Synthesis and application of sugarcane bagasse cellulose mixed esters. Part I: Removal of Co2+ and Ni2+ from single spiked aqueous solutions in batch mode using sugarcane bagasse cellulose succinate phthalate

Abstract

Sugarcane bagasse cellulose mixed ester succinate phthalate (SBSPh) was synthesized by a novel one-pot reaction method. The effects of temperature, time and mole fraction of succinic anhydride (χ_SA) on the responses weight gain (wg), number of carboxylic acid groups (n_T,COOH), and adsorption capacity (q) of Co²⁺ and Ni²⁺ were evaluated by a 2³ experimental design. The chemical structure of the material was elucidated by Fourier transform infrared, ¹³C Multiple Cross-Polarization solid-state NMR spectroscopy and ¹H NMR relaxometry. The best SBSPh synthesis condition (100 °C, 11 h, χ_SA of 0.2) yielded a wg of 59.1%, n_T,COOH of 3.41 mmol g^-1, and values of q_Co²⁺ and q_Ni²⁺ of 0.348 and 0.346 mmol g^-1, respectively. The Sips model fitted better the equilibrium data, and the maximum adsorption capacities (pH 5.75 and 25 °C) estimated by this model were 0.62 and 0.53 mmol g^-1 for Co²⁺ and Ni²⁺, respectively. The Δ_adsH° values estimated by isothermal titration calorimetry were 8.43 and 7.79 kJ mol^-1 for Co²⁺ and Ni²⁺, respectively. Desorption and re-adsorption efficiencies were evaluated by a 2² experimental design, which showed that SBSPh adsorbent can be recovered and reused without significant loss of adsorption capacity.

Keywords: (13)C Multiple Cross-Polarization solid-state NMR; Adsorption; Isothermal titration calorimetry; Metal ion; Mixed esters; Sugarcane bagasse.