Preparation of cationic chitosan-polyacrylamide flocculant and its properties in wastewater treatment |
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Authors: | Ben Wang Yulian Zhang Chunbao Miao |
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Institution: | 1. School of Environment and Safety Engineering, Qingdao University of Science & Technology, Qingdao 266042, P. R. China 2. Qingdao Hygain Chemical (group) Co., LTD, Qingdao 266042, P. R. China |
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Abstract: | Chitosan derived from crab shells, was used to prepare the graft polymer in aqueous solution with acrylamide (AM) and methacrylatoethyl
trimethyl ammonium chloride (DMC) as raw materials and ceric ammonium nitrate (CAN) as initiator. The flocculation ability
of the resulting polymer (PCAD) was studied in waste water treatment experiments. Its properties were determined on the basis
of the transmittance of waste water after flocculation. The effects of chitosan and DMC content on PCAD’s flocculation ability
were studied. Flocculation experiments were also undertaken under various pH conditions. According to the experimental data,
the flocculation ability could be improved when chitosan content decreased in the raw material, but the monomer conversion
would decrease obviously. When the chitosan’s content was more than 65%, AM and DMC groups were less on each chitosan molecule.
So PCAD’s flocculation ability was poor. Similarly, high content of DMC would result in low monomer conversion and high flocculation
ability. PCAD molecules with more DMC group had more positive charges. It was favorable to flocculation. However, monomer
conversion would decrease with the increase of DMC content. The suitable conditions were that chitosan and DMC contents were
65% and 15–20%, respectively. The experiment data showed that PCAD had good flocculation ability under weak acidic condition.
Its ability would be weakened by strong acidic or alkaline condition. The flocculation efficiency was the best at pH of 5.5
when PCAD’s dosage was 8mg·L−1. Compared with cationic polymer (the copolymer of AM and DMC, PAD), PCAD showed better flocculation ability under acid and
neutral conditions, but worse ability under alkaline condition. |
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Keywords: | Chitosan marine chemicals graft polymer cationic polymer flocculant |
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