A Green Cement Plasticizer from Softwood Kraft Lignin

Abstract

A green cement plasticizer was produced in a one-step aerobic oxidation of kraft lignin (KL) in the presence of KOH. In this study, optimizing the reaction conditions led to the maximum carboxylic acid group and charge density of 2.6 mmol/g and 1.9 mequiv/g for oxidized lignin, respectively. The NMR, FTIR, and XPS analyses quantified the alterations in the structure of KL after the oxidation reaction. The molecular weight analysis revealed that lignin depolymerization would depend on the temperature, lignin amount, and KOH concentrations. The oxidized lignin with a higher carboxylic acid group adsorbed on the cement particles more readily than a commercial plasticizer, which increased the flowability of the pastes. The compressive strength of cement was improved much more by using oxidized lignin instead of a commercial plasticizer and lignosulfonate. The current study suggested that the one-pot KOH-mediated oxidation of kraft lignin is a promising approach to producing a green plasticizer for cement application.

Comparison of Oil-Seed Shell Biomass-Based Biochar for the Removal of Anionic Dyes—Characterization and Adsorption Efficiency Studies

“…Table 2 describes the relative mass concentrations of the different bond energies before and after the carbonization of the RM. In Figure 2 , the C1, C2, C3, and C4 are assigned to the specific carbon bonds such as the C-C/C-H, C-OH, C=O (carbonyl), and C=O (carboxylic), respectively [ 28 , 36 ]. Relative mass concentrations of the C1 bond types (C-C/C-H) increased by about 13.8 and 22.6% in the BC samples in both SFS900 and PNS900, respectively, presumably due to the formation of the condensed polyaromatic structures during high-temperature pyrolysis.…”

Full-Components Utilization of Cellulose Nanofibrils and Artificial Stone Wastes for Cement Enhancement

“…(Yang et al, 2023) The complexation of CNFs/ASWs with Ca 2+ alters the cement hydration process. (Sutradhar et al, 2023) Therefore, the introduction of CNFs/ASWs leads to an increase in the diffraction peak at 27 °, which may be due to the formation of C-S-H gels at the interface between the cement particles and the polymer, resulting in a tight binding of CNFs/ASWs to the cement collective thus improving the mechanical properties. Figures 5b 5c 5e and 5f show the microstructure of cement mortar with 0.5% CNFs/ASWs with and without CNFs/ASWs.…”

Separation and Purification of Vanillin and Syringaldehyde from an Oxidized Kraft Liquor – A Mini Review

“…As a result, the kraft process is more accessible for value-added production [26]. Kraft lignin contains a higher amount of phenolic hydroxyl groups than lignosulfonates due to the β-aryl bond cleavage [27] and kraft lignin has many other applications as fertilizers [28,29], pesticides [30,31], carbon fibers [32], dispersing agents [33], leather tanning [34], binders [35], resins [36] and cement plasticizers [37]. Lignin can be fragmented or depolymerized to yield small efficient and useful molecules such as aldehydes (vanillin, syringaldehyde, and p-hydroxybenzaldehyde) and complex mixtures obtained from side reactions such as vanillic, syringic, and p-hydroxybenzoic acids, as well as ketone compounds such as acetovanillone and acetosyringone and phenolics (Tab.…”

“…As a result, the kraft process is more accessible for value‐added production 26. Kraft lignin contains a higher amount of phenolic hydroxyl groups than lignosulfonates due to the β‐aryl bond cleavage 27 and kraft lignin has many other applications as fertilizers 28, 29, pesticides 30, 31, carbon fibers 32, dispersing agents 33, leather tanning 34, binders 35, resins 36 and cement plasticizers 37.…”