Synthesis and application of lanthanum-doped magnetic biochar composite adsorbent for removal of fluoride from water

Fluoride levels greater than 1.5 mg/L in drinking water are a global environmental issue that can seriously harm the health of humans. One of the most effective techniques for defluoridating water is adsorption. The main drawbacks of many adsorbent materials include their poor adsorption capabilities, prolonged contact times, excessively low or high pH levels, and high dosages. The biochar-based magnetic nanocomposite adsorbent was synthesized in the current study and used as an adsorbent for water defluoridation. Through slow pyrolysis, coffee husk waste was converted to biochar. The composite was created by chemically co-precipitating iron and lanthanum oxide nanoparticles onto the surface of biochar. By using X-ray diffraction analysis (XRD), Fourier transform infrared spectrometry (FTIR), Brunauer–Emmett–Teller (BET), and pHPZC values, researchers were able to describe the magnetic biochar nanocomposite material. The Central Composite Design (CCD), which uses four input variables including dosage (2–5 g/L), solution pH (4–8), contact time (30–70 min), and initial concentration (10–20 mg/L), was used to design the experiments. The quadratic model indicated that the ideal conditions for removing 98.994% of the fluoride from water (adsorbent dosage of 5 g L-1, pH 5.74, contact period of 60 min, and initial concentration of 12.245 mg/L) would be attained. The average triplicate value in ideal circumstances produced a removal effectiveness of 98.51%, demonstrating the proposed response surface's capacity for prediction. The findings of this investigation showed that the magnetic biochar nanocomposite that was created is an effective fluoride adsorbent.