WATER TREATMENT frameworks and stringent quality control testing .
Understanding antifoams
Antifoams , especially the most efficient variants , are derived from a unique molecule called silicone , which is not unlike that used in bathroom sealants and in kitchen squeegee utensils . The make-up of silicone is a sand derived –{ Si-O- Si } - silicate backbone , which is very long and flexible , with hydrophobic organic groups attached to the silicon atoms . This structure allows for extremely low surface tension , giving silicone a spreading and flow character across most surfaces ; with a surface tension of just 21 mN / m , it can even wet water . This instant wetting effect is key to the swift quenching of foam bubbles as the molecule can transport into the bubble wall , where the bubble-pricking action takes place . In addition to the silicone , many antifoams are compounded with another sand-derived additive known as fumed or precipitated silica , that when applied correctly , acts synergistically with the silicone to enhance further this bubblepricking phenomena .
Silicone v . non-silicone
Both silicone and non-silicone antifoams are widely used in water treatment , but silicone ’ s speed of action , partnered with an excellent longevity , even at the lowest dosage rates , allows this chemistry to be the most economical in use . Unlike many non-silicone products , silicones function effectively across the broadest temperature range , in both water-containing and waterfree processes . They are easy-to-use , bright , white pumpable liquids , being fully dispersible in water , and their odourless and tasteless character eliminates any chance of final product taint .
One of the great advantages of silicone-based defoamers is their versatility , which means they can be used across the broadest sphere of applications . Their unique physicochemical foam-destroying mechanism means they are just as likely to be found functioning as an antifoam , suppressing the actual formation of foam , as they are as a defoamer , destroying foam that is already in situ . Despite the efficiency of silicone antifoams , there are some applications where non-silicone remains the go-to chemistry . In starch processing for instance , they are the ideal solution , but it is recommended that the cost efficiencies of a silicone solution should be explored in the first instance .
What to look for
Antifoams have become a vital and major element in maintaining the efficient process of treating and cleaning foam-susceptible wastewater streams . A carefully selected antifoam will ensure quick and effective foam
knock-down without impacting the effectiveness of other process aids in the system , such as flocculants and coagulants . The elimination of foam leads to significant improvements in plant throughput , ensuring maximum utility of vessels , pumps and valves which in turn leads to a cleaner , safer workplace . While the range of antifoams and their role in different applications can appear daunting , but with the guidance of the right supplier you will find the product that fits your needs and quenches foaming problems in your water treatment processes . Look for a supplier who is s constantly investing in R & D , has its own fully equipped R & D and analytical laboratories and also invests heavily in new formulations , such as Airedale ’ s distribution partner , BRB International , which is the largest independent silicone formulator in the world . Suppliers should also offer customer site visits to diagnose the primary cause of the foam , then advise them about the optimum solution to counter the issue in the most cost-effective manner . These may entail just a simple pump-dosing arrangement or could amount to a bespoke system requiring foam-measurement probes , continuous dilution and closed-loop ring-main dosing . •
J j
Daniel Marr
GROUP COO
AIREDALE CHEMICAL daniel . marr @ airedalechemical . com www . airedalechemical . com