Green Chemistry, Catalysis, and Waste Valorization for a Circular Economy.

The circular economy represents an economic model that prioritizes sustainability and resource efficiency, aiming to minimize waste minimization, promote reuse, and close material loops. This Special Collection highlights recent advancements in green chemistry, catalysis, and waste valorization, fields critical for achieving sustainable practices and resource efficiency within a circular economy. Researchers from the Asia-Pacific region, Europe, South America, and North America have contributed to designing sustainable chemical processes that minimize environmental impact.

A morphological study of bicontinuous concentric lamellar silica synthesized at atmospheric pressure and its application as an internal micro-reflector in dye-sensitized solar cells.

KCC-1, a nanostructured silica material with a bicontinuous concentric lamellar (bcl) morphology, provides plenty of functional characteristics, such as an open channel structure, excellent accessibility, and a large surface area. Although bcl silica exhibits various superior properties, studies on its morphology and its application in dye-sensitized solar cells (DSSCs) are still limited. Therefore, this work aims to study the influence of the synthesis time on the morphology of bcl silica.

Contribution of the lamellar morphology to the photocatalytic activity of alkaline-hydrothermally treated titania in rhodamine B photodegradation.

TiO particles with a specific morphology are essential for their accessibility and photoactivity. The present study shows that NHOH-based alkaline-hydrothermal treatment affects the transformation of their particle morphology. We investigated the effect of NHOH by varying the synthesis route.

Organically surface engineered mesoporous silica nanoparticles control the release of quercetin by pH stimuli.

Controlling the premature release of hydrophobic drugs like quercetin over physiological conditions remains a challenge motivating the development of smart and responsive drug carriers in recent years. This present work reported a surface modification of mesoporous silica nanoparticles (MSN) by a functional compound having both amines (as a positively charged group) and carboxylic (negatively charged group), namely 4-((2-aminoethyl)amino)-4-oxobut-2-enoic acid (AmEA) prepared via simple mechanochemistry approach. The impact of MSN surface modification on physical, textural, and morphological features was evaluated by TGA, N adsorption-desorption, PSA-zeta, SEM, and TEM.

Recent Advances in Photocatalytic Oxidation of Methane to Methanol.

Methane is one of the promising alternatives to non-renewable petroleum resources since it can be transformed into added-value hydrocarbon feedstocks through suitable reactions. The conversion of methane to methanol with a higher chemical value has recently attracted much attention. The selective oxidation of methane to methanol is often considered a "holy grail" reaction in catalysis.

Facile fabrication of a phosphonium-based ionic liquid impregnated chitosan adsorbent for the recovery of hexavalent chromium.

Chitosan adsorbents impregnated with a phosphonium-based ionic liquid (Chi_IL), trioctyldodecyl phosphonium chloride, were prepared for the adsorption of hexavalent chromium and compared to the performance of native chitosan. The physical and chemical properties of the adsorbents were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Effects of various parameters, such as pH, adsorbent dosage, contact time, temperature, and multi-component systems, were systematically examined.

Thermodynamic Picture of Phase Segregation during the Formation of Bicontinuous Concentric Lamellar () Silica.

The thermodynamic picture describing the formation mechanism of bicontinuous concentric lamellar () nanostructured silica particles, silica, was investigated thoroughly. A series of classical kinetics of silica by varying the synthesis time were employed to observe the morphological evolution of silica. The formation mechanism of silica is proposed as the hydrolysis and condensation reactions in the reverse micelle, followed by the phase segregation process.

Photocatalytic Degradation of Palm Oil Mill Effluent (POME) Waste Using BiVO Based Catalysts.

Disposal of palm oil mill effluent (POME), which is highly polluting from the palm oil industry, needs to be handled properly to minimize the harmful impact on the surrounding environment. Photocatalytic technology is one of the advanced technologies that can be developed due to its low operating costs, as well as being sustainable, renewable, and environmentally friendly. This paper reports on the photocatalytic degradation of palm oil mill effluent (POME) using a BiVO photocatalyst under UV-visible light irradiation.

A Mechanistic Investigation of Sustainable Solvent-Free, Seed-Directed Synthesis of ZSM-5 Zeolites in the Absence of an Organic Structure-Directing Agent.

The solvent-free, seed-directed synthesis using natural precursors has emerged as a sustainable route for the synthesis of zeolite. Albeit the significant progress in the synthesis techniques, the crystallization behaviors of zeolites are somewhat elusive. Herein, we performed a detailed investigation of the crystallization behaviors of ZSM-5 zeolites synthesized through the solvent-free, seed-directed route using rice husk silica as starting materials.

The Effects of stingless bee () honey on streptozotocin-induced diabetes mellitus in rats.

