Study On The Synthesis And Ion Recognition Properties Of Chitosan Based Anion Receptors And Their Antibacterial And Adsorption Properties

Anions play an important role in many biological processes and industrial production,and are also a major pollutant to the environment.Recognition and detection of anions has become a hot topic in life,materials and environmental sciences.Chitosan?CS?is the second most abundant biopolymer following cellulose,in nature with excellent biological activities,biodegradability,environmental friendliness and non-toxicity.The exploring of an effective method for the recognition of oxoanions and removal by adsorption in aqueous solutions is of great significance in the fields of materials and environmental chemistry.Thesis dissertation consists of four chapters.In the first chapter,the development of chitosan,source of chitosan,application of chitosan and its derivatives,as well as the recognition of thiourea/urea based anion receptors have been detailed and the research objective of this dissertation is presented.A new chitosan based colorimetric anion receptor with possessing nitrophenyl as a chromogenic signaling unit,and urea moieties as binding sites have been designed and synthesized in the second chapter,and the resulted product was characterized by ¹HNMR and FTIR.The binding properties of the receptor with anions were examined by UV-Vis spectra methods,respectively.Upon the addition of PO₄^3-and F^-anions,the sensor showed apparent color changes from colorless to yellow and yellowish,while addition of the other anions did not cause any obvious color changes.The data of the UV-Vis spectroscopic titration experiments data showed that,the sensor in DMSO/H₂O?volume ratio 9:1?solution exhibited colorimetric selectivity for PO₄^3-and F^-.The synthesis of thiourea and nitrophenyl based colorimetric anion sensors have been described in the third chapter.The receptor is able to sense anions,especially SO₄^2-and F^-,where the color of the system changes from colorless to yellow.The results show that the host compound not only has a good hydrogen bonding ability with anions SO₄^2-and F^-,but also is a new class of polymer with anion recognition capacity,thus has potential applications in the supramolecular chemistry.The nitrobenzene thiourea chitosan-Cu complex was prepared and the antibacterial properties of the complex were studied.The results showed that the complex NPTUCS-Cu has good antibacterial activity against E.coli and S.aureus.To achieve the adsorption and removal of phosphate anion in water,three kinds of chitosan based polymeric adsorbents were also prepared.The adsorption effect of these three adsorbents on phosphate in sewage was studied.It is found that these three composites have good ability of adsorption and removal of phosphate anion.The maximum adsorption capacity was 61.3mg/g,74.9mg/g and 50.2 mg/g respectively.Finally,the reusability of chitosan-based adsorbents was studied.The results showed that,the chitosan-based adsorbents were renewable and possess high practical values.