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Ma L.,CAS Guangzhou Institute of Geochemistry | Ma L.,University of Chinese Academy of Sciences | Ma L.,Guangdong Provincial Key Laboratory of Mineral Physics and Material | Zhu J.,CAS Guangzhou Institute of Geochemistry | And 10 more authors.
Applied Clay Science | Year: 2015

The exact location of surfactant molecules on clay minerals is critical for the synthesis of clay polymer nanocomposites and their applications in environmental remediation. The location and thermal characteristics of zwitterionic surfactant (Z16) composites with montmorillonite (Mt), Al13-pillared montmorillonite (AlPMt), calcined AlPMt (AlPMt/500), and talc (Tlc) were investigated by using X-ray diffraction (XRD) and thermogravimetric analysis (TG). The basal spacing of Mt was markedly increased after modification with Z16, while that of Tlc, AlPMt, and AlPMt/500 was essentially unchanged. The decomposition temperature of Z16/Tlc composite (~294°C) was similar to that of the pure surfactant. Sulfobetaine apparently failed to penetrate into the interlayer space of talc; instead it was confined to external surfaces. On the other hand, the DTG pattern of Z16-modified Mt showed two main peaks (404 and 336°C), indicating two different intercalation mechanisms of Z16 on Mt. Sulfobetaine, loaded to AlPMt and AlPMt/500, was found to decompose at 355 and 370°C, respectively, suggesting that Z16 occupied the interpillar space in these samples. Much more Z16 was taken up by AlPMt than by AlPMt/500, although the specific surface areas of both materials were practically identical, suggesting that the surfactant molecules in the interlayer space of AlPMt were largely adsorbed by electrostatic attraction between the negatively charged groups of Z16 and the positively charged Al13 cations. © 2015 Elsevier B.V. Source


Ma L.,Queensland University of Technology | Ma L.,CAS Guangzhou Institute of Geochemistry | Ma L.,University of Chinese Academy of Sciences | Xi Y.,Queensland University of Technology | And 7 more authors.
Applied Clay Science | Year: 2016

Fe-montmorillonite (Fe-Mt) was prepared and tested for its potential application in the simultaneous removal of hexavalent chromium (Cr(VI)) and rhodamine B (RhB) from aqueous solution. The adsorption kinetics and capacities of Fe-Mt toward Cr(VI) and RhB were determined in relation to the initial contaminant concentration, pH of the solution and concentration of coexist contaminant. The adsorption kinetics of Cr(VI) or/and RhB in both single and simultaneous systems were investigated, which showed that an equilibrium time of a few hours was needed for the adsorption of Cr(VI) and RhB on Fe-Mt. The pseudo-second order model offers a better fit than pseudo-first order model for the Cr(VI) and RhB adsorption. Compared with the single adsorption systems, adsorption rates and quantities of Cr(VI) and RhB adsorbed on Fe-Mt were slightly enhanced in the simultaneous adsorption system. The most effective pH range for the removal of Cr(VI) and RhB was found to be 3.0-4.0. Cr(VI) adsorption isotherms were best represented by the two-site Langmuir model while RhB isotherms followed the Freundlich model. For both contaminants, the adsorption of one contaminant increases with increase in the initial concentration of the other one. Therefore, Fe-Mt could simultaneously remove Cr(VI) and RhB from water. The properties of Fe-Mt were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG). The findings of this study provide novel information for the development of clay-based adsorbents toward dyes and heavy metals. © 2015 Elsevier B.V. Source


Ma L.,CAS Guangzhou Institute of Geochemistry | Ma L.,Queensland University of Technology | Ma L.,University of Chinese Academy of Sciences | Zhu J.,CAS Guangzhou Institute of Geochemistry | And 9 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2016

