Value-added Products Research Articles

UiO-67 metal-organic frameworks with dual amino/iodo functionalization, and mixed Zr/Ce clusters: Highly selective and efficient photocatalyst for CO2 transformation to methanol

Metal-organic frameworks (MOFs) are promising tools for photocatalytic CO2 reduction (PCR) to produce valuable added-value products. However, existing MOFs demonstrate significantly weaker potential for PCR to MeOH compared to fuels like CO, CHOOH, and CH4. This study address this challenge by exploring a series of bifunctional UiO-67 MOFs containing NH2 and I groups with varying Ce to Zr metal node ratios (0, 10, 20, 29, and 40 % Ce). These MOFs, denoted as Zr/CeX%-UiO-67(NH2, I), were probed for their ability to convert CO2 to MeOH under solar irradiation without the need for a photosensitizer. The results demonstrate a remarkable increase in both selectivity and efficiency for MeOH production with increasing Ce content. Notably, Zr/Ce29%-UiO-67(NH2, I) achieves 100 % selectivity for MeOH production, along with MeOH productivity of 44.7 µmolh−1g−1, significantly surpassing previously reported UiO-based MOFs for PCR-to-MeOH conversion. Furthermore, this MOF exhibits exceptional CO2 uptake capacity compared to pristine UiO-67 and many established MOFs, further highlighting its catalytic efficacy. The outstanding photocatalytic performance of Zr/Ce40%-UiO-67(NH2, I) can be attributed to a synergistic combination factors: (i) the optimal incorporation of redox-active Ce metal sites, (ii) enhanced CO2 capture facilitated by the cooperative interaction of NH2 and I groups, and (iii) the introduction of amino functions that broaden the light absorption range of the MOF. This work demonstrates a successful strategy for incorporating various functionalities into MOFs, paving the way for the design of highly selective and efficient PCR catalysts for MeOH production.

Drying Performance and Economic Analysis of a Greenhouse Solar Dryer for Tomatoes

Purpose: The purpose of this study was to assess the drying performance and economic feasibility of a Greenhouse Solar Dryer for Tomatoes. With a focus on small-scale tomato drying, the study aimed to evaluate the effectiveness of the greenhouse in comparison to traditional sun drying methods. Additionally, the economic analysis sought to determine the investment attractiveness of the greenhouse dryer by considering the initial investment, operational costs, and potential revenue generation. Methodology: The methodology involved conducting drying experiments using the Greenhouse Solar Dryer for Tomatoes under existing weather conditions. The dryer's components include the steel frame, greenhouse plastic cover, and concrete floor. The temperature and relative humidity contributed to the environment inside the greenhouse that facilitated the drying process. Moisture content measurements were taken at regular intervals to assess the drying kinetics and effectiveness of the greenhouse. Economic analysis was conducted to evaluate the project's financial viability, considering initial investment, revenue generation, and operational costs. Findings: The findings revealed that the Greenhouse Solar Dryer outperformed sun drying methods, achieving higher temperatures and faster drying times for tomatoes. Specifically, the greenhouse reached maximum temperatures of 38.4 °C and 45.5 °C on the first and second days, respectively, leading to a moisture content of 14.9% wet basis within 11 hours on the second day. In contrast, sun drying resulted in a significantly higher moisture content of 37.9% at the same time, highlighting the effectiveness of the greenhouse. Economic analysis demonstrated that the project had a payback period of 1.6 years, indicating its attractiveness as an investment opportunity for farmers. Unique Contribution to theory, practice and policy: This study makes a unique contribution to knowledge by providing empirical evidence of the drying performance and economic viability of a Greenhouse Solar Dryer for Tomatoes. By demonstrating the effectiveness of the greenhouse in achieving faster drying times and lower moisture content compared to sun drying methods, the study underscores the potential of solar drying technologies in small-scale agricultural settings. Additionally, the economic analysis offers valuable insights into the financial feasibility of adopting greenhouse dryers, particularly for farmers seeking to enhance their income through value-added tomato products.

