Separation And Extraction Of Willow Lignin With Organic Solvent And Its Application

In this paper,lignin was separated and extracted from isopropanol at different temperature and time in the reactor under the condition of high temperature and high pressure with the solvent of low cost isopropanol.The separation and extraction of lignin was characterized by FT-IR,¹³C-NMR,³¹P-NMR 2D-HSQC.Meanwhile,lignin-based flocculant was formed by grafting of willow-lignin with epoxy propyl trimethylammonium chloride under alkaline condition.Flocculation tests were carried out on analogue dye wastewater?Acid Black,Reactive Black and Direct Grey?.The optimum process for extracting lignin from willow was that the volume of isopropanol and water was 7:3,the reaction temperature and reaction time were 190°C and 10 h,respectively.Under this condition,the separation of lignin yield was 61.3%and the solid residue was 55%.This condiction which not only ensured a higher extraction rate of lignin in willow,but also retained the solid residue.The purity of the obtained organic solvent lignin was 93.7%.The residual solid residues were analyzed by monosaccharide acid hydrolysis.82.3%glucose and 10.77%xylose were retained.Arabinose,mannose and galactose were not detected.Experimental data proved that this method can remove lignin from willow effectively.The results of acid treatment from the extracted lignin was showed that 0.39%of xylan,2.5%of acid lignin,and 91.2%of acid insoluble lignin.The results showed that the purity of the isolated lignin was 93.7%.The main constituent elements of the isolated lignin were C,H and O,and also contain a little of N elements.Among the various elements constituting lignin,the content of C element is the highest in lignin,about 60%,and along with the increase of temperature,the content of C element in the obtained lignin was basically maintained between 57%and 66%.For the O element in lignin,the content of O element keeped decreasing with the increase of temperature.when the temperature increaseed from 170^oC to 210^oC,and the content of oxygen decrease from 30.56%to 25.75%.The O element content also showed a tendency to change less.The monosaccharide and lignin in the solid residue and the dissolved carbohydrate in the mixture were used 2-PrOH/H₂O?v/v,7:3?treatment of the willow in a 190°C reactor for 10 h.The results showed that 82.3%of the initial glucan remained in the solid residue,and 19.3%of the xylan and 41.8%of the mannan remained in the solid residue.63.5%of xylan,75.5%of Arabinan,70.3%of galactan and 35.6%of mannan were degraded into oligosaccharides and monosaccharides during processing and dissolved in the reaction mixture.The mass of carbohydrates lossing occurried therein was believed to be due to the degradation of carbohydrates,the formation of furfural,by-products such as 5-hydroxymethylfurfural.The FT-IR analysis of the raw material and lignin of bamboo willow showed that the lignin sample extracted from the raw material of willow was treated with organic solvent,and the benzene ring structure was intact and the functional groups were well retained.The lignin extracted from the organic solvent was characterized by ¹³C-NMR and ³¹P-NMR.The results showed that the total phenolic hydroxyl content and total hydroxyl content were 1.87 mmol·g^-1,and 2.62 mmol·g^-1,respectively.2D-HSQC showed that the?-O-4 bond associated with guaiacyl and syringyl structures disappeared in lignin.In the decolorization of Reactive Black dyes,the biggest influenced factors were reaction temperature,molar ratio and alkali concentration,while the reaction time has the least influence on the flocculation experiment and the optimal level of each influencing factor can be obtained.The experimental results showed that the optimum synthesis conditions were 1:1.1 of molar ratio,60°C of reaction temperature,4 mol·L^-1of NaOH and reaction time about 4 h.Under these conditions,the dye decolorization experiment was carried out according to the same experimental conditions and the decolorization rate of the active black dye was 99.7%.In the decolorization of Reactive Black dyes,the biggest influenced factors were reaction temperature,molar ratio and alkali concentration,while the reaction time has the least influence on the flocculation experiment and the optimal level of each influencing factor can be obtained.The experimental results showed that the optimum synthesis conditions were 1:1.1 of molar ratio,60°C of reaction temperature,4 mol/L of NaOH and reaction time about 4 h.Under these conditions,the dye decolorization experiment was carried out according to the same experimental conditions and the decolorization rate of the active black dye was 99.7%.In the decolorization of Acid Black dye,the biggest influenced factor was the molar ratio,followed by the reaction temperature and alkali concentration,and the reaction time has the least influence on the flocculation experiment.Therefore,the experimental results showed that the optimal synthesis conditions were 1:1.1 of molar ratio,50°C of reaction temperature,3 mol/L of NaOH concentration and reaction time about 4 h.Under these conditions,the dye decolorization experiment was carried out under the same experimental conditions,and the obtained decolorization rate of the acid black dye was 99.7%.