Abstract The increasing demand and stringent emission norms for sustainable energy have accelerated research into alternative fuels for both SI and CI engines. As promising options, hydrogen‐enriched ethanol‐gasoline and hydrogen‐CNG fuel blends were evaluated for combustion characteristics, engine performance, emission behavior, and design modifications. A bibliometric analysis from 2010 to 2025 was conducted to identify research trends, contributing countries, and related topics. The findings show that hydrogen's inherent properties improve BTE. Various studies consistently report BTE improvements ranging from 5% to 28% across experiments. For instance, hydrogen additions of 3–11% by volume increased thermal efficiency by 7–28%, while in hydrogen‐ethanol‐gasoline blends, BTE values exceeded 32–38% under lean conditions. Similar trends were also observed in BSFC, which decreased by 8–20%. Stable combustion is a benefit of hydrogen enrichment, as reflected in a peak in‐cylinder pressure and reduced ignition delay, resulting in improved power output and thermal efficiency. Hydrogen is carbon‐free, so emissions are significantly reduced. Studies show the drop in CO and HC by 15% to 80%, while a 20% drop in CO 2 . A higher combustion temperature increases NO x emissions by 10–45%. The review also highlights design modifications to the fuel injection system and spark plugs, as well as the optimization of the compression ratio and hydrogen storage and delivery systems. Overall, hydrogen enrichment in gasoline, CNG and ethanol offers a viable pathway. To address NO x emission, storage challenges, and optimized blending strategies. This review provides a strong foundation and identifies future research directions for hydrogen‐assisted SI engine systems.
Abstract The growing global demand for clean and sustainable energy has intensified research into hydrogen production via water electrolysis. In this context, this review provides an integrative analysis of recent advances in electrolytic hydrogen production, emphasizing electrocatalytic materials, electrolyte composition, process efficiency, techno‐economic feasibility, and the use of alternative feedstocks. A systematic literature review was conducted using the Scopus and Web of Science databases, covering English‐language research articles published between 2016 and 2026. The review focused on recent developments in electrocatalysts and electrode materials, their influence on electrochemical performance, and the challenges of comparing reported catalytic activity under different experimental conditions. The review also examines how electrolyte composition and operating parameters affect hydrogen production, as well as the economic factors governing the levelized cost of hydrogen, including electricity prices, capital costs, system efficiency, and utilization. The review also discusses alternative feedstocks, with particular emphasis on wastewater and biomass‐derived compounds such as urea. These approaches can couple hydrogen production with wastewater treatment, contaminant removal, resource recovery, or the generation of value‐added products through alternative anodic oxidation reactions. However, the analysis highlights important challenges related to pretreatment requirements, fouling, electrode and membrane stability, competing reactions, product selectivity, and scalability. Overall, this review identifies key technological trends and research gaps and highlights the need for integrated electrochemical and system‐level approaches to achieve more efficient, sustainable, and economically viable hydrogen production.
Abstract Non‐steroidal anti‐inflammatory drugs (NSAIDs) are among the most frequently detected emerging contaminants in aquatic environments. Their occurrence and environmental fate are governed by complex interactions involving physicochemical and environmental factors. This study aimed to develop, validate, and apply a reliable HPLC–UV method for the simultaneous determination of three NSAIDs: ibuprofen, ketoprofen, and fenoprofen in freshwater samples collected from five sites in northwestern Tunisia. Several experimental parameters were systematically optimized before selecting the final analytical conditions for the analysis of environmental samples. The analytical procedure consisted of off‐line solid‐phase extraction (SPE) followed by HPLC–UV analysis. The method showed excellent linearity ( R 2 ≥0.997), with limits of detection (LODs) ranging from 0.08 to 0.12 μg L −1 and limits of quantification (LOQs) from 0.25 to 0.37 μg L −1 . Recoveries at two spiking levels (1 and 10 μg L −1 ) ranged from 81% to 97%, with relative standard deviations (RSDs) below 3.8%, demonstrating good accuracy and precision. Among the target compounds, ibuprofen was detected at the highest concentrations, reaching 0.60 μg L −1 in Mallegue and 0.50 μg L −1 in Mejerda, whereas ketoprofen and fenoprofen were detected at lower concentrations at the same sites. An ecotoxicological risk assessment based on LC50 values and risk quotient (RQ) calculations indicated low acute toxicity toward representative aquatic organisms and insignificant ecological risk (RQ <0.1) for all investigated NSAIDs at the measured environmental concentrations. These findings confirm the occurrence of NSAIDs in freshwater ecosystems in northwestern Tunisia and emphasize the importance of regular monitoring of emerging contaminants to support the protection of vulnerable Mediterranean aquatic environments.
