Clay derived materials for environmental management

Hydrotalcite-like compounds with Mg\(^2\)\(^+\)/Al\(^3\)\(^+\) and Zn\(^2\)\(^+\)/Al\(^3\)\(^+\) cations in the layer at different mole ratios with different anions in the galleries were synthesised in this study. The materials have been characterised by a range of techniques. The influence of layer cations, and interlayer anions, which in turn influences the crystallinity, can affect the properties of the hydrotalcites. Dodecylsulfate (DS) and dodecylbenzenesulfonate (DBS) anions were intercalated successfully into the galleries and characterisation studies by the same technique that were used for the parent hydrotalcites show that the hydrotalcites structure was maintained and the interlayer space expanded, suggesting that intercalation of other organic compounds may be possible. The intercalated dodecylsulfate and dodecylbenzenesulfonate anions arranged themselves in monolayer and bilayer configuration in the interlayer. These modified hydrotalcites have well-ordered layered structures, divalent/trivalent mole ratios that are close to those of the host precursors, and hydrophobic properties. SEM images show that the modification led to many of the particles being broken down into smaller pieces due to thermal pre-treatment and regeneration with organic anions, but overall morphology was maintained as the host. They show thermal transitions that are comparable to the host, exhibiting three decomposition steps but with increase in the temperature at which weight losses are completed. They show capacity to uptake phenol and 2-chlorophenol (2-CP) from aqueous solution with the compounds containing DBS anions showing higher sorption capacities for 2-CP than the corresponding DS-containing compounds. A pseudo second order reaction best described the sorption process