Adsorption Of Cr(Ⅵ) From Aqueous Solution On Organic-inorganic Hybrid Mesoporous Material

With the increasingly serious water pollution problems and further improvement of the effluent quality required, conventional water treatment technology for the removal of contaminants in polluted water is obviously inadequate. Therefore, it is particularly necessary to develop efficient, economic, and sample technology to get rid of micro-pollution. Adsorption is one of the effective methods to remove pollutants from water, but most of the conventional adsorption materials have low adsorption capacity and poor selectivity, so, in view of the hot issue of adsorption and removal of pollutants in the water, this paper studied and developed some organic and inorganic compound mesoporous materials, which will apply to the treatment process of heavy metal wastewater, as an efficient adsorbent, we investigated its adsorption and removal efficient and mechanism on the Cr (Ⅵ) in water, and will provide effective technology support for the security of water quality, the efficient solutions and means for Cr (Ⅵ) pollution situations at the same time.This paper based on the organic-inorganic hybrid mesoporous materials, according to the Cr (Ⅵ) characteristics in water, investigated the application prospect and mechanism of the materials in the field of Cr (Ⅵ) waste water treatment from the following aspects:(1) comparison and screening experiment study of adsorbentFirst synthesised the organic-inorganic compound mesoporous materials by hydrothermal synthesis with different organic components (Dodecyltrimethylammonium Bromide; Myristyltrimethylammonium bromide; Hexadecyl trimethyl ammonium Bromide; Trimethylstearylammonium Bromide), in different drying temperature (110℃;150℃;190℃;230℃). separately recorded as HMx-y(x=D,T,C,S:=110,150,190,230)We made a comparative study about the effect that all compound materials adsorption Cr (Ⅵ) that in water.Results indicated that under the experimental conditions of the initial concentrations of chromium in50mg/l or100mg/1, pH=2.0, room temperature of25±1℃,0.1g/L adsorbent,16-alkyl trimethyl ammonium bromide as organic compound, dry2days at110℃, composite material (HMC-110) synthesised worked best for Cr (Ⅵ) adsorption.(2) batch experim(?)al study on the adsorption effect of HMC-110for Cr (VI) We studied the adsorbent HMC-110on chrome adsorption under static conditions. Investigated the factors include the pH value of solution, adsorption time, initial concentration of chromium, adsorption temperature, coexistence ions and absorbent dosage, which influenced the adsorption process.The results showed that the factors include the pH value of solution, adsorption time, initial concentration, adsorption temperature, coexistence ions and absorbent dosage, which had an influence of different level on adsorption process. Adsorbent HMC-110represented strong adsorption ability to Cr (Ⅵ) in pH=2, the highest adsorption rate appeared in the pH=2near, value is99.5%;With the initial concentration of Cr (Ⅵ) increased, the removal rate of HMC-110for Cr (Ⅵ) declined, when initial concentration of Cr (Ⅵ) was1000mg/1, adsorption rate was very low.Adsorbent dosage was another important factor affected the adsorption rate, with increase of the content of absorbent, chromium adsorption rate rised fast; under the condition that coexistence ion include NO3-, Cl-, CO32-, PO43-, SiO42-, SO42-existed except SiO42-ions, other competitive adsorptions were barely influence the adsorption of HMC-110for chrome, we infer the mechanism of HMC-110adsorb chrome was Cr2O72-and Si-O-Si that on the surface of HMC-110formed electron donor/receptor coordination effect.The adsorption of Cr (VI) for HMC-110in line with the second-level dynamics model, meet the Langmuir adsorption isotherm models, the maximum adsorption capacity lowering with the raising of temperature, adsorption was exothermic processes; the pH values of solution influenced the adsorption of HMC-110for Cr (Ⅵ); desorption experiments suggested that adhesion of Cr (VI) in HMC-110was strong.(3) Optimize the experimental conditions of adsorption of HMC-110for Cr (VI) by using response surface methodWe used the response surface method to study the adsorption conditions of HMC-110for Cr (Ⅵ), investigated ihe pH value of the solution; dosage; reaction temperature and so (?) that influenced the adsorption, Box-Behnken experimental model design, response surface classification research method analysis data and software was the Design Expert Version8.0(Stat Ease, USA). Finally, material characterization was provided by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), N2adsorption-desorption technology at low temperature, transmission electron microscopy (TEM), differential thermal scanning thermal methods (DSC) and TG-DTA (TG-DTA). The results showed that organic and inorganic components compound together successfully, materials had obvious mesoporous pore structure.