BACKGROUND: The development of efficient and stable catalysts for wastewater treatment is limited by metal leaching under reaction conditions. Copper-based Fenton-like systems offer advantages over iron catalysts, but their long-term stability is influenced by synthesis parameters, including the precursor selection, which controls copper dispersion, oxidation states and metal-support interactions. RESULTS: Cu/Al2O3 catalysts were synthesized by wet impregnation using oxide, nitrate, sulfate and chloride precursors, calcined at 900 degrees C and tested in the catalytic wet peroxide oxidation of phenol at 70 degrees C. All catalysts achieved complete phenol conversion within 30 min, but significant differences in mineralization and copper leaching were observed. Nitrate- and sulfate-derived catalysts (CuAN, CuAS) exhibited smaller crystallite sizes, higher copper dispersion and stronger Cu-support interactions, leading to lower leaching (similar to 35%) and stable activity. Oxide- and chloride-derived catalysts (CuAO, CuACl) showed higher leaching (>40%) but slightly higher total organic carbon removal, attributed to the homogeneous contribution of dissolved copper. X-ray photoelectron spectroscopy and Auger analyses confirmed variable Cu+/Cu2+ distributions depending on precursor type, with higher Cu+ content correlating with enhanced redox activity. Total organic carbon conversions ranged from 86% to 89%, and buffered conditions further improved radical stability and mineralization efficiency. Comparative analysis with literature highlighted the competitive performance of CuAN and CuAS catalysts, obtained through a simple impregnation route without dopants. CONCLUSION: Precursor selection is a key parameter for balancing activity and stability of Cu/Al2O3 catalysts. Nitrate- and sulfate-derived systems provide improved copper retention without compromising efficiency, offering a scalable strategy for designing sustainable catalysts for advanced wastewater treatment. (c) 2025 Society of Chemical Industry (SCI).

TheWater concentrationConcentration of nitrogen oxyanionsNitrogen oxyanions in natural watersNatural water hasCatalyst steadilyAmmonium increased in recent decades, as a result of the intensification of agricultureAgriculture and populationPopulation growth. Reverse osmosisReverse osmosis, ion exchangeIon exchange, adsorptionAdsorption and electrodialysisElectrodialysis are currently used as separation technologiesSeparation technologies for water denitrificationWater denitrification. Also, nitrite reduction technologiesNitrite reduction technologies such as biological treatmentBiological treatment and catalytic reductionCatalytic reduction, are able to convert nitrite into inertInert nitrogen gasNitrogen gas. Several studies have proposed the catalytic reductionCatalytic reduction of nitrite to nitrogenNitrogen in waterWater over Pd supported on different materials as a promising alternative for water treatmentWater treatment. In this chapter, an overview of the currentCurrent state of the art of catalytic nitrite reductionReduction is presented. The use of catalystsCatalyst supported on CeO2, Nb2O5, ZrO2, TiO2, γ-Al2O3, SiO2, and ZSM-5 for the removal of high concentrationsConcentration of nitrite in waterWater is reported in this chapter. All synthesized materials were evaluated and they showed catalytic activityCatalytic activity in the reductionReduction of nitrites in the waterWater. The total conversionConversion was achieved by catalystsCatalyst supported in γAl2O3, ZSM-5 (Si: Al = 30), SiO2, and TiO2. Among this groupGroup, the most nitrogenNitrogen-selective under the evaluated conditions were supported on ZSM-5 (Si: Al = 30) and TiO2. These findings contribute to the existing data, providing insights into previously untested materials as supports for waterWater removal nitrite catalystsCatalyst.

Microplastic pollution has become a global environmental concern with detrimental effects on ecosystems and human health. Effective removal of microplastics from water sources is crucial to mitigate their impacts. Advanced oxidative processes (AOPs) have emerged as promising strategies for the degradation and elimination of microplastics. This review provides a comprehensive overview of the application of AOPs in the removal of microplastics from water. Various AOPs, such as photocatalysis, ozonation, and Fenton-like processes, have shown significant potential for microplastic degradation. These processes generate highly reactive species, such as hydroxyl radicals, which can break down microplastics into smaller fragments or even mineralize them into harmless byproducts. The efficiency of photocatalytic oxidation depends on several factors, including the choice of photocatalysts, reaction conditions, and the physicochemical properties of microplastics. Furthermore, this review discusses the challenges associated with photocatalytic oxidation, such as the need for optimization of operating parameters and the potential formation of harmful byproducts. Overall, photocatalytic oxidation offers a promising avenue for the removal of microplastics from water, contributing to the preservation of aquatic ecosystems and safeguarding human health. However, further research is needed to address the limitations and optimize the implementation of this process for effective and sustainable microplastic remediation.