Inorganic-organic montmorillonites (IOMts) obtained by modifying polyhydroxy-aluminum (Al13)-pillared montmorillonite (AlPMt) with the cationic surfactant (C16) and zwtterionic surfactant (Z16) were investigated with the aim to remove phenol, phosphate and Cd(II) simultaneously. The structures of IOMts prepared using different surfactant doses (0.4 and 1.0CEC) strongly depended on the types and doses of the surfactants. The Al13 contents of C16 modified AlPMts (C-AlPMts) decreased with increasing C16 loading while that of Z16 modified AlPMt (Z-AlPMts) did not. In the single adsorption system, all IOMts could efficiently remove phenol and phosphate, but not Cd(II). IOMts, however, could efficiently remove all three contaminants simultaneously in the multi-contaminant adsorption system. The adsorptions of phenol on IOMts were not affected by the other two inorganic components and vice versa. Whereas the adsorptions of phosphate and Cd(II) were significantly enhanced in the multi-contaminant system, and the adsorption of one increased with increasing initial concentration of the other one, especially the adsorption of Cd(II). The enhancements of adsorption of phosphate and Cd(II) on the IOMts with higher Al13 content were much larger than that on IOMts with lower Al13 content. The adsorption mechanism for phosphate and Cd(II) uptake in the multi-contaminant system possible involve the formation of phosphate-bridged ternary complexes. © 2016 Elsevier B.V. Source


Ma L.,Queensland University of Technology | Ma L.,CAS Guangzhou Institute of Geochemistry | Ma L.,Guangdong Provincial Key Laboratory of Mineral Physics and Material | Rathnayake S.I.,Queensland University of Technology | And 10 more authors.
Chemical Engineering Journal | Year: 2016

Novel heterogeneous Fenton composite materials were developed by grafting acid precursors and nano zero-valent iron particles on an acid leached diatomite, which can sequentially generate acid and ferrous ions in situ. The results show that the composite materials can potentially solve two of the biggest obstacles, which prevent the conventional Fenton reaction from being widely and practically adopted, namely: the continuous feed of ferrous ions and the maintenance of the optimum acidic pH condition during the reaction. In this study, samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Thermogravimetric analysis and micro organic analysis. The novel materials' degradation capacities for bisphenol A (BPA) were evaluated and optimized. This material can be easily applied to treat wastewater via Fenton-like reaction without changing pH or adding ferrous ions. The relationships between BPA removal efficiency, the amount of grafted organosilane acid precursor and doped nZVI particles on the composite materials were investigated. It is evident from the results that the novel composite materials afford highly effective removal of BPA from water at 250 mg/g. The work thus demonstrates that the novel materials could potentially be utilized for efficient remediation of recalcitrant organic compounds from the environment. © 2016 Elsevier B.V. Source


Ma L.,CAS Guangzhou Institute of Geochemistry | Ma L.,Queensland University of Technology | Ma L.,University of Chinese Academy of Sciences | Zhu J.,CAS Guangzhou Institute of Geochemistry | And 9 more authors.
RSC Advances | Year: 2015

Al13 pillared montmorillonites (AlPMts) prepared with different Al/clay ratios were used to remove Cd(ii) and phosphate from aqueous solution. The structure of AlPMts was characterized by X-ray diffraction (XRD), Thermogravimetric analysis (TG), and N2 adsorption-desorption. The basal spacing, intercalated amount of Al13 cations, and specific surface area of AlPMts increased with the increase of the Al/clay ratio. In the single adsorption system, with the increase of the Al/clay ratio, the adsorption of phosphate on AlPMts increased but that of Cd(ii) decreased. Significantly enhanced adsorptions of Cd(ii) and phosphate on AlPMts were observed in a simultaneous system. For both contaminants, the adsorption of one contaminant would increase with the increase of the initial concentration of the other one and increase in the Al/clay ratio. The enhancement of the adsorption of Cd(ii) was much higher than that of phosphate on AlPMt. This suggests that the intercalated Al13 cations are the primary co-adsorption sites for phosphate and Cd(ii). X-ray photoelectron spectroscopy (XPS) indicated comparable binding energy of P2p but a different binding energy of Cd3d in single and simultaneous systems. The adsorption and XPS results suggested that the formation of P-bridge ternary surface complexes was the possible adsorption mechanism for promoted uptake of Cd(ii) and phosphate on AlPMt. © 2015 The Royal Society of Chemistry. Source

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