Preparation of Acid-alkali Modified Coal Fly Ash Adsorbent and Its Removal Performance on Dyes
Coal fly ash(CFA)was modified with HCI and NaOH solutions as to produce a novel modified porous adsorbent(MCFA).The CFAand MCFAwere characterized by SEM、BET、FT-IR、XRD、XPS.Meanwhile,simulated wastewaters containing dyes,such as basic violet,basic green,Congo red,and methyl violet,respectively were prepared,then the effect of the MCFA dosage on the adsorption ca-pacity for dyes,and the effect of pH value of wastewaters on adsorption capacity for dyes were exam-ined.The characterization results showed that the surface of MCFA is rather rough and porous,with a specific surface area of 32.0 m2/g,superior to 5.2 m2/g of the original CFA,accordingly its adsorption per-formance may be enhanced due to the increasing active and adsorptive sites on the surface.The MCFA has excellent adsorption effect on the desired four dyes.The maximum removal efficiency of basic violet and basic green all reached 99％,respectively by using adsorbent dosage of 2 mL for a given dye solu-tion of 100 mg/L.By fitting data with isothermal adsorption and kinetic models,it follows that Freundlich isotherm model was fitted for the adsorption process,and both physical and chemical adsorption are in-volved in the adsorption process.The adsorption behavior of all four dyes could be described better by pseudo-second-order kinetics rather than pseudo-first-order kinetics,and the adsorption effect was signif-icant,which can be used as an excellent adsorbent in the treatment industry of dye wastewaters.
inorganic non-metallic materialsmodification of coal fly ashdye wastewaterdecoloriza-tionadsorption
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