Abstract The present research aims to improve the environmental and thermodynamic efficiency of a solar desalination system using Al 2 O 3 nano‐enhanced phase change material (nano‐PCM). Five different system configurations were experimentally investigated, including a conventional system, PCM system and nano‐PCM systems with different Al 2 O 3 concentration (0.1–0.5 wt%). Energy and exergy analyses were used to assess the system, and artificial neural networks (ANN) and response surface methodology (RSM) for modeling and optimization. The results indicate that the performance of the optimized nano‐PCM system significantly improved the performance of the system, by achieving a 53% relative improvement in freshwater productivity and a nearly 80% relative improvement in the exergy efficiency of the system compared to the conventional system. The entropy generation reduced about 25–30%, which shows that there is a substantial decrease in the irreversibility of the system. Environmentally, the system was capable of reducing CO 2 emissions by roughly 275 kg per year, highlighting its potential for sustainable and eco‐friendly desalination. The results verify that the integration of nano‐PCM and multi‐objective optimization is a sustainable approach to enhance the performance of solar desalination systems.
Abstract Converting waste feedstocks into multifunctional biochar catalysts provides a promising route for coupling solid‐waste valorization with pollution control. However, existing studies often emphasize individual removal performance, while the relationships among feedstock characteristics, synthesis strategies, active‐site evolution, catalytic pathways, and practical constraints remain insufficiently integrated. This review summarizes recent advances in waste‐derived multifunctional biochar catalysts, with emphasis on how pyrolysis, activation, metal loading, heteroatom doping, and composite construction regulate pore structure, surface chemistry, conductivity, and catalytic active sites. Adsorption–catalysis coupling, radical and non‐radical oxidation, electron‐transfer processes, and light‐, electricity‐, and heat‐assisted pathways are critically compared for different pollutant categories, including heavy metals, dyes, antibiotics, emerging contaminants, and gaseous pollutants. A literature‐based comparative assessment is further presented to summarize removal efficiency, reaction kinetics, stability, regeneration, and real‐matrix applicability across representative systems. Finally, key challenges, including active‐site stability, metal leaching, secondary pollution risks, cost‐related constraints, and scale‐up feasibility, are discussed to outline future directions for the design of safer, more efficient, and application‐oriented multifunctional biochar catalysts.
Abstract Nickel oxide nanoparticles (NiO NPs), Magnesium oxide nanoparticles (MgO NPs), and MgNiO 2 ternary metal oxide nanoparticles (MN NPs) were prepared using a green method that employed Sonneratia ovata leaf extract. X‐ray diffraction (XRD) results validated the cubic structure, revealing typical crystallite sizes of 10.01 nm for NiO, 22.67 nm for MgO, and 14.82 nm for MN NPs. Fourier transform infrared (FTIR) spectra identified functional groups in both metal oxides and phytochemicals, whereas the optical results indicated absorption edges at 307 nm (NiO), 214 nm (MgO), and 288 nm (MN NPs). Morphological and particle‐size analyses revealed uniformly distributed nanostructures with average particle sizes of 20.73, 38.55, and 25.38 nm. The elemental mapping confirmed the uniform incorporation of Ni, Mg, and O, whereas X‐ray photoelectron spectra (XPS) revealed the oxidation states Ni 2+ and Mg 2+ on oxygen‐rich surfaces. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) revealed improved charge transfer, reduced resistance, and enhanced redox reversibility in MN NPs compared with the individual oxides. Photocatalytic analyses conducted under sunlight using a dye concentration of 10 mg/L and a catalyst dosage of 1 g/L revealed that MN NPs exhibited the highest degradation efficiencies for Congo red (98.95%), Crystal violet (95.26%), and paracetamol (99.07%), following pseudo‐first‐order kinetics, while recycling tests demonstrated significant stability (>92% efficiency after five cycles). The findings indicate that the synergistic structural formation between NiO and MgO enhances charge separation, radical generation, and pollutant mineralization, highlighting MN NPs as a cost‐effective and environmentally benign nanocatalyst for wastewater treatment and multifunctional applications.
