Study On Preparation Of Chitosan Graft Copolymer And Its Application In PP

In recent years, as a result of industrial development, water has been seriously polluted, especially heavy metal wastewater pollution which caused a serious impact on human and environment.Those traditional methods of wastewater treatment not only is costly, but also will cause secondary pollution to the environment to some extent.So it is necessary to develop a new and environment friendly and more efficient wastewater treatment method.With high intensity, acid and alkali resistant, good chemical stability and high efficiency, low resistance as a filter material filter, polypropylene nonwoven fabric has been widely used as a kind of filtration material. Due to lacking of polar groups, its hydrophilic is poor. This reduces the filtration efficiency severely and limits its application fields. In addition, chitosan is widely used in the field of wastewater treatment with its unique structural properties. But using it to adsorb metal ions has shortcomings, such as small specific surface area, affected by pH,-NH2 can not get an adequate use.So it is necessary to modify the molecular.To solve the above problems reasonably, this study proposes a composite adsorbent material which is made of chitosan graft polymer coated polypropylene nonwoven fabric. The chitosan graft polymer is synthesized by chitosan, acrylamide and maleic acid.Then the graft polymer is coated onto the polypropylene nonwoven fabric surface,the adsorption property can be improved largely. This not only improves the hydrophilic property of polypropylene nonwoven fabric,but the chitosan is modified to improve its adsorption property.Firstly, chitosan is modified by graft polymerization. The optimum conditions for the reaction of graft polymerization are as follows: the amount of initiator is 6 mmol / L, the amount of acrylamide and maleic acid with chitosan is 3:1, the reaction time is 4 h, the reaction temperature is 50℃. Further, the adsorption capacity of the copolymer for Pb2 + is studied and the effect of adsorption time, adsorbent dosage and temperature on the adsorption reaction are explored.The results show that the adsorption capacity of graft polymer for Pb2 + increased by about 23 % compared with chitosan.Finally, the graft polymer is coated onto the polypropylene nonwoven fabric.Its breaking strength and fastness property and a series of performance are studied.Further,their adsorption and desorption and secondary adsorption capacity after desorption of Pb2 +are studied.The results show that the coated fabric has a fine binding fastness and its breaking strength is significantly enhanced.The adsorption capacity of Pb2+ of the copolymer coated fabric is higher than compared samples.Desorption experiments are done with HNO3 and HCl, the desorption rate of Pb2+ can reach 93.4 % and 65.5 %.The above materials are applied to Pb2+ adsorption experiment once again and the results show that the adsorption capacity drops down a little bit,but adsorption capacity for Pb2+ is still well. The results also show that the adsorption rate has not changed obviously and they both reach adsorption equilibrium when adsorption time reaches 200 minutes.