Characterization and Removal of Nickel (II) from Paint Industry Effluent by Rice Husk Adsorbent

Abstract

Rice husk adsorbent was studied to assess its efficiency in adsorption of nickel from paint industry effluent and to derive vital parameters that would assist in making timely decisions in tertiary treatment of wastewater. Standard methods were used in conducting the experiments. Results showed that significant adsorption of 84.77% of nickel was removed by carbonized rice husk (CRH) in 10 minutes and 98.42% in 60 minutes, a difference of 13.65%. Optimum pH of 8 was observed as 98.91% of nickel was adsorbed. Slight change in the adsorption efficiencies was noticed between 0.2 g and 0.4 g doses of CRH adsorbent, but reasonable and insignificant change occurred between 0.4 g and 1.0 g doses. Langmuir isotherm plot showed that separation factor was 0.998 an indication of favorable adsorption and a good fit for the Langmuir isotherm model. Therefore, the adsorption process was better described by the Langmuir equilibrium isotherm model. Adsorption intensity of 2.02 was observed in the Freundlich model, a value greater than 1.0 an indication of unfavorable adsorption. Lagergren pseudo first- and second-order plots showed that R2 = 0.799 for pseudo first-order and R2 = 0.969 for pseudo second-order reactions, an indication that adsorption of nickel by CRH follow Lagergren second-order kinetic. FTIR spectra identified N-H, O-H, C=H, C=O, C=C-C, C-Cl, P-O-C, and cis-C-H out-of-plane bend stretching bands as the functional groups involved in nickel adsorption by CRH adsorbent. It was concluded that rice husk is a good adsorbent in tertiary treatment of wastewater.