TiO2 decorated functionalized halloysite nanotubes (TiO2@HNTs) and photocatalytic PVC membranes synthesis, characterization and its application in water treatment

A self-healing crosslinked-xanthan gum/soy protein based film containing halloysite nanotube and propolis with antibacterial and antioxidant activity for wound healing

Traumatic multidrug-resistant bacterial infections are the most threat to wound healing. Lower extremity wounds under diabetic conditions display a significant delay during the healing process. To overcome these challenges, the utilization of protein-based nanocomposite dressings is crucial in implementing a successful regenerative medicine approach. These dressings hold significant potential as polymer scaffolds, allowing them to mimic the properties of the extracellular matrix (ECM). So, the objective of this study was to develop a nanocomposite film using dialdehyde-xanthan gum/soy protein isolate incorporated with propolis (PP) and halloysite nanotubes (HNTs) (DXG-SPI/PP/HNTs). In this protein-polysaccharide hybrid system, the self-healing capability was demonstrated through Schiff bonds, providing a favorable environment for cell encapsulation in the field of tissue engineering. To improve the properties of the DXG-SPI film, the incorporation of polyphenols found in PP, particularly flavonoids, is proposed. The synthesized films were subjected to investigations regarding degradation, degree of swelling, and mechanical characteristics. Additionally, halloysite nanotubes (HNTs) were introduced into the DXG-SPI/PP nanocomposite films as a reinforcing filler with varying concentrations of 3 %, 5 %, and 7 % by weight. The scanning electron microscope (SEM) analysis confirmed the proper embedding and dispersion of HNTs onto the DXG-SPI/PP nanocomposite films, leading to functional interfacial interactions. The structure and crystallinity of the synthesized nanocomposite films were characterized using Fourier Transform Infrared Spectrometry (FTIR) and X-ray diffraction (XRD), respectively. Moreover, the developed DXG-SPI/PP/HNTs nanocomposite films significantly improved cell growth of NIH-3T3 fibroblast cells in the presence of PP and HNTs, indicating their cytocompatibility. The antibacterial activity of the nanocomposite was evaluated against Escherichia coli (E. Coli) and Staphylococcus aureus (S. Aureus), which are commonly associated with wound infections. Overall, our findings suggest that the synthesis of DXG-SPI/PP/HNTs nanocomposite scaffolds holds great promise as a clinically relevant biomaterial and exhibits strong potential for numerous challenging biomedical applications.

Clay-reinforced PVC composites and nanocomposites

Clay-reinforced polyvinyl chloride (PVC) composites and nanocomposites are one of the newest and most important compounds studied and used in various applications, including the biomedical, automotive industry, water treatment, packaging, fire retarding, and construction. The most important clays used in the synthesis of these composites are Bentonite, Montmorillonite, Kaolinite, and Illite. The addition of these nanoclays to the PVC matrix improves mechanical properties, thermal stability, and yellowness index properties. In this chapter, a detailed study of PVC and its properties, types of nanoclays and their properties, modification of nanoclays, production methods of composites, and nanocomposites of PVC/clay, their characterization, and applications have been performed. Herein, the types, properties, and applications of PVC/clay nanocomposites, as well as their challenges and future remarks, are reviewed.

Nanosized tubular clay minerals as inorganic nanoreactors for energy and environmental applications: A review to fill current knowledge gaps

Modern society pays further and further attention to environmental protection and the promotion of sustainable energy solutions. Heterogeneous photocatalysis is widely recognized as one of the most economically viable and ecologically sound technologies to combat environmental pollution and the global energy crisis. One challenge is finding a suitable photocatalytic material for an efficient process. Inorganic nanotubes have garnered attention as potential candidates due to their optoelectronic properties, which differ from their bulk equivalents. Among them, clay nanotubes (halloysite, imogolite, and chrysotile) are attracting renewed interest for photocatalysis applications thanks to their low production costs, their unique physical and chemical properties, and the possibility to functionalize or dope their structure to enhance charge-carriers separation into their structure. In this review, we provide new insights into the potential of these inorganic nanotubes in photocatalysis. We first discuss the structural and morphological features of clay nanotubes. Applications of photocatalysts based on clay nanotubes across a range of photocatalytic reactions, including the decomposition of organic pollutants, elimination of NOx, production of hydrogen, and disinfection of bacteria, are discussed. Finally, we highlight the obstacles and outline potential avenues for advancing the current photocatalytic system based on clay nanotubes. Our aim is that this review can offer researchers new opportunities to advance further research in the field of clay nanotubes-based photocatalysis with other vital applications in the future.