Abstract Reducing emissions from the cement industry is essential to limiting global temperature rise below 1.5°C, as the sector accounts for approximately 7% of global CO 2 emissions. This paper reviews carbon capture and utilization as a promising decarbonization strategy for cement manufacturing by evaluating the technological readiness levels (TRLs), advantages, and limitations of carbon capture technologies, including amine scrubbing, oxy‐fuel combustion, calcium looping, direct air capture, and Low Emissions Intensity Lime and Cement (LEILAC). Among these, amine scrubbing, oxy‐fuel combustion, and calcium looping have demonstrated significant CO 2 capture potential. In contrast, LEILAC provides a high‐purity CO 2 stream but faces challenges in energy efficiency, process integration, and large‐scale deployment. Although these technologies are technically scalable, high‐energy penalties and operational costs remain significant barriers to widespread implementation. Moreover, the use of captured CO 2 in value‐added products, including fuels and chemicals, as well as for mineralization and enhanced oil recovery, offers significant opportunities to promote industrial sustainability. Studies have reported that CCUS technologies can achieve CO 2 emission reductions of 54% to 99%. It is anticipated that CCUS will contribute approximately 36% and 1370 Mt CO 2 emissions savings by 2050 to meet deep decarbonization and net‐zero goals. Future studies must focus on reducing capture costs by using renewable energy sources, AI, and process optimization, while advancing the TRL of emerging CCU techniques. Achieving net‐zero emissions in the cement industry will require large‐scale deployment of CCU technologies supported by sustained technological innovation, strategic investments, robust policy frameworks, and strong collaboration among industry, academia, and governments.
Abstract This perspective critically synthesizes Life Cycle Assessment (LCA) literature on solar‐powered hydrogen production, evaluating environmental sustainability and proposing an integrated Circular Economy LCA (CE‐LCA) framework. While solar electrolysis offers zero operational emissions, the environmental footprint is overwhelmingly “front‐loaded” in manufacturing infrastructure, with Global Warming Potential ranging from 0.37 to 14.2 kg CO 2 ‐eq/kg H 2 depending on technology and manufacturing energy mix. Carbon‐centric LCAs are inherently subjective, failing to capture broader environmental damage, resource depletion, social inequalities, and “green colonialism.” The manuscript makes three contributions: critically synthesizing green colonialism within the hydrogen transition, showing how carbon‐focused LCAs render extractive injustices invisible; proposing a CE‐LCA framework incorporating material circularity indicators; and combining prospective LCA with supply chain vulnerability analysis, demonstrating that technological learning alone is insufficient without circular strategies. Emerging pathways (photoelectrochemical, thermochemical) achieve GWP below 2.5 kg CO 2 ‐eq/kg H 2 but require iridium, platinum, and rare earths with significant supply chain risks. Water consumption ranges 9–35 L/kg H 2 , maritime transport can contribute up to 95% of life cycle emissions, and dynamic electrolyzer operation with intermittent renewables reduces efficiency 5–15% and increases degradation 20–40%. Embedding circularity via material passports, urban mining, industrial symbiosis, and design for disassembly can substantially mitigate these trade‐offs. We advocate for dynamic, prospective LCA integrated with multi‐objective optimization and circular economy indicators to guide a hydrogen economy that is low‐carbon, resource‐efficient, economically viable, socially responsible, and circular.
Abstract This study used fly ash as the main raw material to prepare porous ceramics via the foaming method, systematically investigating the effects of fly ash content, foaming agent dosage, sintering temperature, and holding time on the material's structure and properties. The results showed that the introduction of the foaming agent SiC significantly reduced material density and regulated the pore structure, but excessive addition led to a decrease in mechanical properties. The optimal process parameters determined through response surface methodology optimization were: fly ash addition of 40%, SiC dosage of 0.5%, sintering temperature of 1100°C, and holding time of 30 min. Under these conditions, the prepared porous ceramic achieved a porosity of 82.11%, a bulk density of 1.08 g/cm 3 , and a compressive strength of 5.63 MPa. Phase and microstructure characterization indicated that the main crystalline phases of the material were quartz and mullite, exhibiting a hierarchical pore structure. The porous ceramic prepared in this study holds potential application value in fields such as thermal insulation, adsorption, and carrier materials, providing a feasible pathway for the high‐value utilization of fly ash.
