Study On The Adsorption Of Heavy Metal Cu²⁺ And Zn²⁺ By Compost Adsorbent

Heavy metal ions are toxic and hard to be converted in the environment. Heavy metal ions in the environment will get into waters through various channels, and finally enter human body through aquatic products after enrichments in various biologic chains in waters, thus doing damage to human health. Researchers have attempted to remove heavy metal ions from waters through adsorption method, ion sediment method, etc. In which, adsorption method was more widely adopted. In recent years, in order to reduce cost and improve economic returns, many scholars have previously made a great many of studies exploring efficient and cost-effective adsorbents. To select appropriate adsorbents according to the actual situation is of important significance in economical treatment of waste water with heavy metal ions. Studies show that a large number of humus in compost can effectively adsorb and fix heavy metal ions. Based on the water samples contaminated by heavy metals, this study explores the absorption efficiency of compost absorbent for heavy metal copper and zinc and determines the best adsorption time, temperature, pH, dosage, rotate speed, pollutant concentration and other parameters. In order to achieve better adsorption effect, the compost absorbent is subject to pretreatment, providing scientific evidences for economical and effective resource utilization of compost. The main conclusions are listed as follows:(1)The compost absorbent’s adsorption for Cu2+or Zn2+reaches a balance at48h and the best absorbent dosage is0.20g-0.25g. Considering both the responses of the two ions to adsorption temperature,30℃is determined as the optimum temperature and150r/min as the best rotate speed. The best adsorption pH of the compost absorbent for Cu2+or Zn2+should be kept at3-4. The experimental data of the adsorption conform to pseudo-first-order kinetic equation very well, with a correlation coefficient of0.946. The equilibrium absorption capacities obtained from the pseudo-first-order adsorption kinetic equation (Cu2+:qe=36.81mg/g; Zn2+:30.341mg/g) are more close to the experiment values (Cu2+:qe=38.82mg/g; Zn2+:30.94mg/g). (2)The experiment showed that after soaking in1%NaOH solution for3h and then in1%H2O2for3h, the compost got the best effects:its adsorption for Cu2+and Zn2+are respectively increased by13.9%and15.0%, basically reaching balances at24h, with the adsorbing capacities of48.16mg/g and47.98mg/g.