Ag-BN/HNT-TiO2 nanofibers produced by electrospinning as catalysts to remove acetaminophen

In this study, we present a novel approach to enhancing the degradation of acetaminophen (ACT) using nanostructured hybrid nanofibers. The hybrid nanofibers were produced by employing both sol-gel and electrospinning methodologies, integrating precise quantities of silver (Ag) and boron nitride (BN) nanosheets into titanium oxide (TiO2) nanofibers and halloysite nanotubes (HNT). We extensively examined the morphology, structure, and optical properties of these materials by employing scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy in our analysis. In the case of the HNT-TiO2 composite, the introduction of Ag nanoparticles at concentrations of 0.5%, 1.5%, and 3% led to a significant improvement in photocatalytic activity. Under visible light exposure for 4 h, the photocatalytic activity increased from 63% (HNT-TiO2) to 78.92%, 91.21%, and 92.90%, respectively. This enhancement can be attributed to the role of Ag nanoparticles as co-catalysts, facilitating the separation of electrons and holes generated during the photocatalytic process. Furthermore, BN nanosheets served as co-catalysts, capitalizing on their distinct attributes, including exceptional thermal conductivity, chemical stability, and electrical insulation. The incorporation of BN nanosheets into the Ag (3%)/HNT-TiO2 composite at a concentration of 5% resulted in a remarkable increase in ACT degradation efficiency. The degradation efficiency improved from 59.47% to an impressive 99.29% within a 2-h irradiation period due to the presence of BN nanosheets. Toxicity and scavenging assays revealed that OH•-, O2•-, and h+ were the major contributors to ACT degradation. Moreover, across five consecutive cycles, the Ag-BN/HNT-TiO2 composite exhibited consistent and stable performance, underscoring the significant contributions of Ag and BN in augmenting the photocatalytic capabilities of the composite. Overall, our findings suggest that this novel hybrid nanofiber composite holds great promise for practical applications in environmental remediation due to its improved photocatalytic activity and stability.

Low-cost photocatalytic membrane modified with green heterojunction TiO2/ZnO nanoparticles prepared from waste

The combination of photocatalysis and membrane procedures represents a promising approach for water treatment. This study utilized green synthesis methods to produce TiO2 nanoparticles (NPs) using Pomegranate extract and ZnO nanoparticles using Tangerine extract. These nanoparticles were then incorporated into a polyvinyl chloride (PVC) nanocomposite photocatalytic membrane. Different devices were used to examine the properties of nanocomposite membranes. The prepared membranes' morphology was examined using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The hydrophilicity of the membrane surface was assessed through the measurement of contact angle, while the crystal structure and chemical bonding were analyzed using Raman and Fourier transform infrared spectroscopy (FT-IR). The study also encompassed an examination of the mechanical properties. The hydrophilicity of the modified membrane exhibited a significant improvement. Additionally, there was an observed increase in both the pure water flux and rejection values. The photocatalytic activity of the membrane was found to be enhanced when exposed to sunlight as compared to when kept in the dark. The TiO2/ZnO nanocomposites membrane exhibited the highest level of photocatalytic degradation, achieving a rejection rate of 98.7% compared to the unmodified membrane. Therefore, it was determined that the TiO2/ZnO nanocomposites membrane exhibited superior performance to the other membranes assessed. The potential utility of our research lies in its application within the water treatment industry, specifically as an effective technique for modifying PVC membranes.

Bi-functional photocatalytic heterostructures combining titania thin films with carbon quantum dots (C-QDs/TiO2) for effective elimination of water pollutants

In this study, carbon quantum dots (C-QDs), prepared via hydrothermal-microwave procedures, were successfully combined with nanostructured titania (TiO2). The photocatalytic oxidation/reduction activity of the C-QDs/TiO2 composite films was evaluated in the decomposition of organic-inorganic contaminants from aqueous solutions under UV illumination. Physicochemical characterizations were applied to investigate the crystal structure of the carbon quantum dots and the composites. It was found that the prepared C-QDs/TiO2 composites had great contribution to the photocatalytic reduction of hexavalent chromium (Cr+6) species and 4-Nitrophenol (PNP) as well as to the photocatalytic oxidation of methylene blue (MB) and Rhodamine B (RhB) dyes. The mechanism of the photocatalytic reaction was studied with trapping experiments, revealing that the electron (e-) radical species were powerfully supported for the photocatalytic reduction of Cr+6 and PNP and the holes (h+) are the main active species for the photocatalytic oxidation reactions.