Microplastics, which are small plastic particles, have become a growing environmental concern due to their prevalence in aquatic and terrestrial environments. They persist for decades and potentially centuries due to their resistance to degradation and can harm organisms and release toxic chemicals. There has been increasing interest in developing methods for their removal from the environment, particularly from water. Catalytic processes have shown promise as a potential method for microplastic elimination, including biological methods, advanced oxidation processes, and hydrolysis. This review article focuses on recent advances in catalytic processes for the removal of microplastics from water, including various types of catalysts and their applications. It also discusses the potential for catalytic processes to be integrated into real-world water treatment systems for the removal of microplastics. The review highlights the challenges and opportunities associated with the removal of microplastics from the environment and aims to contribute to the development of more effective and sustainable methods for addressing this growing environmental issue. Future research should focus on developing hybrid catalyst systems that combine the strengths of multiple processes for improved efficiency and effectiveness. Additionally, research should explore the use of natural materials and biological processes for microplastic elimination, which may offer more sustainable and environmentally friendly options. Collaboration between scientists, engineers, policymakers, and the public will be critical for the development and implementation of these systems. The elimination of microplastics from the environment requires a multifaceted approach, and continued research and collaboration are necessary to develop effective and sustainable methods for their removal and to protect the health of our environment and communities.

Abstract Regenerated cellulose beads were synthesized for supporting copper as the catalytic active site for environmental remediation reactions. Starting from a commercial dissolving pulp, RC beads were prepared from direct dissolution and both solutions of carbamate and viscose. Copper was added to the supports by a simple green method. The material characterization by FTIR, TGA, SEM and XPS confirmed the successful incorporation of copper in all the prepared supports. The degradation of emerging contaminants (ECs) in water by catalytic wet peroxide oxidation (CWPO) was selected as a reaction test. Phenol was adopted as the EC test molecule in the CWPO reaction at 70°C. The results evidenced that the cellulose regeneration route directly affects catalytic yields. The catalysts containing lower than 1 wt.% of copper converted more than 90% of phenol with almost 30% of total mineralization. The novelty and importance of preparing bead-shape catalysts with cellulose reside in the use of an economical, renewable and biodegradable support, and the simple separation of the structured catalyst from the heterogeneous solid/liquid reaction media.

Different regenerated cellulose (RC) beads were synthesized as supports of copper as the active site for catalytic degradation of emerging contaminants (ECs) in water. Starting from a commercial dissolving pulp, RC beads were prepared from the direct dissolution and from both cellulose carbamate and viscose solutions. Copper was added to the supports by a simple green method. The material characterization by FTIR, TGA, SEM and XPS confirmed the successful incorporation of copper in all the prepared supports. Phenol was adopted as EC test molecule, and catalytic wet peroxide oxidation (CWPO) at 70°C was used to analyse the Cu-cellulosic beads catalytic performance. The novelty and importance of preparing bead-shape catalysts with cellulose reside in the use of an economic, renewable and biodegradable matrix, and the simple separation of the structured catalyst from the heterogeneous solid/liquid reaction media.

This paper analyzes the microwave-assisted synthesis of the zirconium-based metal-organic framework (MOF) UiO-66 using acetone as a solvent, in replacement of the traditional and toxic N,N-Dimethylformamide (DMF). It also studies the subsequent loading of this MOF with high amounts of dispersed copper species to be used as catalyst in the advanced oxidation of phenol. To this purpose, the structural development of UiO-66 was monitored studying the effect of synthesis variables such as stirring, temperature, treatment time and volume of the mixture. In this way, a high-crystallinity UiO-66 was obtained with high yields (88 %) at short times (6 h) and under mild conditions (80 degrees C) in a DMF-free media. Subsequently, by studying treatment conditions, a Cu/UiO-66 catalyst supporting high loadings (10 wt %) of highly dispersed copper species (Cu+/Cu-2(+)) was obtained. This nanocatalyst, which was obtained following sustainability criteria, exhibited a high performance in the catalytic we peroxide oxidation (CWPO) of phenol, quickly converting all the phenol at 70 degrees C in the first 5 min and reaching a mineralization (TOC removal) of 88 % and a H2O2 consumption efficiency of 30 % at 120 min. Cu/UiO-66 represents a new nanostructured catalyst based on highly dispersed copper species to be applied in CWPO processes.

