Study on the Adsorption Performance of Mg-HAP-HA Composite Adsorbent for Pb(Ⅱ)

The adsorption method can effectively remove a variety of pollutants in industrial wastewater， and the performance of adsorbent determines the treatment efficiency of the adsorption method. In order to find an adsorbent with high efficiency， low consumption， low cost and green safety， hydroxyapatite (HAP) was prepared by coprecipitation method. Mg(II) ions were introduced by adding mixed solutions of Ca(NO3)2·4H2O and Mg(NO3)2·6H2 O with different molar ratios， and then the Mg-HAP-HA composite adsorbent was prepared by adding humic acid (HA) according to different mass ratios. The microstructures of HA， Mg-HAP (in a molar ratio of 0.2) and two Mg-HAPHA adsorbents with different mass ratios were characterized by SEM， FT-IR and XRD. The effects of material ratio， pH value， initial concentration of adsorbate， adsorption time， temperature and dosage of adsorbent on the adsorption rate of Pb(II) were investigated. Results showed that when the dosage of Mg-HAP-HA14 composite adsorbent was 0.06 g， the initial concentration of Pb(II) was 1 200 mg/L， the volume of Pb(II) solution was 50 mL， the pH of the solution was 6， the temperature was 35 ℃， and the adsorption time was 60 min， the adsorption rate of Mg-HAP-HA14 for Pb(II) was 98.51%， and the adsorption capacity could reach 985.1 mg/g. After desorption and regeneration， the adsorption of Mg-HAP-HA14 composite adsorbent for Pb(II) could be recycled twice， and the adsorption rate was 43.97%. The adsorption process conformed to the pseudo-second-order dynamic model， with the chemical adsorption as the main adsorption form.