Study On The Adsorption Mechanism Of Sb(V) And As(V) In Water By Modified Distiller's Grains Biochar

Antimony and arsenic as non-essential metal elements in the human body,their toxic effects are much higher than some metal elements,China as a large antimony production,antimony mining and smelting make antimony pollution become one of the typical environmental problems in China;The arsenic of the same main group is often used as the associated element of antimony in the mining area,which makes the mine water in antimony mining area often contain high concentration of antimony and arsenic.Antimony and arsenic mainly exist in the form of pentvalent oxygen anions in the oxidized environment.It was found that modification of traditional biochar surface loaded with metal ions can change the surface potential of biochar and effectively adsorb oxygen anions such as antimony and arsenic.In view of this,this thesis with grains As raw materials,waste phosphogypsum has economic value to the use of the modifier,with the method of nitrogen purging in preparation of phosphogypsum modification in the tube furnace pyrolysis vinasse biochar,and explore its adsorption effect and mechanism of pentavalent antimony,arsenic,combined with the actual situation of antimony ore wastewater,the indoor simulation experiment to choose modified vinasse biochar to Sb（Ⅴ）,the As（Ⅴ）the optimum adsorption conditions,Combined with biological carbon adsorption vinasse Sb（Ⅴ）before and after modification,the As（Ⅴ）behavior research experiment and BET,TEM,EDS,XRD,FTIR and XPS characterization method reveals modified vinasse biochar adsorption Sb（Ⅴ）,the As（Ⅴ）mechanism,for related mining area water environment of antimony,arsenic governance repair technology to provide the reference.The results are as follows:（1）With waste phosphogypsum and distillers’grains as the matrix,the distillers’grains’biochar modified by phosphogypsum and distillers’grains were fired in a nitrogen-purged tube furnace at a temperature of 1:2 by mass ratio.Pyrolysis temperature is 600℃phosphogypsum modification of vinasse biochar（MC600）obvious change in physical and chemical properties,the Sb（Ⅴ）,the As（Ⅴ）optimal adsorption effect;In Sb（Ⅴ）initial concentration of 24.36 mg/L,solid-liquid ratio,1.25 g/L,p H=7.5,under the condition of vinasse biochar to Sb（Ⅴ）adsorption quantity of about 1 250 mg/kg,and adsorption quantity does not change with the increase of pyrolysis temperature and,on the As（Ⅴ）almost no adsorption effect;Phosphogypsum modification of vinasse biochar with the increase of pyrolysis temperature,for Sb（Ⅴ）,the As（Ⅴ）adsorption effect also gradually increased,the pyrolysis temperature of 600℃respectively,the initial concentration of 24.36 mg/L,14.98 mg/L MC600 to Sb（Ⅴ）,As（Ⅴ）the amount of adsorption is divided into 3092mg/kg,8 667 mg/kg,phosphogypsum modification effect is obvious.（2）The adsorption of Sb（Ⅴ）and As（Ⅴ）by MC600 can reach saturation at 24 h.In the adsorption kinetic model,the adsorption of Sb（Ⅴ）by MC600 by Elovich equation and double constant equation(R²_{Elovich equation}=0.993;R²_{biconstant equation}=0.985)and As（Ⅴ）(R²_{Elovich equation}=0.842;R²_{biconstant equation}=0.820),indicating that the adsorption of Sb（Ⅴ）and As（Ⅴ）by MC600 is the result of reaction process and diffusion process.Moreover,the adsorption process of Sb（Ⅴ）and As（Ⅴ）by MC600 is more complex,mainly on heterogeneous surface adsorption.The results of adsorption isotherm experiments show that Langmuir and Langmuir-Freundlich models have good fitting effect on MC600 adsorption of Sb（Ⅴ）and As（Ⅴ）（Sb（Ⅴ）:R²=0.994,0.994;As（Ⅴ）:R²=0.978,0.975）,which indicated that the adsorption of Sb（Ⅴ）and As（Ⅴ）by MC600 was mainly monolayer adsorption,accompanied by partial multi-layer adsorption.When the dosage ratio is 2.5 g/L and p H=7.5,the maximum theoretical adsorption capacities of Sb（Ⅴ）and As（Ⅴ）adsorbed by MC600in Langmuir model are 8 737 mg/kg and 45 224 mg/kg,respectively.The adsorption effect of As（Ⅴ）by MC600 is far better than that of Sb（Ⅴ）.（3）The MC600 samples before and after Sb（Ⅴ）and As（Ⅴ）adsorption were characterized and analyzed:TEM results showed that the obvious columnar structure was formed after adsorption of Sb（Ⅴ）by MC600.XPS spectra showed that the C 1s spectra of MC600 did not change significantl-y after adsorption,but Sb 3d spectra showed that Sb（Ⅴ）was successfully fixed on MC600,which was mainly because Sb（Ⅴ）did not directly bind to C in MC600,but combined with Ca,O,S and other new compounds during the adsorption process.However,the AS 3d spectrum after MC600adsorption of As（Ⅴ）showed that a part of As（Ⅴ）was reduced to As（Ⅴ）by MC600 during the adsorption of As（Ⅴ）,while MC600 was oxidized.The wide sweep spectrum showed that the Ca content decreased and the C content increased obviously after the adsorption of As（Ⅴ）by MC600,Ca and C are involved in the process of adsorption MC600 Sb（Ⅴ）,and increased-C-O-,-C=OH carbon oxygen functional groups,Show that in the process of adsorption As（Ⅴ）part of the arsenic acid radical ion by complexation adsorption on the surface MC600.（4）Desorption experiments showed that the adsorption of 60.9 mg/L,121.8 mg/L Sb（Ⅴ）solution and 37.45 mg/L,74.9 mg/L As（Ⅴ）MC600 samples after desorption solution,found that after adsorption of the sample 3 times total desorption rate were 27.5%,29.3%and 59.3%,56.3%,combined with the mechanism of FTIR and XPS analysis showed that MC600 after the adsorption of Sb（Ⅴ）formed a relatively stable compounds,not easy to appear desorption phenomenon,mainly chemical adsorption,adsorption While MC600 adsorption As（Ⅴ）partafter desorption,this suggests that there are physical adsorption and complexation.