Study on Zn(II) Removal Efficiency by Phosphoric Acid Modified Rice Husk

The paper investigated the treatment effect of modified rice husk as an adsorbent on wastewater containing Zn(II). Langmuir and Freundlich equations quantified the Zn(II) removal effect of modified rice husk. We analyzed characteristics of adsorption kinetics, the initial pH value, temperature effect on adsorption process, and compared with the regeneration efficiency of adsorbent. The results showed that: compared to the non-modified rice husk, modified rice husk's Zn(II) adsorption capacity significantly increased from 12.41 mg·g^-1 to 21.32 mg·g^-1. Pseudo-second-order kinetic equation fitted adsorption process better, coefficient R was 0.9731. The best pH value with which modified rice husk removed Zn(II) was 5. Adsorption capacity reached to 15.07 mg·g^-1, and changes in pH value were little before and after adsorption. Effects of temperature on the adsorption process were very small and can be ignored. HCL, H₂SO₄ and HNO₃ of different concentrations and volumes all had desorption capacity to some degree, a desorption rate was mostly between 40%-50%. It was feasible to remove Zn(II) in wastewater with modified rice husk. The study of batch adsorption experiments can provide reference for the research of dynamic adsorption experiments and adsorption mechanism.