Study On The New Synthesis Technology And Application Of Amino Cellulose Derivatives

Amino sugars are nitrogen-containing derivatives of carbohydrates,which are widely found in nature.Chitosan,a typical amino polysaccharide,is environmentally friendly,non-toxic,and has good biocompatibility,so it has a wide range of applications in agriculture,food industry,daily-use chemical industry,textile industries and environmental protection.However,chitosan is extracted mainly through shrimp and crab shells.The process is cumbersome and complex.In addition,there are many disadvantages in the process for instance long production cycle,high wastes,low yield,and the quality of products is not easy to control,and the cost is so high.In view of the above problems,this work used cellulose as raw material to synthesize active ester intermediates of cellulose,then aminolysis was performed to prepare chitosan analogues(NC,aminocellulose derivatives).Finaily,NC was used as an adsorbent to remove Pb2+ in simulated wastewater,and removal rates were initially explored at different conditions.Firstly,the tosylester of cellulose was prepared using cellulose and toluene sulfonyl chloride as raw material,and the intermediate was ammoniated to prepare NC with NH3 H2O or NH3/CH3OH as ammoniation reagent.The better reaction conditions for the synthesis of NC through experimental exploration were as follows:molar ratio of ammoniation reagent to tosylester of cellulose was 5 to 10,reaction temperature was 140? to 180?,reaction time was 24 h,operating pressure was 2.5 MPa to 2.8 MPa.Under these conditions,the DS of NC was 1.09 and the yield was 20.6%to 57.1%.Secondly,because of the better water-solubility,higher utilization ratio of atom and lower cost,the sulfuric acid ester of cellulose as the intermediate also was ammoniated to prepare target product(NC).And the feasibility of reaction was discussed.First of all,alcohol with small molecule reacted with chlorosulfonic acid to obtain alcohol sulfate.The alcohol sulfate was ammoniated to prepare aliphatic amine with NH3 H2O or NH3/CH3OH as ammoniation reagent.The results showed that the target product can be successfully prepared by self-boosting with a yield of 57.8%when the molar ratio of ammoniating reagent to octanol sulphate was 5 to 10,the temperature was 140? to 180?.Thirdly,cellulose was used as raw material and concentrated sulfuric acid(or sulfur trioxide)was used as esterification reagent to prepare cellulose sulfate sodium salt(NaCS).Then NH3 H2O was used as an ammoniating reagent to prepare NC.The better reaction conditions for the synthesis of NC through experimental exploration were as follows:molar ratio of ammoniating reagent to NaCS was 5 to 10,reaction temperature was 180?,reaction time was 6 h to 24 h,operating pressure was 2.9 MPa to 3.8 MPa.Under these conditions,the DS of NC was 1.09 to 1.32.Finally,the NC with the DS of 1.09 was used as an adsorbent for Pb2+adsorption at temperature of 25?.When the initial concentration of Pb2+was 130.0 mg/L and the dose of NC was 4 g/L,the initial solution pH and adsorption time were initially explored.The results showed that NC had the best adsorption effect on Pb2+ when pH was 5.0.The adsorption process reached equilibrium at 6 h,the equilibrium adsorption capacity was 32.0 mg/L and the equilibrium adsorption concentration was 2.0 mg/L.When the initial concentration of Pb2+was 58.0 mg/L,the removal rates of Pb2+ by NC increased with the increase of the dose.The removal rates were 96.4%to 98.3%when the dose was 2 g/L to 6 g/L.NC was successfully prepared with cellulose,and it was applied to the adsorption of heavy metal ions in simulated wastewater with a good adsorption performance.The results can lay a good foundation for industrial application of NC.