Preparation And Properties Of Cationic Taro Starch Flocculant

With the development of modern industry,the problem of water pollution is more and more serious.At this time,an environment-friendly flocculant is urgently needed to solve the problem of water shortage.Starch is one of the most abundant biomass energy in the earth.By means of its etherification,esterification and graft copolymerization,the starch based flocculant can be biodegradable and can be used for the sustainable utilization of starch resources.Taro starch has a wide source of resources and high yield.The waste of taro waste is wasted every year,and there are few reports on development and application.Therefore,this paper provides a scheme for deep processing of taro starch.The preparation of taro starch is made into environmentally friendly starch based flocculant,which can not only reduce the stacking of waste,improve economic efficiency,but also widen the needs of taro starch and used the field to increase the added value of the product.Firstly,the cationic taro starch flocculation material was prepared by NaOH precipitation method and NaOH precipitation method was used to extract taro starch from a vegetable field in Suzhou.The cationic taro starch was prepared by 2,3-epoxy propyl ammonium chloride(GTA)as a cationic etherification agent and NaOH as an alkali catalyst.The optimum process conditions are as follows: starch 5g,reaction temperature 54.95 C,reaction time 2.63 h,GTA dosage of 0.92 g,NaOH dosage of0.09 g.The final product's degree of substitution(DS)is 0.509,the solubility is 53.5%,the swelling power is 46.4%,the transparency of the paste is 67.2%.Compared with the original starch,the solubility,the transparency of the paste becomes larger,and the swelling power becomes smaller.The products were characterized by infrared spectroscopy(FTIR)and scanning electron microscope(SEM).The results showed that the infrared spectrum showed that CTS had quaternary ammonium salt peak,and the scanning electron microscope showed that the surface of the product was rough and wrinkled,both showed that the product was in agreement with the target product.Secondly,C.I.Direct Violet 1,C.I.Reactive blue 21,C.I.Acid yellow 128 and C.I.Disperse Blue 56 were used as the research object,and the flocculation and decolorization performance of CTS flocculation material to dye was further investigated.For C.I.Direct Violet 1,C.I.Acid yellow 128,C.I.Reactive blue 21 and C.I.Disperse Blue 56,The optimum condition is that the dosage is 0.6g/L,0.5g/L,1.0g/L,1.8g/L,and the adsorption equilibrium time is 30 min,50min,20 min,20min,and the dyeing liquid pH is 8,8,7,7.The adsorption thermodynamics of decolorization shows that the flocculation and adsorption of the four dyes by CTS can be described by the Langmuir and Freundlich isothermal adsorption models,in which the C.I.Direct Violet 1 and the C.I.Disperse Blue 56 are more in line with the Langmuir model.It is a complex process based on the adsorption of single molecular layer and the coexistence of multi molecular layer adsorption,and the C.I.Reactive blue 21 and C.I.Acid yellow 128 are more in accordance with the Freundlich model.The adsorption of monolayer is the main process of adsorption and coexistence of monolayer.The results of thermodynamic parameters show that the process of decolorization is a spontaneous endothermic process,and the C.I.Direct Violet 1 is mainly chemical adsorption,and C.I.Reactive blue 21,C.I.Acid yellow 128 and C.I.C.I.Disperse Blue 56 are mainly physical adsorption,and the process is the entropy increase process.The kinetic equation fitting shows that the decolorization process of the four dyes can be described by the quasi two stage kinetic equation.The activation energy is 47.963kJ/mol,69.730kJ/mol,66.278kJ/mol,79.269kJ/mol,which is small in activation energy and fast in reaction rate,and can be carried out spontaneously at normal temperature.At last,in order to increase the scope of application of CTS,three kinds of flocculant polymerized aluminum chloride(PAC),polymeric ferric sulfate(PFS)and polyacrylamide(PFS)were mixed and three kinds of compound flocculants were prepared,and three kinds of compound flocculants were prepared: CTS+PAC,CTS+PFS,CTS+PAM.When CTS:PAC,CTS:PFS and CTS:PAM are 1:1,3:2 and 3:2,they are the best combination.After that,the influence of dosage,pH and settling temperature on turbidity of three kinds of compound flocculants was investigated.The residual turbidity of the kaolin supernatant was the lowest when the amount of CTS+PAC was added to 60mg/L,which was higher than that of the control group CTS and PAC for the optimum flocculation performance of kaolin.Compared with the single CTS,the performance of the kaolin was improved by 14.2%,suitable for weak alkali(pH=8)and middle low temperature conditions(20-30?).When CTS+PFS was added to 80mg/L,the turbidity of the effluent was the lowest and the flocculation performance was higher than that of the control group,but it was equivalent to CTS,It is suitable for neutral and weak alkaline,20-50?;When CTS+PAM is added to 80mg/L,the flocculation performance is higher than that of the control group CTS and PAM,compared with the single CTS,the performance isincreased by 16.2%,suitable for pH=8,20-50?.The comparison results of the three kinds of compound flocculants found that the best flocculating performance of the three flocculants was CTS+PAC ? CTS+PAM>CTS+PFS,and CTS+PAC had excellent flocculation performance compared to the other two kinds of compound flocculants.However,compared with CTS+PFS and CTS+PAM,CTS and CTS+PAC are less affected by pH and temperature.CTS+PAM is less affected by temperature and CTS+PFS is less affected by pH.