WITHDRAWN: Enhanced Heavy Metal Removal from Industrial Produced Water Using Metal-Incorporated α-FeOOH Nanomaterials: Adsorption Kinetics and Isotherm Studies

Environmental contamination with heavy metal ions poses a major public health challenge, particularly groundwater contamination affecting drinking, agricultural, and industrial water supplies. Α-FeOOH (α-FeOOH) and metal-incorporated α-FeOOH (Ca, Co, Mn, Al) nanomaterials were synthesized via simple precipitation (pH = 12, aging time 7 days) for adsorptive removal of cadmium and chromium ions. Samples were characterized by XRD, FTIR, HR-TEM, N₂ adsorption-desorption isotherms, and thermal analyses. Results showed that metal incorporation increased surface hydroxyl group content relative to pure α-FeOOH. Al incorporation dispersed the α-FeOOH needles, reducing their length and width compared to other metal-incorporated variants. Al-α-FeOOH achieved the highest adsorption capacity, improving from 72.9 to 86 mg/g for Cr and 28 to 38 mg/g for Cd. Adsorption kinetics followed a pseudo-second-order model, confirming chemisorption. Cd adsorption obeyed the Langmuir isotherm (R² ≈ 0.99), indicating monolayer formation on the predominant α-FeOOH faces (001 and 010), while Cr adsorption followed both Langmuir and Freundlich models, suggesting mono- and/or multilayer formation. α-FeOOH nanomaterials demonstrated high remediation efficiency for complete heavy metal removal from produced water samples, confirming their promise as effective adsorbents.