Exploring Varied (Green) Extraction Methods to Optimize Galia Melon Peel Antioxidant Potential

Cucumis melo L. (C. melo), commonly known as the melon, is a widely cultivated tropical fruit associated with nutritional benefits and bioactive properties. With global production reaching 40 million tons annually, the fruit processing industry generates significant waste, primarily peels, totaling 8 to 20 million tons yearly. These organic by-products are rich in bioactive compounds such as antioxidants, offering health benefits such as a reduced risk of cancer and cardiovascular diseases, as well as of diabetes and neurogenerative diseases, offering an opportunity for sustainable utilization. C. melo by-products have demonstrated various health benefits, including anti-inflammatory, analgesic, and antioxidant properties, attributed mainly to polyphenols. Recognizing the potential of melon waste, this study systematically explored different extraction methods, including stirring (ST), ultrasound (US), and pulsed electric field (PEF) methods, while considering factors such as extraction time, temperature, and solvent composition. The primary goal was to identify the most effective extraction procedures and optimal conditions for maximizing the yield of total polyphenols and antioxidant capacity (using the FRAP and DPPH methods) from C. melo peel by-products. According to the results, the optimum conditions include ST as the extraction method, an ethanolic solvent with a strength of 50%, a 150 min extraction duration, and an 80 °C extraction temperature. The maximum values of total polyphenols that can be observed are 3.75 mg gallic acid equivalents (GAE)/g of dry weight (dw) and 25.77 μmol ascorbic acid equivalents (AAE)/g dw and 34.44 μmol AAE/g dw from FRAP and DPPH antioxidant assays, respectively. The polyphenols identified were the following: gallic acid, neochlorogenic acid, catechin, chlorogenic acid, epicatechin, and kaempferol. By securing the maximum isolation of bioactive content and antioxidant activity, the research will contribute to sustainable waste management by reducing waste and developing value-added products.

Study on the Challenges Encountered by Eri Silkworm Rearers in Tapioca Cultivation and Eri Rearing in Udalguri District of Assam

Sericulture, specifically eri silk production, plays a crucial role in sustainable rural development and employment generation. This study investigated the constraints faced tapioca cultivation and eri rearing in Udalguri district, Assam. Primary data were collected from 120 respondents through a snowball sampling technique. The rearers encountered personal, social, land utilization, rearing, managerial, economic, marketing, transportation, and institutional challenges. Notable issues included lack of formal education, high labour wages, land scarcity, inadequate rearing facilities, limited knowledge on scientific practices, insufficient capital, price fluctuations, poor marketing infrastructure, transportation costs, and lack of need-based training. The respondents suggested interventions such as government support for infrastructure and equipment, need-based training, formation of cooperatives, effective marketing channels, financial assistance, value-added product training, community rearing centers, land allocation, and extensive plantation of secondary feed plants. Addressing these constraints through targeted strategies is essential for fostering the long-term sustainability of eri silk production and enhancing the socio-economic status of rearers.

Carbon dioxide valorization into resveratrol via lithoautotrophic fermentation using engineered Cupriavidus necator H16

BackgroundIndustrial biomanufacturing of value-added products using CO2 as a carbon source is considered more sustainable, cost-effective and resource-efficient than using common carbohydrate feedstocks. Cupriavidus necator H16 is a representative H2-oxidizing lithoautotrophic bacterium that can be utilized to valorize CO2 into valuable chemicals and has recently gained much attention as a promising platform host for versatile C1-based biomanufacturing. Since this microbial platform is genetically tractable and has a high-flux carbon storage pathway, it has been engineered to produce a variety of valuable compounds from renewable carbon sources. In this study, the bacterium was engineered to produce resveratrol autotrophically using an artificial phenylpropanoid pathway.ResultsThe heterologous genes involved in the resveratrol biosynthetic pathway—tyrosine ammonia lyase (TAL), 4-coumaroyl CoA ligase (4CL), and stilbene synthase (STS) —were implemented in C. necator H16. The overexpression of acetyl-CoA carboxylase (ACC), disruption of the PHB synthetic pathway, and an increase in the copy number of STS genes enhanced resveratrol production. In particular, the increased copies of VvSTS derived from Vitis vinifera resulted a 2-fold improvement in resveratrol synthesis from fructose. The final engineered CR-5 strain produced 1.9 mg/L of resveratrol from CO2 and tyrosine via lithoautotrophic fermentation.ConclusionsTo the best of our knowledge, this study is the first to describe the valorization of CO2 into polyphenolic compounds by engineering a phenylpropanoid pathway using the lithoautotrophic bacterium C. necator H16, demonstrating the potential of this strain a platform for sustainable chemical production.

