Study On Structure Characterization Of Succinic Anhydride Modified Banana Cellulose And Adsorption Heavy Metals

China is the second largest producing banana country.Every year,it produce amount of banana stem waste when harvest many bananas.Banana stem contains abundant natural cellulose which is belongs to renewable resources.In China,the banana stem is almost directly thrown in the fields.It is not only caused waste resources,but also caused environment pollution.So,rational development and utilization of banana stem resources are not only in the concept of the requirements of sustainable development,but also can avoid environmental pollution.For the above reason,we extracted banana cellulose from banana stem by the method of scraping stem and boiling fiber.Then we investigated the dissolution condition of cellulose in ionic liquid and NaOH/thiourea/urea water solution.And banana cellulose was acylated by succinic anhydride without catalysts in ionic liquid and NaOH/thiourea/urea water solution.Finally,succinic anhydride modified cellulose was used to absorb the heavy metal ions.Fresh banana stem contains a lot of sap,the sap also has some medicinal value.The main researches were as follows:(1)The dissolution condition of cellulose was examined in ionic liquid.The results showed that regenerated cellulose has smaller degradation under optimal condition.The optimal condition was at 150r/min,reaction temperature 90? and time 60min.In this condition,cellulose was acylated by succinic anhydride in ionic liquid.The effects of reaction time,temperature,and molar ratio of succinic anhydride to anhydroglucose on the degree of substitution of modified banana cellulose were evaluated.The results showed that the reaction condition was at a ratio of succinic anhydride to anhydroglucose 6:1,reaction time 60 min and temperature 90?.The maximum degree of regenerated cellulose was 0.37.Finally,the characterization analysis of modified cellulose was performed using SEM?FTIR?TG and XRD.The results confirmed that this method can introduce carboxyl into banana cellulose.(2)The dissolution condition of cellulose was examined in NaOH/thiourea/urea water solution.The results showed that the solubility of cellulose is largest when the solvent contains NaOH 7%?thiourea 7.5%and urea 9%.In this condition,cellulose was acylated by succinic anhydride in NaOH/thiourea/urea water solution.The effects of reaction time,temperature,and molar ratio of succinic anhydride to anhydroglucose on the degree of substitution of modified banana cellulose were evaluated.The results showed that the reaction condition was at a ratio of succinic anhydride to anhydroglucose 8:1,reaction time 60 min and temperature 60?.The maximum degree of regenerated cellulose was 0.092.Finally,the characterization analysis of modified cellulose was performed using SEM?FTIR?TG and XRD.The results also confirmed that this method can introduce carboxyl into banana cellulose.(3)Pb2+,Cu2+and Cd2+ were absorbed by IL-cellulose and AL-cellulose,and the effect of pH value?absorbent dosage?initial concentration?temperature and time on the adsorption capacity of metal ion has been studied.For the IL-cellulose,the results showed that the optimal adsorption pH values for Pb2+,Cu2+and Cd2+ are 6.0,6.0 and 7.0,respectively.The optimal absorbent dosage for Pb2+,Cu2+and Cd2+ is 1.0g/1.The optimal initial concentration for Pb2+,Cu2+and Cd2+ are 100mg/l,300mg/l and 100mg/l,respectively.The optimal temperature for Pb2+,Cu2+and Cd2+ are 30?,40 ? and 40?,respectively.Kinetic study shows that absorption of the IL-cellulose to ions Pb2+,Cu2+ and Cd2+ can be well described by the Pseudo-second-order kinetics model.The equilibrium adsorption capacity are 44.30 mg/g,64.22 mg/g and 79.23 mg/g.For the AL-cellulose,the results showed that the optimal adsorption pH values for Pb2+,Cu2+and Cd2+ is 6.The optimal absorbent dosage for Pb2+,Cu2+and Cd2+ are 2g/L,1g/L and 1g/L.The optimal initial concentration for Pb2+,Cu2+and Cd2+ are 300mg/L,200mg/L and 300mg/L,respectively.The optimal temperature for Pb2+,Cu2+and Cd2+ is 50?.Kinetic study shows that absorption of the IL-cellulose to ions Pb2+,Cu2+ and Cd2+can be well described by the Pseudo-second-order kinetics model.The equilibrium adsorption capacities are 78.98 mg/g,59.82 mg/g and 77.78 mg/g.