Enhanced adsorption and recovery of Cu(II) and Fe(II) ions from wastewater using waste cellulose-loaded Mg(OH)₂ composite

In this work, Mg(OH)₂ functionalized cellulose waste (CW@Mg(OH)₂) composite was prepared. The CW@Mg(OH)₂ composite was utilized for the adsorption of Cu(II) and Fe(II) ions from water and waste sludge streams. The characterization results indicated the successful formation of Mg(OH)₂ onto cellulose waste surface with high crystallinity and abundant surface functionalities (OH, C-O, and C-OH), which enhanced the removal % of heavy metals. At optimized adsorption conditions, the maximum monolayer adsorption capacity of CW@Mg(OH)₂ composite was 488 mg/g for Cu(II) and 510 mg/g Fe(II)) at metal concentrations 400 mg/L with solution pH of ≥ 5.2 for both metal ions by 300 min. at 25 °C of system temperature. The experimental data was fitted to the recognized nonlinear isotherm and kinetic models. Energetically, the removal of Cu(II) and Fe(II) ions using CW@Mg(OH)₂ composite was impulsive and endothermic in nature. The adsorption mechanism of heavy metals onto CW@Mg(OH)₂ composite is mainly associated with surface adsorption, chemical, and hydrogen bonding due to surface functionalities as confirmed by FTIR. The CW@Mg(OH)₂ composite was investigated for the recovery of metal ions from microwave-digested sewage sludge and showed a removal % of (21 and 16 %) for iron and copper, respectively. The prepared CW@Mg(OH)₂ composite is cost-effective, stable, promising and effective for decontaminating heavy metals from wastewater.