Synergistic Treatment of Uranium-containing Wastewater by Attapulgite and FeSO_4

By static adsorption experiments,the effects of pH,adsorption time,uranium's initial concentration and adsorbent dosage were studied on biosorption capacity of attapulgite and cooperative adsorption of attapulgite and ferrous sulfate for uranium.The adsorption process was analyzed in thermodynamics and kinetics,and the adsorption mechanism was analyzed by infrared spectroscopy and scanning electron microscope.The results show that the adsorption rate of attapulgite on UO22+ reaches 89.5% and the saturated adsorption capacity of attapulgite is up to 40.8 mg/g in 30 min at 25℃,pH=5.0,15g/L of attapulgite dosage and 100mg/L of uranium initial concentration.When the attapulgite dosage is 20g/L,the uranium initial concentration is100 mg/L,and the ferrous sulfate dosage is 1g/L in 30min at 25℃ and pH=6.5,the uranium initial system of attapulgite and ferrous sulfate on uranium is greatly improved,and the adsorption rate of UO22+ on attapulgite and ferrous sulfate is more than 99.9% and the treated uranium-bearing wastewater can reach the national standard discharge.The adsorption by attapulgite of uranium follows Langmuir adsorption isotherm.In addition,the adsorption by attapulgite and synergistic system are in line with quasisecond order equation.IR micrograph before and after attapulgite adsorbed uranium indicates that the attapulgite is mainly composed of hydroxyl and amido,and the main way of adsorption of uranium is the surface complexing.