Comparative study of malathion removal from aqueous solution by agricultural and commercial adsorbents

Massive use of an insecticide such as malathion has caused a setback to the environment and also has increased potential risk to human health as it is an endocrine disruptor chemical. This work was carried out to study the removal of malathion from aqueous solution using adsorbents, such as rice husk (RH) activated rice husk (ARH) and commercially available powdered activated carbon (PAC). The effect of system variables such as pH, contact time, initial concentration and adsorbent dose were investigated in a batch process. The adsorption equilibria of the system at constant temperature were modeled by Langmuir, Freundlich and Temkin isotherms. Langmuir model showed excellent correlation with experimental data. For kinetic study, the adsorption process fitted the pseudo-second order model. Maximum malathion removal efficiency of 53, 87 and 94% were obtained with RH, ARH and PAC, respectively, under optimum conditions.