Effectiveness of Zr(IV)-Loaded Banana Peels Biomass for the Uptake of Fluoride Anion from Water

The present study reports the fluoride uptake potential of Zr(IV)-loaded saponified banana peels (Zr(IV)-SBP) from water. Zr(IV)-SBP was synthesized by loading Zr(IV) onto banana peel biomass after saponification and sorbent characterization was performed by using different techniques including FE-SEM (Field Emission Scanning Electron Microscopy), FTIR (Fourier Transform Infra-Red) spectroscopy and zeta potential analysis. Batch experiments were carried out to examine the monitoring factors for the uptake of fluoride onto the investigated adsorbent. The optimal pH and contact time were found to be 2.94 and 300 minutes, respectively. The results from characterization techniques concurred that Zr(IV)-SBP have prominent adsorption sites favorable for the sorption of fluoride ions. The sorption behavior of fluoride onto Zr(IV)-SBP was best fitted with the Langmuir adsorption isotherm and pseudo-second-order kinetics model. The maximum adsorption capacity of Zr(IV)-SBP was 36.02 mg/g using the Langmuir isotherm model. The coexisting ions like chloride and nitrate caused very small interference, elevated concentration of sulphate notably lowers the fluoride adsorption percentage in the binary system, and the sorption using multiple systems was lowered significantly which is due to the synergistic effect of co-existing interfering ion. The adsorbed fluoride was completely desorbed using 2M NaOH solution. Fluoride sorption performance of Zr(IV)-SBP demonstrated that it can be a low cost, environmentally benign and one of the highly potent alternatives for the remediation of fluoride ions to avoid ablation on the water.

Adsorption of fluoride from industrial wastewater using polymer adsorbents: a review

Fluoride pollution in ground and surface water originates from naturally occurring reactions and industrial activities such as the disposal of industrial wastewater. Amongst different fluoride removal technologies including chemical precipitation, membrane filtration, ion exchange processes, and electrodialysis, adsorption is an attractive method for fluoride removal from wastewater due to its low operational cost, simplicity, and good sustainability. Various adsorbents are used for fluoride removal including, metal oxides and hydroxide, carbonaceous adsorbents, zeolite, polysaccharides, and polyresin adsorbents. This review studies the application of modified polysaccharides and polyresin adsorbents for the removal of fluoride from wastewater. The relationship between the adsorption conditions and the resulting adsorption capacity is thoroughly discussed. Based on the reported studies, modified polysaccharides and polyresins adsorbents can effectively remove fluoride from wastewater achieving high adsorption capacity, the highest being 92.39 mg/g for aluminum impregnated amberlite at pH 3. Furthermore, aluminum impregnated adsorbents reported a higher fluoride adsorption capacity than other modification methods where the three adsorbents with the highest fluoride adsorption capacity are: aluminum impregnated amberlite 92.39 mg/g at pH 3> zirconium immobilized crossed linked chitosan 48.26 mg/g at pH 6 > chitosan/aluminum hydroxide beads 17.68 mg/g at pH 4. In addition, polymeric adsorbents are also highly sustainable as they can be regenerated multiple times to be reused. Therefore, the high adsorption capacity and good regeneration potential allow polymeric adsorbents to serve as promising and sustainable adsorbents to remove fluoride from industrial wastewater.