Synthesis Of Organic-inorganic Composite Mesoporous Silicon By "one-step Method" And Its Adsorption On Cr(VI) In Water

Cr(?)is highly toxic to all living organisms and carcinogenic to humans,which has been regarded as a priority pollutant.Cr(?)with high solubility and mobility can be readily transported to pollute groundwater and surface waters.Therefore,the removal of Cr(?)from contaminated waters is very important.Moreover,the spent absorbents have also been classified as hazardous materials that need to be further treated by landfill.However,some disadvantages(high cost,secondary pollution)of landfill are inevitable.Therefore,how to comprehensively treat Cr(?)-containing water and the spent adsorbent is of particular importance and a challengeable task.Herein,we reported an "one-pot" route to synthesize Organic-Inorganic Hybrid Mesoporous Silica(OIHMS)that can selectively adsorb Cr(?)and the spent adsorbents can be used as the most effective catalysts to decompose CH3SH with extreme toxicity and very low olfactory threshold.In this paper,organic and inorganic composite mesoporous silica adsorbents were synthesized by one-step method and their properties were studied as follows:1)The effects of initial concentration of chromium,adsorption temperature,pH value of solution and coexisting ions on the adsorption The impact of the process.The effects of various parameters(pH value,influent Cr(?)concentration,flow rate,bed depth and coexisting ions on the adsorption of Cr(?)by organic and inorganic composite mesoporous silica were investigated by dynamic experiments.Thomas,Adam-Bohart and Yoon-Nelson models to predict the predicted penetration curves and to evaluate the model parameters of the fixed bed column,which is useful for process design.3)carried out extensive characterization studies,including BET,XRD,XPS,FT-IR and UV-Vis,so that the structure and surface properties of the adsorbent were related to the adsorption properties of Cr(?)removal,Mechanism of adsorption of Cr(?)by.4)Reuse of Cr(?)adsorbent in a fixed bed microreactor to degrade CH3SH.The results of BET and XRD showed that the OIHMS had obvious mesoporous channels.The results of static adsorption show that the organic and inorganic hybrid mesoporous silica can adsorb Cr(?)in water under acidic conditions very well,and the effect of coexisting ions on its adsorption is negligible,which indicates that the adsorbent can adsorb Cr(?)selectively.The results of dynamic adsorption show that the adsorption capacity of the organic and inorganic composite mesoporous materials is the highest when pH = 2,and the three models can fit the experimental results well.The adsorption mechanism was investigated by XPS,FT-IR and UV-Vis characterization.The results showed that the ammonium ions on the surface of the adsorbent were adsorbed with HCrO4-and HCr2O7-ions in the solution.At the same time,partial reduction of Cr(?)to Cr(?)was also found in the adsorption process.Waste Cr-containing adsorbents are considered to be effective catalysts for the decomposition of CH3SH than conventional Ce-based materials and can provide a special route for handling other spent heavy metal adsorbents and other VOCs contaminants.