Quaternary ammonium compounds (QACs) are widely used in household and industrial products such as cosmetic and cleaning products. The most commonly used QACs are benzalkonium chlorides (BACs). Benzalkonium chlorides are frequently found to be used in many household disinfection products. They also have been utilized in many industries (food industries, textile industries, paper industries, oil and gas industries, plastic industries, etc.) to prevent biofouling in the pipelines and product deterioration. These compounds are highly toxic and widely detected in the water surface and sediment. Several processes have been proposed to remove these BACs during water treatment processes, and adsorption is one option. In this study, we investigated the fundamental mechanism of BACs adsorption to better understand the removal of BACs in water treatment. Especially, the adsorption characteristics of representative substances of BACs, benzyl dimethyl dodecyl ammonium chloride (BDDA) and benzyl dimethyl tetradecyl ammonium chloride (BDTA) using powdered activated carbon (PAC) were investigated by examining the effects of initial concentration of BACs (50~ 450 mg/L), initial pH, contact time, and temperature on the adsorption of BACs. The results showed that the adsorption kinetics followed the pseudo-second order kinetics (qe of 400 mg/g and k2 of 2.72 × 10-3 mg-1 min-1). The BAC adsorption showed the highest removal of rate at neutral pH (90% removal within 15 min). BACs adsorption isotherms of BACs were well fitted to Langmuir isotherm (q0 = 357.14 mg/g, KL: 4.54 L/mg). The adsorption rate of BACs at 4oC (1.17 × 10-3 mg-1 min-1) was 14% less than in 25oC (2.73 × 10-3 mg-1 min-1). In the presence of humic acid (2 and 5 mg DOC/L), the adsorption of BACs were inhibited, but higher concentration of DOC (10 mg/L) enhanced the removal of BACs, indicating that the competative adsorption occurs. Our results imply that activated carbon can be a promising prospect in terms of removal efficiency of BACs.

Adsorption characteristics of benzalkonium chloride (BAC) by activated carbon

255th National Meeting (2018)

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