Abstract Calcined limestone overburden clay was investigated as a supplementary cementitious material (SCM) for partial clinker replacement. Cement blends containing 30%, 50%, and 70% calcined clay, produced at 500–800°C, were cured for 1–90 days and evaluated for mechanical, durability, chemical, and microstructural properties. Calcination at 600°C produced optimum performance, with the 30% replacement mixture achieving 40.0 MPa compressive and 5.9 MPa flexural strengths at 90 days, compared with 54.0 and 7.8 MPa, respectively, for the CEM I control. The combined SiO 2 , Al 2 O 3 , and Fe 2 O 3 content exceeded 70 wt %, confirming substantial pozzolanic potential, while water absorption remained below 10%. Multiple linear regression and ANOVA indicated that calcined clay replacement significantly influenced compressive and flexural strengths ( p < 0.05), whereas calcination temperature was statistically insignificant ( p > 0.05). The models demonstrated strong predictive performance, with R 2 values of 97.96% and 95.00% for compressive and flexural strengths, respectively. XRD and SEM–EDS confirmed quartz and silica‐rich phases in the calcined clay. Overall, limestone overburden clay demonstrates potential as an effective SCM for reducing clinker consumption, CO 2 emissions, and environmental impacts of cement production.
Abstract Coastal blue carbon ecosystems, including mangroves, seagrass meadows, and salt marshes, are globally important carbon sinks because they store organic carbon in vegetation biomass and waterlogged sediments over long timescales. However, nutrient enrichment, heavy metals, petroleum hydrocarbons, macroplastic and microplastic debris, and emerging contaminants increasingly threaten their capacity to sequester carbon. These pollutants reduce photosynthetic productivity, weaken root and rhizome systems, alter sediment redox conditions, disrupt microbial decomposition pathways, and may increase emissions of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O). This review synthesizes current evidence on how pollution alters carbon cycling across major blue carbon ecosystems, with emphasis on plant physiology, sediment stability, microbial processes, greenhouse gas (GHG) fluxes, and carbon stock permanence. It also evaluates monitoring, reporting, and verification (MRV) approaches that could integrate carbon measurements with pollutant diagnostics. In response to current methodological gaps, the review presents the Pollution‐Carbon Impact Framework (PCIF) as a conceptual decision‐support approach rather than a fully operational protocol. The PCIF is intended to guide future co‐located monitoring, indicator selection, site prioritization, and policy integration, while recognizing that standardized templates, open datasets, validated models, and Geographic Information System (GIS)‐based decision tools remain future requirements. The review concludes that reliable blue carbon accounting requires stronger integration between water‐quality governance, restoration planning, pollution control, and carbon‐credit verification.
Abstract Weeds are abundant lignocellulosic biomasses that represent a largely underutilized resource for renewable energy production. This study evaluated the biomethane production potential of five terrestrial weed species— Amaranthus retroflexus , Medicago sativa , Lactuca serriola , Chenopodium album , and Onopordum acanthium —using an integrated framework combining biochemical methane potential (BMP) assays, kinetic modeling, and multi‐criteria decision‐making (MCDM) techniques. Batch anaerobic digestion experiments were conducted under mesophilic conditions (37 ± 1°C), and methane production performance was assessed through cumulative methane yield, specific methane yield, methane concentration, and hydrolysis kinetics. First‐order kinetic modeling provided excellent agreement with experimental data ( R 2 = 0.9496–0.9896), with hydrolysis rate constants ranging from 0.0305 to 0.0539 d −1 . Among the investigated substrates, C. album achieved the highest cumulative methane production (9.32 L CH 4 ) and specific methane yield (95.83 mL CH 4 g −1 OM), whereas L. serriola exhibited the lowest specific methane yield (63.50 mL CH 4 g −1 OM). To support substrate prioritization, experimental and kinetic indicators were integrated using AHP, TOPSIS, VIKOR, and SMAA approaches. The MCDM analyses consistently ranked C. album as the most promising substrate due to its balanced performance in methane yield, hydrolysis kinetics, and process stability. The results demonstrate that anaerobic digestion performance of terrestrial weeds cannot be reliably assessed using a single parameter and highlight the value of integrating experimental and decision‐support methodologies. The proposed framework provides a practical tool for evidence‐based substrate selection and sustainable weed valorization within circular bioeconomy‐oriented biogas systems.
