Study On The Removal Effect Of Arsenic And Antimony By Titanium Carbide Composite Metal Organic Framework Under Electric Field

Arsenic-antimony in wastewater is a widespread source and,in either its oxidised form or bound state,is a serious health hazard and effective removal of arsenic-antimony is essential.Adsorption methods are widely used in water pollution control due to their simplicity and effectiveness.Titanium carbide(MXene),a two-dimensional inorganic compound with high electrical conductivity and abundant functional groups,and metalorganic framework(MOF)with high surface area and excellent adsorption sites are very promising in the field of heavy metal treatment,and the composite of MXene and MOF can effectively prevent the collapse and loss of MXene.In this study,titanium carbide composite metal-organic framework(MXene@MOF)materials were prepared,and the effect of MXene@MOF on the removal of arsenic-antimony composite contamination was investigated through batch influence factor study tests;the removal mechanism of contaminants on the surface of MXene@MOF was investigated using combined kinetic,thermodynamic and isotherm fitting characterisation analysis;and the recycling performance of MXene The performance of recycling of MXene@MOF was investigated through simulation tests.The experimental results of this study are as follows:(1)The preparation and characterisation studies of MXene@MOF showed that oxygencontaining groups such as C-OH,C=O and C-O were retained on the surface of MXene@MOF material,and new functional groups such as Mg-O and Ti-O appeared.X-ray diffraction showed that the main characteristic diffraction peaks of MOF existed within MXene@MOF,while in the XPS fitting analysis,the presence of C1s,O1s,O1s,Ti2p and Mg1s,proving that MOF was successfully compounded on the surface of MXene,and the dense 2D intercalated morphological structure of the particles effectively prevented the collapse and agglomeration of MXene,increased the specific surface area of the composite and provided a large number of adsorption sites.(2)Batch simulations of As(III)adsorption on MXene@MOF showed that the adsorption rate increased linearly during the first 30 min and then slowed down to saturation within 120 min;the reaction was more favourable under acidic conditions and at higher temperatures.The adsorption of As(III)was improved by a factor of about 4 after MXene@MOF was prepared as an electrode,with a saturation adsorption capacity of 112.73 mg/g.The processed experimental data were more suitable for the quasi-secondary kinetic and Langmuir adsorption isotherm models,and the adsorption thermodynamic analysis indicated that the adsorption process was heat-trapping and spontaneous.(3)Bulk simulations of As(III)and Sb(III)at the MXene@MOF electrode showed that the adsorption amount increased with initial concentration before reaching equilibrium at 100 mg/L and increased with pH before reaching saturation at pH 5.0.The maximum adsorption of As(III)and Sb(III)in solution at 25℃ and pH 5.0 was 80.16 mg/g and 50.78 mg/g for MXene@MOF.The adsorption process is more suitable for the quasi-secondary kinetic model where chemisorption is the main effect,depending on the number of active sites,involving ligand complexation of surface functional groups and ion exchange,and for the Langmuir adsorption isotherm model where adsorption on the surface of a single molecular layer is the main effect.(4)The study of the removal mechanism of MXene@MOF for arsenic-antimony composite pollution showed that a large number of oxidation intermediates(·OH and·O2-)played a dominant role in the removal of arsenic-antimony composite pollution,while direct oxidation also occurred on the electrode surface under electric field conditions,and the large specific surface area and the abundance of oxygen-containing functional groups(-OH,C=O,C-O)of MXene@MOF facilitate the subsequent adsorption of As(V)and Sb(V)arsenical antimony.Sb and As are immobilised on the surface of the material by ligand substitution of hydroxyl groups on the surface of MXene@MOF,forming complexes(Sb-O,As-O).(5)The results of the recycling performance study of MXene@MOF showed that after 5 cycles of MXene@MOF electrode cathode interchange,the removal rate of pollutants by the eluted and regenerated MXene@MOF decreased by about 30%,and the removal rate of the eluted and regenerated MXene@MOF by 0.1 M NaOH decreased by about 60%.Compared to conventional desorption,the MXene@MOF electrode has better reusability and can be desorbed by simply swapping the cathode and anode,achieving a simple,efficient and environmentally friendly result.