Biomimetic lipophilic activated carbon for enhanced removal of triclosan from water

Triclosan, an antimicrobial micro-pollutant with a high bio-accumulation potential represented by its high octanol-water partition coefficient (log K_ow) of 4.76 is commonly encountered in water and wastewater worldwide. The present study focuses on biomimetic surface modification of commercial activated carbon (PAC) with long chain fatty acid namely docosahexaenoic acid (DHA) resulting in enhanced affinity for the hydrophobic micro-pollutant; triclosan (TCS). The sorption process of the resulting modified lipophilic carbon (PAC_M) was investigated for the effect of various experimental conditions. The Freundlich isotherm and pseudo-second-order kinetic models had a better fit. PAC_M exhibited the maximum adsorption capacity of 395.2 mg g^-1 in contrast to 71.5 mg g^-1 obtained for PAC. The surface morphology in terms of surface area, surface acidity, pore size, contact angle, etc. and were also evaluated. The contact angle of 134.3° obtained for PAC_M confirmed its highly hydrophobic nature. The efficacy of PAC_M was also evaluated using real-world secondary treated effluent containing triclosan confirming its applicability for tertiary treatment of wastewater. The study established that the biomimetic approach of creating lipid-like sites on the carbon surface results in the enhanced removal of lipophilic micro-pollutants. It can also be utilized for the removal and recovery of a wide variety of other organic micro-pollutants.