Global Challenges最新文献

Metal-free g-C₃N₄ (graphitic carbon nitride) is a promising candidate for the next-generation visible light-responsive photocatalyst; however, the recombination and transfer of the photogenerated charge carriers restrict its photocatalytic performances. The exfoliated g-C₃N₄ sensitized with brominated perylenediimide (dBrPDI) and perylene tetraester (dBrPTE) enhances the photocatalytic performance due to improved charge separation, light absorption, charge transfer and, thereby, overall efficiency in pollutant degradation. The g-C₃N₄/dBrPTE hybrid composite exhibits the fastest photocatalytic degradation against rhodamine B (RhB) pollutants. The g-C₃N₄/dBrPTE hybrid composite degrades RhB with a 2.34-fold improvement over pure g-C₃N₄, while the g-C₃N₄/dBrPDI hybrid composite degrades with a 1.56-fold increase over pure g-C₃N₄. The g-C3N4/dBrPDI hybrid composite shows the highest photocatalytic efficiency against methyl orange (MO) pollutants. The g-C₃N₄/dBrPDI hybrid composite degrades MO with a 2.25-fold improvement over pure g-C₃N₄, while the g-C₃N₄/dBrPTE hybrid composite degrades with a 1.8-fold increase over pure g-C₃N₄. Unlike MO and RhB, the perylene dye sensitization does not enhance the photocatalytic degradation of 2,4-dichloro phenoxy acetic acid (2,4-D) and no sustained increase in efficiency is not observed. Overall, these results suggest that photocatalytic efficiency depends not only on the sensitized photocatalyst material but also on the interaction between the sensitized photocatalyst and the chemical and ionic properties of the pollutants in the aquatic media.

Little scholarly research has been published on the cosmetic uses of tannins. This study identifies the emerging uses of tannin as cosmeceutical ingredient in skin and hair care products. A green chemistry, health, and economic perspective is offered on future developments concerning the use of tannins in cosmetic products massively employed such as hair dyes and hair relaxers. Besides filling a gap in the literature, the study will hopefully accelerate the uptake of tannins as cosmeceutical ingredients in cosmetic products widely used worldwide such as hair dyes and hair relaxers, eventually replacing harmful chemicals with a class of natural products imparted with broad-scope health-beneficial properties.

The increasing demand for energy and the environmental challenges posed by fossil fuel consumption prompts the exploration of clean and sustainable energy solutions. This review article focuses on the innovative approach of generating energy through the electrolysis of wastewater, which not only facilitates clean energy production but also aids in wastewater treatment. Significant advancements in electrooxidation processes for the sustainable production of hydrogen and other valuable chemicals are highlighted. This article specifically analyzes the techno-economic aspects of electrooxidation for small molecules, including alcohol, amine, hydrazine, iodine, and urea, within the framework of wastewater treatment. Cost estimations for hydrogen and value-added products derived from the oxidation reactions are presented, with production costs calculated at $6.37, $6.06, $2.68, $5.69, and $10.69 per kilogram of H₂, respectively. However, the costs associated with alcohol oxidation reactions and urea oxidation reactions are deemed unfeasible. An analysis of profitability reveals that the oxidation processes for iodine, hydrazine, and amine wastewater generate revenue profits of 28%, 16%, and 6%, respectively.

Engineered Living Materials (or ELMs) are an emerging class of materials that utilize microorganisms that can either generate their own structure (such as biofilms) or that can be incorporated into synthetic matrices using technologies (such as 3D printing). ELMs can be designed to have multiple functions, such as biosensing, self-repair, or bioremediation. Such materials have the potential to address a variety of problems related to sustainability, including water security, energy, and health. One major challenge to widescale social acceptance and adoption of these materials is the so-called yuck factor, or the propensity these materials may have to elicit disgust reactions. This Perspective provides an overview of social science research directed at the yuck factor to identify the drivers and demographics of disgust experiences and to examine how each of these are likely to arise in relation to ELMs. Strategies for overcoming these challenges are also addressed. Finally, areas where future empirical research is needed to better understand disgust toward ELMs, or particular ELM applications, are identified.

Air pollution is a pressing environmental and public health issue, with volatile organic compounds (VOCs) and nitrogen oxides (NO_x) being among the most hazardous airborne pollutants. Photocatalytic membrane reactors (PMRs) have emerged as a promising technology for air purification due to their ability to integrate photocatalytic degradation and membrane separation in a single system. This paper provides a comprehensive review of the advancements, challenges, and future prospects of PMR technology for VOC degradation and NO_x treatment. Various photocatalytic membranes and their fabrication techniques, including material selection, structural modifications, and catalyst immobilization strategies, are critically analyzed. The study further explores different PMR configurations, operational parameters, and their efficiency in air treatment applications. A theoretical PMR test system is also presented to evaluate design optimization strategies. Despite its potential, challenges such as membrane fouling, catalyst deactivation, and scale-up limitations remain critical barriers to widespread adoption. Future trends focus on enhancing photocatalytic performance, developing cost-effective materials, and optimizing reactor designs to facilitate large-scale industrial applications of PMRs.

