The adsorption of fluoride from aqueous solutions using natural and modified clinoptilolite was investigated with a focus on optimizing operational parameters through the Box-Behnken Design (BBD). Natural clinoptilolite, mined in Western Anatolia, Turkey, was modified with iron (Fe), manganese (Mn), or a combination of both (Fe/Mn) to enhance its fluoride removal capacity. The modification process involved ion exchange using FeCl₃ and MnCl₂ solutions, resulting in significant changes in elemental composition and surface characteristics. Characterization techniques including X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis confirmed structural integrity and increased surface area post-modification. Notably, Fe-modified clinoptilolite (CLP-Fe) exhibited the highest specific surface area at 61.24 m²/g, indicating enhanced adsorption potential.CD3G Antibody web
Batch adsorption experiments were conducted under controlled conditions to evaluate the influence of three key variables: adsorbent dose (0.MATN1 Antibody manufacturer 5–1.5 g/50 mL), initial fluoride concentration (2–50 mg/L), and pH (4–11). Equilibrium was reached within 5 hours for all modified samples, suggesting rapid adsorption kinetics. BBD was employed to design experiments and model the response function, allowing for statistical evaluation of main effects, interactions, and quadratic terms. The regression models showed high correlation coefficients (R² = 0.95–0.96), indicating strong agreement between predicted and observed fluoride removal efficiencies. Analysis of variance (ANOVA) confirmed the statistical significance of the models, with low p-values (<0.05) and adequate precision values exceeding 4, affirming model reliability. Results revealed that pH significantly influenced fluoride adsorption, with maximum removal efficiency achieved at pH 11. At this alkaline condition, the surface charge of CLP-Fe became highly positive due to its point of zero charge (pHpzc = 9.26), favoring electrostatic attraction of negatively charged fluoride ions. Adsorbent dose also played a critical role; removal efficiency increased up to an optimal dose of 1.08 g/50 mL for CLP-Fe before slight decline due to particle aggregation and site saturation. Higher initial fluoride concentrations reduced removal efficiency, as limited active sites could not accommodate excess ions.PMID:35032970 However, increasing the adsorbent dose compensated for this limitation.
Maximum fluoride removal efficiency of 80.23% was attained under optimized conditions: pH 11, 1.08 g/50 mL of CLP-Fe, and 2 mg/L initial fluoride concentration. Freundlich isotherm modeling demonstrated excellent fit (R² = 0.9198), indicating multilayer adsorption on heterogeneous surfaces. Kinetic studies confirmed that pseudo-second-order model best described the process (R² = 0.9934–0.9971), suggesting chemisorption as the dominant mechanism. The equilibrium adsorption capacity of CLP-Fe was determined to be 1.72 mg/g at 50 mg/L initial fluoride concentration.
Regeneration tests showed that CLP-Fe retained over 80% of its original efficiency after six cycles, demonstrating good reusability. Desorption with 0.1 M HCl effectively released bound fluoride, enabling material recovery. Residual iron and manganese levels remained below regulatory limits, confirming environmental safety. In conclusion, BBD proved to be a robust tool for optimizing fluoride adsorption, and Fe-modified clinoptilolite emerged as a highly effective, reusable, and sustainable adsorbent for water defluoridation, particularly suitable for regions with abundant natural clinoptilolite resources.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com