| With the development of arsenic metal mineral mining and non-ferrous metal smelting and chemical products containing arsenic,arsenic and a large number of pollutants into the environment,the destruction of the ecosystem,causing great harm to human beings.Both at home and abroad for arsenic pollution a lot of researches has been studied,but the mechanism of migration and transformation of arsenic existing problems is not clear and long term treatment effect is not ideal.This experiment adopts nano iron,carbon nano materials,clay material as adsorption material for treatment of wastewater containing arsenic,and through the investigation of adsorbent dosage,pH,reaction time,reaction temperature and other factors affecting the adsorption effect,determine the optimum adsorption conditions of several adsorption materials.At the same time in Nanhua County Historical arsenic slag chemical factory as the research object,using ferric salt as stabilizer for stabilizing treatment,evaluate the stabilization effect of arsenic "sulfuric acid nitric acid leaching method,type of investigation" stabilizer,dosage,pH,arsenic slag granularity,reaction time,reaction temperature and other factors affecting the stability of experiment,determine the pharmacy The best chemical stabilization and optimal stabilization conditions.Combining with BET,FT-IR,XRD,SEM and other instruments to phase analysis of arsenic liquid solid phase transformation and stability mechanism,to provide experimental data and theoretical basis for the treatment of arsenic in the environment.The experimental results show that nano iron>carbon nano materials>iron modified stone powder removal of arsenic have in water well,modified graphene nano iron modified stone.The optimum adsorption conditions of nano Fe:0.5 g/L dosage,pH=6,adsorption time 1H,reaction temperature is 35 DEG C and the removal rate was above 99%.The optimum adsorption conditions of modified graphene:dosage of 0.1 g/L,pH=7,adsorption time 1H,reaction temperature is 35 DEG C,the removal rate of close to 100%.modified stone optimum adsorption conditions were as follows:the dosage of 2 g/L,pH=5,adsorption time 2h,reaction The temperature of 35 DEG C,the removal rate was above 97%.The adsorption of several materials are very quickly,can reach close to the saturation adsorption capacity in 20min,the optimum pH was slightly acidic conditions,the optimal reaction temperature is 35 degrees centigrade.The particle size has a certain impact on arsenic leaching granularity,when the size is less than 1mm,the leaching concentration of arsenic increased rapidly with the decrease of the diameter,the said arsenic slag and the smaller the particle size of the relative amount of arsenic is high,but also easy to transfer.Arsenic iron salt,aluminum salt and magnesium salt of arsenic has certain stable effect,the adsorption effect order:ferric salt>aluminum salt>magnesium salt.The stability of ferric iron is better than two valent iron,and the Fe(NO3)3 is optimal.The optimal operating conditions were:the molar ratio of Fe/As was 1,pH=6,room temperature stabilized 1H,arsenic the leaching concentration is lower than 2.5 mg/L and basically stable,Meet the requirements of safe landfillThe study by RT-IR,XRD,SEM,BET were characterized by means of adsorption materials and slag phase analysis,observe the morphology,crystallinity and morphology,to explore the mechanism of stability.The stability mechanism of arsenic arsenic may as follows:(1)precipitation,iron ions and arsenic ions direct reaction of free acid production insoluble iron compounds;(2)non specific adsorption,liquid phase,porous material load iron after surface with positive charge,and arsenate anions by electrostatic attraction and adsorption of arsenic slag in solid ferric salt as a stabilizer,the formation of iron hydroxide surface with positive charge and arsenate anions Through electrostatic attraction and adsorption;(3)the specific adsorption of ferric iron hydroxide generated in liquid phase and solid phase,the adsorption of arsenate,arsenite,substituted iron hydroxide surface polynuclear ligand complex ion-OH,-OH2 ligand,the coordination effect of formation of amorphous ferric arsenate the precipitation.This study has a certain reference value for the solid phase transfer and stabilization mechanism of arsenic and arsenic,and has a certain guiding significance for the practical application of arsenic... |
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