Study On The Decolorization Of Industrial Lignins

The industrial lignin is divided into two kinds of alkali lignin and lignosulfonate,which are completely different in structure and performance.Few of these lignin are recycled,and most of the lignin are burned out as waste or concentrated,and the effective utilization is not high.Because of the industrial lignin is usually dark in color,which greatly limits its application especially light materials widely used in various industries,this paper adopts the traditional methods for decolorization decolorization of industrial wood,in-depth study through the structure of lignin chromop Hore,enhancement of lignin structure and reactive mechanism to provide theoretical basis and scientific guidance for the comprehensive utilization of lignin,and then expand the utilization potential of wood fiber resources.This paper design the orthogonal experiment method using oxidizing and reducing bleaching agent for industrial lignin discoloration,to sodium sulfite bleaching of red liquid,the temperature,time,dosage of sodium sulfite by three factors five levels orthogonal experiment,the results show that the primary and secondary factors of affect the decoloring effect temperature > time > the dosage of sodium sulfite.The best decolorization conditions were selected as follows: temperature 150 C,time 1H,and 40% sodium sulfite dosage.Under this condition,the whiteness,surface tension and molecular weight of red liquid reach the best effect.The effect of p H on decolorization was investigated by using a good bleaching sample of orthogonal experiment.The experiment found that the change of p H did not improve the whiteness significantly.In this paper,we selected the conditions of bleaching samples with good effect of orthogonal experiment,and replaced half of the sodium sulfite with sodium disulfite,and other conditions were unchanged,and the decolorization experiment was carried out.The results showed that the whiteness decreased by about 3 percentage points relative to the total use of sodium sulfite,but the ash also decreased by about 6 percentage points.In the study of the decolorization of sodium sulfonic acid in different formaldehyde ratio,the p H of the reaction was better than 4,and the p H in 1 or so would lead to the degeneration of the calcium lignin sulfonate solution into a gel.The structure property of lignin sulfonate also changed.In terms of surface tension,p H was the most influential factor.When the p H is too low,the internal structure of the sample is cross-linked,resulting in a large number of molecules,which is not only denaturing,but also the surface tension is extremely high.For the orthogonal reaction,bleaching while retaining surface activity under the optimal conditions for the purpose of:temperature 140 ?,time of 1.5 h,drug ratio of formaldehyde to 0.8,p H = 4.Chlorine dioxide was bleached for alkali lignin,and the best bleaching conditions were investigated by using four-factor five-level orthogonal experiment.Dialogue degree influence factor is the primary and secondary p H > Cl O2 dosage >temperature > time,the optimal condition is: temperature 90 ?,20% ClO2 dosage,pH = 6,time 3.5 h.