In this work the catalytic performance of Cu(5%)/Al2O3 catalysts prepared by we impregnation and calcined at three different temperatures, 400 degrees C (WI 400), 650 degrees C (WI 650) and 900 degrees C (WI 900), was analyzed. These materials were tested in the phenol we oxidation reaction using H2O2 (0.22 or 0.88 M) as an oxidizing agent, 1000 mg/L of phenol at 70 degrees C and atmospheric pressure. A complete conversion of phenol and a high extent of phenol mineralization were obtained for the three catalysts. Surface Cu2+ species suffered a reduction process during the catalytic reaction due to the drop of the pH value and a fraction of the reduced copper was leached to the liquid phase. Despite this, the increment in the calcination temperature produced a decrease in this reduction extent, inducing a protective effect to the Cu2+ species through the interaction between these and the support. Moreover, the existence of Cu-Al-O interactions not only diminished Cu2+ species reduction but also their leaching. Even though the WI 900 catalyst presented the lower leaching extent (36%), the remaining amount of copper in the solution still exceeded the allowed limit value for drinking water (1 mg Cu/L).

Catalysts containing 1.8wt.% of Pd and different In loadings were prepared by sequential electroless plating on activated carbon felts (ACF). Homogeneous structures were obtained, with In particles deposited at the top of a tiny Pd film. The catalyst with the higher In loading (Pd:In ratio of 2.0) presented high activity and good selectivity towards nitrogen, with negligible deactivation after 6h of time-on-stream and three consecutive nitrate pulses. Besides the promising catalytic behavior, PdIn/ACF have the advantages of an open structure, which is highly accessible to the reactants, with no need of separation after the reaction.

The catalytic performance of Pd–In–Au/TiO 2 was studied for the reduction of nitrites and nitrates in water and compared with that of Au, Pd, Pd–In, In–Au and Pd–Au supported on TiO 2 . Different characterization techniques were used to study the bulk and surface physicochemical properties of the trimetallic catalyst. The catalyst so obtained was active and stable in the nitrate reduction reaction, having a good selectivity to nitrogen. This improvement caused by the presence of gold is attributable to a strong interaction with surface palladium and can therefore act to regulate the hydrogenation activity of the Pd particles. Over 80% of Pd is deposited on top of the Au nanoparticles, which interact with surface Au during the reduction process. The NO 2 − species is an intermediate product in the NO 3 − reduction and the surface In–Pd intermetallic species are responsible for this first reaction step.

The catalytic properties of Pd/Al2O3 coating onto cordierite monolith channels for the nitrite reduction in water were studied. This coating was synthesized producing an alumina layer via washcoat and adding the palladium species to this layer by immersion into a PdCl2 solution. Different characterization techniques, XRD, XPS, SEM and EDX were used to study the physicochemical and morphological properties of the catalytic coatings. The comparison of these results along with the catalytic behaviors allowed comprehension of Pd active sites and their way of acting. The structured catalyst so obtained was active and stable in the nitrite reduction.

SARA (saturate, aromatic, resin and asphaltene) fractions composing an atmospheric tower resid from a naphthenic crude were separated using the ASTM 2007 method. Two commercial equilibrium catalysts, of the conventional and resid types, were used to convert the aromatic, resin and saturate fractions under conditions of the FCC process. The reaction experiments were performed in a CREC Riser Simulator reactor. Reaction temperature was 550 degrees C, reaction times were from 5 to 20 s, the catalyst mass was 0.8 g and the catalyst to oil relationship was 5.0. The various fractions were used dissolved in toluene at 20 wt.%. The hydrocarbon reaction products were grouped into dry gas, LPG, compounds in the gasoline and LCO boiling ranges and coke. All the fractions converted almost completely, but differences in the yields of the main hydrocarbon groups were observed which revealed the fractions' nature. (C) 2013 Elsevier Ltd. All rights reserved.