Abstract Rice straw is one of the most abundant yet underutilized agricultural residues, largely due to its recalcitrant lignocellulosic structure. A total of 10 bacterial strains were isolated from diverse lignin‐rich sources and screened for alkali lignin and rice straw lignin degradation, along with their lignocellulolytic enzyme secretion. Integrated analysis of enzymatic and degradation parameters, identified four efficient isolates, namely Lysinibacillus boronitolerans strain CP–2, Bacillus sp. strain D–6, Pseudomonas sp. strain S–4, and Priestia megaterium strain T–3. These isolates were combined to formulate two compatible microbial consortia, namely, consortium 1 ( Pseudomonas sp. strain S–4 + Priestia megaterium strain T–3 + Lysinibacillus boronitolerans strain CP–2) and consortium 2 ( Pseudomonas sp. strain S–4 + Priestia megaterium strain T–3 + Bacillus sp. strain D–6). Highest reduction in lignin and cellulose content of rice straw was observed on treatment with consortia 2 with 19.9% and 37.5% for lignin and cellulose respectively over the control. Scanning electron micrographs of degraded material with consortia 2 further confirmed extensive microstructural disintegration. GC–MS profiling of degraded rice straw using consortium 2 also resulted in reduction in phytotoxic volatile compounds and the presence of unique metabolites on degradation. Degraded material was used as potting mixture and growth and yield attributes of cowpea were assessed. There was an increase of 78.5% in number of pods and 81% increase in pod weight from consortia 2 derived potting mixture compared to control. Application of bacterial consortium 2 could be a sustainable and eco‐friendly strategy for rice straw management and generation of value‐added organic amendment.
Abstract Reactivity Controlled Compression Ignition (RCCI) engines are a promising way to decarbonize the internal combustion engine industry. Despite this extensive literature covering dual‐fuel setups, a critical knowledge gap persists regarding the steady‐state combustion behavior of highly specific, waste‐derived oxygenated lipids when paired directly with carbon‐free LRFs. To address this gap, the current study focuses on the waste‐to‐wealth principle of utilizing Milk Scum biodiesel and mineral diesel (as a High‐Reactivity Fuel) and hydrogen (as an LRF) to achieve the minimum carbon‐based emissions. Experimentally, performance and emissions were measured using a constant‐rpm diesel engine with a compression ratio of 18, fuel injection pressure of 500 bar, fuel injection time of 23 bTDC, and common‐rail direct‐injected (B10, B15, and B20) and port‐injected hydrogen (0.077 and 0.121 kg/h) at 25%, 50%, 75% and 100% engine loads. The measurements indicate that the RCCI optimality (0.121 kg/h H 2 , B10 blend) achieved a maximum Brake Thermal Efficiency of 31.2% and 10–15% lower Brake Specific Fuel Consumption under high‐load conditions. Moreover, this hydrogen‐enriched RCCI mode achieved average reductions in CO, HC, NOx, and smoke emissions of 24%, 27%, 35%, and 40%, respectively. Interestingly, while the overall experimental matrix yielded an average NOx reduction of 35%, the optimum RCCI B10 configuration at 100% load inhibited peak NOx formation by more than 60% compared with the baseline diesel mode at the same load.
