Benzoic Compounds Removal from Aqueous Solutions by Acidic Silk: Equilibrium and Kinetic Study

Background & Aims of the Study: p-Chloronitrobenzene is a benzoic compound that widelyused in many chemical industrials. p-Chloronitrobenzene may be absorbed through the skin andis suspected to causing cancer. So, developing an easy method to remove of it from theenvironment is necessary. Equilibrium isotherms and adsorption kinetics of p-Chloronitrobenzene onto modified silk waste were studied experimentally.Materials and Methods: Silk waste was modified by HCl and used as an adsorbent to removeof p-Chloronitrobenzene from aqueous solutions. After preparing of adsorbent, the adsorptionexperiments were down in a batch system in an erlen mayer at different concentrations of p-Chloronitrobenzene (20, 40, 60, 80, 100 mg/L), pH (2, 4, 6), dosage of modified silk waste (1, 2,3, 4, 5 g/250 mL), temperature (20, 30, 40 oC) and contact time.Results: Data revealed that the adsorption of p-Chloronitrobenzene on to modified silk wastewas reached equilibrium after 20 min. The adsorption of p-Chloronitrobenzene decreased withthe increasing of pH and the concentration of p-Chloronitrobenzene which is increased byincreasing of modified silk waste dosage. Also, data confirmed that changing of temperature didnot have significant p-Chloronitrobenzene removal efficiency. Pseudo-first-order and pseudosecond-order equations were used to determine the kinetics of removal process. It was found thatthe adsorption of p-Chloronitrobenzene onto modified silk waste was obeyed from pseudosecond-order kinetic model.Conclusion: The results indicated the adsorption of p-Chloronitrobenzene onto modifiedsilk waste could be well fitted with the Freundlich isotherm and pseudo-second-orderkinetic models.