Polymeric Membranes Doped with Halloysite Nanotubes Imaged using Proton Microbeam Microscopy

Polymeric membranes are useful tools for water filtration processes, with their performance strongly dependent on the presence of hydrophilic dopants. In this study, polyaniline (PANI)-capped aluminosilicate (halloysite) nanotubes (HNTs) are dispersed into polyether sulfone (PES), with concentrations ranging from 0.5 to 1.5 wt%, to modify the properties of the PES membrane. Both undoped and HNT-doped PES membranes are investigated in terms of wettability (static and time-dependent contact angle), permeance, mechanical resistance, and morphology (using scanning electron microscopy (SEM)). The higher water permeance observed for the PES membranes incorporating PANI-capped HNTs is, finally, assessed and discussed vis-à-vis the real distribution of HNTs. Indeed, the imaging and characterization in terms of composition, spatial arrangement, and counting of HNTs embedded within the polymeric matrix are demonstrated using non-destructive Micro Particle Induced X-ray Emission (µ-PIXE) and Scanning Transmission Ion Microscopy (STIM) techniques. This approach not only exhibits the unique ability to detect/highlight the distribution of HNTs incorporated throughout the whole thickness of polymer membranes and provide volumetric morphological information consistent with SEM imaging, but also overcomes the limits of the most common analytical techniques exploiting electron probes. These aspects are comprehensively discussed in terms of practical analysis advantages.

Halloysite-TiO2 Nanocomposites for Water Treatment: A Review

Halloysite nanotubes (HNTs) are clay minerals with a tubular structure that can be used for many different applications in place of carbon nanotubes. Indeed, HNTs display low/non-toxicity, are biocompatible, and can be easily prepared. Moreover, the aluminum and silica groups present on HNTs' inner and outer surfaces facilitate the interaction with various functional agents, such as alkalis, organosilanes, polymers, surfactants, and nanomaterials. This allows the deposition of different materials, for instance, metal and non-metal oxides, on different substrate types. This review article first briefly presents HNTs' general structure and the various applications described in the last 20 years (e.g., drug delivery, medical implants, and energy storage). Then, it discusses in detail HNT applications for water purification (inorganic and organic pollutants). It focuses particularly on HNT-TiO₂ composites that are considered very promising photocatalysts due to their high specific surface area and adsorption capacity, large pore volume, good stability, and mechanical features.

Antibacterial and Physicochemical Properties of Orthodontic Resin Cement Containing ZnO-Loaded Halloysite Nanotubes

Demineralized white lesions are a common problem when using orthodontic resin cement, which can be prevented with the addition of antibacterial substances. However, the addition of antibacterial substances such as zinc oxide alone may result in the deterioration of the resin cement's functions. Halloysite nanotubes (HNTs) are known to be biocompatible without adversely affecting the mechanical properties of the material while having the ability to load different substances. The purpose of this study was to prepare orthodontic resin cement containing HNT fillers loaded with ZnO (ZnO/HNTs) and to investigate its mechanical, physical, chemical, and antibacterial properties. A group without filler was used as a control. Three groups containing 5 wt.% of HNTs, ZnO, and ZnO/HNTs were prepared. TEM and EDS measurements were carried out to confirm the morphological structure of the HNTs and the successful loading of ZnO onto the HNTs. The mechanical, physical, chemical, and antibacterial properties of the prepared orthodontic resin cement were considered. The ZnO group had high flexural strength and water absorption but a low depth of cure (p < 0.05). The ZnO/HNTs group showed the highest shear bond strength and film thickness (p < 0.05). In the antibacterial test, the ZnO/HNTs group resulted in a significant decrease in the biofilm's metabolic activity compared to the other groups (p < 0.05). ZnO/HNTs did not affect cell viability. In addition, ZnO was cytotoxic at a concentration of 100% in the extract. The nanocomposite developed in this study exhibited antimicrobial activity against S. mutans while maintaining the mechanical, physical, and chemical properties of orthodontic resin cement. Therefore, it has the potential to be used as an orthodontic resin cement that can prevent DWLs.

