Study On Arsenic Removal Mechanism And Passivation Of Arsenopyrite By Hunan Manganese Ore

Arsenic is a highly toxic metalloid element that is widely present in the earth's crust and potential threat to the human body.After entering the natural environment through such as production and life,it will cause pollution to water bodies and soils and enrich them through the food chain,causing a series of irreversible harm to the human body.Therefore,it is particularly important to study the effective remediation technology and preventive measures for arsenic pollution.In this paper,the adsorption and removal of arsenate?As?V??and arsenite?As?III??in solution by manganese ore were studied by means of isothermal adsorption curves and adsorption kinetics experiments.Finally,in the experiment of the manganese ore arsenopyrite system,by changing the mass ratio of manganese ore to arsenopyrite,as well as the influence factors such as temperature and external iron source,the arsenic adsorption and migration behavior of arsenopyrite under the influence of manganese ore.The release of arsenic will provide theoretical basis and new minerals for in-situ treatment of arsenic pollution.The main results are as follows:1?Characterization of physical and chemical properties of test samples of manganese ore and arsenopyrite.?1?XRD results show that vernadite,cryptomelane,quartz,and kaolinite are the main minerals in the manganese sample,and also contain some clay minerals;the main diffraction peaks in the arsenopyrite sample The agreement with the characteristic peak of pure poisonous sand is very high,and no other peaks appear,indicating that the arsenopyrite sample is purity.XRF results show that the main elements of the manganese sample include Mn,Al,Si,and Fe;the main elements in the arsenopyrite sample include As,Fe,and S.?2?XPS shows that the main forms of Mn on the surface of manganese samples are Mn⁴⁺and Mn²⁺,and the main forms of Fe are Fe³⁺and Fe²⁺;As⁵⁺and As³⁺are As elements in arsenopyrite.The main existence forms of the Fe element are Fe³⁺and Fe²⁺,and the main forms of the S element are S^2-,?AsS?^2-,and S_n^2-.2?Manganese ore sample adsorption and removal capacity.?1?Through batch and column experiments,research the adsorption and migration behavior of manganese ore.Temperature has no significant effect on the adsorption performance of manganese ore,while the effect of pH is greater than As?III?.The adsorption of As?V?and As?III?by manganese ore is different,but both conform to the Langmuir model.The amounts were 1.32 and 0.30 mg/g,respectively;the adsorption kinetics conformed to pseudo-second-order kinetics,and the rate constant K₂^[As???]>K₂^[As???],indicating that the rate of As?V?adsorption was faster;The difference in the removal of As?V?and As?III?by manganese ore indicates the oxidation and adsorption process of As?III?by manganese ore in the system.?2?In column experiments,the effect of flow rate on the retention of As?V?in manganese ore is greater than that of As?III?;at the same flow rate,the adsorption amount of manganese ore to As???is twice that of As???;the adsorption of manganese ore to cations All of them produced antagonistic effects.Among them,Al³⁺had a greater effect on As?III?adsorption,and the amount of adsorption decreased by about 11 times.In the anion experiment,the antagonism of PO₄^2-and SiO₃^2-on As???adsorption was greater than As?V?,PO₄^2-reduces the adsorption amount of As?III?by about 7 times,and SiO₄^2-about 6 times.?3?XPS found characteristic As?III?peaks on the surface of As?III?-manganese system samples,and infrared spectra found weak As?III?peaks on the surface of As?III?-manganese system samples,indicating that manganese ore not only uses its own Oxidation characteristics:As?III?is oxidized and re-adsorbed,as well as direct adsorption.?4?Manganese ore makes the pH of arsenopyrite solution rise,Eh decreases and remains stable;manganese ore plays an adsorption and oxidation role in the manganese ore-arsenopyrite system,which is manifested in the direct adsorption of arsenic and the dissolution of arsenic pyrite The oxidation of Fe²⁺and S promotes the formation of Fe?OH?₃ and FeAsO₄ and accelerates the adsorption of arsenic.