Diabetes mellitus (DM) is a metabolic disease characterised by chronic hyperglycaemia with impaired carbohydrate, fat and protein metabolism caused by defects in insulin secretion or action. Based on our previous research, stingless bee honey (SLBH) from and can inhibit alpha-glucosidase activities. Therefore, the aim of the present study was to determine the effects of daily oral administration of SLBH on body weight (BW) and fasting blood glucose (FBG) levels of male rats with streptozotocin (STZ)-induced DM.

pH-Triggered Drug Release Controlled by Poly(Styrene Sulfonate) Growth Hollow Mesoporous Silica Nanoparticles.

In the current report, hollow mesoporous silica (HMS) nanoparticles were successfully prepared by means of a hard-templating method and further modified with poly(styrene sulfonate) (PSS) via radical polymerization. Structural analysis, surface spectroscopy, and thermogravimetric characterization confirmed a successful surface modification of HMS nanoparticles. A hairy PSS was clearly visualized by high-resolution transmission electron microscopy measurement, and it is grown on the surface of HMS nanoparticles.

Revisiting the seed-assisted synthesis of zeolites without organic structure-directing agents: insights from the CHA case.

Herein, the crystallization behaviour of the CHA zeolite synthesized the seed-assisted method and in the absence of an organic structure-directing agent has been revisited. To date, the working hypothesis of the seed-assisted synthesis method is that the parent gel and seed share the common composite building unit (cbu) of the targeted zeolite crystal. In the case of the CHA zeolite, we reveal that the parent gel in the absence of CHA seeds leads to the formation of the MER zeolite, which does not follow the cbu working hypothesis.

Structural alteration within fly ash-based geopolymers governing the adsorption of Cu from aqueous environment: Effect of alkali activation.

Fly-ash based geopolymers have been considered as a low-cost yet effective adsorbent for the removal of heavy metal cations, including Cu, from the aqueous environment. In the synthesis of geopolymers, the fly-ash needs to be alkali activated using several systems rich in either Na or K. Herein, we investigate the effect of alkali activation on the structural alteration and its consequence on the adsorption capacity.

Highly crystalline mesoporous SSZ-13 zeolite obtained controlled post-synthetic treatment.

The generation of mesoporosity in SSZ-13 zeolite by means of desilication post alkaline treatment normally results in severe damage to the microporous framework hence giving an undesirable decline in catalytic performance. Herein, we propose a post-synthetic desilication treatment that is controllable with an aim to preserve the high crystallinity of SSZ-13 zeolite during the formation of mesopores. The extent of desilication in alkaline media is controlled by deliberately leaving the organics within SSZ-13 frameworks as they can effectively hinder the attack of hydroxyl ions on siloxane bonds.

Effect of Extra-Framework Cations of LTL Nanozeolites to Inhibit Oil Oxidation.

Lubricant oils take significant part in current health and environmental considerations since they are an integral and indispensable component of modern technology. Antioxidants are probably the most important additives used in oils because oxidative deterioration plays a major role in oil degradation. Zeolite nanoparticles (NPs) have been proven as another option as green antioxidants in oil formulation.

Inhibition of palm oil oxidation by zeolite nanocrystals.

The efficiency of zeolite X nanocrystals (FAU-type framework structure) containing different extra-framework cations (Li(+), Na(+), K(+), and Ca(2+)) in slowing the thermal oxidation of palm oil is reported. The oxidation study of palm oil is conducted in the presence of zeolite nanocrystals (0.5 wt %) at 150 °C.

Eco-friendly synthesis for MCM-41 nanoporous materials using the non-reacted reagents in mother liquor.

Nanoporous materials such as Mobil composite material number 41 (MCM-41) are attractive for applications such as catalysis, adsorption, supports, and carriers. Green synthesis of MCM-41 is particularly appealing because the chemical reagents are useful and valuable. We report on the eco-friendly synthesis of MCM-41 nanoporous materials via multi-cycle approach by re-using the non-reacted reagents in supernatant as mother liquor after separating the solid product.

Critical nuclei size, initial particle size and packing effect on the phase stability of sol-peptization-gel-derived nanostructured titania.

The influence of the initial particle size and packing of anatase crystallites on the phase stability of nanostructured titania was investigated. Dried anatase gels with different degrees of particle packing were prepared through the peptization-induced electrostatic stabilization of primary particles in the sol. The initial size of anatase primary particles was varied by precalcination prior to the anatase-rutile phase transformation that occurred during final calcination.

Direct hydrothermal synthesis of hierarchically porous siliceous zeolite by using alkoxysilylated nonionic surfactant.

A hierarchically porous siliceous MFI zeolite (silicalite-1) with narrow mesoporosity has been hydrothermally synthesized by using trialkoxysilylated alkyl poly(oxyethylene ether) as mesopore-directing agent. A mesostructured silica-surfactant composite was formed at the early stage of the reaction, and zeolite crystallization proceeded during subsequent hydrothermal treatment. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations of the crystallized products showed that micro- and mesopores were hierarchically assembled in unique particle morphology with rugged surfaces.