Coke formation on different metal-modified (Co, Mo and Zr) ZSM-5 in the catalytic pyrolysis of cellulose to light aromatics

Catalytic pyrolysis of biomass is regarded as a promising method for preparing value-added products. However, the main factors limiting the development of the process at present are the low yield of value-added products and poor selectivity, especially for rapid catalyst deactivation due to coke deposition. The present study focuses on the catalytic pyrolysis of cellulose over metal Co-, Mo-, and Zr-loaded catalysts using a falling fixed bed at 600 °C to evaluate the type of coking of the catalysts as well as the effect of the different metal active sites on the formation of coke deposits. The introduction of Co and Mo metal sites increased the light aromatics yield of ZSM-5 from 128.9 mg/g to 147.2 mg/g and 143.0 mg/g. And the yield of coke deposits decreased from 8.3 to 6.8 and 5.1 wt%. The stability evaluation of the catalyst showed that the deactivation degree of ZSM-5 of the supported metal Co was lower than that of commercial ZSM-5, while the ZSM-5 of the supported metal Mo was rapidly deactivated. The deactivation of the catalysts depended more on the morphology or location of the accumulated coke than on the total amount deposited. The clogging of metal and acidic sites on the surface of the zeolite and the pore channels by the amorphous encapsulating coke was the main cause of catalyst deactivation. The metal Mo active sites promoted dehydrogenation coupling and hydrogen transfer during coke formation, forming a more highly disordered multiring structure, and the metal Co active sites were more capable of decomposing macromolecular compounds, olefins and alkanes, and promoted the formation of graphite-like structural carbon.

Ultrasound-Assisted Alkaline Pretreatment of Biomass to Enhance the Extraction Yield of Valuable Chemicals

As a renewable and sustainable resource, lignocellulosic biomass serves as a crucial raw material for the production of biofuels, biochemicals, and various value-added products. This paper aims to develop and optimize a mild alkaline treatment of sawdust assisted by ultrasound, along with enzymatic hydrolysis of the pretreated material. The alkaline sonochemical pretreatment emerged as the optimal approach to enhance the susceptibility of cellulose to subsequent enzymatic hydrolysis to improve the yield of reducing sugars. A comparative study was performed using various ultrasonic applicators (horn and bath) and conventional assisted alkaline pretreatment. The ultrasonic-assisted pretreatment revealed a higher delignification of 68% (horn) and 57% (bath) compared with conventional pretreatment. Processes were optimized using a statistical analysis based on a 23 factorial design. The ratios between sawdust and alkaline solution (RSL = 0.5–1.5 g/100 mL), US amplitude (A = 20–60%), and working temperature (t = 30–50 °C) were selected as process factors. The optimal operating conditions to maximize the reducing sugar yield (138.15 mg GE/gsubstrate) were found as follows: a solid/liquid ratio of RSL,opt = 1.25 g/100 mL, US amplitude of Aopt = 60%, and pretreatment temperature of topt = 50 °C. The overall outcomes clearly confirmed the intensification of delignification by ultrasound-assisted alkaline pretreatment.

A comprehensive review of flue gas bio-mitigation: chemolithotrophic interactions with flue gas in bio-reactors as a sustainable possibility for technological advancements.

