Study On Preparation And Application Of Macromolecular Flocculant Based On Waste Mulberry Branch

Cellulose and lignin of waste mulberry branch from sericiculture and hexadecyl trimethyl ammonium bromide (CTAB) were used to prepare macromolecular flocculant by waterbath heating and microwave irradiation. The optimal conditions of preparation of the flocculant were determined by single-factor experiment and the orthogonal experiment. The flocculant was characterised and used to treat wastewater. The results show that the optimal conditions of preparation of flocculant by waterbath heating are as follows: waste mulberry branch were washed, dried, crushed into powder and screened to obtain mulberry branch powder with 60 meshes. Mulberry branch powder was marinated by sodium hydrate with concentration of 8% for 0.5 h at room temperature. Then, initiator Fe2+/H2O2 with concentration of 14 mmol/L and CTAB with mass ratio of mulberry branch to CTAB of 1:1 were added to react by heating with waterbath for 3 h at 90℃.And the optimal conditions of preparation of flocculant by microwave irradiation are as follows: Mulberry branch powder was marinated by sodium hydrate with concentration of 8% for 0.5 h at room temperature. Then, initiator Fe2+/H2O2 with concentration of 14 mmol/L and CTAB with mass ratio of mulberry branch to CTAB of 1:1 were added to react by heating via microwave irradiation with the power of 500w for 1 h at 90℃. The flocculants prepared by waterbath heating and microwave irradiation have similar flocculation efficiency, the removal efficiency of turbidity of kleit suspension reaches 96.3% and 95.5%, respectively. Floccus was large and settled quickly. Time of etherification reaction by microwave irradiation shortened by 2h, compared to time of the etherification reaction by waterbath heating.The result of characterization of flocculant shows that chemical bondbond C-N exists in struction of flocculant, indicating occurrence of etherification reaction between cellulose in mulberry branch and hexadecyl trimethyl ammonium bromide. Hot weightlessness rate of the flocculant is lower than 3% under the temperature range of 30℃~ 205℃, which shows the flocculant has good thermostability. The flocculant isoelectric point is pH8.4 and the limiting viscosity is 8.3mL/g.The result about the application of flocculant on wastewater treatment indicates that the flocculant has good flocculation efficiency for pulp wastewater, landscape water and dining wastewater. When the flocculant is employed to treat pulp wastewater, the removal rate of COD and turbidity reaches to 48.2% and 81.4%, respecitively. The flocculation efficiency is obviously superior to aluminum chloride (AC) and polyacrylamide (PAM) and is similar with polymerized aluminum chloride (PAC), but the dosage of the flocculant is significantly lower than that of PAC. When the flocculant is used to treat the landscape water, the removal rate of COD and turbidity reaches to 78.3% and 95.1%, the flocculation efficiency is similar with AC and PAC, slightly lower than PAM. When the flocculant is used to treat dining wastewater, the removal rate of COD and turbidity reaches to 36.3% and 72.8%, respectively. The flocculation efficiency is higher than PAM, lower than PAC, similar with AC. The flocculation efficiency of treating the printing waste water is inferior, the removal rate of COD and turbidity only reaches to 27.9% and 53.1%, the flocculation efficiency is higher than PAM, but is seriously lower than AC and PAC.