Research On The Synthesis And Adsorption Properties Of Composites Based On Molybdenum Heteropolyacid Decorating Metal Organic Frameworks

The novel composites based on metal-organic framework and polyoxometalate was synthesized by solvothermal method,The composition,structure,morphology,stability,toleration and surface charge of composites based on metal-organic Framework and polyoxometalate have been characterized through X-ray powder diffraction pattern（XRD）,Fourier transform infrared spectrum（FT-IR）,Inductively coupled plasma mass spectrometry（ICP-MS）scanning electron micrographs（SEM）,Zeta Potential,thermogravimetric（TG）,brunaue Emmett teller（BET）.The adsorption of methylene blue onto composites based on metal-organic framework and polyoxometalate in aqueous solution was studied.The specific contents are as follows:The 1,3,5-Benzenetricarboxylic acid and H₃PMo₁₂O₄₀ with Cupric nitrate was used to a tmetal organic frameworks composites,namely H₃PMo₁₂O₄₀@Cu₃（BTC）₂was synthesized.The adsorption property of the composites on methylene blue from water solution was investigated,and the effects of the experimental parameters including the temperature,the initial pH value and initial concentration of methylene blue solution were discussed.The experimental results showed that the lower p H and lower temperature value were beneficial to the methylene blue solution adsorption.The experimental isotherm data and adsorption process of H₃PMo₁₂O₄₀@Cu₃（BTC）₂was found to fit the Langmuir model and pseudo-sencond-order kinetic model.The thermodynamic data showedΔG<0 andΔΗ<0 onto H₃PMo₁₂O₄₀@Cu₃（BTC）₂,indicated that the adsorption of MB is spontaneous and endothermic,the adsorption towards methylene blue,It’s maximum adsorption capacity value reached 240.96mg/g at 193 K and pH 2.The H₃PMo₁₂O₄₀@Cu₃（BTC）₂ rhodamine B and malachite green cationic dyes also showed good adsorption properties.Using H₃PMo₁₂O₄₀ and metal-organic frameworks（MOF-5）as active species and supports,respectively,The novel H₃PMo₁₂O₄₀/MOF-5（Zn₄O（BDC）₃）adsorbent has been prepared by hydrothermal synthetic method;the quite efficient adsorption of methylene blue cationic dyes in aqueous solution on H₃PMo₁₂O₄₀/MOF-5 was studied.The effects of initial pH,temperature and initial concentration of dye solution adsorption onto the composite were systematically explored.The experimental isotherm data and adsorption process of H₃PMo₁₂O₄₀/MOF-5 was found to fit the Langmuir model and pseudo-sencond-order kinetic model.The thermodynamic data showedΔG<0,ΔΗ<0 andΔS>0 onto H₃PMo₁₂O₄₀/MOF-5,indicated that the adsorption of methylene blue is spontaneous and endothermic,The H₃PMo₁₂O₄₀/MOF-5 maximum adsorption capacity was 194.93 mg/g.rhodamine B and malachite green cationic dyes also showed good adsorption properties.The quite efficient adsorption of cationic dyes in aqueous solution on H₃PMo₁₂O₄₀/MOF-5 was studied.The novel composites based on polyoxometalate decorating metal organic frameworksincludingH₆P₂Mo₁₈O₆₂/Zn（BDC）（Bipy）_0.5,H₆P₂Mo₁₅W₃O₆₂/Zn（BDC）（4,4^’-Bipy）_0.5,H₃PW₆Mo₆O₄₀/Zn（BDC）（4,4^’-Bipy）_0.5.5 and H₃PMo₁₂O₄₀/Zn（BDC）（4,4^’-Bipy）_0.5.5 was synthesized by one pot solvent-thermal method its dyes absorption properties were also investigated.The H₆P₂Mo₁₈O₆₂/Zn（BDC）（4,4^’-Bipy）_0.5 hybrid were further applied to remove methyl violet,the effect of pH,initial dye concentration and initial dye temperature were investigated using a batch experiment.By employing polyoxometalate to modify metal organic frameworks,in order to increase the adsorption active site and the driving force of metal organic frameworks.Not only that,polyoxometalate can be polarized to generate the driving force when the composite metal organic framework material adsorbed methylene blue and it can also be used as an active adsorption site to adsorb methylene blue.The kinetic studies showed that the adsorption of dye on three composites follows the pseudo-second-order kinetics,The experimental isotherm data and adsorption process of H₆P₂Mo₁₈O₆₂/Zn（BDC）（4,4^’-Bipy）_0.5 was found to fit the Langmuir equations.The thermodynamic study revealed the adsorption of MB onto three composites to be an exothermic and spontaneous ordered adsorption process.The quite efficient adsorption of to methyl violet,malachite green,rhodamine B in aqueous solution on H₆P₂Mo₁₈O₆₂/Zn（BDC）（4,4^’-Bipy）_0.5 was studied.The H₆P₂Mo₁₈O₆₂/Zn（BDC）（4,4^’-Bipy）_0.5,H₆P₂Mo₁₅W₃O₆₂/Zn（BDC）（4,4^’-Bipy）_0.5,H₃PW₆Mo₆O₄₀/Zn（BDC）（4,4^’-Bipy）_0.5andH₃PMo₁₂O₄₀/Zn（BDC）（4,4^’-Bipy）_0.5maximum adsorption capacity was 277.78 mg/g,267.6 mg/g,588.24 mg/g,478.5mg/g.