Flue gas mitigation technologies aim to reduce the environmental impact of flue gas emissions, particularly from industrial processes and power plants. One approach to mitigate flue gas emissions involves bio-mitigation, which utilizes microorganisms to convert harmful gases into less harmful or inert substances. The review thus explores the bio-mitigation efficiency of chemolithotrophic interactions with flue gas and their potential application in bio-reactors. Chemolithotrophs are microorganisms that can derive energy from inorganic compounds, such as carbon dioxide (CO2), nitrogen oxides (NOx), and sulfur dioxide (SO2), present in the flue gas. These microorganisms utilize specialized enzymatic pathways to oxidize these compounds and produce energy. By harnessing the metabolic capabilities of chemolithotrophs, flue gas emissions can be transformed into value-added products. Bio-reactors provide controlled environments for the growth and activity of chemolithotrophic microorganisms. Depending on the specific application, these can be designed as suspended or immobilized reactor systems. The choice of bio-reactor configuration depends on process efficiency, scalability, and ease of operation. Factors influencing the bio-mitigation efficiency of chemolithotrophic interactions include the concentration and composition of the flue gas, operating conditions (such as temperature, pH, and nutrient availability), and reactor design. Chemolithotrophic interactions with flue gas in bio-reactors offer a potentially efficient approach to mitigating flue gas emissions. Continued research and development in this field are necessary to optimize reactor design, microbial consortia, and operating conditions. Advances in understanding the metabolism and physiology of chemolithotrophic microorganisms will contribute to developing robust and scalable bio-mitigation technologies for flue gas emissions.

Photovoltaic-driven electro-reforming of poly (ethylene terephthalate) (PET) waste plastics and nitrate pollutants

The electrochemical conversion of waste plastics and nitrate pollutants has advantages in the simultaneous achievement of value-added chemical production and environmental pollutants remediation. Here, we report a photovoltaic-driven electro-reforming strategy to convert poly (ethylene terephthalate) (PET) to platform chemical formic acid, and simultaneously reduce nitrate to ammonia. This strategy directly uses commercial silicon photovoltaic panel as the power source that achieves the oxidation of PET hydrolysate to produce formic acid by NiCo2O4/N-doped carbon nanotubes (NCNTs) anode, and the reduction of nitrate-containing wastewater to produce ammonia by CuO nanowires (NWs) cathode. This integrated system exhibits a high Faraday efficiency of 98 % for formic acid production and conversion of 90 % for nitrate under 30 mW cm−2 simulated sunlight. This study suggests that photovoltaic-driven electro-reforming of PET waste plastic coupled with nitrate reduction could be a feasible strategy to realize the sustainable production of chemicals from environmental pollutants.

CONCEPTUALIZING AGILE DEVELOPMENT IN DIGITAL TRANSFORMATIONS: THEORETICAL FOUNDATIONS AND PRACTICAL APPLICATIONS

Agile development has emerged as a prominent approach in digital transformations due to its flexibility and adaptability to changing requirements. This review explores the theoretical foundations and practical applications of agile development in the context of digital transformations. Theoretical foundations of agile development stem from iterative and incremental methodologies that prioritize customer collaboration, adaptive planning, and continuous improvement. Agile principles, as outlined in the Agile Manifesto, emphasize individuals and interactions over processes and tools, working software over comprehensive documentation, customer collaboration over contract negotiation, and responding to change over following a plan. These principles are supported by various agile frameworks and methodologies, such as Scrum, Kanban, and Extreme Programming (XP), which provide specific practices and guidelines for implementing agile development in digital transformations. Practical applications of agile development in digital transformations are diverse and impactful. Agile methodologies enable organizations to respond quickly to changing market demands and customer needs, allowing for faster delivery of value-added products and services. Agile practices, such as daily stand-up meetings, sprint planning, and retrospective reviews, promote collaboration among cross-functional teams and foster a culture of continuous improvement. Agile development also enhances project transparency and stakeholder engagement through regular demonstrations and feedback loops, ensuring that the final product meets customer expectations. Overall, the conceptualization of agile development in digital transformations is characterized by its theoretical foundations in iterative and incremental methodologies and its practical applications in enabling organizations to adapt to change, deliver value, and foster collaboration. Understanding the theoretical underpinnings and practical implications of agile development is crucial for organizations seeking to leverage agile methodologies in their digital transformation efforts. Keywords: Conceptualizing, Agile Development, Digital Transformation, Theoretical Foundations, Practical Applications.

