Bryophyllum pinnatum activated biochar for competent removal of fluoride from water: sorption and equilibrium studies

With the advent of industrialization and other anthropogenic activities, water sources are being contaminated incrementally. Groundwater contaminated by fluoride has been a major global concern for public health in recent years. Various types of materials have been employed for the removal of contaminants from water. Among all, biochar has gained attention in recent times. Biochar is a carbon-rich and environmentally friendly pollutant adsorbent important in remediating inorganic contaminants like fluoride from water. In the current study, Bryophyllum pinnatum-raw biochar and activated biochar doped with aluminum were prepared from the leaves of the Bryophyllum pinnatum (B. pinnatum) plant. The removal efficiency of raw/pristine biochar (RB) and Bryophyllum pinnatum-activated biochar (BAB) was investigated by treating both biochars with fluoride-contaminated water. The biochar was characterized using FTIR, FESEM-EDX, XRD, BET, and pH_pzc techniques, which showed that the positive charges and adsorption sites were created due to the effective loading of the metal hydroxide on the biochar surface during BAB formation which played a significant role in defluoridation. To investigate the effect of different factors on the percentage of fluoride removal, batch tests were carried out. Kinetic and isotherm models were also applied to evaluate the mode of action and mechanistic approach. The results revealed that BAB exhibited a higher fluoride removal efficiency of 92% compared to RB and followed the pseudo-second-order model and Langmuir model showing chemisorption. Thus, the prepared activated biochar holds a good potential to be used as a sorbent for defluoridation.