ZnAl Layered Double Hydroxides As Potential Molybdate Sorbents and Valorize the Exchanged Sorbent for Catalytic Wet Peroxide Oxidation of Phenol

Molybdate uptake was studied using ZnAl layered double hydroxides (LDHs) having different interlayer anions namely chloride, carbonate, or nitrate with various Zn/Al atomic ratios. A maximum molybdate uptake of 114 mg Mo/g was observed for ZnAl3-Cl-LDH. The uptake is due to ion-exchange for chloride and nitrate containing samples and surface adsorption for carbonate bearing samples. Temperature of the medium had little influence on the uptake while nearly 100% uptake was observed for a wide pH range (23 to 10.0). The material after molybdate uptake was volarized for catalytic wet peroxide oxidation of aqueous phenol (100mg/L). A maximum phenol degradation of 43% was achieved at catalyst loading of 0.5g/L. The potential for dual application of LDHs for the removal of both inorganic and organic pollutants in the perspective of wastewater remediation by acting as sorbents for molybdate and valorize the used sorbent as catalyst for the removal of phenol is demonstrated.