Manufacturing of synthetic tanning agent from kraft lignin
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Date
2014-09
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Addis Ababa University
Abstract
In chromium tanning adsorptive processes are minimal and leading to empty inter fibrillar spaces. Of these, the phenolic syntans are used which prepared from petroleum by products such as phenol, naphthalene and cresol. Being petroleum by products, the cost of these products is highly fluctuating. Therefor there is a need to evaluate alternatives for these products. In the current work, an effort has been made to develop phenolic synthetic tanning agent from waste of paper and pulp industry. Black liquor from pulp and paper waste was obtained and fully characterize. The treatment of this lignin with ferrous sulfate and hydrogen peroxide (5, 15 and 25 mmol of the reagent) and reaction temperature (25 oC, 45 oC and 65 oC) induces an extensive degradation in the native lignin. The effects of amount of H2O2 concentration, Fe2+concentration and reaction temperature on percentage of were determined by using Design Expert 7.0.0 software three factor Central Composite Design. As observed from optimized design at H2O2 concentration of 25 mmol, Fe2+ concentration of 15 mmol and 45oC the maximum percentage of lignin degradation was found 76.91%. Syntan preparation stage were investigate viz, sulphonation temperature, type of sulphonation agent, duration of reaction and amount of formaldehyde. The combined sulphonation product of sulphuric acid and sodium meta bisulfite (SS2) show better softens, roundness and grain smoothness and colour. Emission load of TS for commercial phenolic syntan is 43.61, whereas there is reduction in TS load by 41.7%-24.1% has been observed using lignin based syntan.
Key word: Lignin degradation; Kraft black liquor; syntans; Hydrogen peroxide; Ferrous ion; free formaldehyde
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Keywords
Lignin degradation; Kraft black liquor; syntans; Hydrogen peroxide; Ferrous ion; free formaldehyde