Preparation of Lignosulfonates from Biorefinery Lignins by Sulfomethylation and Their Application as a Water Reducer for Concrete.

Caoxing Huang,Weiyu Zhang,Qiang Yong,Junmei Ma,Guohong Huang

doi:10.3390/polym10080841

Abstract

Lignosulfonate (LG), a water-soluble polymer from sulfite pulping process of lignocellulosic biomass, has been commercially applied as admixture for concrete. In this work, lignosulfonates were produced from alkaline lignin (AL) and enzymatic hydrolysis residue (EHR) by sulfomethylation and these lignosulfonates as water reducers for concrete were then evaluated. Results showed that 94.9% and 68.9% of lignins in AL and EHR could be sulfonated under optimum sulfomethylation conditions, respectively. The sulfonic groups in lignosulfonates from AL (AL-LG) and EHR (EHR-LG) were 1.6 mmol/g and 1.0 mmol/g, respectively. Surface tension and zeta potential analysis indicated that both AL-LG and EHR-LG can be potentially used to as dispersant for improving the fluidity of the cement paste, similarly to commercial lignosulfonate (CM-LG). Adding 0.2 wt % of AL-LG, EHR-LG, and CM-LG in the concrete, the compressive strength (28 days) of concretes increased from 38.4 Mpa to 41.6, 42.6, and 40.9 Mpa, respectively. These findings suggest that the lignosulfonate from biorefinery lignin by sulfomethylation can meet the industrial standards as water reducers for cement admixtures.

Highlights

Lignin is the world’s most abundant naturally phenolic polymer, serving a variety of integral functions for non-woody and woody biomass [1]
Existing pulp and paper operations have specific usages for their lignin by-products, but biorefinery processes have yet to implement any sort of strategy for dealing with the lignin by-products that they produce [4,5]
The present study investigated systematically the performance of sulfomethylation on the production of lignosulfonate from biorefinery lignin (AL and enzymatic hydrolysis residue (EHR))

Summary

Introduction

Lignin is the world’s most abundant naturally phenolic polymer, serving a variety of integral functions for non-woody and woody biomass [1]. Processed lignin can be obtained from biomass pulping industries, where it is usually regarded as a value-adding byproduct [2,3]. Unlike the lignin derived from pulping and papermaking processes, biorefinery lignins are produced from biorefinery processes which generate energy, fuels, and materials from renewable lignocellulosic biomass [4]. Existing pulp and paper operations have specific usages for their lignin by-products (e.g., fuel source and chemical recovery in kraft, value-adding lignosulfonates in sulfite), but biorefinery processes have yet to implement any sort of strategy for dealing with the lignin by-products that they produce [4,5]. Unique valorization of the lignin generated from lignocellulosic biorefinery process is essential to establish economic viability of such processes. Only 30% of these residues are valorized as energy or used

Methods

Results

Conclusion