The Adsorption Effect Of Thermally Activated Limonite On Trivalent Arsenic In Water

Limonite is an important nano-mineral resource.It is an aggregate of minerals widely distributed on the surface of the earth.The main mineral is goethite at the nano-particle level.This paper selects three types of limonite ore of Tongshan area(Yeshan black limonite formed by weathering of andalusite,Xinqiao limonite formed by weathering of siderite,Shaujiluo limonite of weathering of pyrite),Using goethite synthesized by artificial hydrothermal method as a control,the arsenic removal efficiency of different types of limonite and its thermally activated products is compared;the mechanism of thermally activated limonite on the removal of trivalent arsenic ions in water;The functional material of nano minerals for removing arsenic in groundwater.Powder crystal X-ray diffraction(XRD),X-ray fluorescence spectroscopy(XRF),transmission electron microscopy(TEM)and other main research methods were used to characterize and analyze the composition of the four samples and their thermally activated products;Thermal activation temperature,solution p H,As(?)concentration,reaction temperature and adsorption time and other factors affect the effect of thermally activated limonite in removing As(III)in water,fitting and calculating reaction kinetics and thermodynamic parameters;through in-situ DO comparison experiment and data review explain the mechanism of action on As(?);through the comparison of As(III)removal effect of four limonite thermal activation products,analysis shows that Mn2 + adsorbs trivalent arsenic in water by thermally activated limonite Effect.The main results and cognition of the paper are as follows:(1)The optimal temperature of the four heat-activated limonite is 300 ?,the mineral changes from goethite phase to nanocrystalline hematite,with the largest specific surface area and more active sites.(2)The thermally activated Yeshan and Xinqiao limonite products have a good effect of removing As(III)in water,and the p H value in the range of 2-7 has little effect on the removal of As(III)by thermally activated limonite;The product with the best thermal activation temperature of 300 ? is selected to participate in the reaction under room temperature and neutral environment,and the removal rate is above 90%;the reaction follows the quasi-second order kinetic equation and the Langmuir adsorption isotherm model;by ? G <0,? H> 0 It can be seen that the reaction is an endothermic reaction that can proceed spontaneously;? S> 0 means that the molecular arrangement is more chaotic during the reaction and is an irreversible process.(3)Through in-situ DO / p H experiment and with / without oxygen control experiment,the thermally activated limonite product has adsorption and catalytic oxidation on As(?),and the thermally activated limonite product heats As(III)The adsorption efficiency is reduced to about 30%;(4)Comparing the adsorption effect of four heat-activated limonite products,it is found that the manganese oxide in the mineral has a significant enhancement effect in the removal of As(?).The better.(5)The effect of removing As(III)in water by heat activated limonite at 300 ? can achieve purification effect.The removal efficiency of Yeshan limonite with the highest manganese oxide content is better than that of the other three minerals,at 1 mg / LAs)The removal rate of the solution system is 100%.The nano-mineral functional materials prepared by this method have great application value in the treatment of groundwater arsenic pollution,and at the same time provide new ideas for the utilization of limonite resources.