Preparation of Bi2O3/TiO2–Montmorillonite Nanocomposites and Their Applications to the Photodegradation of Pentachlorophenol

In the past decades, there has been a growing tendency to study the different techniques that can increase the photocatalytic efficiency as well as recyclability of new products “photocatalysts” for water treatment. In this last research the effect of bismuth addition to titanium was investigated. Bi/Ti-pillared montmorillonites have been prepared from natural Algerian bentonite exactly from deposits of Maghnia situated in the west side of the country. These nanocomposites were characterized by X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET), scanning electron microscopy (SEM) methods, and Fourier Transformed Infrared (FT-IR). The photocatalytic activities have been tested for the removal of pentaclorophenol (PCP) in water. The effect of preparation conditions, the pH of the solution and photocatalysts concentration, on these activities has been investigated. It was found that the photocatalytic degradation increase by addition of bismuth in pillaring process. The Mont-Bi-Ti is shown to be the best photocatalyst in term of photocatalytic activity. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Structural Transformations of Hydrolysates Obtained from Ti-, Zr-, and Ti, Zr-Solutions Used for Clay Pillaring: Towards Understanding of the Mixed Pillars Nature

Structural characteristics of hydrolysates formed from the aqueous Ti-, Zr-, and Ti, Zr-pillaring solutions prepared from inorganic precursors (TiCl4 and ZrOCl2), was investigated and compared with that of precipitates obtained from the same solutions after a slight alkalization of pH to the values reported for the conditions of clay pillaring. The materials were recovered by lyophilization and subsequently subjected to calcination at 500, 800 and 1000 °C. Of special interest was the effect of pH on the possible formation of mixed Ti, Zr-oxide species. Powder X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscope/energy dispersive spectrometer (SEM/EDS) analysis showed that even a relatively moderate alteration of pH in Ti-, Zr-, or Ti, Zr-precursor solutions caused substantial changes in the outcome of hydrolytic transformations, manifested by different phase and/or chemical composition of the resulting hydrolysates. Analysis of thermal evolution of hydrolysates showed that alkalization facilitated the transformation of anatase into rutile in materials obtained from Ti-pillaring solution, but retarded tetragonal to monoclinic zirconia conversion in samples derived from Zr-pillaring agent. The most striking effect was observed for the mixed Ti, Zr-pillaring solution, where an increase of pH enabled the formation of zirconium titanate as the only crystalline phase, rather than a multiphase mixture of anatase, monoclinic zirconia and zirconium titanate obtained from the more acidic precursor. The finding supports the model of mixed Ti-O-Zr network in props generated in Ti, Zr-pillared montmorillonites.

Facile preparation of copper impregnated aluminum pillared montmorillonite: nanoclays for wastewater treatment

Copper impregnated aluminum pillared montmorillonites (Cu-iAlpill-MMTs) were prepared by adding Cu2+ solution into dried aluminum polyohydroxy cation intercalated montmorillonite using various Cu2+ concentrations, i.e. 4, 7, 10 and 13 wt% and then calcining at 500°C. The Cu-iAlpill-MMTs possessed slit-liked mesopores with pore diameters of 3.3–3.8 nm and ~6–35 nm as observed from the nitrogen adsorption isotherms. The mesopore quantities of Cu-iAlpill-MMTs gradually decreased with the increase of impregnated Cu2+ concentrations. The impregnated CuO occupied not only the interior interlayers, but also the exterior surfaces of Cu-iAlpill-MMTs. The Cu-iAlpill-MMTs with 10 and 13 wt% of impregnated Cu2+ could inhibit the growth of Escherichia coli. The Cu-iAlpill-MMTs effectively acted as the heterogeneous catalyst for removal reactive orange 16 (RO16) in Fenton or photo-Fenton oxidation treatments. The higher impregnated Cu2+ and/or the longer treatment time brought about the higher percentage of RO16 removal.

Simultaneous adsorption of Cd(ii) and phosphate on Al13 pillared montmorillonite

Al13 pillared montmorillonites (AlPMts) prepared with different Al/clay ratios were used to remove Cd(ii) and phosphate from aqueous solution.

Single Pot Benzylation of O-Xylene with Benzyl Chloride and Benzyl Alcohol Over Pillared Montmorillonites

Improvement of product selectivity is a major concern of the day. Presence of a coreactant can alter the rate as well as product selectivity of many key reactions like Friedel-Crafts benzylation. Single pot benzylation of o-xylene with benzyl chloride and benzyl alcohol was studied over transition metal exchanged pillared clay catalysts. Complete conversion of benzyl alcohol occured within one hour with 100% monoalkylated product selectivity. The reaction of o-xylene with benzyl alcohol was found to proceed fast in presence of benzyl chloride in single pot, than when present alone as the benzylating species. This enhancement occurs at the expense of no reaction of benzyl chloride, which when present alone reacts faster than benzyl alcohol. Existence of a second transition metal exchanged between the pillars increased the rate of the reaction. A detailed investigation of the reaction variables suggested preferential adsorption of benzyl alcohol to catalyst active sites as the reason.