Modelling Thiocyanate Adsorption onto Surfactant-Modified Coir Pith, an Agricultural Solid ‘Waste’

Thiocyanate (SCN−) is used in many industrial processes and is found in industrial wastewaters. Adsorptive removal of thiocyanate by surfactant-modified coir pith, an unwanted byproduct of coir fibre industry was studied. Cationic surfactant, hexadecyltrimethylammonium bromide was used as modifier. Optimum pH for maximum adsorption of SCN− was found to be 2.0. Langmuir, Freundlich and Dubinin Radushkevich (D-R) isotherms were used to model the adsorption equilibrium data and the system followed all the three isotherms and the adsorption capacity of the adsorbent was found to be 8.6 mg g−1. Kinetic studies show that the adsorption obeyed second order. Desorption studies showed that upto 90% recovery of SCN− from the spent adsorbent was feasible. Effect of foreign anions on the adsorption of SCN− was also examined.