| Aniline Aerofloat(AAF)and Ammonium dibutyl dithiophosphate(ADD)are two kinds of sulfhydryl phosphate collectors,which are widely used in leadzinc ore flotation due to their complex reaction with metals.Excessive use of chemicals and stable chemical properties make it the main pollutant in mineral processing wastewater and cause the total phosphorus in wastewater to exceed the standard.The adsorption method using modified biochar as an adsorbent has an environmentally friendly and efficient removal effect on refractory organic pollutants.In this paper,AAF and ADD are the characteristic pollutants,and copper-loaded biochar(CuBC)is prepared by using aquatic plant wastes and grass as raw materials to study the adsorption performance and mechanism of CuBC on AAF and ADD.(1)Preparation,characterization and screening of biochar.The biochar made by Vallisneria natans was prepared by pyrolysis at 300,400,500 and 600?,and CuBC was prepared by impregnation with copper nitrate solution,respectively.The biochar was characterized by elemental analysis(CHNS,ICP-OES),specific surface area(BET),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),High resolution transmission electron microscopy(HTEM)and X-ray photoelectron diffraction(XPS).The experimental results show that the copper-loaded biochar(CuBC600)prepared by the modification of 600 ? pyrolysis biochar(BC600)has the highest removal rate of AAF and ADD,which are 89.03 % and 91.11 %,respectively.The analysis and characterization of BC600 at different temperatures show that BC600 has stronger ?-? bond formation ability with high aromaticity;BC600 with high content of inorganic elements has higher ion exchange capacity to increase the load of Cu;C600 with high specific surface area,large pore volume and pore diameter provided sites for Cu(II)loading and contaminant adsorption.Various characterization methods show that Cu exists in the form of Cu(II)on the surface of biochar,which indicates that Cu(II)-loaded biochar with high adsorption capacity has been successfully prepared.(2)The adsorption performance of CuBC on AAF and ADDThe effects of factors such as p H,dosage,and adsorption time on the removal rate and adsorption of AAF and ADD in simulated wastewater,as well as the reusability of CuBC were studied respectively.The results showed that when the dosage was 5.0 g/L,the removal rates of AAF and ADD reached 89.03 % and90.11 %,respectively.The p H of the initial solution maintained the best removal efficiency in the range of 4-11,indicating that CuBC has strong p H adaptability to the AAF solution.The maximum theoretical adsorption capacity of CuBC for AAF and ADD is 24.83 and 118.67 mg/g,respectively.After 5 adsorptiondesorption-adsorption cycles,the removal rates of AAF and ADD by CuBC were51.04 % and 65.08 %,respectively.(3)Adsorption mechanism of AAF and add by CubcThe adsorption process of AAF and add by Cubc was consistent with the pseudo second order adsorption kinetic model,and the isotherms were well fitted with Langmuir and Freundlich models,while the former was better.It is indicated that the adsorption of AAF by Cubc is affected by many mechanisms.The results of FT-IR,XRD,SEM-EDS and XPS showed that the adsorption mechanism of AAF and add on Cubc was similar.First,it depends on the surface complexation of Cu(II)with sulfhydryl group.At the same time,the adsorption process is also affected by the hydrophobic interaction: van der Waals force and ?-? Coordination.In addition,the adsorption of AAF and add by Cubc is accompanied by redox reaction.(4)Application of CUBC in mineral processing wastewaterThe removal of phosphorus from lead-zinc mine wastewater by copperloaded biochar has been carried out.The total phosphorus in wastewater is 1.4mg/L,which exceeds the discharge standard by 40%.When the dosage of CUBC was 0.1 g/L and p H was 5,the total phosphorus removal rate reached 94.79 %.In conclusion,CuBC is a highly efficient and environmentally friendly mercapto phosphate wastewater adsorbent. |
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