A comparison of sodium lignosulfonate (Sls) synthesis from black liquor lignin and commercial lignin

Sulfonation of lignin has been considered as a promising step to produce lignosulfonate which may serve as dispersant, flocculant, and surfactant. Lignosulfonate has been reported as a potential low-cost surfactant to improve oil production from existing wells through Enhanced Oil Recovery (EOR). The aim of the present study was to compare the synthesis of sodium lignosulfonate (SLS) from different lignin feedstocks named commercial lignin and lignin isolated from black liquor (BL) of pulp and paper industry. A novel technique to isolate lignin from BL was introduced with the aid of CO2 and coagulant of Al2(SO4)3.12H2O. The FTIR spectra of BL lignin performed the similarity to commercial lignin which indicates that the isolation of BL lignin with the present technique did not alter the chemical structure of lignin. Furthermore, sulfonation of commercial and BL lignin with NaHSO3 solution had been well conducted to obtain SLS powder which verified by the appearance of absorption peak indicating that SO3 functional group vibration was lightly detected on the lignin structure of both samples. In general, the FTIR spectra of SLS from commercial and BL lignin were similar to their parent lignin. This result was later confirmed by elemental analysis with EDX which presented the enhancement of Na and S content in SLS compared to the original lignin sample. The ability of SLS to increase the oil mobility for Enhanced Oil Recovery (EOR) was measured by the interfacial tension (IFT). The results showed that the IFT values of SLS solution from commercial lignin and BL lignin were 0.3759 mN/m and 0.2675 mN/m, respectively. Further formulation of SLS from BL lignin with octanol and Palm Fatty Acid Distillate (PFAD) solution may lower the IFT value to 0.0186 mN/m. © 2019 Trans Tech Publications Ltd, Switzerland.