaltenes precipitate when these resins are disrupted. Asphaltene inhibitors are thus chemistries that either prevent the resins from being removed or function in the same manner as these resins. (7)
Dispersants. Dispersants are the most common form of oilfield chemistry. The surfactant industry is vast, and oil field chemical companies are just a small part of that spectrum. Many of the surfactants manufactured and used in other industries are also used in the oil field. Many of the chemistries manufactured by oilfield chemical companies are similar to surfactant materials used in other industries. A minimal review of the different surfactant types used would entail a much longer presentation. Therefore, a very general discussion with some illustrative examples is all that can be attempted in this setting.
Surfactants function by modifying the chemical interaction of liquids at a surface boundary. Surfactants form the majority of oilfield chemistries. Dispersants are surfactants that prevent the agglomeration and adherence of solids. Based on this, dispersants have efficacy in all oilfield chemistry. They are used in the manufacture of chemistries as well as in formulations of different raw materials throughout product lines. They are used in corrosion inhibition to prevent under-deposit corrosion. They are used to prevent solids from hindering production, whether the solids are from scale, paraffin or asphaltenes. They are also used to treat emulsions related to solids formation or accumulation. Many of the water clarification and emulsion problems in the oil field are
a result of the introduction of these materials in the process, either in drilling, workover or production. (8)
Some commonly used dispersants are sulfonic acids and their salts (Fig. 8), phenolic ethoxylates (Fig. 9), ethoxylated alcohols (Fig. 10), and quaternary ammonium compounds, which are discussed under corrosion control.
[FIGURES 8-10 OMITTED]
CORROSION CONTROL
Corrosion control chemistries function by preventing solids deposition, passivation, a combination of solids prevention and passivation, or by gas scavenging. The mechanisms of these effects can be accomplished by numerous chemistry types. It should also be noted that gas scavenging may be used for environmental or health and safety concerns as well as corrosion.
The molecule types used have an aliphatic tail and a portion that will couple with the corroding metal. This creates a layer of chemical, which prevents electron transfer and interrupts the corrosion cell. Imidazoline is an example, Fig. 11.
[FIGURE 11 OMITTED]
In addition, some chemistries function as both passivating agents and solids dispersants. Examples of this chemistry are the quaternary ammonium chlorides, Fig. 12.
[FIGURE 12 OMITTED]
There are many other corrosion control chemistries. The latest research is focused around making more environmentally friendly molecules for use in sensitive environments. (9)