Study On Synthesis And Performance Of Bamboo Cellulose-based Flocculant Material

Water shortage is increasing.With the development of modern industry,the discharge of waste water also increased,which followed by water pollution.Thus,the effective technology for industrial wastewater treatment has become urgent.Flocculation precipitation is the most economical,direct and most effective.At present,organic synthetic polymer flocculant is most widely used in wastewater treatment,which has excellent flocculation performance.However,it has some disadvantages such as non-renewable raw materials and hard to degrade,which is incompatible with the needs of green development.As a result,environmentally friendly natural polymer flocculants are favored by people.Cellulose is suitable as a backbone for natural modified flocculants,due to its long and soft segments with high reactivity.There is rich bamboo in South China,which is non-toxic,harmless and pollution-free.Applying bamboo cellulose to the production of natural polymer flocculants can not only reduce the consumption of petroleum resources,but also achieve cost reduction and efficiency increase.Furthermore,it can also expand the application fields and increase the added value of products.In this work,the synthesis process optimization and characterization of the bamboo cellulose-based flocculant were first studied.Ployacrylamide(PAM)was grafted onto the bamboo cellulose(BC)by free-radical graft copolymerization.When the bamboo cellulose-graft-ployacrylamide flocculant(BC-g-PAM)was prepared at the optimal synthesis conditions,the turbidity removal rate of the flocculation treatment kaolin suspension reached96.8%.The biodegradation experiment showed that the sample can degrade 58.7% of its weight in 60 days,and the degradation rate reaches 63.4% in 90 days.The above data fully showed that the BC-g-PAM has good flocculation performance and biodegradability.Then,the flocculation performance of the BC-g-PAM flocculating materials in actual industrial wastewater was studied.And the turbidity removal rate of the supernatant is the standard to evaluate the flocculation efficiency.When the dosage of BC-g-PAM is at 65 mg/L,the dosage of PAC is at 1.6 g/L,pH=4,the turbidity removal rate was 99.6% and the SS removal rate was 99.6%,and the pH remained basically stable before and after flocculation.Determine the flocculation process conditions for BC-g-PAM to treat trademark coating wastewater: the dosage of BC-g-PAM at 30 mg/L,the dosage of PAC at 6.7 mg/L,pH=7.The turbidity removal rate was 97.5%,the SS removal rate was 87.1%.The pH changed from 11.25 to 7.80.The flocculation performance of BC-g-PAM was comparable to anionic polyacrylamide(APAM)and had higher biodegradability,which was expected to become an efficient and environmental-friendly flocculation material for actual industrial wastewater treatment.Finally,the flocculation mechanism of the BC-g-PAM flocculant is explored.Through the measurement of Zeta potential at different pH,it can be known that BC-g-PAM is an anionic flocculant,and polyaluminum chloride is selected as the coagulant aid.Under acidic conditions,the flocculation mechanism of BC-g-PAM is more likely to be net roll sweeping.Under neutral conditions,when the dosage of BC-g-PAM at 0-140 mg/L,the flocculation mechanism is mainly the adsorption electric neutralization mechanism,supplemented by the adsorption bridging effect.The dosage of BC-g-PAM is more than 140 mg/L,and the flocculation mechanism is mainly the adsorption bridging effect.Under alkaline conditions,when the dosage of BC-g-PAM at 0-120mg/L,the flocculation mechanism of BC-g-PAM is mainly based on the adsorption electric neutralization mechanism,supplemented by the adsorption bridging effect,and the BC-g-PAM dosage is more than 120 mg/L,the flocculation mechanism of BC-g-PAM is mainly adsorption bridging effect.The optimal dosage will increase stepwise with the increase of pollutant concentration,that is,the higher the pollutant concentration,the greater the dosage of BC-g-PAM required.