Photocatalytic degradation of chlorazol yellow dye under sunlight irradiation using Ce, Bi, and N co-doped TiO2 photocatalyst in neutral medium

Chlorazol yellow (CY) is a commonly used anionic, toxic, mutagenic, and potentially carcinogenic azo dye, which is menacing to the environment, aquatic system, food chain, and human health as well. To remove CY dye molecules from an aqueous medium, a series of Ce, Bi, and N co-doped TiO₂ photocatalysts were prepared by varying the composition of the dopants. Under sunlight irradiation, the resultant 5 wt% (Ce-Bi-N) co-doped TiO₂ composite catalyst was found to show the best catalytic activity. Hence, the required characterization of this catalyst was performed systematically using energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) techniques. From the thorough investigation, it is revealed that the CY molecules reached adsorption-desorption equilibrium onto the surface of the catalyst within 30 min following second-order kinetics. Herein, the catalyst attained 97% degradation when exposed to sunlight at neutral (pH ~ 7, [CY] = 5 mg L^-1) medium. The developed catalyst can destruct CY molecules with a maximum rate of 23.1 µg CY g^-1 min^-1 and the photodegradation kinetics follows first-order kinetics below 23.5 mg L^-1, a fractional order between 23.5 and 35.0 mg L^-1, and a zeroth order above 35.0 mg L^-1 of CY concentration. Finding from scavenging effect implies that [Formula: see text] and [Formula: see text] radicals have significant influence on the degradation. A suitable mechanism has been proposed with excellent stability and verified reusability of the proposed photocatalyst.

Experimental Study on Kinetics and Mechanism of Ciprofloxacin Degradation in Aqueous Phase Using Ag-TiO2/rGO/Halloysite Photocatalyst

In this study, Ag-TiO2/rGO/halloysite nanotubes were synthesised from natural sources using a simple method. The material was characterised by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Raman spectroscopy, BET, scanning electron microscopy (SEM) and UV-vis DRS techniques. The as-synthesised material has a sandwich-like shape, with the active phase distributed evenly over the rGO/HNT support. Compared to pure TiO2, the material has a lower band gap energy (~2.7 eV) and a suitable specific surface area (~80 m2/g), making it able to participate effectively in the photochemical degradation of pollutants. The catalyst showed exceptional activity in the degradation of CIP antibiotics in water, achieving a conversion of about 90% after 5 h of irradiation at an initial CIP concentration of 20 ppm. This efficiency was significantly higher than that of pure TiO2 and Ag-TiO2, which could prove the important effect of the support and silver doping. The results of the experiments show that the process follows a pseudo-first-order kinetic model in the case of (1%)Ag wt. and pseudo-second-order in the case of (3%)Ag wt., which could be explained by the aggregation of silver and the increasing role of chemisorption. Tests with radical scavengers showed that the •OH radical had the greatest effect on CIP decomposition, while •O2− had the least. The neutral pH value and the high degree of mineralisation (approx. 80%) confirm the potential of the material for use in wastewater treatment.

Bioremediations analysis using multifactorial porous materials derived from tea residue

Titanium dioxide nanoparticles (TiO₂ NPs) are becoming more and more renowned as biocompatible nanomaterials with diverse biological functions. In the present study, the aqueous extract of tea residue (tea filtered waste powder) was used to synthesize the TiO₂ NPs and treated for effluent bioremediations. Maximum absorption in the UV-Vis spectrum of the TiO₂ NPs was seen at 358 nm, and the XRD pattern reveals peaks at 2 h values of 25.78, 38.24, 47.98, 54.76, 55.32, 62.64, 69.05, 70.15, 75.24, and 83.59 that may be indexed to the (101), (004), (200), (105), (211), (204), (116), (220), (215) and (303). The FT-IR spectra of TiO₂ NPs showed a peak at 3420, 2925, 1621, 1382, 1098, and 687 cm-1. The spherical form and size were disclosed by FE-SEM analyses, and the EDAX pattern verified the purity of the TiO₂ NPs. The average particles size of the TiO₂ NPs was 32 nm. The photodegradation of paper mill waste water is significantly deteriorated up to 99.08% for 600 min, but textile waste water is degraded up to 98.06% for the same duration. Furthermore, we reported that TiO₂ NPs may rapidly breakdown industrially hazardous effluents when exposed to sunshine. Overall, this new, straightforward, and environmentally beneficial strategy may be of interest to the management of efficient degradation of dye solutions in the polluted regions.

