Process optimization via response surface methodology for thallium removal wastewater by manganese-modified mesoporous ceramsite

To develop novel adsorbents for treating thallium (Tl) contaminated water, manganese-modified mesoporous ceramsite (Mn@Sic-MC) was prepared and employed as the adsorbent. Single-factor experiments combined with response surface methodology (RSM) were applied to optimize the absorption conditions and to explore the T1-removal mechanism. Under the RSM-optimized parameters (initial pH of 3.8, adsorbent dosage of 53.5 g/L, a contact time of 9.9 h), a Tl removal efficiency of 94.97% was achieved. The adsorption process was well described by the pseudo-second-order kinetic model and the Freundlich isotherm model. Competitive adsorption experiments revealed that, relative to the singleTl system, the removal efficiency of T1 decreased by 16.47%, 18.93%, and 7.80% in the TlPb, TlZn, and TlPbZn systems respectively. Nevertheless, a high removal performance was maintained, demonstrating the favorable selective adsorption capability of Mn@SicMC. Desorption-regeneration experiments confirmed the material's recyclability, as the removal efficiency remained above 85% after three cycles, with a material loss rate below 5%. The study provides useful insights for the treatment of heavy-metal-contaminated wastewater.