Bone-char from various food-waste: Synthesis, characterization, and removal of fluoride in groundwater

Fluoride (F), an essential trace element, plays a significant role in the skeletal systems of teeth and bone. However, drinking water with a high level of fluoride (more than 1.5 ppm) would cause fluorosis, seriously damaging the teeth and bone structures. In central Vietnam, there is a village called no smile village, where local people highly drink fluoride-contaminated groundwater. Finding an efficient fluoride removal solution with an acceptable cost is required. In this work, highly porous carbonaceous bone-char (Bc) materials were synthesized by calcination of various sources of bones (fish, chicken, pig, and cow) at 600 °C for removing fluoride in drinking water. We investigated the effects of the precursors on synthesized materials’ characteristics and their efficiency of fluoride removal. As a result, the Bc materials exhibit interesting characteristics via high specific surface area (up to 211.8 m2/g, and the abundance of micro-mesoporous, and hydroxyapatite structures formed during the calcination process. In addition, Bc materials illustrated an outstanding fluoride adsorption performance with a removal efficiency of more than 98 %. Moreover, the pseudo-first and pseudo-second-order kinetic models were applied to determine the fluoride adsorption behaviors of the prepared Bc. The studied results promoted a potential and sustainability pathway for utilizing low-cost food waste synthesizing green adsorbent to remove fluoride in drinking water without using toxicity chemical approaches.