Efficient fluoride removal from water and industrial wastewater using magnetic chitosan/β-cyclodextrin aerogel enhanced with biochar and MOF composites

Mechanism for Fluoride removal using CS/β-CD aerogel/CSBC/MnFe 2 O 4 /Al-La MOF . • Chitosan/β-CD aerogel composites were developed for fluoride removal in water. • CS/β-CD/CSBC/MnFe 2 O 4 /Al-La MOF had a high surface area (9 m 2 /g) and magnetism. • Achieved 99.41 % fluoride removal at pH 6, 50 °C, and 0.9 g/L in 70 min. • Adsorption followed Freundlich isotherm, indicating multilayer adsorption and bonding. • Real wastewater tests show 72–83 % fluoride removal by the developed adsorbents. Fluoride ion (Fl) is essential for human and environmental health but can cause serious health issues at high levels. This study developed chitosan/β-cyclodextrin (CS/β-CD) aerogels, enhanced with coconut shell biochar (CSBC) and a magnetic composite (MnFe 2 O 4 /Al-La MOF), to assess their efficiency in eliminating Fl from water and industrial wastewater. Structural analysis confirmed that CS/β-CD/CSBC/MnFe 2 O 4 /Al-La MOF had the highest surface area (9.232 m 2 /g) and a saturation magnetization of 5.32 emu/g, enabling efficient adsorption and magnetic separation. Under optimal conditions (pH 6, 50 °C, 0.9 g/L adsorbent, 70 min), it achieved a 99.41 % removal rate, with a maximum sorption capacity of 38.59 mg/g. Adsorption followed Freundlich isotherm and pseudo-second-order kinetics, indicating heterogeneous surface interactions and chemical bonding. The value of the Gibbs free energy parameter (ΔG°) for the adsorption of Fl ion using the aforementioned samples was determined to be in the range of −4.619 to −14.669 kJ/mol, indicating that the adsorption process is physical and spontaneous. The enthalpy (ΔH°) parameter value for the adsorption of Fl ion using CS/β-CD aerogel , CS/β-CD aerogel/CSBC, and CS/β-CD aerogel/CSBC/MnFe 2 O 4 /Al-La MOF samples was determined to be 21.213, 45.549, and 65.816 kJ/mol, respectively, indicating that the process is endothermic. Also, the results showed that the aforementioned adsorbents have a good ability to remove Fl ions from industrial wastewater and can be used as effective adsorbents in cleaning industrial wastewater.