Influences of Environmental Factors on Lanthanum/Aluminum-Modified Zeolite Adsorbent (La/Al-ZA) for Phosphorus Adsorption from Wastewater

Lanthanum/aluminum-modified zeolite adsorbent (La/Al-ZA) was prepared and investigated for their ability to remove phosphorus from wastewater. Various batch adsorption conditions, e. g., pH, ionic strength, temperature, contact time, initial phosphorus concentration, and the dosage of adsorbent were tested. The results showed that the adsorption amount increased with the increase of temperature, contact time, and initial phosphorus concentration and decreased with the increase of adsorbent dosage and initial anion concentration. The adsorption amount first increased with increasing pH from 2.0 to 4.0 and reached a plateau over the pH range from 4.0 to 8.0, then significantly decreased from 8.0 to 12.0, and the suitable adsorption was achieved with the pH range 4-9. The phosphorus removal efficiency decreased slightly from 95.86 to 93.39 and 92.53 %, respectively, in the presence of Cl- and SO42- at the lower concentration of 0.1 mmol/L, while they decreased significantly from 95.86 % to the ranges of 85.02-88.80 % and 83.77-87.45 %, respectively, in the presence of Cl- and SO42- at higher concentrations ranging from 0.5 to 2.0 mmol/L, and the effects on adsorption of La/Al-ZA follow the order: Cl->SO42-. Phosphorus adsorption matched with both Langmuir and Freundlich isotherms. The results presented here supported the potential use of the new La/Al-ZA as a material for the treatment of phosphorus in wastewater.