Bigneat filters developed to meet environmental concerns

In response to customer concerns over personnel safety and the environment (the disposal of exhausted carbon in landfill sites), ductless fume cabinet specialist Bigneat decided several years ago to develop an in-house range of filters for the adsorption of a variety of chemical species . Many commercial filters using impregnated carbons contain chemicals that are undesirable from personnel safety and environmental viewpoints. Hexavalent chromium, in the form of potassium dichromate, is a good impregnant for acid-retaining carbons, but is also toxic, corrosive to skin and eyes, and carcinogenic. Copper (II) chloride, used to treat carbons for ammonia, amine and other alkaline species retention, presents additional hazards to health and to the environment.

Development work for these filters was carried out in the laboratories of the department of applied chemistry at the University of Portsmouth, which has 40 years experience in the field of porous carbon solids.

Development was carried out to ensure that:

• filters had to give high retention capacity;

• chemical treatments for enhanced acid or alkali retention had to be non-hazardous to operatives undertaking the carbon impregnation work and to the environment when exhausted carbon is sent for landfill;

• when used in conjunction with ductless fume hoods, filter performance had to conform to the requirements of internationally recognised test procedures, such as AFNOR and BS 7989:2001;

• rigorous quality control procedures had to be developed for all stages of filter production, from activated carbon manufacture through to the performance of the final product.