Study On The Removal Performance Of Heavy Metal Cu(Ⅱ) From Auto Parts Plating Wastewater By Biochar

The unprecedented boom in the automotive,electronics,machinery and aerospace industries has contributed to the rapid development of the electroplating industry.At the same time,the discharge of electroplating wastewater cannot be ignored,and special attention and solutions are needed for the deep treatment of electroplating wastewater containing heavy metals.In this paper,by simulating the main component factors in the plating wastewater of automotive parts,acidic environment and high concentration of surfactants,the adsorption of heavy metals Cu(Ⅱ)in plating wastewater using biochar and potassium humate modified four kinds of biochar to adsorb Cu(Ⅱ)in simulated plating wastewater were studied,and the optimal modified biochar was screened as the adsorption object to provide ideas for the later research.The main findings of this paper are as follows.(1)For the same adsorption material,when the initial solution hydrochloric acid concentration increased from 1.5%to 4.0%,the effect of H~+on the adsorption of Cu(Ⅱ)in the simulated electroplating wastewater solution by biochar did not change significantly,but the adsorption efficiency of Cu(Ⅱ)in the simulated electroplating wastewater solution by biochar decreased from 3.62%to 2.88%.With the increase of the initial pH value of the electroplating simulated waste water solution,the adsorption effect of biochar on Cu(Ⅱ)in the simulated auto parts electroplating waste solution increased.When the simulated electroplating waste water solution used less than 1.5%concentration of hydrochloric acid and the pH value was greater than 1.64,the effect of H~+on the adsorption of Cu(Ⅱ)in the simulated auto parts electroplating waste solution by biochar was more obvious,and when the concentration of hydrochloric acid decreased from 1.5%to 0%,the adsorption of Cu(Ⅱ)in the simulated auto parts electroplating waste solution by its biochar The adsorption efficiency of Cu(Ⅱ)in the simulated automotive parts plating waste solution increased from 3.62%to 40.59%when the concentration of hydrochloric acid was reduced from1.5%to 0%.It can be seen that the higher the initial pH value of the solution,the more favourable the adsorption of Cu(Ⅱ)in the simulated auto parts plating waste solution by the biochar.(2)In this paper,fatty alcohol polyoxyethylene ethers(JFC)and cetyltrimethylammonium bromide were directly referenced to simulated wastewater to investigate the adsorption of Cu(Ⅱ)in water by biochar under different initial solution conditions.For the same adsorbent materials,the addition of cetyltrimethylammonium bromide and fatty alcohol ethoxylates to the simulated wastewater resulted in a clear reduction in the adsorption efficiency of biochar for Cu(Ⅱ),and the adsorption efficiency of biochar with the addition of fatty alcohol ethoxylates was lower compared to the same environment.The main influencing factors are that cetyltrimethylammonium bromide contains a large number of cations,which compete with metallic Cu ions as the concentration of surfactant increases,and that fatty alcohol ethoxylates contain a large number of non-ions,which can alter the interfacial properties between the solid particles and the contaminant,which in turn affects the adsorption of the material.At the same initial solution,the adsorption efficiency of Cu(Ⅱ)in the simulated solution of electroplating wastewater increased significantly when the dosage of biochar was added.The final adsorption effect at an initial solution Cu(Ⅱ)concentration of 100 mg/L was better than the initial concentration of 50 mg/L solution.The biochar adsorption effect was greatly influenced by the surfactant in the water.When no surfactant was added,the coconut shell biochar input increased from 0 g to 2 g,the adsorption rate increased from0%to 83%for a 50 mg/L Cu ion solution and from 0%to 78%for a 100 mg/L Cu ion solution,with a significantly higher removal effect.The adsorption rate under 0.5%cetyl conditions increased gradually with the addition of the two surfactants,and the change in the removal rate of copper ion solution at 50 mg/L was the same as the change in the adsorption rate with the addition of JFC.It can be seen that in the actual treatment of electroplating wastewater,the amount of biochar input should be increased and the surfactant content should be reduced in order to improve the efficiency of removing heavy metals Cu(Ⅱ)from water bodies.(3)In this paper,four types of biochar were modified with potassium humate and the adsorption capacity of various modified activated carbons under the optimized conditions was coconut shell>columnar>fruit shell pellet>corn cob by single-factor adsorption test.The increase of modification time was beneficial to improve the adsorption efficiency of Cu(Ⅱ)by biochar.The modified coconut shell biochar showed the highest removal rate of Cu(Ⅱ)from simulated auto parts plating simulated wastewater.The maximum adsorption efficiency was 74.02%,which was 1.3 times higher than the adsorption efficiency of the original coconut shell biochar for Cu(Ⅱ),when the solution pH was set at 6 and the adsorption time was set at 570 min at room temperature.The adsorption process followed the Langmuir isothermal adsorption equation,and the maximum adsorption capacity was19.26 mg/g,which was more than 1.3 times that of the original activated carbon;and the adsorption of Cu(Ⅱ)on potassium humate modified coconut shell biochar was consistent with the quasi-secondary kinetic model.It can be seen that the optimum conditions of biochar type,modification concentration,modification time and temperature should be selected in the process of potassium humate modified biochar in order to achieve the optimum adsorption effect.