| Heavy metals in the environment mainly come from the discharge of industrial wastewater.How to economically and effectively remove the heavy metals in industrial wastewater is the difficulty in the field of water treatment.The heavy metal ions in wastewater has the advantages of high efficiency,low energy consumption,economy and less pollution.However,there are still some problems,such as complex preparation methods,easy secondary pollution,poor mechanical properties and weak selective adsorption capacity,which limit their wide application prospects.Therefore,we developed a new green composite gel sphere adsorbent and studied its adsorption behavior and mechanism for copper（Ⅱ）.In this paper,H2O2 oxidized biochar（MPB）was prepared as raw material,polyacrylic acid（PAA）as water-soluble thickening（Ca Cl2）as crosslinking agent,calcium chloride（Ca Cl2）as cross-linking agent by sodium alginate.In addition,the synthesis conditions of MPB-ALG gel balls were optimized and the functional groups,specific surface area and properties of each prepared material were characterized by FTIR,BET,SEM,TGA and XPS.The adsorption properties of MPB,alginate（ALG）and MPB-ALG gel spheres for copper（Ⅱ）were compared by batch adsorption experiments.The effects of solution pH,adsorption time,initial solution concentration,initial solution temperature,and coexisting ions on copper adsorption（Ⅱ）of each adsorbent were studied,and MPB-ALG gel ball was applied to simulate the treatment of copper-containing wastewater,its regeneration properties were tested and the adsorption mechanism was explored.The study results are as follows:1)The synthesis conditions of MPB-ALG were explored and biochar.It was suspended to alginate with a mass ratio of 1:1,double crosslinked into a calcium chloride solution with a concentration of about 20%,and the resulting adsorbent MPB-ALG-1 had better removal performance against copper（Ⅱ）.2)The maximum adsorption capacity of MPB-ALG-1 to copper（Ⅱ）at pH of 5 is117.4 mg g-1,which is much higher than MPB(37.4 mg g-1).The Elovich kinetic model and the Freundlich adsorption isotherm data on MPB-ALG-1 can be most accurately described with the isotherm data.3)The adsorption process of copper（Ⅱ）by MPB-ALG-1 is a non-uniform multilayer adsorption of physicochemical interaction.After five cycles,the adsorption capacity of MPB-ALG-1 and ALG remained at 84.5%and 54.7%of the first cycle cycle,respectively.Combined ion coexistence experiments showed that the regeneration and anti-ion interference performance of MPB-ALG-1 material was significantly better than the blank control ALG.4)According to the BET results,the MPB surface area of the biochar oxidized by peroxide(2.0 m2 g-1)is about twice that of the original biochar(0.95 m2 g-1).According to the FTIR and XPS analysis,the carboxyl and hydroxyl groups in the material participate in the adsorption process of copper（Ⅱ）.As calculated from the experimental data,the contribution of the material MPB-ALG-1 adsorption mechanism follows the order of ion exchange>complexed>electrostatic attraction. |
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