Conversion of MDF waste into CoCl2-functionalized activated carbon for enhanced phosphate removal from landfill leachate

The efficient removal of excess phosphate from aquatic environments is essential for preventing eutrophication and preserving water quality. In the present study, a novel adsorbent material, CACoCl2, was synthesized from medium-density fiberboard (MDF) residues and subsequently modified with cobalt(II) chloride. This modification resulted in a material with significant potential for phosphate adsorption. Notably, to the best of our knowledge, this is the first report of biochar derived from MDF waste that has been modified with cobalt(II) chloride for applications in phosphate removal. Both the unmodified (pristine) MDF biochar and the cobalt-modified MDF biochar underwent comprehensive characterization using various analytical techniques. A series of adsorption experiments were systematically conducted to investigate the effects of key parameters, including pH, adsorbent dosage, contact time, adsorbate concentration, temperature, and ionic competition. Furthermore, phosphate adsorption tests were performed using real wastewater effluent sourced from landfill leachate that had been concentrated by reverse osmosis. The study identified optimal conditions for phosphate adsorption at a temperature of 328 K and a pH of 4. Under these conditions, the maximum adsorption capacity was determined to be 228.04 mg g−1, as predicted by the Langmuir isotherm model. Kinetic analyses revealed that the adsorption process conformed to a pseudo-first-order model, while equilibrium data were best described by the Langmuir isotherm. Thermodynamic evaluations demonstrated that the adsorption process was favorable, spontaneous, and endothermic in nature. When tested with real effluent samples, CACoCl2 achieved a phosphate removal efficiency of 94.94%. Overall, the experimental findings underscore the excellent potential of CACoCl2 as an effective and efficient adsorbent for phosphate removal from aqueous solutions, including challenging matrices such as landfill leachate.