Fabrication and Evaluation of Basil Essential Oil-Loaded Halloysite Nanotubes in Chitosan Nanocomposite Film and Its Application in Food Packaging

Increasing health concerns regarding the use of plasticware have led to the development of ecofriendly biodegradable packaging film from natural polymer and food additives. In the present study, basil essential oil (BEO) loaded halloysite nanotubes (HNTs) composite films were synthesized using a solution casting method. The effects of BEO and nanotube concentration on the mechanical, physical, structural, barrier, and antioxidant properties of films were evaluated. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) demonstrated well-dispersed HNTs and BEO in tailored composite films. The addition of BEO in Chitosan (Ch) film caused darkening of the film color; furthermore, the incorporation of HNTs in varied concentrations increased opaqueness in Ch/BEO film. The Ch/BEO film, upon adding HNTs 5-30 wt%, exhibited a corresponding increase in the film thickness (0.108-0.135 mm) when compared with the Ch/BEO film alone (0.081 mm). The BEO-loaded HNTs composite films displayed reduced moisture content and characteristic barrier and UV properties. The Ch/BEO film with 15 wt% HNTs was found to have enhanced antioxidant activity. The Ch/BEO/HNTs composite also managed to prevent broccoli florets from losing weight and firmness during storage. The enhanced barrier and antioxidant qualities of the nanocomposite film suggest its potential application in the food processing and packaging sector. This is the first ever report on the fabrication of nanocomposite film using BEO and HNTs for food packaging. The low production cost and ecofriendly approach make the film acceptable for further research and commercialization thereafter.

Investigation of wound healing efficiency of multifunctional eudragit/soy protein isolate electrospun nanofiber incorporated with ZnO loaded halloysite nanotubes and allantoin

One significant aspect of the current therapeutic agents employed in wound healing involves the engineering of nano polymeric scaffolds to mimic the properties of extracellular matrix (ECM). The present work aimed to prepare and evaluate Eudragit® L100 (EU) nanofibers in combination with soy protein isolate (SPI). Allantoin (Ala) with a 2 wt% was encapsulated as a model drug renowned for its anti-inflammatory and antioxidant agents. Moreover, the synthesized ZnO-halloysite nanotubes (ZHNTs) with different concentrations of 1, 3, and 5 wt% were incorporated into the EU/SPI/Ala nanofiber as a reinforcing filler and a remarkable antibacterial agent. The scanning electron microscope (SEM) analysis showed that by increasing the weight percentage of SPI from 1 % to 2.5 %, the average diameter of nanofibers decreased from 132.3 ± 51.3 nm to 126.7 ± 47.2 nm. It was 223.5 ± 95.6 nm for nanofibers containing 5 wt% ZHNTs (the optimal sample). The evaluation of in vitro release kinetics of Ala for 24 h, showed a burst release during the first 2 h and a sustained release during the subsequent times. Moreover, the structure, crystallinity, and thermal stability of synthesized nanofibers were characterized by Fourier Transform Infrared Spectrometry (FTIR), X-ray diffraction (XRD), and Thermo gravimetric analysis (TGA), respectively. In vitro degradation and mechanical characteristics of these nanofibers were studied. Furthermore, the capability of the nanofibers for cell proliferation was revealed through the MTT test and field emission scanning electron microscopy (FESEM) images of cell attachment. The antimicrobial activity of EU/SPI/Ala/ZHNTs showed that this sample with high ZHNTs content (5 w%t) had the most remarkable antibacterial activity against S. aureus. The results revealed that EU/SPI/Ala/ZHNTs mats could be promising potential wound dressings.

Photocatalytic TiO2@MIL-88A (Fe)/polyacrylonitrile mixed matrix membranes: Characterization, anti-fouling properties, and performance on the removal of natural organic matter

Photocatalytic membrane reactors (PMRs), coupling photocatalysts and membranes in a single system, have shown a considerable potential to reduce membrane fouling, which is one of the major drawbacks of using membranes to treat water and wastewater. In this study, the visible light-activated photocatalysts were incorporated into the polyacrylonitrile (PAN) casting solution to synthesize the photocatalytic composite membranes. The physicochemical properties and the morphology of the membranes and photocatalysts were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction analysis (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-visible DRS), photoluminescence (PL), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Brunauer-Emmett-Teller (BET), porosimetry, and contact angle analyses. The performance of the synthesized photocatalytic mixed matrix membranes (MMMs) in treating water containing humic acid, as one of the major components in natural organic matter (NOM) existing in drinking water sources, was investigated. Under visible light irradiation, the PAN/TiO₂@MIL-88A (Fe) MMMs simultaneously adopted photocatalysis and membrane separation in the PMR and thereby enhanced humic acid removal and anti-fouling properties. The best synthesized photocatalytic membrane could remove 92.4% of the humic acid once exposed to visible light. The optimum membrane had suitable water permeability, a high flux recovery ratio (99.5%), and a 13.5% decline in the humic acid flux after a 10-h run, considerably lower compared to the corresponding decline of the pristine membrane (37.5% over the same period). The remarkable properties of the PAN/TiO₂@MIL-88A (Fe) membrane, including its high anti-fouling specification, confirm the appropriateness of the synthesized MMM for treating water involving humic acid.