The reactivity of a heavy model molecule (quinolin-65, named Q65, a 2,3,7,8-dibenzopyrene derivative) over two different equilibrium fluidized catalytic cracking catalysts of the conventional and resid types was studied at 550 degrees C and with reaction times that varied from 5 to 20 s, in a batch fluidized-bed laboratory reactor. Two types of experiments were performed to determine the hydrocarbon products resulting from the conversion of Q65. This compound is solid at room temperature, and a solution of Q65 at 4.6 wt % in toluene and pure toluene were used. Conversions and yields were assessed by means of careful mass balances. The product distributions showed that Q65 produced a wide range of hydrocarbons from C1 to C20. These distributions were different according to the formulations of the catalysts. Olefins were predominant among gases and, neatly, aromatics among liquids. Coke yields were high, exceeding 12 wt %. The characteristics of the catalysts were also revealed through the higher activity and hydrogen-transfer ability of the conventional catalyst and the better coke selectivity of the resid catalyst. It was shown that both the linear alkyl chain and the multi-ring core react.

Fil: Sedran, Ulises Anselmo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Santa Fe. Instituto de Investigaciones en Catalisis y Petroquimica ; Argentina

In order to validate a new method for the evaluation of resid in the laboratory, the conversion of a mixture of 10% of an ATR resid with a FCC VGO feedstock was assessed with two equilibrium catalysts of the conventional and resid type at 550°C and contact times up to 25s, and compared with the conversion of the base VGO and ATR under the same conditions. The experiments were performed in a batch, fluidized bed CREC Riser Simulator laboratory reactor. Under these circumstances, the overall conversions of the mixture were not very different from those of the base VGO in the case of the resid catalyst, but increased up to 5% points with the conventional and more active catalyst. For a given conversion level, the yields of the main hydrocarbon groups like dry gas, LPG and gasoline did not change significantly, and were consistent with the reactivity of the pure reactants (VGO and ATR), that showed essentially the same selectivities. The higher coking trend of the ATR was observed moderately in the case of the most active catalyst. The most important changes were noticed in the composition of the various products; for example, with both catalysts, the gasoline cuts produced by the ATR–VGO mixture were less aromatic and more olefinic than those obtained with the pure VGO. It was shown in this new laboratory method that in order to achieve realistic results in the evaluation of the addition of resid to a FCC feedstock, it is necessary to consider simultaneously the mixture intended, the proposed catalyst and the operative conditions.

The conversion and product distributions from a mixture of 10% atmospheric tower bottom resid and a DO hydrocarbon cut similar to LCO that represented commercial feedstocks were assessed over two equilibrium commercial FCC catalysts in a laboratory CREC Riser Simulator reactor. The reaction temperature was 550 degrees C, the catalyst to oil ratio was 5.8 and the reaction times were up to 25 s. The conversion of the mixture as compared to the DO base feed was higher in the case of the most active, conventional catalyst, and remained very similar on the resid catalyst. Since the yields of the main hydrocarbon groups dry gas, LPG, gasoline and coke followed very similar trends when the two pure feedstocks were converted, the corresponding yields from the mixture also obeyed that behaviour, and were the consequence of the conversion reached. The impact of the different catalyst formulations was observed in, for example, the selectively different yields obtained from the conversion of the resid, and in the composition of the gasoline. Independently of the catalyst, the gasoline was more olefinic and less aromatic when the resid was present. It was shown that in order to evaluate properly a given combination of feeds, catalysts and conditions, they must be considered together. (C) 2008 Elsevier B.V. All rights reserved.

A method was developed to evaluate the conversion and product distribution of a resid that could be added to conventional VGO feedstocks for FCC processing. An atmospheric tower resid was dissolved into toluene and methylnaphthalene at 15% and 25%, respectively, and converted at 550 degrees C over an equilibrium conventional FCC catalyst in a CREC Riser Simulator laboratory reactor. Reaction times were from 5 to 25 s. The pure solvents were also converted under the same conditions to provide background information. The method was based on the careful assessment of the masses of the reaction products. Results showed that, considering that an interaction is developed between resid and solvent in relation to the catalyst surface, it is possible to evaluate the specific contribution of the resid to the product slate in terms of hydrocarbon groups or compounds of particular interest. In this way, different catalysts could be compared for their performance with different resids and VGOs, or the impact of various factors on the FCC operation could be predicted as a function of resid-related changes.