Directed thermo-mechano-chemical-irradiative methodologies that can permeate significant plastic chemical resistance are central to achieving circularity in the life cycles of plastics. Here, a novel combined deep eutectic solvent (DES) microwave irradiation technique for fast, high-efficiency, high-yield polyethylene terephthalate (PET) hydrolytic depolymerization with high amenability for sustainable industrial scalability is presented. In this work, depolymerization of PET was performed using a dissolution/degradation approach. A dual-functioning DES served as the solubilizing and catalyzing agent for PET alkaline hydrolysis. Microwave (MW) irradiation was utilized for facilitating the depolymerization process with high energy efficiency. The PET depolymerization process was optimized using Box–Behnken design while studying the volume of DES, concentration of depolymerizing agent and MW irradiation time as independent variables. A percentage weight loss of PET reaching 84% was obtained in 90 s of MW irradiation. Various characterization techniques such as FTIR, DSC and HPLC validated the depolymerization of PET and obtained monomers (mainly terephthalic acid (TPA)). Finally, a postconsumer PET sample was also evaluated to prove that the developed dissolution/degradation approach could have practical application in market. Post analysis, the insoluble matter content was calculated to be 3.70% and the yield of pure TPA was 91.54%. Full article

Most plastic degradation methods are currently inefficient and are limited by processing difficulties, quality loss, and diminished value. This research focuses on the development of novel mechano-chemical disintegration processes for the breakdown of waste plastics. The outputs will be biocatalyzed and used as building blocks for new polymers or other bioproducts. For the purpose of this research, microwave pre-treatment technology was used. Microwave technology is an ideal pre-treatment process for the degradation of plastics due to its lower treatment times under lower energy inputs. In the previous work, extensive research has been carried out utilizing different solvents and catalysts to develop efficient degradation mechanisms under microwave irradiations. A new class of ionic liquids (deep eutectic solvents) were used as catalysts to make a suspension with poly(ethylene terephthalate) (PET) and develop an alcoholysis reaction. Certain degradation parameters like crystallinity index, weight loss, and carbonyl index were depicted using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR) characterization techniques. Furthermore, enhanced enzymatic degradation using LCC variant ICCG proved that microwave technology is an efficient process for the alcoholysis reaction and degradation of PET under mild conditions into its monomers. Full article

Direct conversion of CO₂ into chemical compounds has become a prospective pathway to transform CO₂ into valuable chemical compounds. The introduction of porous materials with high uptake into photocatalytic systems can enrich the CO₂ absorption on the surface of the photocatalyst for catalytic conversion. In this regard, another feasible strategy can be accomplished via combining commercial photocatalyst materials with porous supporting materials. The present study investigated a series of ZnO-incorporated ZSM-5 catalysts to produce solar fuels under UV–visible light irradiation. ZnO/ZSM-5 was synthesized using the wet impregnation method using Zn(CH₃COO)₂ as a reagent, followed by calcination. Various characterizations were also conducted to study morphology, structure, absorbance, and physiochemical properties of the photocatalysts. SEM-EDX images showed that ZnO was successfully incorporated into ZSM-5 surfaces with a particle size of around 50 nm. The optical properties of ZnO/ZSM-5 correspond to 3.36 eV, showing an increase in the bandgap value compared to pure ZnO, with 3.18 eV. The solar fuel production, including formic acid (HCOOH), formaldehyde (HCOH), and methanol (CH₃OH) evolution was evaluated under UV–visible light irradiation. The designed composite ZnO/ZSM-5 catalyst achieved methanol and formic acid yields of 39.2 µmol/g·h and 0.72 µmol/g·h µmol/(g·h), respectively, which are about 1.5- and 2.5-fold higher than the neat ZnO catalyst. The improved yield and selectivity towards methanol products are attributed to the greater light absorption, more efficient charge transfer, nanostructure morphology, and more active sites available for CO₂ adsorption. Full article

The data obtained by the authors in the field of chemistry of 1,3,5-cycloheptatrienes and 1,3,5,7-cyclooctatetraenes with the participation of complexes of transition metals are summarized. The reactions of cyclocodimerization of 1,3,5-cycloheptatrienes and 1,3,5,7-cyclooctatetraenes with alkenes, dienes and alkynes in the presence of transition metal complexes, carried out by the type of [6π + 2π]- and [4π + 2π]-cycloaddition, are considered. Special attention is paid to the application of these reactions in the synthesis of practically important bi-, tri- and polycyclic strained compounds, as well as in the development of stereoselective methods for the synthesis of natural compounds. Full article

