Preparation Of Silicon Materials Modified By SDBs And DDAC And Their Adsorption To

Bisphenol A (BPA) is widely used in organic chemical industry, which is one of the typical Environmental Endocrine Disruptors. Since bisphenol A has a serious threat to ecological environment and human health, it is very important and significant to efficiently remove BPA from environment.As a common method for removing BPA, adsorption method has attracted more and more attention from researchers because it has the advantages of high speed, high removal efficiency and easy operation. The silica modified by surfactant, which has showed higher adsorption capacity for removing BPA and it may be a kind of potential environmental endocrine disruptors adsorbent. In this paper, blended-surfactant made of dodecyl benzene sulfonic acid sodium and poly(ethylene oxide)-b-poly(propyleneoxide)-b-poly(ethylene oxide) Pluronic PI23was used to form a hydrophobic core, which has a π-π interaction with BPA molecules. With this hydrophobic core, ethyl silicate was used as silicon source to prepare the modified-SiO2material by hydrothermal method. In addition, the mixtured surfactants of12-alkyl dimethyl ammonium chloride and polyethylene glycol were used to form a hydrophobic core with positive charge. With this charged hydrophobic core, sodium silicate was used to prepare the modified-silica powder materials through precipitation method. The two kinds of adsorbent materials were characterized by Scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectra and specific surface area analyzers. The adsorption properties of the two kinds of adsorbent on bisphenol A were studied. The influence factors of solution pH value, adsorption time, bisphenol A initial concentration, temperature and inorganic salt on the absorption process for the adsorptin of bisphenol A (BPA) were investigated. Kinetics equations, Langumir adsorption isotherm model, Freundlich adsorption isotherm model and thermodynamic equation were used to fit and analyze the experiment results.Silica modified by dodecyl benzene sulfonic acid sodium had the structure including a hydrophobic core made of dodecyl benzene sulfonic acid sodium and poly(ethylene oxide)-b-poly(propyleneoxide)-b-poly(ethylene oxide) Pluronic PI23and SiO2as a shell. The π-π interaction between dodecyl benzene sulfonic acid sodium and BPA as well as the solubilization effect of the hydrophobic micelle made the material own high adsorption capacity for the hydrophobic organic compounds. The theoretical maximum capacity for bisphenol A (BPA) was as high as255.1mg/g, and the adsorption equilibrium time was360minutes.The silica modified by12-alkyl dimethyl ammonium chloride had a higher adsorption capacity than silica modified by dodecyl benzene sulfonic acid sodium. Due to the strong electrostatic attraction between the modified-silica and bisphenol A molecules its theoretical maximum capacity for bisphenol A (BPA) was up to333.33mg/g, adsorption equilibrium time was240minutes.Adsorption mechanism of the two materials indicated that silica modified by dodecyl benzene sulfonic acid sodium fitted well with pseudo-first order kinetics, silica modified by12-alkyl dimethyl ammonium chloride complyed with pseudo-second order kinetics. For both the prepared adsorbents, thermodynamic isotherms fitted well to Langmuir equation. The adsorption process was spontaneous endothermic for both the two materials. During the adsorption process, the entropy was positive values for both the two kinds of materials, which indicate that the chaotic degree is increasing in the adsorption process on the solid-liquid interface.