• Energy Research

Microbial fuel cell (MFC) has received much attention in the last decade as a promising technology to simultaneously generate electricity and decontaminate wastewater. This study aims to quantitatively review the published literature on MFC, published in the period of 1970–2020, based on the Web of Science (WoS) database. For the first time in literature, a comprehensive quantitative review of MFC has been conducted by employing the technique of bibliometric and content analyses. A total of 11,397 publications have been retrieved from WoS, out of which 81.6% are research articles. The evaluation in the field of MFC has been mapped in various categories, such as publication history, publication distribution, subject category distribution, leading journals, leading countries and leading organizations in MFC research. Additionally, content analysis has been conducted to unearth the research trends in MFC; and some hot research topics in MFC have been spotted. Results depict that the period 2011–2020 has been the most appreciating era for MFC research, as it contributed 87% of the total publications. Among the subject categories, energy fuel and microbiology lead with contributions of 26.5% for each, butthe overall growth of the energy fuel category in the last decade has been the highest. Out of 1,147 journals publishing MFC research, Bioresource Technology is the leading one; and countries like China, USA and India are the main hub of MFC research with 26.47%, 16.95% and 7.69% contributions in publications, respectively. The hottest topics in MFC research are nanoparticles, catalysts, air electrodes, graphene electrodes, power enhancement, air cathode and nitrogen removal. Moreover, major research areas are engineering, energy fuels and biotechnology with each contribution 26.5% of the total publications.

Microbial fuel cell, as a promising technology for simultaneous power production and waste treatment, has received a great deal of attention in recent years; however, generation of a relatively low power density is the main limitation towards its commercial application. This study contributes toward the optimization, in terms of maximization, of the power density of a microbial fuel cell by employing response surface methodology, coupled with central composite design. For this optimization study, the interactive effect of three independent parameters, namely (i) acetate concentration in the influent of anodic chamber; (ii) fuel feed flow rate in anodic chamber; and (iii) oxygen concentration in the influent of cathodic chamber, have been analyzed for a two-chamber microbial fuel cell, and the optimum conditions have been identified. The optimum value of power density was observed at an acetate concentration, a fuel feed flow rate, and an oxygen concentration value of 2.60 mol m−3, 0.0 m3, and 1.00 mol m−3, respectively. The results show the achievement of a power density of 3.425 W m−2, which is significant considering the available literature. Additionally, a statistical model has also been developed that correlates the three independent factors to the power density. For this model, R2, adjusted R2, and predicted R2 were 0.839, 0.807, and 0.703, respectively. The fact that there is only a 3.8% error in the actual and adjusted R2 demonstrates that the proposed model is statistically significant.

Microalgae-based wastewater treatment has previously been carried out in huge waste stabilization ponds. Microalgae, which can absorb carbon dioxide while reusing nutrients from sewage, has recently emerged as a new trend in the wastewater treatment business. Microalgae farming is thought to be a potential match for the modern world's energy strategy, which emphasizes low-cost and environmentally benign alternatives. Microalgae are being used to treat wastewater and make useful products. Microalgae, for example, is a promising renewable resource for producing biomass from wastewater nutrients because of its quick growth rate, short life span, and high carbon dioxide utilization efficacy. Microalgae-based bioremediation has grown in importance in the treatment of numerous types of wastewater in recent years. This solar-powered wastewater treatment technology has huge potential. However, there are still issues to be resolved in terms of land requirements, as well as the process's ecological feasibility and long-term viability, before these systems can be widely adopted. Due to cost and the need for a faultless downstream process, it is difficult to deploy this technology on a large scale. Other recent breakthroughs in wastewater microalgae farming have been investigated, such as how varied pressures affect microalgae growth and quality, as well as the number of high-value components produced. In this review, the future of this biotechnology has also been examined.

