Synthesis of sewage sludge‐based carbon/TiO2/ZnO nanocomposite adsorbent for the removal of Ni(II), Cu(II), and chemical oxygen demands from aqueous solutions and industrial wastewater

Abstract The removal of heavy metal ions and organic materials from wastewater due to their toxicity is necessary. In the present study, the titanium dioxide/zinc oxide (TiO2/ZnO) nanocomposite has been coated on the sewage sludge carbon (SSC) surface and its application was investigated for the adsorption of Ni(II), Cu(II), and chemical oxygen demands (COD) reduction from aqueous solutions and industrial wastewaters in Eshtehard, Iran. The effect of adsorption parameters in a single system such as TiO2/ZnO ratio, TiO2/ZnO concentration, pH, adsorbent dosage, contact time, ionic strength, temperature, and initial concentrations of Ni(II), Cu(II), and COD was investigated on the adsorption capacity of synthesized SSC/TiO2/ZnO adsorbent. The pseudo‐second order and Redlich–Peterson isotherm models were best described the kinetic and equilibrium data of Ni(II), Cu(II), and COD sorption. The maximum monolayer sorption capacities of Ni(II), Cu(II), and COD were found to be 62.3, 75.1, and 1,120.3 mg/g, respectively. The central composite design was used to investigate the interaction effects of pH and initial concentrations of Ni(II), Cu(II), and COD on the simultaneous removal of Ni(II), Cu(II), and COD from aqueous solutions in a ternary system. The potential of synthesized SSC/TiO2/ZnO adsorbent was investigated for Ni(II), Cu(II), and COD adsorption from industrial wastewaters of Iran. Practitioner points The novel sewage sludge carbon/TiO2/ZnO adsorbent was synthesized. Adsorption of Ni(II), Cu(II), and chemical oxygen demands (COD) from industrial wastewaters was investigated. Maximum Ni(II), Cu(II), and COD sorption capacities were 62.3, 75.1, and 1,120.3 mg/g. Simultaneous removal of Ni(II), Cu(II), and COD was investigated in a ternary system.