| Fly ash is the byproduct of coal combustion, and is one of the leading solid wastes. Much work has been done about zeolite synthesized from coal fly ash (ZFA) in our laboratory. It has been proved that ZFA was an excellent adsorption material with high CEC (cation exchange capacity), it has great adsorption of inorganic anion (phosphate) and cation (Cr (Ⅲ), ammonia). However, ZFA without any surface modification was not efficient for removing organic pollutants in water, which affected the actual application of ZFA as a versatile sorbent. How to improve the removal capacity of organic pollutants on ZFA is one of the obligatory issues to popularize sorbent synthesized from fly ash.The research objective of this dissertation is to develop a novel adsorption material of organic pollutants to treat organic wastewater. In this study, synthesized zeolites by fly ashes (ZFAs) were regarded as raw materials, ZFAs were pretreated by cationic surfactant ( hexadecyl trimethyl ammonium bromide. The organic pollutants sorption capacities of ZFAs and surface modified ZFAs were compared and the effect of common ion (NaCl), pH and other factors on organic pollutants removal efficiency was also analyzed. Adsorption mechanism of organic pollutant by ZFAs sand SZFAs was studied to evaluate the potential of synthesized ZFAs in application for real effluent.The experiment of synthesized and surface organic modified zeolite showed that synthesized zeolites with multiaperture on its surface possess high CEC and large specific surface area. The isoelectric point of SZFA has changed from pH=3 to pH=10 compared with ZFAs. Surface of SZFAs formed bilayer HDTMA which was showed vibration of C=C at the FTIR. At the range of pH=4~11, SZFA showed a great stability.The experiment of cation organic pollutant (MB) on ZFAs and SZFAs showed that sorption of MB by ZFAs are higher compared with SZFAs. The mechanism of MB adsorption on ZFAs is the cation exchange adsorption. HDTMA loading on the surface of ZFAs repulsed with MB which blocked the exchange of cation with MB. The maximum absorbance of MB on ZFAs is between 23.70～50.51 mg g-1 which is an endothermic reaction, at the pH range between 4 to11, with the decrease of pH, MB removal efficiency fell correspondingly. NaCl which is one of the most common electrolytes had a little inhibit function to the MB removal. ZFAs after regeneration still have considerable adsorbent capacity of MB, 450℃is the optimal regeneration temperature with about 90~105% MB absorbance compared with ZFAs before regeneration.The experiment of anionic organic pollutant (humid acid soldium, HA-S) on ZFAs and SZFAs showed that SZFAs had a high adsorption potential of HA-S while ZFA didn’t possess significantly adsorption of HA-S. The maximum adsorbance of HA-S on SZFAs is between 31.65~131.58mg/gSZF which is an endothermic reaction. At equilibrium pH range of 4 to 11, with pH decreasing, HA-S removal efficiency increased reversely. Increasing concentration of NaCl could promote HA-S removal.The experiment of ionic organic pollutants (phenol, parachlorophenol, BPA, 2,4-Dichlorophenol) on ZFAs and SZFAs showed SZFAs had a certain adsorption potential of ionic organic pollutant while ZFAs didn’t posses adsorption capacity of ionic organic pollutants. Adsorption capacity on SZFAs was diverse with different kinds of ionic organic pollutants with a correlation of solubility and polarity. At the equilibrium pH range of 4 to 11,with pH decreasing, removal rate of four kinds of ionic organic pollutants all fell with different level. Concentration of NaCl in the solution almost had no effect to the ionic organic pollutants removal rate.The experiment of nonionic organic pollutants (nitrobenzene, naphthalene, aniline) on ZFAs and SZFAs showed that ZFAs had no adsorption capacity of nonionic organic pollutants, while surface organic modified synthesized zeolites had certain capacity of different kinds of nonionic organic pollutants. Mechanism of adsorption of nonionic organic pollutants was similarity and intermiscibility between HDTMA on the surface of ZFAs and organic pollutants. Adsorption rate of nonionic organic pollutants was slow compared with cation organic pollutants, anion organic pollutants, ionic organic pollutants which needed 24 hours to reach the reaction equilibrium. |
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