Digitalization and Firm Performance in ASTRA: The Mediating Role of Differentiation Strategy

Digitalization has emerged as a key factor in achieving sustainable performance. This is shown by the number of companies that utilize digital technology and related research to increase competitive advantage. The purpose of this study is to examine the relationship between digitalization mediated by strategic differentiation and firm performance. The research methodology used in this research is quantitative method. The target of this research is companies in the ASTRA with a research sample consisting of 80 respondents. The findings show that digitalization has been proven to have an impact on firm performance, strategic differentiation has been proven to have an impact on firm performance, and strategic differentiation is able to mediate between digitalization and firm performance. Practical implication: Digitalization allows companies to implement differentiation strategies more effectively. By adopting the right digital technology, companies can create unique, personalized, and value-added products or services for customers. These advantages can differentiate the company from competitors and provide a strong attraction for customers, which in turn can improve the firm performance. This report is derived from research conducted at the middle and top management levels in several companies in the ASTRA.

Comparative life cycle assessment of landfill gas utilization in South Korea with parametric uncertainties

Landfill gas, a major contributor to global CH4 emissions, which have a much greater impact on global warming than CO2 does, is inevitable as a waste derivative. Upcycling landfill gas into value-added products is a powerful strategy to reduce greenhouse gas emissions and to use materials in a circular system. This study presents a full life cycle assessment of electricity produced using landfill gas at the Sudokwon landfill site, the largest case of landfill gas upcycling in South Korea. To ensure the representativeness of the results, we used statistical data to capture the technical and regional characteristics of the national market share as primary data. In addition, a parametric uncertainty analysis integrated with data quality assessment was conducted to reflect the temporal dynamics of landfills and enhance the reliability of this study. Our findings demonstrate that upcycling landfill gas into electricity is environmentally beneficial across sixteen impact categories compared with two baseline scenarios that do not involve landfill gas upcycling. The methodological approaches presented herein can address multifunctional challenges in waste treatment systems and improve the reliability of life cycle inventories.

Consumer Awareness, Utilization, and Acceptance of Orange-fleshed Sweet Potato (Ipomoea batatas (L.) Lam) Value-added Food Products in Elgeyo Marakwet County, Kenya

Sweet potatoe is a crucial crop for food security. promoted in Kenya due to its reported health benefits and resilience to drought. The benefits and application of the sweet potato with orange flesh (OFSP) in Elgeyo Marakwet County have, however, not been established. The current research sought to establish knowledge, method of utilization, and acceptability of specialty products made from OFSP. Information on sweet potato knowledge and use was gathered from 201 smallholder farmers in Endo Ward, Elgeyo Marakwet County, using a multi-stage sampling technique. Promotion of recipes of OFSP value-added products was undertaken among 30 selected farmers through practical demonstration and a farmer participation approach. The evaluation was undertaken through semi-structured questionnaires and scoring sheets for the preferred products and reasons to support their preferences. The results indicated that 82.6% of farmers in Elgeyo Marakwet are aware Compared to other crops, sweet potatoes are easier to grow and more suited to difficult climates (80.1 %). They were also aware of the advantages OFSP has for health (61.7%) and as a household food security crop (79.1%). However, 89.1% of the farmers have inadequate knowledge and skills in value addition. The majority of the farmers (70%) boil the sweet potatoes while 30% make snacks out of the OFSP. Consumer knowledge, utilization, and acceptability are influenced by demographic factors such as gender, education levels, size of land, and occupation. Products made with OFSP puree are the most preferred over wheat justifying its uses to produce acceptable and nutritious chapati, mandazi, and yogurt as part of diversification from the current practice of simply eating the boiled roots. These results suggest that increased efforts are required to educate farmers about the nutritional advantages of cultivating and consuming OFSP. to boost agricultural value addition and boost the amount of vitamin A in households’ diet.

Purification of soda lignin

Purity of technical lignin is one of the main obstacles in the utilization of lignin to value-added chemicals, products, and materials. The objective of this study was to investigate and compare single and two stage purification methods for obtaining soda lignin with high purity. Extensive washing and extraction with water was found effective, increasing the abundance of acid insoluble lignin while reducing its ash content. Extraction with organic solvents was conducted with 2-propanol or blends of n-heptane/1-butanol or cyclohexane/acetone. These solvents were shown to have little effect on the total lignin content, as determined by wet-chemical methods. Two-stage treatments (washing with water followed by solvent extraction) were hence not better than single stage water extraction in terms of the lignin purity. Still, selective removal of low molecular weight components after solvent extraction was noted, reducing the overall polydispersity of the lignin. Evaporation at 40 °C also showed little effect, whereas calcination at 150 °C significantly increased the molecular weight of the soda lignin. The latter effect was explained by thermally induced cross-linking. In addition, the UV absorbance of the calcinated lignin increased, which is likely related to changes in the aromatic structure. Such effect also entailed that UV/vis spectrophotometry was found less reliable in determining the total lignin content. At last, a mathematical model was adapted to predict the total lignin content from FTIR spectrometry. In conclusion, the tested procedures can be used to purify soda lignin and adjust its molecular weight.

