Porous Basalt Fiber Modified By Ferric And Zirconium Oxide Applying In Phosphate Removal In Water

Phosphate?P?is an essential nutrient element for the growth of many organisms,and especially plays an important role in the cell metabolism of the organisms.However,excessive P in water would result in undesirable eutrophication,leading to disaster of aquatic organisms and hazardous algae bloom due to the deterioration of water quality.Eventually,not only the ecological environment was persistently damaged,but also the health of human beings was greatly affected,and it would cause huge social economy losses.At present,metal oxides are the most important materials for phosphorus removal.However,the faced challenge is the difficult separation and recovery of adsorbent after usage due to the tiny particle size of adsorbents in aqueous solution,limiting the implement in the real engineering application.The alternative strategies considered is supporting Fe-based adsorbents on suitable substrate for easy recovery without decreasing the adsorption efficiencies.Therefore,the purpose of achieving efficient dephosphorization and easy recycling has become a hot topic in engineering applications.At present,iron-based and zirconium-based materials have been widely considered to be environmentally-friendly adsorbents due to high affinity for phosphate and excellent adsorption performance.In this paper,basalt fibers?BF?are modified by ferric chloride and zirconium dichloride,and the optimal modification conditions and phosphorus removal performance are explored.Detailed research contents and results are present as following:?1?Iron oxyhydroxide-containing basalt fiber?FeOOH/BF?was prepared by using a simple oil bath condensation reflux method using absolute ethanol as the hydroxyl donor.The optimal preparation conditions were obtained as follows:FeCl₃concentration was 1.0 mol/L,reaction temperature was 60oC,reaction time was 12 h,and the drying temperature was 60oC.The adsorption of FeOOH/BF on phosphorus agrees quasi-second-order kinetics and follows the Freundlich equation.The maximum saturated adsorption capacity is 39.08 mg/g,and the optimal pH is 5.5?10.The composite has good anti-interference ability and selective adsorption for phosphorus.?2?Basalt fibers?Fe-Zr/BF?supporting iron?hydrogen?oxide and zirconium?hydrogen?oxide were prepared by a simple oil bath heating method using NaOH as the hydroxyl donor.The experimental results show that the optimal molar ratio of iron to zirconium is 8:1.The adsorption of Fe-Zr/BF on phosphorus agrees quasi-second-order kinetics and follows the Freundlich equation.The maximum saturated adsorption is 59.04 mg/g.When the pH is in the range of 2 to 7,the phosphorus removal efficiencies is the highest.The composite also has good selective adsorption and anti-interference ability for phosphorus removal.In the simulated wastewater,The Cl^-,NO3^-,SO₄^2-had no significant effect on the removal of phosphate except for CO₃^2-.The characterization from XRD,FTIR,SEM-EDX and XPS showed that metallic iron and metallic zirconium are fixed on the basalt fiber in a mixed state of iron?zirconium?oxide and hydroxide,metallic Fe is the crystalline phase and Zr is amorphous Phase.The main adsorption mechanism of Fe-Zr/BF on phosphate removal consist of electrostatic adsorption,ligand exchange,inner layer complexation and surface deposition.?3?The Fe-Zr/BF dephosphorization adsorption material used to simulate the dynamic adsorption experiment.The result showed that the time required for the Fe-Zr/BF composite to penetrate the material is 3.5 h when the iron-zirconium molar ratio=8:1,the inlet water flow rate V=1.0 mL/min,the height of packing layer Z=14 cm,and the initial phosphate concentration C0=10 mg/L.The dynamic adsorption fitting results show that the Yoon-Nelson model is most suitable for the dynamic adsorption process of the adsorption column from Fe-Zr/BF composite,and the time??10 h when phosphate concentration in export=a half of the initial phosphate concentration.This provides a certain reference value for the industrialization and engineering of Fe-Zr/BF composite materials.