Preparation Of Natural Green Flocculant By Microwave And Its Flocculation Properties

With the improvement of living standards,the flocculant used in the disposal of sewage and sludge is in increasing demand.Meanwhile,the safety,toxicity and degradation of the traditional inorganic flocculant and organic flocculant have been paid more and more attention.The requirements of these characteristics could be met with natural polymer flocculants.And its wide source and cheap raw materials make it possible for the waste of the flocculant to be reused,which keeps up with the needs of the current social development.In this study,shells of peanuts and walnuts,which are widely cultivated in China,are selected as the raw materials through general comparison.Synthetic work of bioflocculant,in which potassium peroxydisulfate is used as initiator and the DAC and DMC are served as modifier,is conducted by microwave.Four natural polymer modified flocculants,namely,peanut shell-DMC,peanut shell-DAC,walnut shell-DMC and walnut shell-DAC,are prepared in the experiment.Composition,crystal structure and thermal stability of four kinds of modified flocculants are characterized through infrared scanning,X-ray diffraction,thermogravimetry,specific surface area,etc.The result of characterization shows that the grafting of the four flocculants is successful,the crystallization is changed,the thermal stability is enhanced and the specific surface area is increased.By the means of single factor analysis,the effects of microwave power,actuation duration,mixture ratio of natural organic matter and quaternary ammonium salt on the reaction process are studied and the optimum synthesis conditions of flocculant are determined.The research shows that the best synthetic effect of peanut shell-DMC is in the condition that microwave power is 400 w,actuation duration is 3 minutes,mass ratio of peanut shell and DMC is 3:4.For peanut shell-DAC,the best synthetic effect is in the condition that microwave power is 400 w,actuation duration is 4 minutes,mass ratio of peanut shell and DAC is 1:2.For walnut shell-DMC,the best synthetic effect is in the condition that microwave power is 80 w,actuation duration is 2 minutes,mass ratio of walnut shell and DMC is 1:3.For walnut shell-DAC,the best synthetic effect is in the condition that microwave power is 400 w,actuation duration is 5 minutes,mass ratio of walnut shell and DMC is 1:3.Flocculating performance of flocculant to turbidimetric liquid is verified by experiments under different dosages,pH and temperature.The experimental results show that the best flocculation condition for peanut shell-DMC is pH7,30? and dosage 3g/L;for peanut shell-DAC,it is pH7,30? and dosage 2g/L;for walnut shell-DMC,it is pH3,40? and dosage 1.5g/L and for walnut shell-DAC,it is pH4,60? and dosage 2g/L.