Strainer-Separable TiO2 on Halloysite Nanocomposite-Embedded Alginate Capsules with Enhanced Photocatalytic Activity for Degradation of Organic Dyes

Photocatalysis driven by natural sunlight is an attractive approach to removing pollutants from wastewater. Although TiO₂–based photocatalysts using various support nano-materials with high catalytic activity and reusability have been developed for purifying wastewater, the centrifugal separation methods used for the nanocatalysts limit their use for treating large amounts of water. Here, we prepared a TiO₂ nano-catalyst supported on a halloysite nanotube (HNT)-encapsulated alginate capsule (TiO₂@HNT/Alcap) to recapture the catalysts rapidly without centrifugation. The structure of TiO₂@HNT/Alcap was characterized by X-ray diffraction, SEM, and TGA. In our system, the combination of HNTs and alginate capsules (Alcaps) improved the efficiency of adsorption of organic pollutants to TiO₂, and their milli = meter scale structure allowed ultra-fast filtering using a strainer. The TiO₂@HNT/Alcaps showed ~1.7 times higher adsorption of rhodamine B compared to empty alginate capsules and also showed ~10 and ~6 times higher degradation rate compared to the HNT/Alcaps and TiO₂/Alcaps, respectively.

Impedimetric detection of 2,4,6-trinitrotoluene using surface-functionalized halloysite nanotubes

Herein, we report the application of amine-surface-functionalized halloysite nanotubes (HAs) as active materials for the quantitative detection of 2,4,6-trinitrotoluene (TNT). The findings indicated that HA could selectively capture TNT via a strong reaction between the amine groups on its surface and the TNT molecules. Plate electrodes were fabricated from HA to evaluate its TNT-sensing capacity by electrochemical impedance spectroscopy. Upon binding with TNT, the proton conductivity on the HA plate electrodes increased linearly with the TNT concentration from 1.0 × 10⁻¹¹ M to 1.0 × 10⁻⁴ M. The HA plate electrodes exhibited good sensitivity with a detection limit of 1.05 × 10⁻¹² M. Subsequently, the cycling measurements of the TNT binding/removal were performed on the HA plate electrode, and the material exhibited high stability, good regenerative ability, and good reversibility without a significant decrease in efficiency. The present work highlights the significant application potential of HAs for the electrochemical detection of TNT.

Amine-surface-functionalized halloysite nanotubes are used for electrochemical sensing TNT.

Photocatalytic Oxidation of PLA/TiO2-Composite Films for Indoor Air Purification

Non-decomposable plastic has been replaced with polylactic acid, which is a biodegradable aliphatic polyester stationary phase, in composite films embedded with a TiO₂ photocatalyst for mitigation of indoor air pollution. PLA has superior properties relative to those of other biopolymers, such as a relatively high melting point, crystallinity, and rigidity. This study aimed to incorporate TiO₂-anatase into PLA for use as a photocatalyst using the blown film method. Photocatalytic oxidation, an advanced oxidative process, has been recognized as an economical technique providing convenience and efficiency with indoor air treatment. Therefore, the use of new environmentally friendly biodegradable polymers provides an alternative way to address the severe environmental concerns caused by non-decomposable plastics. UV-vis spectrophotometry and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) were used to observe the dispersibility and mixing capacity of the TiO₂-anatase PLA matrix. TiO₂ dosages were 5, 10, and 15% (wt/wt), and they were incorporated with a twin-screw extruder. SEM-EDX images demonstrated the homogeneity of TiO₂ distribution in the PLA matrix. The energy band gaps of TiO₂ in the PLA/TiO₂-composite films were between 3.14 and 3.22 eV. The relationship between the photocatalytic oxidation rate and the TiO₂ dosage in the PLA/TiO₂-composite films was determined. A prototype reactor model is geared toward the development of air purifiers for indoor air conditioning. Rate constants for benzene degradation were obtained using first-order kinetics to find rate constants matching experimental findings. In the PLA/TiO₂-composite film, the TiO₂-anatase photocatalyst was able to degrade 5 ppm benzene. This work contributes to the use of ecoefficient photocatalytic oxidation.

