Study on Treatment of Wastewater Containing Heavy Metal Ions Using Modified Metallurgical Residue Produced from Oceanic Cobalt-rich Crusts Leaching Process

摘要

In this paper,the application of the metallurgical residue produced from oceanic cobalt-rich crusts leaching process is studied in the area of wastewater treatment.The modification of the sulfuric acid leached residue and the adsorption behaviour of heavy metal ions such as (Pb(Ⅱ),Cu(Ⅱ),Zn(Ⅱ),Cd(Ⅱ),Ni(Ⅱ),Mn(Ⅱ),Co(Ⅱ),As(Ⅲ)) in the wastewater on the surface of the residue are investigated.The adsorption efficiency of heavy metal ions in the wastewater on the modified sulfuric acid leached residue is investigated.It is showed that when the initial pH value of wastewater containing heavy metal ions including Pb(Ⅱ),Cu(Ⅱ),Co(Ⅱ),Ni(Ⅱ),Mn(Ⅱ),Zn(Ⅱ),Cd(Ⅱ) and As(Ⅲ) range from 1.4 to 1.9,with the use of the modified leached residue,As(Ⅲ) ion can be selectively separated from wastewater,and the separation efficiency can reach 90%～100%.The adsorption efficiency is affected by pH,reaction time,amount of adsorbent and the initial concentration of heavy metal ions in wastewater.The results showed that the optimum pH was natural pH value and the absorption equilibrium time was 2 hours.The adsorption efficiency of heavy metal ions increases with the addition of adsorbent and decreases with the increase of the initial concentrations of heavy metal ions in wastewater.The heavy metal ions polluted wastewater,of which concentration is about 22.5～793.6 mg/L,can meet the national disposal standard for industrial wastewaters in China very well,after 2 hours treated by 3.75～7.50 g/L modified adsorbent at room temperature.Standard methods were used to investigate the absorption behaviour between absorbent and metal ions in the wastewater.It is concluded that the adsorption behaviour of Co(Ⅱ),Mn(Ⅱ) and As(Ⅲ) ion fits Freundlich isotherm,while the adsorption behaviour of Pb(Ⅱ),Cu(Ⅱ),Zn(Ⅱ),Cd(Ⅱ) and Ni(Ⅱ) ions fits Langmuir isotherm,and the saturated adsorption amount of the modified adsorbent is about 54.0～336.7mg metal/g·absorbent.It is suggested that the modified sulfuric acid leached residue produced from oceanic cobalt-rich crusts is environmentally attractive and meaningful as absorbent used in heavy metal ions polluted wastewater.