Spark plasma sintering of SiC-based bulk materials from carbonaceous residue of rice husk thermal processing

Relevance. The search for a useful application of carbonaceous residues of rice husks thermal processing. These residues due to high silicon content in the inorganic part can potentially be used to produce silicon carbide – an important functional material for various fields of science and technology. Useful utilization of this waste will allow not only solving the environmental problem associated with their inefficient application and formal disposal, but also obtaining value-added products in the form of SiC-based ceramics. Aim. To obtain SiC-based bulk products from carbonaceous residues of rice husk thermal processing by spark plasma sintering with a minimum number of additional stages of feedstock processing. Objects. SiC-based bulk products obtained using carbonaceous residues of rice husk thermal processing. The samples were obtained by spark plasma sintering at 1800 °C, pressure of 60 MPa and holding time of 10 minutes. Methods. Spark plasma sintering; X-ray diffractometry (X-ray phase analysis); scanning electron microscopy; vacuumless arc discharge synthesis method. Results. The authors have carried out the experimental studies to assess the possibility of applying carbonaceous residue of rice husk thermal processing as a precursor for the synthesis of silicon carbide in bulk (ceramics) and dispersed (powder) forms. A series of experiments on spark plasma sintering of carbonaceous residue from rice husk thermal processing in the initial and milled form, with SiO2 silica sand additives, as well as with the use of silicon carbide powders synthesized from carbonaceous residue by vacuumless arc discharge method were implemented. The latter is performed within a one-stage fast-flowing process in an air environment and does not require the use of a vacuum system. Preliminary results demonstrated the possibility of obtaining bulk products and dispersed powders based on silicon carbide with a content of at least 50 and 60 wt %, respectively, and indicate the prospects of further increasing phase purity by optimizing spark plasma sintering and vacuumless arc discharge synthesis.

Revealing the nitrogen migration mechanism during pyrolysis and steam gasification of biomass: A combined ReaxFF MD and DFT study

The biomass pyrolysis/gasification technology takes advantages of high efficiency and carbon neutrality, which is promising for high value-added products fabrication. However, biomass possesses relatively high amount of N especially for seaweeds and municipal sludge wastes, and the lack of N migration mechanism has resulted in emission of N-containing pollutants and limited its industrial application. In this work, a simulation investigation combining reactive force field molecular dynamic and density functional theory calculations was performed to study the conversion mechanisms of N-containing species in the pyrolysis/gasification of biomass processes. The glutamic acid and cellulose were selected as the model compounds of N-containing and typical compositions of biomass, respectively, and six models containing multiple mass ratios of glutamic acid to cellulose and steam to feedstock were constructed. The results show that the majority of nitrogen in the original model is converted towards NH3-N (62%) during glutamic acid pyrolysis by direct cleavage, hydrogen capture, deamination, and decarboxylation. The presence of cellulose effectively inhibits the decomposition of NH3 at high temperature range, thereby increasing the yield of NH3-N (up to 70%) and restraining the conversion of nitrogen into mesomolecules. The introduction of H2O provides a substantial amount of •H radicals, which facilitates the conversion of nitrogen into NH3-N. During DFT calculations, eight reaction pathways for the formation of N-containing products were proposed on the basis of distribution of pyrolysis products. The glutamic acid cleavage reaction achieves the lowest energy barrier, and the deamination of glutamic acid towards a ternary cyclic ether is found to be the most feasible pathway for the NH3 production. This work can provide theoretical support for nitrogen pollutants mitigation during pyrolysis and steam gasification of biomass processes.

Modulating Oxygen Vacancy in Pt/TiO2 for Thermo-Photo Reforming Lignin and Its Derivatives to H2 and Value-Added Product

Modulating Oxygen Vacancy in Pt/TiO₂ for Thermo-Photo Reforming Lignin and Its Derivatives to H₂ and Value-Added Product

Anodic Reactions in Alkaline Hybrid Water Electrolyzers: Activity versus Selectivity.

