Lanthanum and magnesium activated palygorskite for adsorption of phosphate in piggery wastewater

Abstract

Removing phosphate from wastewater can help alleviate eutrophication. Therefore, in this study, lanthanum and magnesium were loaded onto the thermally modified palygorskite (PAL) using a coprecipitation method, and a composite material was prepared for phosphate recovery. In the pH range of 2–7, the material can effectively adsorb the phosphate. In the kinetic experiment, the material was able to rapidly adsorb phosphate within 4 h of the beginning of the reaction. The adsorption isotherm result of the material was in accordance with Freundlich isotherm model. When pH was 7, the theoretical maximum adsorption capacity was 20.4 mg P/g. When phosphate coexisted with CO32− and HCO3−, the adsorption was significantly inhibited. In the adsorption–desorption experiment, the material can be reused at least five times after elution with 1 mol/L of sodium hydroxide solution. The equilibrium adsorption capacity of the material for total phosphorus in piggery wastewater was 7.25 mg P/g, achieving a total phosphorus removal rate of 95.3%. The characterization of XRD, FT-IR and XPS suggested that phosphate was mainly exchanged with La–OH in the material, forming an amorphous LaPO4 complex. HIGHLIGHTS The LM-HPAL material was prepared by doping lanthanum and magnesium on palygorskite after high-temperature treatment.; The specific surface area of the LM-HPAL material increased to 98.2063 m2/g.; The LM-HPAL material can be regenerated through sodium hydroxide solution and can be reused at least five times.; The removal rate of total phosphorus in piggery wastewater by the LM-HPAL material reached 95.3%.;

Keywords

• adsorption
• lanthanum
• palygorskite
• phosphate
• piggery wastewater