Fish Swim Bladder-Derived Porous Carbon for Defluoridation at Potable Water pH

Abstract

The levels of fluoride in various ground water sources in East Africa are above the World Health Organization upper limit of 1.5 mg/L. Research on diverse defluoridation technologies has proven that adsorption stands out as an affordable, efficient, and facile technology. Fish swim bladder-derived porous carbon (FBPC) activated by KOH and surface oxidized by nitric acid was successfully investigated as an adsorbent for defluoridation at portable water pH. The FBPC was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-raydiffraction (XRD) and energy dispersive spectroscopy (EDS). Batch methods were used to study physiochemical parameters viz., initial fluoride concentration, temperature, adsorbate dosage, contact time and pH. Freundlich, Temkin, Langmuir and Dubinin-Radushkevich isotherms were plotted and analyzed to understand the adsorption process. Bangham, Weber Morris, pseudo first and second-order models were used to elucidate the kinetics of adsorption. Optimal conditions for fluoride removal were found to be: pH of 6, FBPC adsorbent dose of 5.0 g/L and contact time of 50 min. Flouride adsorption followed pseudo second-order kinetic model and Langmuir isotherm best describes the adsorption process.

Selective heavy metal removal and water purification by microfluidically-generated chitosan microspheres: Characteristics, modeling and application

“…The mean free energy of adsorption E (kJ mol -1 ) can be calculated to estimate the type of sorption process using the following equation [40]:…”

Removal of fluoride ions using a polypyrrole magnetic nanocomposite influenced by a rotating magnetic field

“…The deprotonation of uoride adsorption sites at higher pH (>pH 6) leads to a decrease in the quantity of uoride ions removed, owing to the strong competition for binding sites on the adsorbent between OH À and uoride ions. [47][48][49][50]…”

Water Defluoridation Methods Applied in Rural Areas over the World

“…They found average uptake F capacities to be 1.2 ± 0.3 mg/g and 3.0 ± 1.0 mg/g, respectively. A study to explore activated carbon from fish bladder showed a maximum F removal of 1.43 mg/g [122]. In related work, Kawasaki et al [123] who investigated four types of animal biomass and Singanan [124] who studied certain bone char adsorbents for F removal, reported more or less similar defluoridation potential.…”