Preparation And Properties Of Magnetic Adsorbent

With high water volume, complicated water quality, high toxicity, igh acidity etc, heavy metal wastewater can cause heavy pollution to the water environment. Cr(Ⅵ) and Hg(Ⅱ) are widely applied to the dye production, but its drainage containing Cr (Ⅵ) and Hg (Ⅱ) is attributable to difficult metal wastewater.In addition,Cr(Ⅵ) and Hg(Ⅱ) have carcinogenic, teratogenic, mutagenic effects on human body, which are listed as the most harmful chemicals to human health and the internationally recognized cancer-causing metals. Adsorption methods have been developed in the treatment of Cr(Ⅵ) wastewater and a good effect has been made. Metal reduction process has been developed in the treatment of Hg(Ⅱ) wastewater and the removal efficiency is also high.Firstly, magnetic adsorbent FMS was preparated and used to remove Cr(Ⅵ) wastewater. Secondly this study also selected reduction and extraction process to pretreatment the actual wastewater with high concentration of Hg(Ⅱ) and anthraquinone dye.The experimental results of the preparation of magnetic adsorbent show that precursor 1,6-hexamethylenediamine affected the adsorption performance of FMS. So three kinds of magnetic adsorbents, named FMSn=1,2,3,were obtained by reasonably regulating contents of the 1,6-hexamethylenediamine in the optimizing experiments process, respectively. Magnetic adsorbents were used to adsorb Cr(Ⅵ) from aqueous solution Effects of contact time, initial concentration and pH on adsorption amount of Cr(Ⅵ) were investigated, and the best adsorbent was found to be FMS3, which was characterized by Field emission scanning electron microscope (FESEM), Fourier transform infrared spectrometer (FT-IR), and Zeta potential. The experimental results indicated that the highest adsorption capacity of Cr(Ⅵ) was around pH=2. At room temperature, the adsorption of Cr(Ⅵ) on FMS3 reached equilibrium within 120 min and saturated adsorption capacity for Cr(Ⅵ) was approximately 63.78 mg/g when that the adsorbent amount was 1.0 g/L. The adsorption isotherm can be well described by the Langmuir equation and the adsorption kinetics fitted to the pseudo-second-order model. The thermodynamic parameters (△G°, △H° and △S°) indicated that the adsorption was spontaneous and endothermic process with increased entropy, and higher temperature would benefit the adsorption. The adsorbent can be repeatedly utilized with no significant loss of adsorption capacity. In addition, the FMS3 is spherical particles with the average particle size of 45～65 nm, and its surface possesses positive electricity in acidic solution.This study also selected reduction and extraction process to pretreatment the actual wastewater with high concentration of Hg(Ⅱ) and anthraquinone dye. The experimental results indicated that concentration of Hg(Ⅱ) was decreased to 0.81 mg/L from 955.12 mg/L by adding iron powders hierarchically, that meant the removal efficiency of the Hg(Ⅱ) reached above 99.0%. At the same time, the COD was decreased to 45100.0 mg/L from 955.12 mg/L by adding iron powders hierarchically. The anthraquinone dye were decreased to 1760.0 mg/L from 45100.0 mg/L by extraction separation, that meant the removal efficiency of anthraquinone dye reached above 96.1%. The aqueous alkali could promote the recycle of composite extracting agent by reextraction process.And the extraction efficiency reached 96%.