Abstract Present study examines the influence of waste cooking oil methyl ester (B20) blended with TiO 2 nanoparticles (75 ppm) with hydrogen induction (10 lpm) on performance, combustion, and emission behavior on CRDI engine operating at different loads. The research includes the atomization characteristics and the current need for cleaner and sustainable alternative fuel in compression ignition engines by assessing the synergistic effect of heated and unheated biodiesel, induction of gaseous fuel, and nano‐additives. The blend B20 + 75TiO 2 ensured the lowest sauter mean diameter (SMD) at all injection pressures, while diesel showed lowest SMD at all ambient pressures among all test fuels. The blend PB20 + 75TiO 2 _10H2 confirmed the maximum brake thermal efficiency (BTE) of 34.38%, and 10.2% decrease in brake specific fuel consumption (BSFC) compared to diesel. Also, the maximum heat release rate and cylinder pressure were 96 J/ o CA and 91 bar, indicating the enhanced energy conversion respectively. The unburned hydrocarbon (HC) and carbon monoxide (CO) emissions indicated maximum reduction of 43.3% and 41.2% respectively compared to diesel. There was a rise in NOx emission for all blends as compared to diesel due to hydrogen's high flame propagation and in‐cylinder temperature. The combined effect of biodiesel, hydrogen enrichment, and metal oxide nanoparticles improved the combustion efficiency and performance parameters with lowering carbon emissions. Overall, the conclusive summary presents that the ternary blend is capable of replacing diesel due to more energy efficient and cleaner combustion in CI engine without modification.
Abstract Pinus roxburghii (Chir Pine) residues are a serious ecological problem in the highlands of the Indian Himalayan Region that are causing regular forest fires and causing top soils to become less fertile. This detailed review provides a systematic techno‐chemical and thermodynamic framework for converting these abundant conifer wastes from a resource into a high utility, multi‐vector bioenergy matrix. The results of solid‐phase evaluations show that mechanical densification can successfully overcome the extreme bulk density problem of raw pine needles (≈60 to 80 kg/m 3 ) to produce bio‐briquettes with a high carbon density macromolecular lignin fraction (≈26%) and a strong Higher Heating Value of ≈19 MJ/kg. Due to low ash content of the fuel (≈5%), there is no need for the serious alkali‐silicate sand agglomeration and bed slagging problems associated with lowland agricultural wastes, achieving a fairly constant cold gas efficiency ≈65% with a producer gas production rate of ≈1.6 Nm 3 /kg of dry fuel. α‐pinene and limonene from pine have a Lower Heating Value close to that of petroleum diesel (≈43 MJ/kg). The ultra‐low kinematic viscosity (1.3 cSt) improves the homogeneity of fuel spray atomization, resulting in a quantitative 40% to 60% reduction in exhaust smoke opacity. Finally, this work provides a vision of future research paths with regard to selective catalytic ring‐cracking of bicyclic terpenes and suggests policy instruments to economically promote “local” bio economies in mountain regions.
