The Role of Clay Mineral-Derived Photocatalysts in Insights of Remediation (original) (raw)

Recent Clay-Based Photocatalysts for Wastewater Treatment

Separations

Photocatalysis is a remarkable methodology that is popular and applied in different interdisciplinary research areas such as the degradation of hazardous organic contaminants in wastewater. In recent years, clay-based photocatalyst composites have attracted significant attention in the field of photocatalysis owing to their abundance, excellent light response ability, and stability. This review describes the combination of clay with focusing photocatalysts such as TiO2, g-C3N4, and Bi-based compounds for degrading organic pollutants in wastewater. Clay-based composites have more active surface sites, resulting in inhibited photocatalyst particle agglomeration. Moreover, clay enhances the creation of active radicals for organic pollutant degradation by separating photogenerated electrons and holes. Thus, the functions of clay in clay-based photocatalysts are not only to act as a template to inhibit the agglomeration of the main photocatalysts but also to suppress charge recombination...

Photocatalysed reactions on clay surfaces

This paper reviews recent work on the photochemical and photocatalytic properties of coordination compounds adsorbed within the intracrystal space of smectites or on the external surface of fibrous clays. The examples include: (i) the cis * tram isomerisation of [Ru(II)(bpy)2(HZ0)2]2+, (bpy = 2,2'-bipyridine);

Modification and characterization of selected Zambian clays for potential use as photocatalysts

European Journal of Chemistry

Natural materials such as clay are valued for their favorable physical and chemical characteristics on the surface. In this study, the selected Zambian clay materials are immobilized with TiO2 and manganese ions to determine their suitability for use as photocatalysts. SiO2 and Al2O3 oxide composition of Zambian clays was obtained in the range of 35.08-52.63/35.15-52.72 and 13.85-21.73/13.77-21.80, respectively, by inductively coupled plasma (ICP) and X-ray fluorescence (XRF); while Energy dispersive spectroscopy (EDS) of modified clays showed that they have 1.54% incorporation of Ti and 4.98% Mn for Chingola clay to act as UV-Vis absorbers. According to the powder X-ray diffraction analysis of raw clays, the primary phase of all samples is quartz and contains low concentrations of bentonite and kaolinite. The scanning electron microscope (SEM) showed fluffy morphology with agglomeration, while the particle sizes of the clay photocatalysts with the use of transmission electron micro...

Hydrothermal Sol-gel TiO2 Nanoparticles fixed to Clay and its Photocatalytic Application for the Degradation of Methyl Orange

Mediterranean Journal of Chemistry, 2019

In this paper, Clay-TiO2 nanomaterials were synthesized via hydrothermal sol-gel method using Ivorian clays and titanium tetra-isopropoxide as precursors. The synthesized composite was characterized through XRD, SEM/EDX, FTIR and BET surface measurements. The photocatalytic activity of composite towards the degradation of methyl orange (MO), a model pollutant, has been investigated under UV and simulated solar radiation. Comparative experiments done in a solution with and without H2O2 indicate an increase in efficiency for methyl orange removal from the polluted water in the presence of H2O2. The optimized parameters (contact time, amount of nanocomposite and amount of Fe2+/H2O2) allowed to reach removal efficiency up to 60 % of MO. Immobilization of TiO2 on clay facilitate repeated using of nanomaterials, two time.

Efficiency of Clay−TiO 2 Nanocomposites on the Photocatalytic Elimination of a Model Hydrophobic Air Pollutant

Environmental Science & Technology, 2009

Clay-supported TiO 2 photocatalysts can potentially improve the performance of air treatment technologies via enhanced adsorption and reactivity of target volatile organic compounds (VOCs). In this study, a bench-top photocatalytic flow reactor was used to evaluate the efficiency of hectorite-TiO 2 and kaolinite-TiO 2 , two novel composite materials synthesized in our laboratory. Toluene, a model hydrophobic VOC and a common indoor air pollutant, was introduced in the air stream at realistic concentrations, and reacted under UVA (λ max = 365 nm) or UVC (λ max = 254 nm) irradiation. The UVC lamp generated secondary emission at 185 nm, leading to the formation of ozone and other short-lived reactive species. Performance of clay-TiO 2 composites was compared with that of pure TiO 2 (Degussa P25), and with UV irradiation in the absence of photocatalyst under identical conditions. Films of clay-TiO 2 composites and of P25 were prepared by a dip-coating method on the surface of Raschig rings, which were placed inside the flow reactor. An upstream toluene concentration of ~170 ppbv was generated by diluting a constant flow of toluene vapor from a diffusion source with dry air, or with humid air at 10, 33 and 66 % relative humidity (RH). Toluene concentrations were determined by collecting Tenax-TA ® sorbent tubes downstream of the reactor, with subsequent thermal desorption-GC/MS analysis. The fraction of toluene removed, %R, and the reaction rate, T r , were calculated for each experimental condition from the concentration changes measured with and without UV irradiation. Use of UVC light (UV/TiO 2 /O 3) led to overall higher reactivity, which can be partially attributed to the contribution of gas phase reactions by short-lived radical species. When the reaction rate was normalized to the light irradiance, T r /I λ , the UV/TiO 2 reaction under UVA irradiation was more efficient for samples with a higher content of TiO 2 (P25 and Hecto-TiO 2), but not for Kao-TiO 2. In all cases, reaction rates peaked at 10% RH, with T r values between 10 and 50% higher than those measured under dry air. However, a net inhibition was observed as RH increased to 33% and 66%, indicating that water molecules competed effectively with toluene for reactive surface sites and limited the overall photocatalytic conversion. Compared to P25, inhibition by co-adsorbed water was less significant for Kao-TiO 2 samples, but was more dramatic for Hecto-TiO 2 due to the high water uptake capacity of hectorite.

Synthesis and characterisation of clay-supported titania photocatalysts

Journal of colloid and interface science, 2007

Titanium dioxide (TiO 2 ) has been extensively investigated as a photocatalyst for environmental remediation, as it is photostable, nontoxic, highly reactive and is a relatively inexpensive material [1], [2], [3], [4] and [5]. When TiO 2 is illuminated by UV light (λ less-than-or-equals, slant ...