Adsorption of Cu(II) from Aqueous Solution by Wine Processing Waste Sludge

Wine processing waste sludge (WPWS) has been shown to be an effective sorbent for sorption of nickel, lead, and chromium, but the sorption of copper (Cu) in aqueous solution by WPWS has not been conducted. The objective of this study was to explore the sorption mechanism of WPWS for copper. Infrared analysis revealed carboxyl was the major functional group in WPWS. The WPWS sorption isotherms of copper were only well described by Langmuir sorption isotherm. The maximum adsorption capacity (Q m ) was 14.26 mg/g at 50 °C. A pseudosecond-order sorption kinetic model successfully described the kinetics of copper sorption onto WPWS. The Gibb free energies (ΔG°) ranged from -20.69 to -24.29 kj mol⁻¹, and the ΔH° and ΔS° were 5.048 kj mol⁻¹ and 91.05 J mol⁻¹ K⁻¹, respectively. The trend of the intra-particular diffusion rate is the opposite of the adsorption constant of the pseudosecond-order equation.