Affordable and abundant sources of green hydrogen can give a large impetus to the Energy Transition. While conventional water electrolysis has positioned itself as a prospective candidate for this purpose, it lacks cost competitiveness. Hybrid water electrolysis (HWE) has been praised for its ability to address the issues of conventional water electrolysis due to its decreased energy requirements and its ability to generate value-added products, among other advantages. In this perspective, we discuss the challenges related to the applicability of HWE, using the glycerol oxidation reaction as an example, and we identify pitfalls often found in the literature. Reported catalysts, especially those based on abundant materials, suffer from a severe selectivity-activity tradeoff, hampering their industrial applicability due to large costs associated with product separation and purification. Additionally, testing electrocatalysts under conditions that are relevant for their applications is encouraged, yet these conditions are largely unknown, as in-depth knowledge of the catalytic mechanisms is largely missing. Lastly, an opportunity to increase the amount of interdisciplinary research concerning both the engineering requirements and financial performance of HWE is discussed. Increased focus on these objectives may boost the development of HWE on an industrial scale.

Single-crystal oxygen-rich bismuth oxybromide nanosheets with highly exposed defective {10–1} facets for the selective oxidation of toluene under blue LED irradiation

Reactive radicals are crucial for activating inert and low-polarity C(sp3)-H bonds for the fabrication of high value-added products. Herein, novel single-crystal oxygen-rich bismuth oxybromide nanosheets (Bi4O5Br2 SCNs) with more than 85 % {10–1} facets exposure and oxygen defects were synthesized via a facile solvothermal route. The Bi4O5Br2 SCNs demonstrated excellent photocatalytic performance in the selective oxidation of toluene under blue light. The yield of benzaldehyde was 1876.66 μmol g−1 h−1, with a selectivity of approximately 90 %. Compared to that of polycrystalline Bi4O5Br2 nanosheets (Bi4O5Br2 PCNs), the activity of Bi4O5Br2 SCNs exhibit a 21-fold increase. Experimental studies and density functional theory (DFT) calculations have demonstrated that the defect Bi4O5Br2 (10–1) facets exhibits exceptional adsorption properties for O2 molecules. In addition, the single-crystal structure in the presence of surface defects significantly increases the separation and transport of photogenerated carriers, resulting in the effective activation of adsorbed O2 into superoxide radicals (•O2–). Subsequently, the positively charged phenylmethyl H is readily linked to the negatively charged superoxide radical anion, thereby activating the CH bond. This study offers a fresh perspective and valuable insights into the development of efficient molecular oxygen-activated photocatalysts and their application in the selective catalytic conversion of aromatic C(sp3)-H bonds.

Production of vaterite via wet carbonation of carbide residue: Enhancing cement properties and CO2 sequestration

The influence of limestone powder (primarily composed of calcite) on hydration and properties of concrete has been extensively researched. However, there is limited understanding of how different calcium carbonate (CC) polymorphs affect cement hydration due to the difficulty in formation of vaterite. Therefore, preparing calcite and vaterite from solid waste carbide residue (CS) by wet carbonation and examining influence of these two CC polymorphs (0–20 %) on cement hydration and properties are comprehensive investigated in the paper. The results reveal that pure cubic calcite can be obtained through CS carbonation, while high-purity spherical vaterite can be synthesized using glycine as a regulator. The specific surface area (SSA) of spherical vaterite (15.47 m2/g) is approximately three times that of calcite (4.8 m2/g) with a comparable particle size distribution (PSD). The addition of calcite reduces the flowability of cement, whereas vaterite enhances it. The cement mortar with calcite demonstrates a lower compressive strength, while the incorporation of vaterite results in a higher or comparable compressive strength in contrast to control sample. Compared with control cement hydration, new hydration products, like monocarbonate aluminate and hemicarbonate aluminate, are formed with the addition of both calcite and vaterite. The metastable vaterite exhibits increased reactivity. The research presents a novel approach for the valorisation of solid wastes through CO2 sequestration, offering insights into the preparation of highly added-value products.