Abstract This study presents a comprehensive techno‐economic assessment of a reverse osmosis (RO) plant, designed to produce 147.2 m 3 of potable water per day for 100 households using renewable energy sources, namely bifacial photovoltaic (PV) and wind turbine (WT) systems, as alternatives to conventional grid electricity. A detailed numerical modeling coupled with Water Application Value Engine (WAVE) and System Advisor Model (SAM) simulation tools is utilized to evaluate the sustainable system configurations capable of meeting the RO plant with 112 kW power demand. The energetic performance of the hybrid RO plant is comprehensively evaluated under two configurations (PV‐RO and WT‐RO) based on energy, economic, and environmental analyses under harsh conditions in Dhahran, Saudi Arabia, for one complete year. The simulation results show that to optimistically meet the power demand of the RO plant, the PV system design is desired to be 592 mono‐crystalline silicon modules with an efficiency of 21.54%, covering a total area of approximately 700 m 2 , with an estimated capital cost of $163,895. This configuration achieved a levelized cost of electricity (LCOE) of 3.35 ¢/kWh, an internal rate of return (IRR) of 5.21%, a net present value (NPV) of $34,565, and a payback period of 12 years. In comparison, the wind‐powered RO plant optimized for a 14‐turbine array with a rated power of 10 kW each required a higher capital investment of $214,085. This resulted in an LCOE of 3.99 ¢/kWh, an IRR of 2.34%, and an NPV of $10,738, with a payback period of 15.4 years. For the levelized cost of water (LCOW), PV‐RO results are more favorable at 0.79 $/m 3 compared to $0.825/m 3 for wind‐RO. The carbon footprint analysis also showed that the WT‐RO system emits 20.55 gCO 2 /kWh, while the PV‐RO system records 38 gCO 2 /kWh. Both of these values are significantly lower than those of fossil fuel‐based power systems. Overall, the results demonstrate that the PV‐RO configuration is the preferred option when economic performance is the primary objective, owing to its lower LCOE, LCOW, and shorter payback period, whereas the WT‐RO configuration offers the lowest carbon footprints and may be preferred where environmental impact is the dominant design criterion.
Abstract This study evaluates the combined influence of an aqueous ammonia emulsion (AAE) and carbon nanotubes (CNTs) on the combustion, performance, and emission characteristics of a soybean biodiesel‐fueled diesel engine. A novel ternary fuel comprising soybean biodiesel (SB), AAE, and CNTs was developed to overcome two key limitations of biodiesel, namely elevated nitrogen oxide (NO x ) emissions and moderate thermal efficiency. Soybean biodiesel was produced through transesterification, while the CNTs were characterized using X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) before being incorporated into the SB–AAE blend at concentrations of 50 and 100 ppm. The addition of 10% AAE promoted in‐cylinder hydrogen generation and reduced NO x emissions through charge‐cooling effects associated with its high latent heat of vaporization. However, the SB–AAE blend exhibited higher carbon monoxide (CO), hydrocarbon (HC), and smoke emissions because of the relatively slow decomposition of aqueous ammonia. The incorporation of CNTs enhanced ammonia decomposition, improved fuel atomization, and accelerated oxidation reactions, resulting in more efficient combustion. The CNT‐enriched blends reduced brake‐specific energy consumption by up to 12.8% and substantially lowered CO, HC, and smoke emissions compared with SB–AAE. Although NO x emissions increased slightly relative to SB–AAE, they remained lower than those of neat soybean biodiesel. Overall, the synergistic interaction between AAE and CNTs improved fuel utilization while simultaneously enhancing the emission characteristics of soybean biodiesel, demonstrating the potential of the proposed ternary fuel as a cleaner and more energy‐efficient alternative for diesel engine applications.
Abstract The photocatalytic degradation of azo dyes using semiconductor oxides has emerged as a promising strategy for wastewater remediation. In this study, pure, mixed, and Fe‐doped oxide catalysts based on Zinc Oxide and Titanium Dioxide were synthesized and evaluated for the degradation of Ponceau 4R under ultraviolet irradiation. The catalysts were characterized by X‐ray diffraction, scanning electron microscopy/energy dispersive X‐ray, Fourier Transform Infrared Spectroscopy, N 2 adsorption–desorption, photoacoustic spectroscopy, and point of zero charge analyses. Fe incorporation reduced the band gap energy of the catalysts to values close to 2.0 eV, indicating enhanced visible‐light absorption. However, photocatalytic experiments demonstrated that Fe doping did not improve catalyst performance. Among all evaluated materials, commercial ZnO exhibited the highest activity, achieving 100% dye decolorization with pseudo‐first‐order rate constants of up to 0.0506 min −1 . Calcination at 400°C generally enhanced photocatalytic activity, whereas Fe addition reduced the performance of ZnO‐based systems, likely due to increased charge recombination and particle agglomeration. Kinetic analyses showed that the pseudo‐first‐order model best described the degradation process. The results demonstrate that pure ZnO remains more effective than Fe‐doped and mixed oxide systems for Ponceau 4R degradation under the investigated condition.
