Synthesis, characterization, and secondary sludge dewatering performance of a novel combined silicon–aluminum–iron–starch flocculant

•Silicon, aluminum, and iron were grafted onto starch chains to synthesize CSiAFS.•The sludge dewatering performance of CSiAFS was superior to PAC, PAM, and FeCl3.•CSiAFS exhibited a good dewatering efficiency over a wide range of pH (3.0–11.0).•CSiAFS had a discontinuous surface with channels which...

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Bibliographic Details
Published in:Journal of hazardous materials 2015-03, Vol.285, p.199-206
Main Authors: Lin, Qintie, Peng, Huanlong, Zhong, Songxiong, Xiang, Jiangxin
Format: Article
Language:English
Subjects:
Aluminum
Aluminum - chemistry
Backbone
Channels
Chlorides
Copolymers
Dewatering
Flocculant
Flocculation
Grafting synthesis
Hydrogen-Ion Concentration
Infrared spectroscopy
Iron - chemistry
Microscopy, Electron, Scanning
Powder Diffraction
Sewage - chemistry
Silicon - chemistry
Sludge
Sludge dewatering
Spectroscopy, Fourier Transform Infrared
Starch
Starch - chemistry
Starches
Thermogravimetry
Waste Disposal, Fluid - methods
Water - chemistry
X-Ray Diffraction
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Summary:•Silicon, aluminum, and iron were grafted onto starch chains to synthesize CSiAFS.•The sludge dewatering performance of CSiAFS was superior to PAC, PAM, and FeCl3.•CSiAFS exhibited a good dewatering efficiency over a wide range of pH (3.0–11.0).•CSiAFS had a discontinuous surface with channels which helped to sludge dewatering. Flocculation is one of the most widely used cost-effective pretreatment method for sludge dewatering, and a novel environmentally friendly and efficient flocculant is highly desired in the sludge dewatering field. In this study, a novel combined silicon–aluminum–ferric–starch was synthesized by grafting silicon, aluminum, and iron onto a starch backbone. The synthesized starch flocculant was characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy, X-ray powder diffraction, and thermogravimetric analysis. The dewatering performance of secondary sludge was evaluated according to the capillary suction time, settling volume percentage, and specific resistance to filtration. The results indicated that the copolymer exhibited: (1) a good dewatering efficiency over a wide pH range of 3.0–11.0, (2) superior sludge dewatering performance compared to those of polyaluminum chloride (PACl), polyacrylamide (PAM), ferric chloride, and (3) a discontinuous surface with many channels or voids that helps to mobilize the impermeable thin layer of secondary sludge during filter pressing. Such a novel copolymer is a promising green flocculant for secondary sludge dewatering applications.
ISSN:0304-3894
1873-3336
DOI:10.1016/j.jhazmat.2014.12.005