Adsorptive Removal of Benzophenone-4 (BP-4) Using Magnetically Recoverable Fe₃O₄/Alhagi maurorum Activated Biochar: Optimization, Kinetics, Reusability, and Mechanistic Insights.

Authors

Shahad A Raheem, Entidhar Jawad Kadhim

Published in

Water environment research : a research publication of the Water Environment Federation. Volume 98. Issue 8. Pages e70519.

Abstract

Benzophenone-4 (BP-4) is an emerging pollutant with extensive applications in daily life. BP-4 is extensively documented as a persistent, bioaccumulative, hydrophilic compound that spreads rapidly in water and is toxic to aquatic organisms. This study aims to develop a novel adsorbent that efficiently adsorbs BP-4 from aqueous solutions. Thus, biochar was prepared from Alhagi maurorum biomass (AM-BC). To enhance the adsorption capacity of this adsorbent by increasing surface area, promoting the formation of micro/mesopores, improving structural stability, and introducing oxygen-containing functional groups, a chemical activation with KOH followed by thermal activation was employed. Then, magnetic biochar (Fe₃O₄/AM-BC) was prepared by co-precipitation using FeCl₃ and FeCl₂. Fe₃O₄ nanoparticles were incorporated to provide magnetic recoverability and facilitate the rapid separation and reuse of the adsorbent after BP-4 adsorption. Fe₃O₄/AM-BC was characterized by scanning electron spectroscopy (SEM/EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) analysis, and vibrating sample magnetometer (VSM). Results confirmed that Fe₃O₄/AM-BC exhibited significant characteristics, including saturation magnetization (Ms) of 23.4 emu/g, a hierarchical porous structure with a specific surface area of 741.383 m²/g, and abundant functional groups. Adsorption experiments of BP-4 revealed a maximum removal efficiency of 94.05% at optimized conditions of pH 5, 0.5 g/L Fe₃O₄/AM-BC dose, 15 mg/L BP-4 concentration, and 180 min contact time. Langmuir isotherm model fitted the data with R² of 0.955 and a maximum adsorption capacity of 62.87 mg/g. PSO kinetic model described the adsorption of BP-4 with R² of 0.996, confirming the chemisorption process. The study indicated that the adsorption of BP-4 on Fe₃O₄/AM-BC occurred through various mechanisms, including electrostatic attraction, pore filling, π-π interactions, hydrogen bonding, and surface complexation. The regeneration study confirmed the significant reusability and structural stability of Fe₃O₄/AM-BC, with a slight reduction in efficiency after 5 cycles. In conclusion, Fe₃O₄/AM-BC proved to be an efficient adsorbent for the remediation of emerging contaminants and a potentially effective means of reusing and managing agricultural waste. To the best of our knowledge, no comprehensive study has evaluated magnetically modified biochar as a recyclable adsorbent for the removal of BP-4 from aqueous solutions.

PMID:
42581735
Bibliographic data and abstract were imported from PubMed on 12 Aug 2026.

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