Production and decolorization of lignin from industrial waste of pulp and paper based on the coagulation method using poly aluminium chloride.

Pulp and paper industrial waste or what is known as black liquor contains toxic contents, if not treated first, it can cause environmental pollution. So far, black liquor has only been used for the manufacture of biofuels and fuel for the paper industry, while 46% of lignin is the total solids in the black liquor component itself. This study aims to determine how much the percentage of decolorization of black liquor and producing lignin with bright colors using the coagulation method. The coagulant used in this study was Poly Aluminium Chloride (PAC) with various concentrations (0.5%, 1%, 1.5%, 2%, and 2.5%) v / v. The results showed that the coagulation method proved effective in decolorizing lignin made from black liquor as raw material. The optimum condition to obtain decolorization was 90.44% using 2% PAC coagulant concentration and the total retention time of 24 hours. In addition, FTIR was used to qualitatively analyze the sludge produced during the coagulation process, and the results showed that there are several different groups in the lignin unit. The lignin obtained using the coagulation method produces a brighter brown color, is insoluble in water and odorless with a yield of 38.3%, a pH of 1.68, a purity of 54.8%, and water content and an ash content of 0.2% and 27.2%, respectively. [ABSTRACT FROM AUTHOR]