Organoclay hybrid materials as precursors of porous ZnO/silica-clay heterostructures for photocatalytic applications

Abstract

In this study, ZnO/SiO2-clay heterostructures were successfully synthesized by a facile two-step process applied to two types of clays: montmorillonite layered silicate and sepiolite microfibrous clay mineral. In the first step, intermediate silica–organoclay hybrid heterostructures were prepared following a colloidal route based on the controlled hydrolysis of tetramethoxysilane in the presence of the starting organoclay. Later on, pre-formed ZnO nanoparticles (NP) dispersed in 2-propanol were incorporated under ultrasound irradiation to the silica–organoclay hybrid heterostructures dispersed in 2-propanol, and finally, the resulting solids were calcinated to eliminate the organic matter and to produce ZnO nanoparticles (NP) homogeneously assembled to the clay–SiO2 framework. In the case of montmorillonite the resulting materials were identified as delaminated clays of ZnO/SiO2-clay composition, whereas for sepiolite, the resulting heterostructure is constituted by the assembling of ZnO NP to the sepiolite–silica substrate only affecting the external surface of the clay. The structural and morphological features of the prepared heterostructures were characterized by diverse physico-chemical techniques (such as XRD, FTIR, TEM, FE-SEM). The efficiency of these new porous ZnO/SiO2-clay heterostructures as potential photocatalysts in the degradation of organic dyes and the removal of pharmaceutical drugs in water solution was tested using methylene blue and ibuprofen compounds, respectively, as model of pollutants.

Synthesis, Characterization, Uses and Applications of Porous Clays Heterostructures: A Review

“…These authors incorporated Zr into the synthetic step to further increase the delamination of the sheets and the photolocatalytic efficiency of the material in the degradation of antipyrine . In order to improve the photocatalytic behavior, these materials were used as catalytic support of other photocatalytically active phases, such as ZnO, or CeO 2 , reaching higher conversion values.…”

Immobilization of Nanoparticles on Fibrous Clay Surfaces: Towards Promising Nanoplatforms for Advanced Functional Applications

“…Here again the use of organophilic interfaces as that provided by organoclays may help to facilitate the process. In this context, we have recently reported various examples of nanoarchitectures in which ZnO NP remain assembled to sepiolite fibers giving rise to active photocatalyst of interest for instance in the removal of drug pollutants in water . The assembly of ZnO NP to sepiolite fibers previously modified with hexadecyltrimethylammonium ions is carried out in isopropanol, being the suspension treated under ultrasonication to produce the homogeneous co‐dispersion and further co‐assembly of both types of NP .…”

“…The assembly of ZnO NP to sepiolite fibers previously modified with hexadecyltrimethylammonium ions is carried out in isopropanol, being the suspension treated under ultrasonication to produce the homogeneous co‐dispersion and further co‐assembly of both types of NP . The previous incorporation of SiO 2 NP to the fibrous clay for enlarging the surface available for the ZnO NP assembly does not result in materials with improved photoactivity, in contrast to that observed on smectites‐based systems where the in situ formed SiO 2 NP produces delamination of the clay and so larger reactive surface for the anchorage of ZnO NP . ZnO NP can be also bonded to sepiolite previously modified by assembly of magnetite NP (Figure a) .…”

Advanced Inorganic Nanosystems for Skin Drug Delivery

“…Their role is mainly based on an interaction with the skin appendages and skin lipids leading to a facilitated release, a sustained release caused by drug depot and/or stimuli‐induced release, as well as the use of microneedles to penetrate the skin barrier, which is another in‐vogue technique . In the last years, inorganic nanoparticles have achieved important success in diverse technical fields as manufacturing and materials, environment, energy, electronics and what is more interesant for us, in the medical field. Their unique features as optical and superparamagnetic properties, biocompatibility, stability and high drug loading efficiency have caused their countless use as carriers for diverse biomolecules …”