Removal of nitrobenzene from aqueous solution by a novel lipoid adsorption material (LAM)

Abstract

In this study, a novel adsorbent referred to as a lipoid adsorption material (LAM) was synthesized with a hydrophobic nucleolus (triolein) and hydrophilic membrane structure (polyamide). The LAM was applied to the adsorption and removal of nitrobenzene from aqueous systems. Experiments were carried out to investigate the adsorption behavior of nitrobenzene on LAM, including the development of adsorption isotherms, the determination of adsorption kinetics, and to explore the influence of adsorbent dosage, contact time, temperature and the initial concentration of nitrobenzene on adsorption. The performance of LAM was compared with equal amounts of granular activated carbon (GAC) for adsorption. The adsorption isotherms for LAM were found to be described by the Linear equation, while the adsorption isotherms for granular activated carbon (GAC) were described by the Freundlich equation. Results indicated that the adsorption of nitrobenzene by LAM occurred mainly due to the partition function caused by the triolein nucleolus. Two kinetics models, pseudo-first-order and pseudo-second-order models were used to fit the experimental data for LAM adsorption. By comparing the correlation coefficients, it was found that the pseudo-first-order model was most suitable to describe the adsorption of nitrobenzene on LAM. The results also indicated that the factors that affect the adsorption rate would be either the nitrobenzene concentration or the character of the adsorbent. Thermodynamic calculations indicated that the adsorption of nitrobenzene on LAM was spontaneous and was an exothermic reaction. With an initial nitrobenzene concentration of 200μgl−1, an equilibrium concentration was reached within 8h using LAM as an adsorbent and the average removal efficiency was 94.3%. For GAC, the adsorption equilibrium was achieved after 12h with a 91.9% nitrobenzene removal efficiency.