Study On The Treatment Of Dye Wastewater With Chitosan Composite Fly-ash

In this paper, fly ash and chitosan were sellected as raw materials, three adsorbents were prepared under microwave irradiation. The simulated dye wastewaters for reactive and disperse dyes were sellected as references, the adsorption properties of the adsorbents were tested, and decolorization ratio was a main evaluated index. With CODcr removal ratio as monitoring indexes, under the room temperature, the effects of pH, adsorbent dosage, stirring time, dye type and other major factors on the decolorization ratio and flocculation precipitation were investigated. The results showed that: (1) The three adsorbents of chitosan composite fly ash, chitosan composite modified fly ash, crosslinked chitosan composite modified fly ash have good adsorption properties active and disperse dyes under pH = 3~4. (2) When pH was 4, adsorbent dosage was 1g/L, dye concentration for initial wastewater was 60mg/L, the adsorbent has best performance on the decolorization ratio and flocculation for orange dye. Then, the decolorization ratios of the three adsorbents for the orange dye wastewater were 96.96%, 97.07%, 93.07%. (3) High temperature activation method was used to modify fly ash, the modified temperature was 200~800℃, and the decolorization ratio increased firstly and then decreased, the highest decolorization ratio was found at 500℃. (4) The adsorbent with glutaraldehyde as cross-linking agent, its composite ratio: 8g fly ash, 1mL 25% glutaraldehyde, and 0.5g chitosan; The adsorbent with vanillin as cross-linking agent , its composite ratio: 5g fly ash, 1g vanillin, and 0.3g chitosan. (5) The CODcr removal ratio of the dye wastewater was best for the adsorbent with glutaraldehyde cross-linked chitosan. Treated by 0.5g adsorbent of glutaraldehyde cross-linked chitosan composite modified fly ash, the CODcr removal ratios of 240mg/L active and disperse dye wastewaters were over 60% and 80%, respectively. Under neutral conditions, treated by the adsorbent prepared by cross-linked chitosan composite modified fly ash, the decolorization ratio for active dye wastewater reached 40%.