Preparation, Characterization, and Application of Lanthanum Doped Magnetic Biochar Composite Adsorbent for Removal of Fluoride from Water

Abstract

Fluoride level more than 1.5mg/L in drinking water is an environmental problem around the world that causes serious health damage for a human. Adsorption is considered one of the best methods for water defluoridation applications. Poor adsorption capacities, long contact time, extremely low or high pH, and high dosage are the major limitations of various adsorbent materials. In the present study, the biochar-based magnetic nanocomposite adsorbent was prepared and applied as an adsorbent for water defluoridation application. The biochar was prepared from waste coffee husk through slow pyrolysis. The composite was prepared by coating iron and lanthanum oxide nanoparticles on the surface of biochar through a chemical coprecipitation method. The magnetic biochar nanocomposite material was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectrometry (FTIR), Brunauer-EmmettTeller (BET), and the surface charge of the adsorbents were evaluated by determining values of pHPZC. The laboratory experiments were carried out using the Central Composite Design (CCD) with four input variables of dosage (2-5 g L–1 ), solution pH (4–8), contact time (30–70 min), and initial concentration (10–20 mg/L). The optimum conditions for fluoride removal of 98.994 % from water were predicted by the quadratic model (adsorbent dosage of 5g L–1 , pH 5.74, contact time 60 min, and initial concentration of 12.245 mg/L) was achieved. The mean triplicate value at optimum conditions resulted in a removal efficiency of 98.51%, which indicates the prediction capability of the proposed response surface model. The results of the present study displayed that the prepared magnetic biochar nanocomposite is a good adsorbent of fluoride.