Microbial fuel cell (MFC), a clean and promising technology that has the potential to tackle both environmental degradation and the global energy crisis, receives tremendous attention from researchers over recent years. The performance of each system component, including the membrane and electrode utilized in MFCs, has a great effect on the efficiency of converting chemical energy found in organic waste to power generation through bacterial metabolism. The MFCs have diverse applications that are growing day by day in developed countries. This review discusses recently available various potential applications including wastewater treatment, biohydrogen production, hazardous waste removal, generation of bioelectricity, robotics, biosensors, etc. There are still several challenges (e.g., system complexity, economic, commercialization, and other operational factors) for large-scale practical applications, particularly for relatively low power output and delayed start-up time, which is also reported in this review article. Moreover, the operational factors (e.g., electrode materials, proton exchange system, substrate, electron transfer mechanism, pH, temperature, external resistance, and shear stress and feed rate) that affect the performance of MFCs, are discussed in detail. To resolve these issues, optimizations of various parameters are also presented. In the previously published studies, this paper indicates that MFCs have demonstrated power densities ranging from 2.44 to 3.31 W m⁻², with Coulombic efficiencies reaching up to 55.6% under optimized conditions. It is also reported that MFCs have achieved the removal efficiency of chemical oxygen demand (COD), total organic carbon (TOC), and antibiotics up to 93.7%, 70%, and 98%, respectively. Finally, this paper highlights the future perspective of MFCs for full-scale applications.

The cover image is based on the article “Sustainable Strategies for Converting Organic, Electronic, and Plastic Waste From Municipal Solid Waste Into Functional Materials” by Abdelaziz Gouda et al., https://doi.org/10.1002/gch2.202400240

Researchers are increasingly focused on eco-friendly concrete with reduced carbon footprints. Among sustainable options, Limestone Calcined Clay Cement (LC3) concrete offers enhanced strength and durability with lower greenhouse gas emissions. This study evaluates the mechanical, microstructural, and durability characteristics of LC3 concrete modified with surkhi and nano-silica as cementitious materials, replacing metakaolin and gypsum. Surkhi and nano-silica are varied from 0%–40% and 0%–4%, respectively, while fine aggregate is completely replaced with M-sand to improve packing density. Ten M30-grade concrete mixes are analyzed after 28 and 90 days of curing. By incorporating surkhi and nano-silica as partial replacements for metakaolin and gypsum in LC3 concrete, the research investigates potential improvements in strength, durability, and microstructural integrity of the concrete and provides lower greenhouse gas emissions compared to traditional Portland cement. Results revealed that surkhi and nano-silica significantly improved strength and microstructure, with surkhi optimally limited to 30%. M-sand proved effective in enhancing durability against weathering. These findings position modified LC3 concrete as a sustainable alternative, offering improved performance and advancing its potential within the circular economy framework.

The discharge of industrial wastewater containing toxic dyes has significantly increased, posing risks to human health and aquatic ecosystems. The growing demand for dyes in the textile industry has driven research into effective and economical removal methods. Adsorption is widely preferred due to its low cost, non-toxic by-products, and eco-friendly nature. This study investigates the removal of Reactive-Blue-160 textile azo dye using a local natural clay mineral. The effects of contact time, pH, adsorbent dosage, and temperature on adsorption are examined, along with adsorbent characterization. Optimal conditions (pH 5.70, adsorbent dosage 2.0 g L⁻¹, contact time 60 min, and dye concentration 150 mg L⁻¹) achieve 93.05% removal. Characterization reveals a heterogeneous clay surface dominated by smectite and chlorite. The adsorption data are evaluated using isotherm and kinetic models, with Freundlich and pseudo-second-order providing the best fit. Thermodynamic analysis indicates spontaneous and endothermic adsorption, with a negative Gibbs free energy and a positive enthalpy change of 15.71 kJ mol⁻¹, confirming physical adsorption. These findings highlight the potential of natural clay minerals for dye removal, offering a sustainable solution for industrial wastewater treatment.

Limiting the global temperature rise to 1.5 °C is becoming increasingly difficult. The study analyzed data from 700 locations (1962–2100) to assess climate change impacts on heating-cooling energy and carbon footprint in under-researched Central Asia (CA). Under SSP2-4.5, icing and frost days reduce, while summer days and tropical nights increase. Central Asian countries will see an increase in cooling needs despite the projected decline in heating demands, with Kyrgyzstan experiencing the highest rise in cooling degree days, projected to increase by 132% and 165% in the near-future under SSP2-4.5 and SSP5-8.5, respectively. As a result, cooling energy generation is expected to rise by 39% and 92% under SSP2-4.5 and SSP5-8.5, respectively. However, CO₂ emissions for cooling are much lower in Kyrgyzstan and Tajikistan due to their reliance on renewable energy. CO₂ emissions in these countries are projected to be ≈10 times lower than in other parts of CA. From 2022 to 2100, cooling-related emissions are estimated to increase by 41% and 80% under SSP2-4.5 and SSP5-8.5, respectively across CA. Urgent adaptation is needed for resilient cities and stable power by expanding renewables, modernizing infrastructure, boosting efficiency, adopting policies, and fostering cooperation.