Absorbing matters
April 1st 2006 Adsorbent or absorbent? Gary Wiley, managing director of Safety Unlimited, explains the difference and looks at the products available to deal with different kinds of spills
Few people appreciate that there are in fact both absorbents and adsorbents. In the main, with a few notable exceptions the majority of commercially available products in today's market are adsorbents. These rely on surface tension to do their work and release the adsorbed liquid when subject to pressure such as squeezing or wringing. Meltblown products such as pads, rolls, wipers, socks and cushions behave in this way and as a result are classed as such.
An absorbent is distinguished by the fact that it will increase in size by taking the liquid through its cellular structure.
Release is much slower and requires considerable amounts of energy such as heat and pressure. Some manufacturers combine the properties of adsorbents and absorbents making socks and cushions that are fast wicking and have a greater capacity of absorption. These tend to be general-purpose products, having the ability to absorb and gel aqueous liquids as well as adsorbing oils and mild chemicals.
Most spill kits and adsorbents are specified in one way or another to allow ease of selection.
Oil Only: This means that the product displays hydrophobic/oleophilic properties whereby it repels water or aqueous products, such as acids and alkalis, but adsorbs oil-based products. These products can float on water and adsorb any oils found on the surface. They are particularly good for use outside in wet conditions, they are the adsorbent of choice for oil spill on water or in a wet environment. They can be stored outside in containers with little fear of deterioration in their performance.
Most oil-only products (though not all) are manufactured from meltblown polypropylene and have a high capacity for low weight. A typical 400g adsorbent pad 48 x 43cm, usually packed 100 to a pack will adsorb about 1L of oil. Oil-only products supplied by UK manufacturers tend in the main to be white or blue.
General Purpose (Non hazardous): Some manufacturers make their general purpose products from a combination of materials. Cellulose, polypropylene and polyester are commonplace and, as a result, it is important that these products are only used on non-aggressive chemicals.
Cellulosic materials used on oxidising agents like Hydrogen Peroxide, for example, can cause excessive heat and combustion. General purpose, or maintenance products as they are sometimes called, tend to be grey in colour as they are used in factory workshops or maintenance shops where the floor is oily or dirty.
Chemical (Hazchem): In the main pads, socks and rolls are manufactured from polypropylene because of its inert nature. Most UK manufacturers produce these in yellow. There are, of course, many other types of loose adsorbents and absorbents within the chemical range, as well as neutralising products many of which need to be specified and used by trained personnel with the benefit of expert chemical advice and guidance.
Spill Kits follow the same approach as the absorbents that form part of their inventory in that they are designated Oil Only, General Purpose (non Hazardous) or Chemical (Hazchem). These are emergency kits, perhaps thought of as being first aid kits for spills, which contain a variety of products that have been specified to handle a volume of spilled liquid which falls into one of the three categories details above. Depending on the volume of liquid likely to be spilled and the conditions, kits are packaged in such a way as to provide suitable containers, kit bags or rip-open, single use.
Beware the kit that includes PPE.
Personal Protective Equipment should be provided on an individual basis, the user should be trained in its use and have been fit tested in the case of masks. Kits that have been purchased and deployed without suitable risk assessment, containing PPE for general use, by anyone, where no risk assessment has taken place or been recorded put you at risk of personal injury claims.
Legislation:
Why buy spill products? Very simply legislation is slanted against you if you undertake any processes that use, or cause you to store, any liquids that are considered to be pollutants.
The UK's environment agencies the EA, SEPA and EHS (Northern Ireland) have onerous powers and if, as a result of spillage, they can prove negligence they have the ability to fine individuals as well as companies.
Everyone now has a duty of care to the environment and it is your responsibility to prove that you have not knowingly, or should have known that you could, pollute. The only liquid that is allowed to enter a surface drain, a drain that ends up in a river or stream, is rainwater. Spills entering the ground which have the potential to enter sources of drinking water or aquifers can result in immediate fines. Remember fines are against the individual and are often thousands of pounds, depending on circumstances.
Health and Safety legislation also plays its part when spill products are being specified since duty of care raises its head here also. It is important therefore that no company deploys spill kits or PPE without being able to demonstrate that adequate training and simulations have been carried out to ensure the competence of the work force and spill responders who would be using the equipment.
Bulletin
Established in 1974, Safety Unlimited manufactures environmental spill prevention products.
Its core business is a range of products for the safe storage and containment of highly flammable liquids and other hazardous liquids.
The company is a UK importer and distributor for the Protectoseal Co (USA) range of safety cans for safe storage, dispensing and disposal of solvents and chemicals.
The company will be exhibiting at this year’s Safety & Health Expo – Stand E80/81.
Safety & Health Expo E80/E81 More articles from Safety Unlimited: | 
