Aquatic environment

Effect of viscosity, basicity and organic content of composite flocculant on the decolorization performance and mechanism for reactive dyeing wastewater

Yuanfang Wang , Baoyu Gao , Qinyan Yue , Yan Wang


Received December 07, 2010,Revised March 01, 2011, Accepted , Available online

Volume 23,2011,Pages 1626-1633

A coagulation/flocculation process using the composite flocculant polyaluminum chloride-epichlorohydrin dimethylamine (PAC-EPI-DMA) was employed for the treatment of an anionic azo dye (Reactive Brilliant Red K-2BP dye). The effect of viscosity (ηup), basicity (B = [OH]/[Al]) and organic content (WP) on the flocculation performance as well as the mechanism of PAC-EPI-DMA flocculant were investigated. The ηup was the key factor affecting the dye removal efficiency of PAC-EPI-DMA. PAC-EPI-DMA with an intermediate ηup (2400 mPa.sec) gave higher decolorization efficiency by adsorption bridging and charge neutralization due to the co-effect of PAC and EPI-DMA polymers. The WP of the composite flocculant was a minor important factor for the flocculation. The adsorption bridging of PAC-EPI-DMA with ηup of 300 or 4300 mPa.sec played an important role with the increase of WP, whereas the charge neutralization of them was weaker with the increase of WP. There was interaction between WP and B on the removal of reactive dye. The composite flocculant with intermediate viscosity and organic content was effective for the treatment of reactive dyeing wastewater, which could achieve high reactive dye removal efficiency with low organic dosage.

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