Flocculation And Removal Of Antibiotics By Modified Chitosan Under Combined Pollution

Water is important material to the survival of mankind. With the improper utilization of water resource, a variety of antibiotics get into the water environment and pose a huge threat to human health. Traditional water treatment agents have a little effect on the treatment of antibiotics contaminants. According to the morphological characteristics of antibiotics under different compound pollution conditions,in this paper, chitosan was selected as basic material, which is low cost,renewable and widely available,and 2-chlorine-4,6- dimethylamino-1,3,5-triazine,tryptophan and tyrosine are modified materials. A variety of modified chitosan flocculants (BDAT-CTS, ctrp and ctyr) were prepared. In order to study the effect of the flocculation performance of antibiotics, compound pollution conditions and various factors on flocculation removal were systematically investigated, including water pH?flocculant dosage?coexistence suspended inorganic pollutants,coexistence dissovled inorganic pollutants and natural organic pollutants. Finally, the flocculation mechanism of different flocculants was discussed in depth. The results show that:(1) BDAT-CTS has a good flocculation effect on TC under the coexistence of heavy metals (like Cu(II)). For the flocculation and purification of Cu(II)-TC complex polluted water, the electrical neutralization is the main flocculation mechanism. The positively charged flocculant BDAT-CTS and negatively charged hydroxyl-complexed copper ions are bound by electrostatic attraction; At the same time, the positively charged aromatic ring on BDAT-CTS and the negatively charged aromatic ring on TC also have strong ?? interaction. Therefore, BDAT-CTS, Cu(?)and TC are closely combined with each other to promote the formation of flocs and realize the efficient removal of TC.(2) In the coexistence of suspended particulate matter (like kaolin) and natural dissolved organic matter (like humic acid), the different structure of amino acid modified flocculation effect on NOR, SDZ and TYL. Among them, the negatively charged phenol-based ctyr is more favorable by ?? electron donor-acceptor(EDA) to flocculate NOR and TYL (both of them are positively charged). And ctrp, which contains positively charged indole group, is effective for flocculation of SDZ. In addition to that, in comparison to chitosan and PAC, Ctrp and Ctyr have a significantadvantage in the flocculant dosage, flocculation efficiency and environmentalfriendliness.(3) Based on the study of antibiotics (NOR, SDZ, TYL) with coexistencecontaminants (kaolin and HA) flocculated by ctrp/ctyr. In order to further investigatethe effects of Ca(II) and Cu(II) complexes on antibiotic flocculation. Through the U30*(307) uniform design table, Design Expert software was used to analyze the response surface diagram and the optimal condition fitting. It was found that adjustthe concentration of kaolin, HA, Ca(II), Cu(II) and flocculants (ctrp and ctyr) couldbe further removed by the removal of NOR and SDZ. This can provide guidance forthe removal of antibiotics in real water system.In view of the above, different structural modification have been carried out bymodify chitosan. This can show a more ideal flocculation effect on a variety ofcomplex polluted water that contaminated antibiotics; At the same time, multi-factorpollutant compound research can help us to explore the regular pattern of materialtransfer and transformation, and it has a good application significance in the realwater treatment.