Fabrication Of Aminated Cellulose And Its Adsorption And Flocculation Behaviors

At present,environmental problems are becoming more and more serious.Water pollution has become a constraint factor for economic development and a threat to people's health.In view of the complexity of pollutants in industrial wastewater and the diversified charge of pollutants in water bodies,the sewage treatment process is complicated.Therefore,developing a green economy,simple preparation and easy large-scale process has become a hot research topic.In this paper,we establish a simple preparation process,using green cellulose as raw material,polyethylenimine(PEI)as functional monomer,preparing bi-functional cellulose-PEI with the property of adsorption and flocculation by chemical crosslinking,which is optimized for the treatment of dyes and kaolins,and further applied to industrial wastewater,with the following results:(1)Preparation,characterization and properties of aminated Cellulose: The cellulose-PEI with high amino group content was successfully prepared under heterogeneous conditions by chemical cross-linking.The amino group content of the obtained material can be controlled at 17.5 mmol/g,and the optimal conditions were obtained by orthogonal experiment design.The optimum conditions were as follows: swelling time 12 h,cellulose/polyethyleneimine ratio 1/1,temperature 45 ?,glutaraldehyde dosage 1.5 g,reaction time 3 h,the amino content of bi-function reach up 17.5 mmol/g,indicating that the preparation process is simple and practical,but the functional rate of cellulose is also get improved.The successful introduction of PEI was tested by FTIR and XPS.SEM showed that the surface morphology of the grafted cellulose changed obviously,but it still maintained high thermal stability by TGA.(2)Study on the adsorption properties of aminated cellulose: Effect of aminated cellulose on the anionic dye reactive yellow X-RG(XRG),nonionic dye disperse brown S-3RL(DB 3)and cationic dye M-7G(M7G)Shows excellent adsorption properties.The maximum adsorption capacity calculated by Langmuir model reached 970.87,571.43 and 581.40 mg/g.The maximum capacity of XRG was 845.4 mg/g,M7 G was 536.2 mg/g and DB 3 and 532.0 mg/g respectively.The adsorption process followed the pseudo-second-order kinetics and dominated by chemical adsorption;the introduction of the amino group is responsible for electrostatic attraction and hydrogen bonding interaction causing effectively remove the dye.(3)Study on adsorption of aisperse ayes by aminated cellulose: In order to further improve the adsorption of disperse dyes by aminated cellulose,the adsorption and mechanism of disperse blue ZBLN and disperse yellow E-3G were studied.It was found that at the optimum pH,the amounts reached 98 mg/g(disperse blue)and 98.1 m/g(disperse yellow),respectively.At pH 3,the product size was the highest up to 6685 nm and 3092 nm.The effects of pH on the morphological structure of disperse dyes were investigated.It was found that the disperse yellow dye had demulsification in both acidic and alkaline conditions,and disperse blue only had the phenomenon of breaking in alkaline condition.The main mechanism of dye adsorption is further demonstrated by kinetic and infrared FRIR.The main principle of adsorption is chemical adsorption,which mainly acts on demulsification and electrostatic adsorption,so as to achieve the removal effect on disperse dyes.(4)Study on flocculation performance of aminated cellulose: The flocculation performance of aminated cellulose was investigated by adjusting the dosage,flocculation time,pH and sedimentation rate,using kaolin suspension as a model.The flocculation performance of flocculant was investigated with the change of sedimentation height.The flocculation effect of the highest content of flocculant is the best,the turbidity can reach 8.7 NTU,the floc is the largest and the size is 48.6 ?m.Flocculant showed good focculation performance when floccution time after 30 min;the flocculation effect was the best;at different pH,the flocculation effect is the best when the whole system is neutral,and the bifunctional material with the highest amino content has the best effect.Through the flocculation mechanism,the main mechanism of flocculation is charge neutralization and bridging.(5)The treatment of aminated cellulose in wastewater treatment: The optimum flocculation performance was demonstrated by optimizing the treatment of printing and dyeing wastewater and machining wastewater.For dyeing and printing wastewater treatment,COD values dropped from 490 mg/L to 65 mg/L,a decrease of 86.7 %,a reduction of 80.3% for the mechanical processing wastewater from 390 mg/L to 77 mg/L,and a good removal effect on the dyeing color of printing and dyeing wastewater.This paper provides a simple preparation process,aminated cellulose(cellulose-PEI)was prepared by chemical cross-linking under the heterogeneous conditions using green cellulose as raw material and polyethyleneimine(PEI)as a functional monomer,which shows good adsorption and flocculation performance,and further applied to enterprise wastewater.The research results of this thesis prove that a simple preparation process is developed,which is good for large-scale applications and opens up new ideas and directions for the development and application of multifunctional materials in the future.