Chinese Journal of Applied Chemistry ›› 2016, Vol. 33 ›› Issue (4): 473-480.DOI: 10.11944/j.issn.1000-0518.2016.04.150265

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Pure Ca-Al- Layered Double Hydroxides as an Efficient Sorbent for Phosphate

XIE Fazhi(),WANG Xuechun,YANG Peipei,LI Haibin,SHENG Dandan,HU Tingting,XIE Zhiyong   

  1. School of Materials Science and Chemical Engineering,Anhui Jianzhu University,Hefei 230601,China
  • Received:2015-07-24 Accepted:2015-11-18 Online:2016-04-01 Published:2016-04-01
  • Contact: XIE Fazhi
  • Supported by:
    Supported by the National Natural Science Foundation of China(No.21107001), the Natural Science Foundation of Anhui Province(No.1608085MB43), Key Program of the Education Department of Anhui Province, Excellent Young Talents Supporting Plan for University of Anhui Province(2014)

Abstract:

High purity Ca-Al-layered double hydroxides(LDH) was prepared in an ethanol/water solution at a volume ratio of 4:1. Effect of sorbent dosage, adsorption time, pH value, inorganic electrolyte(Na2CO3, KCl, Na2SO4, KNO3), temperature for phosphate adsorption were investigated. As prepared Ca-Al-LDH is an effective sorbent for phosphate adsorption. The maximum adsorption capacity of phospahte is 160.78 mg/g and the phosphate removal efficiency reaches to 95.88% at pH 5.1, temperature 318 K, time 600 min, solid/liquor ratio of 0.15 g/250 mL and initial phosphate concentration of 80 mg/L. Inorganic anions can restrain the adsorption of phosphorus on Ca-Al-LDH absorbent. Sorption capacity of phosphate is decreased 23.99% from 69.96 mg/g to 53.18 mg/g with increasing the concentration of Cl- from 2.5 g/L to 25 g/L. The sorption capacity is reduced about 24.79% with SO42- at the same conditions. Other inorganic anion also has a certain influence on phosphate sorption in pure Ca-Al-LDH. The second order kinetic equation is suitable for describing the adsorption process, and the Langmuir isotherm model fits the data well. The sorption mechanism is electrostatic attraction, chemosorption and anion intercalation.

Key words: liquid phase coprecipitation, layered double hydroxides, phosphate adsorption, thermodynamics and kinetics equation