Adsorption of anionic dyes onto natural, thermally and chemically modified smectite clays

Abstract

The aim of this study was to determine the adsorption capacity of the smectite clays (from the overburden of the lignite deposit in Belchatow) for two anionic dyes, i.e. Reactive Blue 81 (RB-81) and Direct Blue 74 (DB-74). Additionally, the infl uence of the thermal and chemical (acid and alkali) clay modifi cations on the amount of bonded dyes was investigated. The adsorption capacity of the clay (natural and modifi ed) was different for studied dyes and depended on the initial concentration and modifi cation type. All the modifi ed clays adsorbed the dyes at pH>pH PZC as the negatively charged surfaces of their particles (in accordance with the formula: AOH ↔ AO -+ H + ) prevented the formation of electrostatic bonds between the anionic dyes and the clay surface. The dyes were mainly bound with the hydrogen bonds forming between the donor groups in the dyes and the acceptor groups (-SiO and -Al 2 OH) in the clays. The coeffi cients in the adsorption isotherms were estimated with the linear and non-linear regression. The linear regression method was found that the Freundlich and Dubinin-Radushkevich isotherms described the dye sorption much better than the Langmuir model. On the other hand, all three models described well the experimental data in the non-linear regression method. Furthermore, the 1/n value (<1) obtained from the Freundlich equation for all the dye-sorbent systems indicated the favorable sorption.

Physicochemical Characterization of Regional Clay: Application to Phenol Adsorption

“…But the high price of activated carbon has prompted many researchers to look for other alternatives. e abundance of many cheaper materials in nature attracted the attention of many researchers including Chaari et al [12,13], Bentahar et al [14], Sakin Omer et al [15], Khosla [16], and Kyzioł-Komosinska et al [17]. Clay materials have a good adsorption capacity of organic pollutants, heavy metals, and dyes to aqueous media [18].…”

Determining the possibility of using selected composts to remove aqueous solutions from zinc ions in concentrations of up to 1000 mg.L-1

“…The use of composts as sorbents of numerous substances described in the specialist literature [7] can be confirmed by their sorption capacity. As composts are quite frequently used as sorbents of dyes from aqueous solutions [2,6], the method of methylene blue was chosen to determine the sorption capacity of the selected composts [25]. The results are listed in Table 2.…”

“…The growing demand for cheap and efficient sorbents capable of removing various types of pollutants from water and sewage spurs multidirectional studies which aim at finding new materials with adsorptive properties [1][2][3]. Researchers frequently resort to unconventional materials [4,5], as they prove to be much more economical than the widely used but rather costly activated carbon.…”

Application of smectite for textile dyeing and fastness improvement

“…However, synthetic dyes are causing many problems for the environment and humans owing to the hazardous materials produced during dye manufacture, preparation, and handling and to wastewater produced during dyeing. [1][2][3][4][5] When natural dyes are used, chemical (i.e., metallic) mordants such as Cu 2+ and Cr 6+ are used to increase dyeability and fastness. As a result, such mordants accumulate over a long time without readily dissolving in soil and water, which may retard crop growth and have harmful effects on human health.…”