Assessment of toxic copper(II) biosorption from aqueous solution by chemically-treated tomato waste

Abstract

Agricultural wastes or industrial wastes can be used as biosorbent with quite little processing when theyare locally available in large quantities. A great number of studies were done to uptake copper(II) ionfrom aqueous solutions. The biosorption of copper(II) ion from aqueous solutions by hydrochloric acidtreated tomato factory waste was investigated to identify metal ion removal efficiency of biosorbent forthefirst time in the literature. Proximate analysis of tomato waste was performed; also waste andbiosorbent were characterized by applying Fourier transform infrared spectroscopy and elemental an-alyses. pH, biosorbent dosage, initial metal concentration, temperature and contact time effects wereexamined to determine optimum conditions of copper(II) uptake. According to the pH effect experi-ments, the maximum % metal removal was achieved at pH 8 as 92.08%. Optimum biosorbent dosage andinitial copper(II) concentration were found as 0.2 g/50 mL solution and 50 ppm, respectively. Langmuiradsorption isotherm was found to bestfit the adsorption data; and also reaction kinetics was determinedto be appropriate to the pseudo-second order reaction model. Thermodynamic functions, the change offree energy (DG ), enthalpy (DH ) and entropy (DS ) of biosorption were calculated for copper(II) ion. Theresults showed that the biosorption of copper(II) ion on tomato waste biosorbent was exothermic at 293e313 K. Results of biosorption studies are in line with the literature. A promising outcome based onexperiments shows that, tomato waste could be used as an alternative and low-cost biosorbent forremoval copper(II) ion from aqueous solutions, when suitable conditions are performed.