Microwave - Ethanol Extraction Of Lignin And Its Adsorption Of Cr (vi)

Lignin is the sole aromatic compound that can be obtained from renewable resources. Lignin utilization is a valuable work. Because of complex chemical constitute, difficulty of Separation and extraction,condensation of lignin, lignin is far from being utilized satisfactorily. At the methods of extraction of lignin, the best is organic solvent extraction method. But response condition of organic solvent extraction method is severe. Under atmospheric pressure, the efficiency of extraction is low. Aim at those defects, this paper study on the extracting technology of lignin by Microwave-Assisted ethanol-water and the adsorption of production for Cr(VI).The conclusions are as follows:(1)Using wastewood for raw material, this paper studied the extracting technology of lignin by microwave. The effect of the parameters, i.e. microwave power, treatment time, volume ratio of ethanol, proportion of material and solution on yield, catalyst concentrations was analyzed. The results showed that the extract ratio raised 23.35% in the optimal technological condition than that of non-microwave's, the optimal technological condition concluded for the extraction lignin are as follows: microwave power 850W, treatment time 30s, volume ratio of ethanol 50%, proportion of material and solution on yield 8:1, catalyst concentrations 6% and heated for 1 hour. Therefore, extracting lignin by microwave is an efficient method.(2)This paper analyzes the group of lignin through IR and ¹H-NMR. The conclusion shows the chemical structure of lignin be made use of phenyl—propanoid. At there basic structure the oblate is major group. Meanwhile the paper shows that the lignin contains a large amount of hydroxyl radicals, which is import meaning for chemical modification. Moreover, ¹H-NMR shows that the structure of lignin has great change.(3)This paper study on the adsorption of lignin for Cr(VI). The conclusion shows it is good adsorption material. At pH=l and temperature is 20°C, the maximum adsorption capacity is 161mg/g.The adsorption process accord with Langmuir adsorption isotherm.(4)This paper analyzes the change of group through IR, when the lignin adsorb Cr(VI). The conclusion shows that hydroxyl radicals are the major group at the adsorption process. The adsorption process is based on chemical absorption. First, Cr(VI) can be reduction to Cr³⁺.Later, Cr³⁺ exchange for hydrogen of hydroxyl radicals is taken place.