Readiness of lignosulfonate adsorption onto montmorillonite

Abstract

Five types of lignosulfonate (LS) for example the sodium LS (SLS), ammonium LS (ALS), calcium LS (CLS) and magnesium LS (MLS) were compared through the term of functional group and adsorption capability. Main goal of this research was to study the readiness of LS adsorption onto montmorillonite. Fourier transform infrared-attenuated total reflectance (FTIR-ATR) has been utilized to investigate a functional group before and after the LS adsorption. Depletion method had been used to examine the LS adsorption capability. Four functional groups, namely (a) hydroxyl group in phenolic as well as aliphatic, (b) methyl and methylene, (c) aromatic, and (d) sulfonic acids and extending aliphatic, have been involved in the adsorption process onto montmorillonite. Formation of new peaks in the FTIR image after adsorption indicated that LS was successfully adsorbed onto montmorillonite. The SLS displayed high readiness to adsorb onto montmorillonite, based on the following sequence: SLS>ALS>CLS>MLS. Higher salinity led to higher adsorption, especially changing between monovalent salt to divalent salt. Nevertheless, pH had nil impact on adsorption. Thus, pH modification can be ignored when using LS as sacrificial (SA). As for kinetic adsorption, LS adsorption followed the pseudo-second order. Electrostatic forces, cation-π interaction, hydrophobic interaction, and cation bridging exerted a major role in the adsorption system between LS and montmorillonite. This research indicates that LS are readily to adsorb onto montmorillonite. These findings are important because both readiness and adsorption capability of LS as SA can provide meaningful insight on how well LS can serve as a shield to protect the rock surface from adsorption of subsequent injected surfactant, which directly can reduce the surfactant adsorption in the process of chemical enhanced oil recovery (CEOR).