Adsorption of copper from water using TiO₂-modified activated carbon derived from orange peels and date seeds:...

This study evaluated the application and efficiency of modified activated carbon in the removal of copper (Cu) from synthetic aquatic samples. The surface of activated carbon derived from orange peel (AC-OP) and date seeds (AC-DS) have been modified by Titanium dioxide nanoparticles (TiO₂ NPs) (1:10 wt% mixing ratio) and used in a series of experiments designed by Response Surface Methodology (RSM) incorporating Central Composite Design (CCD). The Brunauer-Emmett-Teller (BET) test demonstrated that the modification has increased the surface area of AC-OP from 2.40 to 6.06 m² g^-1 and AC-DS from 51.10 to 81.37 m² g^-1. Effects of pH (1-7), ion initial concentration (10-60 mg L^-1), adsorbent dose (0.5-8 g L^-1), and contact time (0.4-6 h) have been investigated. The results showed that the optimum conditions for TiO₂-modified AC-OP (OP-TiO₂) are pH 5, initial concentration of 24.6 mg L^-1, adsorbent dose of 4.9 g L^-1, and contact time of 3.6 h. The optimum conditions for TiO₂-modified AC-DS (DS-TiO₂) are pH 6.4, initial concentration of 21.2 mg L^-1, adsorbent dose of 5 g L^-1, and contact time of 3.0 h. The modified quadratic models represented the results well with regression coefficients of 0.91 and 0.99 for OP-TiO₂ and DS-TiO₂, respectively. The maximum Cu removal for OP-TiO₂ and DS-TiO₂ were 99.90 % and 97.40 %, and the maximum adsorption capacity was found to be 13.34 and 13.96 mg g^-1, respectively. Kinetic data have been fitted to pseudo first-order, pseudo second-order, intra-particle diffusion, and Elovich models. The pseudo second-order showed a better fit to the experimental data (R² > 98 %). This study demonstrates the successful development of modified activated carbon derived from orange peels and date seeds, modified by TiO₂ nanoparticles, for efficient adsorption of copper ions from water. The findings contribute to understanding the adsorption mechanism and provide valuable insights for designing environmentally friendly adsorbents.