TiO2@HNTs Robustly Decorated PVDF Membrane Prepared by a Bioinspired Accurate-Deposition Strategy for Complex Corrosive Wastewater Treatment

As industrialization has spread all around the world, the problems of water pollution such as offshore oil spill and industrial sewage discharge have spread with it. Although many new separation materials have been successfully developed to deal with this crisis, a large number of water treatment materials only focus on the treatment of classified single water pollutant under mild conditions. It is a great challenge to treat soluble contaminants such as water-soluble dyes and insoluble contaminants, for example, emulsified oils simultaneously in a strong corrosive environment. Herein, in this work, corrosive resistance and multifunctional surface on a commercial polyvinylidene difluoride (PVDF) membrane via a tunicate-inspired gallic acid-assisted accurate-deposition strategy is created. Owing to the titanium-carboxylic coordination bonding and accurate-deposition strategy, the as-prepared membrane exhibits extraordinary stability, facing various harsh environmental challenges and incredibly corrosive situations (e.g., 4 M NaOH, 4 M HCl, and saturated NaCl solution). The robust multifunctional surface also endows commercial PVDF membrane with the ability for in situ separation and adsorption of surfactant-stabilized oil-in-water (corrosive and dyed) emulsions with high adsorption efficiencies up to 99.9%, separation efficiencies above 99.6%, and permeation flux as high as 15,698 ± 211 L/(m²·h·bar). Furthermore, the resultant membrane can be regenerated facilely and rapidly by flushing a small amount of HCl (4 M) or NaOH (4 M), making the corrosive resistance membrane attain a long-term and high-efficiency application for complex dyed wastewater treatment. Therefore, the multifunctional membrane has a broad application prospect in the industrial field.

Bio-assisted synthesized Pd nanoparticles supported on ionic liquid decorated magnetic halloysite: an efficient catalyst for degradation of dyes

Using natural materials, i.e. halloysite nanoclay that is a biocompatible naturally occurring clay and Heracleum persicum extract that can serve as a green reducing agent, a novel magnetic catalyst, Fe₃O₄/Hal-Mel-TEA(IL)-Pd, has been designed and fabricated. To prepare the catalyst, halloysite was first magnetized (magnetic particles with mean diameter of 13.06 ± 3.1 nm) and then surface functionalized with melamine, 1,4 dibromobutane and triethanolamine to provide ionic liquid on the halloysite surface (5 wt%). The latter was then used as a support to immobilize Pd nanoparticles that were reduced by Heracleum persicum extract. The characterization of the catalyst established that the loading of Pd in Fe₃O₄/Hal-Mel-TEA(IL)-Pd was very low (0.93 wt%) and its specific surface area was 63 m²g⁻¹. Moreover, the catalyst showed magnetic property (Ms = 19.75 emu g⁻¹) and could be magnetically separated from the reaction. The catalytic performance of the magnetic catalyst for reductive degradation of methyl orange and rhodamine B in the presence of NaBH₄ in aqueous media was investigated. The activation energy, enthalpy, and entropy for the reduction of methyl orange were estimated as 42.02 kJ mol⁻¹, 39.40 kJ mol⁻¹, and −139.06 J mol⁻¹ K⁻¹, respectively. These values for rhodamine B were calculated as 39.97 kJ mol⁻¹, 34.33 kJ mol⁻¹, and −155.18 Jmol⁻¹K⁻¹, respectively. Notably, Fe₃O₄/Hal-Mel-TEA(IL)-Pd could be reused for eight reaction runs with negligible loss of the catalytic activity (~3%) and Pd leaching (0.01 wt% of the initial loading).