Rhodium is an effective catalyst in the CO+H₂ reaction into C₂-oxygenates. Among the products, acetaldehyde (AA) is an important hydrogen carrier, which is also produced in the decomposition of ethanol on metal surfaces. The chemisorbed acetaldehyde starts to decompose at 200 K. The main products of the chemisorbed AA are CO, H₂ and CH₄. In the chemisorbed layer η₁-(O)-CH₃CHO_a and η₂-(O,C)-CH₃CHO_a adsorption forms have been identified. Electronegative and electro positive modifiers (oxygen and potassium) suppress the oligomerization of aldehyde, they may influence the stability of these surface complexes such as: (i) surface C_a acts as a simple contaminant by site blocking mechanism. (ii) A direct surface reaction with O_a led to the formation of acetate. (iii) K_a increases the thermal stability of acetaldehyde and the decomposition products by an extended electronic interaction. Full article

An annulus type of photocatalytic reactor was designed, constructed, and characterized for its performance for the oxidation of ethanol and hexane vapors in air. The photocatalytic device utilized ultraviolet (λ = 365 nm) light-emitting diodes (UV-LEDs) as light sources and photocatalytic (Degussa P25 TiO₂) films coated on the inside surfaces of the reactor. These reactor systems can be applied to mobile and niche applications. UV-LEDs are small, robust light sources that require low direct current (DC) power, which could be provided by a battery. The study results demonstrate that the UV-LED-based photocatalytic system is capable of reducing or eliminating ethanol and hexane vapors in air. Test results have demonstrated the sensitivity of the effectiveness of the UV-LED-based photocatalytic system on operating parameters, including flow rate, concentration, type of VOC, humidity, and longevity. Full article

Different countries in Europe have proposed some restrictions about bisphenol A (BPA), considered an endocrine disruptor, for the production of food packing and toys for children, for example, Denmark, France, Sweden, Belgium, Austria and Norway. However, it is still being found in wastewater effluents. In this study, BPA was degraded by catalytic wet air oxidation employing ruthenium-impregnated carbon nanosphere catalysts (CNS). The catalyst was synthesized with a mixture of resorcinol and formaldehyde and later, a pyrolysis treatment was impregnated by 1, 2, 5, 7 and 10% of ruthenium and activated with hydrogen at 350 °C. The experimental installation was a batch Hastelloy high-pressure reactor of 100 mL of volume with an electrical jacket and a variable-speed magnetic drive. The concentration of BPA was followed by high-performance liquid chromatography. After the study of different experiment variables (temperature (110–150 °C), pressure (20–50 bar), initial concentration of BPA (5–30 mg L⁻¹) and catalyst mass (50–300 mg)) in a batch reactor of 100 mL of volume, two different potential models (r = k C^a_BPA and r = k C^a_BPA P^b C^c _Ru) were used for simulating the kinetic behavior of BPA from the adjustment of the experimental data obtained for CWAO reactions. It also tested different loads of ruthenium (1–10%) in BPA degradation. Both adjustments had a correlation factor of 0.98 and reproduced all the experiments well, being better than those ones with 20 mg L⁻¹ of initial concentration of BPA. BPA degradation was above 97% at 90 min of reaction time from 2% of Ru in the catalyst. Full article

