Oxidized Renewable Materials for the Removal of Cobalt(II) and Copper(II) from Aqueous Solution Using in Batch and Fixed-Bed Column Adsorption

Abstract

Batch and continuous adsorption of Co 2+ and Cu 2+ from aqueous solutions by oxidized sugarcane bagasse (SBox) and oxidized cellulose (Cox) were investigated. The oxidation reaction of sugarcane bagasse and cellulose was made with a mixture of H 3 PO 4 ‒NaNO 2 to obtain SBox and Cox, with the introduction of high number of carboxylic acid functions, 4.5 and 4.8 mmol/g, respectively. The adsorption kinetics of Co 2+ and Cu 2+ on SBox and Cox were modeled using two models (pseudo-first-order and pseudo-second-order) and the rate-limiting step controlling the adsorption was evaluated by Boyd and intraparticle diffusion models. The Sips and Langmuir models better fitted the isotherms with values of maximum adsorption capacity<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mfenced separators="" open="(" close=")"><mml:mrow><mml:msub><mml:mrow><mml:mi>Q</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">max</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:mfenced></mml:math>of 0.68 and 0.37 mmol/g for Co 2+ and 1.20 and 0.57 mmol/g for Cu 2+ adsorption on Cox and SBox, respectively. The reuse of both spent adsorbents was evaluated. Adsorption of Cu 2+ and Co 2+ on SBox in continuous was evaluated using a 2 2 factorial design with spatial time and initial metal concentration as independent variables and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:msub><mml:mrow><mml:mi>Q</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">max</mml:mi></mml:mrow></mml:msub></mml:math>and effective use of the bed as responses. The breakthrough curves were very well described by the Bohart–Adams original model and the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:msub><mml:mrow><mml:mi>Q</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">max</mml:mi></mml:mrow></mml:msub></mml:math>values for Co 2+ and Cu 2+ were 0.22 and 0.55 mmol/g. SBox confirmed to be a promising biomaterial for application on a large scale.