Rice husk as a low cost nanosorbent for 2,4-dichlorophenoxyacetic acid removal from aqueous solutions

Rice husk is an enormously generated agroindustrial waste which causes serious environmental pollution. The aim of the current study is to constructively utilize rice husk nanosorbents (n-RH) for the biosorptive removal of 2,4-D from aqueous solution. The combined effect of the important process parameters such as initial pH, temperature, n-RH dosage, initial 2,4-D concentration and contact time on 2,4-D percentage removal was evaluated using five-level Box Benhken design (BBD). Maximum 2,4-D removal (%) of about 96.87% was perceived at pH of 5.0, temperature 30 degrees C, n-RH dosage of 1.5 gl(-1), initial 2,4-D concentration of 100 mgl(-1) and contact time of 60min. The n-RH experimental data was fitted to the equilibrium and kinetic models which revealed a heterogenous and chemisorption mode of adsorption. A highest 2,4-D adsorption capacity of 76.92 mg g(-1) was achieved with the help of n-RH adsorbent, while the spontaneous and endothermic nature of the adsorption process was revealed via thermodynamic studies. The FT-IR results revealed the presence of amino, carbonyl, hydroxyl and silica functional groups on the surface of the n-RH biosorbent confirming the kinetic result. Thus, the reported n-RH agro-industrial waste biosorbent could be promising for pesticide removal from contaminated aqueous systems. (C) 2016 Elsevier B.V. All rights reserved.