Photocatalytic and bactericidal properties and molecular docking analysis of TiO2 nanoparticles conjugated with Zr for environmental remediation

Despite implementing several methodologies including a combination of physical, chemical and biological techniques, aquatic and microbial pollution remains a challenge to this day. Recently, nanomaterials have attracted considerable attention due to their extraordinary prospective for utilization toward environmental remediation. Among several probable candidates, TiO₂ stands out due to its potential for use in multifaceted applications. One way to improve the catalytic and antimicrobial potential of TiO₂ is to dope it with certain elements. In this study, Zr-doped TiO₂ was synthesized through a sol–gel chemical method using various dopant concentrations (2, 4, 6, and 8 wt%). Surface morphological, microstructural and elemental analysis was carried out using FESEM and HR-TEM along with EDS to confirm the formation of Zr–TiO₂. XRD spectra showed a linear shift of the (101) anatase peak to lower diffraction angles (from 25.4° to 25.08°) with increasing Zr⁴⁺ concentration. Functional groups were examined via FTIR, an ample absorption band appearing between 400 and 700 cm⁻¹ in the acquired spectrum was attributed to the vibration modes of the Ti–O–Ti linkage present within TiO₂ nanoparticles, which denotes the formation of TiO₂. Experimental results indicated that with increasing dopant concentrations, photocatalytic potential was enhanced significantly. In this respect, TiO₂ doped with 8 wt% Zr (sample 0.08 : 1) exhibited outstanding performance by realizing 98% elimination of synthetic MB in 100 minutes. This is thought to be due to a decreased rate of electron–hole pair recombination that transpires upon doping. Therefore, it is proposed that Zr-doped TiO₂ can be used as an effective photocatalyst material for various environmental and wastewater treatment applications. The good docking scores and binding confirmation of Zr-doped TiO₂ suggested doped nanoparticles as a potential inhibitor against selected targets of both E. coli and S. aureus. Hence, enzyme inhibition studies of Zr-doped TiO₂ NPs are suggested for further confirmation of these in silico predictions.

Despite implementing several methodologies including a combination of physical, chemical and biological techniques, aquatic and microbial pollution remains a challenge to this day.

Environmentally responsive and anti-bugs textile finishes - Recent trends, challenges, and future perspectives

Bugs, such as microorganisms and insects, are present in the environment and sometimes can be health-hazardous if the living environment is not maintained following proper hygienic regulations. In the present scenario of increasing public awareness, environmental consciousness, and growing demand for easy-care, and disinfected textiles, the manufacturing of protective and easy-to-care textiles has become a key necessity of the modern world. Comfortable, clean, hygienic, antimicrobial, and insect repelling properties of textile goods are gaining the accelerating research momentum as a basic requirement to produce multifunctional textiles. These functional finishes have numerous applications such as in-home textiles, bed nets, and tenting, camping gear as well as in military uniforms. Synthetic antimicrobial and insect repellents are quite effective against insects and microscopic organisms but are slightly toxic to the human being and the environment. To overcome these problems, researchers are considering natural agents for functional finishes, but their effectiveness is less durable to textile material. Besides needful advantages, the excessive use of dyes in finishing processes heavily required washing cycles and ultimately release various types of hazardous dyes or wasteful effluents in the environment. This review reports the chemical composition and recent developments in textile finishes, particularly antimicrobial and insect repellent textile finishes. A large number of commonly used antimicrobial agents (i.e. chitosan, zwitterionic compounds, silver and silver-based compounds, titanium dioxide nanoparticles, imidazolium salts, triclosan and quaternary ammonium salts) and insect repellent textile finishes (i.e. N‑N‑diethyl‑m‑toluamide, permethrin, cypermethrin, pyrethrum, picaridin, bioallethrin, citriodiol and essential oils) have been presented. Finally, the review is wrapped up with major research gaps/challenges, concluding remarks, and future opportunities in this area of research.

Efficient preparation of kaolinite/methanol intercalation composite by using a Soxhlet extractor

Kaolinite/methanol intercalation composite (KMe) is a key precursor for preparing clay-based inorganic/organic hybrid materials and kaolinite nanoscrolls. However, synthesis of KMe is a time and methanol dissipative process and the complexity of this process also limits its further applications. In this study, Soxhlet extractor was introduced to synthesize an intercalation composite and KMe was efficiently synthesized in a Soxhlet extractor through a continuous displacement process by using kaolinite/DMSO intercalation composite (KD) as a precursor. The formation process of kaolinite/methanol intercalation composite was studied by X-ray diffraction (XRD) and infrared spectroscopy (IR). The results showed that the DMSO in kaolinite could be completely displaced by methanol in this process and the preparation of KMe could be completed in 8 hours, which was far faster than the reported methods. Moreover, methanol used in this process could be recycled. Furthermore, the resulting material could be successfully used to prepare kaolinite nanoscrolls in high yield.