Equilibrium and Kinetics Study for Adsorption of 2,4-Dinitrophenol from Aqueous Solutions by Using Cucumis Sativus Peels and Kidney Bean Shells as New Low-cost Adsorbents

Abstract

Main goal of this study was to investigate the adsorptive potential of 2,4-Dinitrophenol (2,4-DNP) from aqueous solutions onto Cucumis Sativus peels (CSPs) and kidney bean shells (KBS). These adsorbents were used first time to adsorb 2,4-DNP from aqueous solutions. Both the adsorbents were pretreated with 37% HCl to enhance the 2,4-DNP uptake ability. Adsorption parameters such as influence of pH, adsorbent dose, contact time and initial concentration of 2,4-DNP were determined. Maximum % adsorption of 2,4-DNP take place, at pH of 4.0, initial concentration of 40 mg/L, contact time of 120 min and adsorbent dose of 100 mg which was 93.13% for Cucumis sativus peels and 99.02% for kidney bean shells. Kidney bean shells was found to be more efficient in adsorption of 2,4-DNP from aqueous solutions as compared to Cucumis sativus peels. Kinetic study indicated that the adsorption of 2,4-DNP was best followed by pseudo second order kinetic model. Results show that the rate of adsorption was better controlled by intra-particle diffusion as well as film diffusion. It was accomplished that the adsorption of 2,4-DNP onto Cucumis sativus peels and kidney bean shells was best defined by Langmuir adsorption model and maximum adsorption capacities of both the adsorbents were obtained by Langmuir equation which were 47.61 mg/g for Cucumis sativus peels and 52.63 mg/g for kidney bean shells. It is concluded that agricultural waste such as Cucumis sativus peels and kidney bean shells can be used as low-cost adsorbents for adsorption of 2,4-DNP from aqueous solution at large scale in replacement of high cost adsorbents.