Trichlorophenol removal from aqueous solutions by modified halloysite: kinetic and equilibrium studies

Abstract

A B S T R A C TTo obtain new materials, we modified Algerian halloysite by thermal activation (HalC), acid activation (HalA), combined thermal-acid activation (HalCA) and acid-thermal activation. X-ray diffraction, Fourier Transform infrared and BET textural analysis were used to characterize changes. After the HalC of halloysite at 600˚C, no XRD peaks were shown and a total disappearance of the absorption bands ranging from 3,700 to 3,600 cm −1 . The treatment of halloysite by sulphuric acid increases the surface area from 185.4 to 321.0 m 2 /g. Halloysite is first calcined and then activated by acid, its surface area increases from 74.3 to 538.6 m 2 /g. The effect of initial pH, adsorbent dose, contact time and temperature on the removal of 2,4,5-trichlorophenol (TCP) by modified halloysite samples was investigated. Equilibrium data were fitted to the Langmuir, Freundlich and Toth models. The best fit of the cited models was the Freundlich model, which suggested infinite adsorption onto heterogeneous surface. The pseudo-first-order, pseudo-second-order and intraparticle diffusion models were applied to the experimental kinetic data. The results showed that the pseudo-second-order is the best model to describe the process. The study of thermodynamic parameters shows that the process of adsorption of TCP onto the prepared samples was spontaneous, endothermic and physical in nature.

Characterization of selectively etched halloysite nanotubes by acid treatment

“…These two main diffraction peaks in untreated HNTs indicate that these HNTs correspond to a dehydrated halloysite structure (halloysite-7Å) [54]. The intense diffraction observed at 2θ = 20.0º, which is attributed to the d020 plane with a basal spacing of 0.444 nm, confirms the tubular structure of halloysite [55]. The diffraction peak at 2θ = 26.6º, corresponds to quartz (SiO2) d020 plane in halloysite [56].…”

Enhanced adsorption of Direct Orange 26 dye in aqueous solutions by modified halloysite

“…In recent years, numerous papers have described adsorption of many pollutants on raw and modified halloysites, including metal ions (Matusik, 2016;Yu et al, 2016), chlorophenols (Sahnoun et al 2016), chloroanilines (Szczepanik et al, 2014;Szczepanik et al, 2017), pharmaceuticals (Jiang et al, 2016), and some dyes (Zhao and Liu, 2008;Luo et al, 2010;Kiani et al, 2011;Liu et al, 2011;Belkassa et al, 2013;Zhao et al, 2013;Bessaha et al, 2016). The latter authors chose different dyes belonging to different classes and groups of coloring substances as model water pollutants.…”

Preparation of intercalating halloysite by in situ synthesized polymethyl methacrylate and its effects on the crystallization behaviors and mechanical properties of polylactic acid composites

“…These peaks are characteristic peaks of dehydrated halloysite. [ 30 ] Meanwhile, the diffraction peak at 20.1° corresponds to the (020) plane with an interlayer spacing of 0.44 nm, which indicates that the HNTs are tubular. [ 31 ] After DMSO intercalation, the diffraction peak of (001) plane moves to 2 θ = 8°, with the interlayer spacing increasing to 1.12 nm.…”