Abstract This study developed and evaluated a solar dryer with a zigzag airflow pathway for drying henna leaves under Egyptian climatic conditions. The system was designed to improve air‐product contact in tray drying by directing heated air alternately above and below the drying trays. Drying experiments were conducted at two airflow rates, 0.09 and 0.14 m 3 /s, three‐layer thicknesses, 2, 4, and 6 cm, and four tray positions. An Arduino‐based local data‐logging system was used to record temperature and relative humidity during drying. Henna leaf moisture content decreased from 62.7% to below 5% wet basis. The shortest drying time was 10 h at 0.14 m 3 /s and 2 cm layer thickness, whereas the longest drying time was 26 h under the lowest airflow and highest loading condition. The corrected peak drying rate ranged from approximately 0.28 to 0.35 g water g −1 dry matter h −1 . The maximum solar‐collector energy efficiency reached 67.8%, while the drying‐room exergy efficiency ranged from 25.27% to 86.66%, depending on airflow rate, layer thickness, and tray position. Higher airflow enhanced useful energy recovery, but its effect was interpreted as a balance between increased mass flow rate, shorter air residence time, and improved vapor removal. A simplified environmental assessment showed that the energy payback time decreased from 9.83 years at 2 cm layer thickness to 3.27 years at 6 cm layer thickness, while lifetime CO 2 mitigation reached up to 2399.2 kg CO 2 .
Abstract This study examines the asymmetric effects of nuclear energy consumption on ecological sustainability in major nuclear‐powered economies. It investigates whether increases and decreases in nuclear energy consumption have different impacts on environmental quality, measured by carbon dioxide (CO 2 ) emissions, ecological footprint (EF), and load capacity factor (LCF), while also testing the Environmental Kuznets Curve (EKC) and Load Capacity Curve (LCC) hypotheses. The empirical framework initially considers three environmental indicators: CO 2 emissions, EF, and LCF, while long‐run asymmetric effects are estimated for the LCF and EF models, for which cointegration is established. The analysis uses panel data for 27 countries over 1993–2022, representing 97.4% of global nuclear energy consumption. A panel ARDL framework with pooled mean group (PMG) and mean group (MG) estimators is employed, and nuclear energy consumption is decomposed into positive and negative shocks to capture asymmetric effects. The results reveal asymmetries in the LCF and EF models. Positive shocks to nuclear energy consumption enhance ecological sustainability by increasing the LCF, whereas negative shocks raise EF. Moreover, the environmental benefits of positive nuclear energy shocks are stronger than the adverse effects of negative shocks. The findings confirm the LCC hypothesis and support the EKC hypothesis for the EF model, while no long‐run cointegration is established for the CO 2 model. These results highlight the practical importance of expanding and maintaining nuclear generation, particularly where it substitutes for fossil‐fuel‐based electricity. Carefully governed nuclear energy policies can therefore support ecological sustainability and advance progress toward Sustainable Development Goals 7 and 13.
Abstract Evaporative Cooling Systems (ECSs) are among cost‐effective and applied gas turbine compressor inlet air cooling systems to mitigate the negative impact of high ambient temperatures leading to performance degradation and lower power generation. Their cooling mechanism relies on the evaporation of water over porous media, such as cooling pads, to reduce the inlet air temperature. Effective management of both power generation and water consumption is essential due to economic considerations as well as environmental and climatic constraints. In this study, the performance of an ECS applied to a 25 MW gas turbine unit is investigated using real operational data from a power plant under varying ambient temperature conditions. The results showed that the average output power across the six gas turbine units increased by approximately 4.5% during the hours when the ECS was in operation. Furthermore, the intersection of the output power curves with and without ECS indicates the minimum inlet temperature at which the ECS becomes effective. The results also demonstrate that the effectiveness of ECS is strongly dependent on ambient temperature, with significantly higher performance at elevated temperatures. Finally, from a managing water consumption point of view, it can be concluded that the operation of the ECS between 13:00 and 18:00, when ambient temperatures are high, output power is minimal, and the ECS efficiency (temperature difference between inlet and outlet) is at its maximum, is recommended. Outside this time interval, although the system still increases output power, the significant water consumption makes it less worthwhile.
