Fe-Modified Cupressus sempervirens Cone Biochar as an Efficient Adsorbent for Removal of Malachite Green

The discharge of synthetic dyes into aquatic environments without adequate treatment constitutes a serious environmental problem due to their toxicity, chemical stability, and resistance to biodegradation. Among these contaminants, Malachite Green (MG), a commonly used cationic dye, has attracted considerable attention because of its harmful effects on both aquatic ecosystems and human health, thereby emphasizing the necessity for efficient and sustainable remediation approaches. In recent years, biochar produced from lignocellulosic biomass has gained increasing interest as a potential adsorbent owing to its low production cost and environmentally friendly nature. In this study, biochar derived from Cupressus sempervirens (CSb) and its iron modified form (CSmb) were investigated for the removal of MG from aqueous solutions. The structural and surface properties of the adsorbents were characterized using FT-IR, XRD, and SEM-EDS analyses, which revealed noticeable alterations in surface morphology and functional groups after the modification process. Batch adsorption experiments were carried out to examine the effects of various parameters, including pH, temperature, initial dye concentration, contact time, and adsorbent dosage. The kinetic results indicated that the adsorption of MG onto both adsorbents was best described by the pseudo-second-order model. Thermodynamic analysis further suggested that the adsorption process is spontaneous and endothermic. Equilibrium data were best fitted by the Langmuir isotherm model, with maximum adsorption capacities of 33.670 mg g-1 for CSb and 38.462 mg g-1 for CSmb. Overall, the results indicate that biochar derived from Cupressus sempervirens, particularly after iron modification, can serve as an effective and economically feasible adsorbent for the treatment of dye contaminated wastewater.