Study On Treatment Of Shizhuyuan Polymetallic Mine Wastewater By CP Carbonaceous Adsorbent

Nonferrous metal mining industry is the industry with the largest discharge of industrial wastewater,mineral processing wastewater discharge a large amount of pollutants with high concentration and complex types,causing serious harm to the surrounding environment,how to deal with the mineral processing wastewater in nonferrous metal mining industry is a urgent problem needed to be solved.The adsorption is a widely used method of water treatment.Currently,the adsorbents used are activated carbon,resin and so on,however,various problems including high cost,desorption difficulty after adsorption,transfer of organic pollutants after desorption,poor adsorption effect after multiple adsorption and desorption make it difficult for these adsorbents to realize industrialization.Therefore,an adsorbent with lowest possible price and without requiring regeneration is very desirable.In this paper,a cheap adsorbent obtained from industrial by-product,named CP adsorbent,was used to adsorb the mineral processing wastewater.Three beneficiation flotation agents including Benzohydroxamic acid,Ethyl thiazide and Sodium oleate were selected as the characteristic pollutants,and the mechanism of adsorption was discussed.Different properties of CP adsorbent were prepared by different modification methods,and the influence of modification on surface structure and physicochemical properties of CP adsorbent was investigated.The adsorption isotherm,adsorption rate control process and thermodynamic function calculation of the adsorption wastewater of CP adsorbent were studied.CP adsorbent additive quantity,adsorption time,adsorbent particle size,pH,etc would affected the adsorption.The greater the dosage,the longer the adsorption time and the finer the particle size of the adsorbents,the better the adsorption effect.The COD value of mineral processing wastewater was 150.14 mg/L,and the removal rate was 45.46%,with particle size-0.074 mm,dosage of adsorbent 20 mg/L,adsorption time 30 min,temperature 298 K,oscillation speed 150 r/min,and pH not regulated.Acid modification had obvious dilatation capacity for CP adsorbents,and the specific surface area of CP-HNO₃ and CP-H₂SO₄ increased to 15.745 m²/g and 15.433m²/g,in addition,the alkali modified CP adsorbent had a larger specific surface area than the acid modification,reaching 17.764 m²/g.However,the actual adsorption effect of CP-HNO₃ and CP-H₂SO₄ were better than that of CP-NaOH,which was due to the dissolution of CP adsorbent surface minerals due to acid modification,which made the hydrophobic surface more exposed and provided more active sites.At the same time,acid modification resulted in the increase of acid group content of CP adsorbents,increasing the adsorption of polar organic pollutants,such as Benzohydroxamic acid,Ethyl thiazide and Sodium oleate,but the alkali modification would neutralize the acid groups on the surface of the adsorbent,which was not conducive to the adsorption of polar substances.The modified CP adsorbents improved the adsorption of three kinds of wastewater containing Benzohydroxamic acid,Ethyl thiazide and Sodium oleate significantly.The adsorption behavior of four kinds of CP adsorbent on Benzohydroxamic acid,Ethyl thiazide and Sodium oleate could be described by Freundlich model,indicating that their adsorption behavior was multilayer adsorption based on surface.In addition,the adsorption capacity of CP-H₂SO₄ for three pollutants was the best.The maximum adsorption capacity of Benzohydroxamic acid,Ethyl thiazide and Sodium oleate were 4.77 mg/g,9.24 mg/g and 2.26 mg/g,respectively.The adsorption of CP adsorbents on three kinds of wastewater containing Benzohydroxamic acid,Ethyl thiazide and Sodium oleate were better in accordance with the Pseudo-second-order kinetic model.The control steps of the adsorption rate included external liquid film diffusion,surface diffusion and particle diffusion,but surface diffusion was the dominant factor.The activation energy of Benzohydroxamic acid adsorbed by CP adsorbent were between 15-35 kJ/mol,the activation energy of Ethyl thiazide were 20-45 kJ/mol,and the activation energy of Sodium oleate were20-33 kJ/mol.The adsorption of pollutants on the surface of CP adsorbent was mainly physical adsorption,and the activation energy was small,the adsorption was easy to carry on.Thermodynamic function calculation,△G⁰of Benzohydroxamic acid,Ethyl thiazide and Sodium oleate were positive,which indicated that the adsorption process of CP adsorbent for beneficiation wastewater pollutants was a non spontaneous thermodynamics.And for three kinds of pollutants,as the temperature increasing,△G⁰ gradually increased,△H⁰ was negative,those were exothermic reaction.While△S⁰ was negative,indicating that the adsorption of three kinds of pollutants on the CP adsorbent surface was a process of reducing the degree of confusion in thermodynamics.The modified CP adsorbents were used to treat the actual beneficiation wastewater.The results of the experiment were in agreement with the modified CP adsorbent for the treatment of simulated mineral wastewater.The effect of modification could obviously enhance the adsorption effect of CP adsorbents on mineral processing wastewater.The modified CP adsorbent for acid treatment had a better adsorption effect on the actual beneficiation wastewater,and the COD value after treatment was 105.58 mg/L and the removal rate was 61.65%.