Abstract Wastewater from vegetable oil refineries (VORW) is heavily loaded with oils, greases, and phenolic compounds that are harmful to aquatic life and human health and requires effective treatment before discharge. This study reports the first use of the cationic polyacrylamide C8035 as a flocculant for VORW, applied after a low‐cost natural flotation pretreatment, and optimizes the process using response surface methodology. The effects of pH, flocculant concentration, and stirring time on the removal of color, aromatic organic matter (UV 254nm ), and polyphenols were investigated through jar tests. The raw effluent contained 168 mg/L of polyphenols and exhibited UV 254nm and color absorbances of 2.993 and 3.97 (dilution factor 10). Natural flotation alone removed 86.33% of polyphenols, 77.32% of color, and 61.91% of UV 254nm , while the subsequent flocculation step substantially improved performance. Analysis of variance confirmed that the quadratic models were highly significant ( R 2 = 0.948–0.980, adjusted R 2 = 0.90–0.96, p < 0.0001) and reliable for prediction. Under the optimal conditions (pH 8, 20 mg/L flocculant, and 20 min stirring), removal efficiencies reached 98.27% for color, 88.82% for UV 254nm , and 83.27% for polyphenols, in close agreement with model predictions. These results demonstrate that C8035‐based flotation–flocculation is an efficient, low‐cost, and scalable approach for VORW treatment.
Abstract The global demand for sustainable, biodegradable, and economically viable alternatives to synthetic materials has intensified the research into plant‐based waste resources. Coir pith is a lignocellulosic byproduct generated during the extraction of coir fiber from coconut husks which remains largely underutilized. It is traditionally discarded or minimally used as low‐value mulch or compost. Coir pith is mostly accumulated near processing facilities posing environmental challenges due to land occupation and unmanaged degradation. The intrinsic properties such as high cellulose content, low bulk density, biodegradability, water retention capacity, and tensile strength make it an attractive value‐added material, particularly cellulose‐based polymer composite. This review provides a comprehensive analysis of the valorization of coir pith focusing on its transformation into functional materials through chemical, physical, and biological modifications. The main consideration is given to the pre‐treatment and surface modification techniques aimed at enhancing the interfacial adhesion between coir‐derived cellulose and polymer matrices. This review outlines the methods for isolating cellulose and developing composites with thermoplastic and thermosetting polymers. The resultant composites exhibit improved mechanical strength, thermal stability, durability, and environmental performance. The recent applications of coir pith‐based composites are critically reviewed, including their use in automotive interior components, building materials, biodegradable packaging, agricultural tools such as geotextiles, soil stabilizers, etc. This review highlights the potential of coir pith as a sustainable reinforcement material through a thorough evaluation of the material's properties, preparation techniques, and practical applications. It also outlines future research directions to advance its industrial utilization and promote circular economy practices in the agro‐industrial sector.
Abstract Access to clean and affordable energy is a key enabler of development. Biogas is an essential renewable and sustainable energy that has great potential in meeting energy requirements, especially in areas with limited access to the grid. However, the presence of impurities such as hydrogen sulfide limits its application by corroding equipment parts and reducing the calorific value. Biogas desulfurization is therefore important; however, there are limited studies available. The current study critically evaluated existing biogas sweetening technologies applied on an industrial scale in three main categories: pre‐digestion, during digestion, and post‐digestion. The removal of H 2 S using sorption processes employing a variety of organic and inorganic sorbents was comprehensively reviewed. The effectiveness of inorganic materials such as red rock, ash, and zero‐valent iron as well as organic sorbents including sweet potato leaves, organic solvents, and water hyacinth was assessed. The effect of process conditions such as pH and moisture content especially for organic sorbents was evaluated. The study proposed new ways of increasing the performance of the sorbent materials through functionalization, recovery, regeneration, and reuse as well as biogas pre‐treatment to remove moisture. While most studies previously reported focused on H 2 S during removal post‐digestion, the current study evaluated the entire process train from pre‐digestion, during digestion, and post digestion thereby providing a more concise approach to biogas desulfurization.