Two sets of commercial activated carbon (AC) were surface functionalized by an acid treatment using a) strong acid HNO₃ (AC80 and AC90) and b) a weak acid C₆H₈O₇ (ACC). The effect of the functionalization on the surface chemistry and structure of the AC samples was studied by means of TGA-DSC, XRD, FT-IR, N₂ adsorption, and TPD and tested in the decomposition of isopropanol. The catalysts were synthesized by the deposition of copper using a recirculation impregnation method. Metal dispersion, average size of metallic domains and metal-support interactions were correlated with the surface functionalization by using XRD, S_BET, SEM-EDS, AAS and N₂O dissociative adsorption. The acid treatments showed no effect on the crystal structure; however, increments in the acid/basic site concentration and the surface oxygen-containing functional group (OFG) content were observed, mainly in the AC80 and AC90 samples. BET surface measurements show a small decrease due to OFGs and/or copper incorporation. Copper distribution was uniform and its content shows a direct correlation with the OFG concentration. XRD reveals the presence of Cu° and Cu₂O in the Cu/AC80 and Cu/AC90 samples, possibly associated with an auto-reduction process assisted by the OFGs near the metallic centers. Cu/AC and Cu/ACC XRD patterns show no evidence of copper phases, due to low content and high dispersion. The HNO₃-treated supports showed the higher dispersions and the smallest metallic domain sizes (30%—3.3 nm Cu/AC80 and 22%—4.5 nm Cu/AC90), while Cu/ACC showed a 17% dispersion and an average metallic domain size of 5.8 nm. The presence of surface OFGs promotes selective adsorption of Cu, an increase in metal dispersion, a decrease of domain size and the presence of alternative copper-derived phases, showing increased metal-support interactions. Full article

NADES represent a new generation of biocompatible solvents that are formed by eutectic mixtures of two or more hydrogen bond donor and hydrogen bond acceptor compounds of natural origin and that have a lower melting point compared to pure components. The ease of preparation, sustainability, low cost, and low toxicity of NADES have allowed these solvents to be investigated in biocatalysis. In this communication, we describe the stability and the enzymatic activity of two oxidoreductases, HLADH and TsER, in buffer solution and in choline-based NADES/buffer mixtures. In particular, we report on the enantioselective lactonization of 3-methyl-1,5-pentanediol into 4-methyl-δ-valerolactone and the bioreduction of ketoisophorone into levodione. Full article

Catalysts are substances that can increase the speed of a chemical reaction and are often used in the chemical industry. Palladium is one of the most widely used metal centers in metal-based catalysts, and a lot of palladium complexes have been extensively used in many reactions, particularly in cross-coupling reactions with a carbon−carbon bond formation. All their possible applications as catalysts, along with their uses in biological assays as anticancer agents, make these family of complexes very interesting and highly studied, allowing the modification of the ligands around the metal and the extreme modulation of their properties. Herein we report the synthesis of several palladium cyclometallated compounds with thiosemicarbazone ligands and bis(diphenylphosphino)methane (dppm). Additionally, we evaluate their catalytic activity in a Suzuki−Miyaura cross-coupling reaction, using 4-bromoacetophenone and phenylboronic acid as reagents and following the reaction with ¹H-NMR spectroscopy. A final comparison between the catalytic conversions and the complexes allows us to propose the best structure for a catalytic purpose in these conditions. Full article

Surface properties of prereduced (Co+Pd)/Al₂O₃ and (Co+Pd)/TiO₂ catalysts were studied. Metal dispersion was 1–3%. CoPdA demonstrated high temperature H₂ desorption and firmly held CO and carbonate species on the surface. SMSI operated on CoPdT even after contact with H₂O and air. Metal surface reconstruction and increased formation of CH₂ groups occurred during catalysis. At low pressure, CoPdT was more active, whereas CoPdA had higher CH₄ selectivity. At high pressure, catalysis on CoPdA revealed dependence on T_red, synthesis of C₂₊ hydrocarbons, decreased CO₂ production, and higher CH₄/CO₂ ratio. CO conversion decreased with time due to difficulties in the surface diffusion of reagents, intermediates, and products, and metal particle agglomeration. Full article

The Clostridium alkalicellulosi DSM17461^T genome contains several glucoside hydrolase encoding genes essential for cellulose degradation. Herein, the family 9 glycoside hydrolase enzyme (CalGH9_2089) was cloned and expressed. The enzyme contains one GH9 catalytic module, a family 3 carbohydrate-binding module, and one Type I dockerin at its C-termini. The optimal pH and temperature for CalGH9_2089 to hydrolyze CMC were 55 °C and pH 6.0, with the remaining activity of more than 60% at pH 10.0. CalGH9_2089 produced a series of cello-oligomers (G2-G6) from CMC, suggesting that the enzyme has an endo-acting capability. When regenerated amorphous cellulose was hydrolyzed with CalGH9_2089, the ratio of reducing ends in the soluble fraction to that in the insoluble pellets was 4.8, suggesting that this enzyme acts processively on RAC. This work extends our knowledge of the behavior of the GH9 endoglucanase from the microorganism living in an alkaline environment. Full article