Les émissions de CO2, en particulier du secteur de l'énergie, ont augmenté de 1,7% ces dernières années, ce qui représente une augmentation énorme. Par conséquent, divers matériaux ont été utilisés pour capturer le CO2 libéré. Bien que de nombreuses études aient également été menées pour examiner l'état de la technologie de capture du CO2, un examen quantitatif du développement de ce domaine reste une nouveauté. Gardant cela à l'esprit, la présente étude vise à examiner quantitativement la littérature disponible sur cette technologie qui a été publiée au cours de la période 1970–2020, en appliquant des techniques bibliométriques et d'analyse de contenu. L'analyse bibliométrique révèle que 62,68 % du total des articles indexés dans Web of Science sont publiés au cours des cinq dernières années. L'International Journal of Greenhouse Gas Control a été identifié comme la revue ayant la contribution la plus élevée, avec une contribution de 9,97 % et 8,02 % dans les publications et les citations, respectivement. En outre, la Chine et les États-Unis sont les principaux centres de recherche dans ce domaine. Encore une fois, en utilisant des techniques d'analyse de contenu, la fixation chimique, la cycloaddition, les carbonates cycliques, les époxydes et la membrane à matrice mixte sont déterminés comme les sujets chauds de ce domaine. De plus, l'application de nanotubes et de nanoparticules peut être une option prometteuse dans la recherche future. Las emisiones de CO2, especialmente del sector energético, han aumentado un 1,7% en los últimos años, lo que supone un enorme incremento. Por lo tanto, se han empleado varios materiales para capturar el CO2 liberado. Aunque también se han realizado muchos estudios para revisar el estado del arte de la tecnología de captura de CO2, una revisión cuantitativa del desarrollo de este campo sigue siendo una novedad. Teniendo esto en cuenta, el presente estudio tiene como objetivo revisar cuantitativamente la literatura disponible sobre esta tecnología que se ha publicado durante el período 1970–2020, mediante la aplicación de técnicas bibliométricas y de análisis de contenido. El análisis bibliométrico revela que el 62,68% del total de artículos indexados en Web of Science se publican en los últimos cinco años. International Journal of Greenhouse Gas Control ha sido identificada como la revista con mayor contribución, con un 9,97% y un 8,02% de contribución en publicaciones y citas, respectivamente. Además, China y EE. UU. son los principales centros de investigación en este campo. Nuevamente, mediante el uso de técnicas de análisis de contenido, la fijación química, la cicloadición, los carbonatos cíclicos, los epóxidos y la membrana de matriz mixta se determinan como los temas candentes de este campo. Además, la aplicación de nanotubos y nanopartículas puede ser una opción prometedora en futuras investigaciones. The CO2 emission, especially from the energy sector, has increased by 1.7% in recent years, which is an enormous increase. Therefore, various materials have been employed to capture the released CO2. Although many studies have also been conducted to review the state-of-the-art of CO2 capture technology, a quantitative review of the development of this field is still a novelty. Keeping this in mind, the present study aims to quantitatively review the available literature on this technology that has been published during the period of 1970–2020, by applying bibliometric and content analysis techniques. The bibliometric analysis reveals that 62.68% of the total articles indexed in Web of Science are published in the last five years. International Journal of Greenhouse Gas Control has been identified as the highest contributing journal, with 9.97% and 8.02% contribution in publications and citations, respectively. Further, China and USA are the main research hubs of this field. Again, by using content analysis techniques, chemical fixation, cycloaddition, cyclic carbonates, epoxides and mixed-matrix membrane are determined as the hot topics of this field. Moreover, the application of nanotubes and nanoparticles can be a promising option in future research. ارتفعت انبعاثات ثاني أكسيد الكربون، خاصة من قطاع الطاقة، بنسبة 1.7 ٪ في السنوات الأخيرة، وهي زيادة هائلة. لذلك، تم استخدام مواد مختلفة لالتقاط ثاني أكسيد الكربون المنبعث. على الرغم من إجراء العديد من الدراسات لمراجعة أحدث تقنيات احتجاز ثاني أكسيد الكربون، إلا أن المراجعة الكمية لتطور هذا المجال لا تزال جديدة. مع أخذ ذلك في الاعتبار، تهدف هذه الدراسة إلى مراجعة كمية للأدبيات المتاحة حول هذه التكنولوجيا التي تم نشرها خلال الفترة 1970–2020، من خلال تطبيق تقنيات تحليل المراجع والمحتوى. يكشف التحليل الببليومتري أن 62.68 ٪ من إجمالي المقالات المفهرسة في ويب أوف ساينس يتم نشرها في السنوات الخمس الماضية. تم تحديد المجلة الدولية لمراقبة غازات الدفيئة كأعلى مجلة مساهمة، حيث ساهمت بنسبة 9.97 ٪ و 8.02 ٪ في المنشورات والاقتباسات، على التوالي. علاوة على ذلك، تعد الصين والولايات المتحدة الأمريكية مركزين رئيسيين للبحوث في هذا المجال. مرة أخرى، باستخدام تقنيات تحليل المحتوى، يتم تحديد التثبيت الكيميائي والتحميل الحلقي والكربونات الحلقية والإيبوكسيدات وغشاء المصفوفة المختلطة كمواضيع ساخنة في هذا المجال. علاوة على ذلك، يمكن أن يكون تطبيق الأنابيب النانوية والجسيمات النانوية خيارًا واعدًا في الأبحاث المستقبلية.

Abstract Poly(vinylidene fluoride-co-hexafluoro propylene) is a prospective material for the fabrication of polymer electrolyte membranes (PEMs) for direct methanol fuel cells, primarily due to its low methanol permeability, high mechanical integrity and significantly low cost compared to conventionally used Nafion. However, low proton conductivity has hindered its independent use; therefore, most studies on this prospective copolymer have been done by using it in conjunction with Nafion. Nevertheless, partial sulfonation of this copolymer has resulted in increased proton conductivity while maintaining its low methanol permeability. Therefore, it seems appropriate that blending this sulfonated copolymer with a second low-cost component, which can complement its low conductive nature, can result in PEMs with high selectivity. Use of partially sulfonated polyaniline, as the second component, produced selectivity ratio of 5.85 × 105 Ss cm−3, ion-exchange capacity of 0.71 meq g−1, and current density of 90.5 mA cm−2 at +0.2 V and 60 °C and corresponding maximum power density of 18.5 mW cm−2.

At present, water pollution and demand for clean energy are most pressing global issues. On a daily basis, huge quantity of organic wastes gets released into the water ecosystems, causing health related problems. The need-of-the-hour is to utilize proficient and cheaper techniques for complete removal of harmful organic contaminants from water. In this regard, microbial fuel cell (MFC) has emerged as a promising technique, which can produce useful electrical energy from organic wastes and decontaminate polluted water. Herein, we have systematically reviewed recently published results, observations and progress made on the applications of MFCs in degradation of organic contaminants, including organic synthetic dyes, agro pollutants, health care contaminants and other organics (such as phenols and their derivatives, polyhydrocarbons and caffeine). MFC-based hybrid technologies, including MFC-constructed wetland, MFC-photocatalysis, MFC-catalysis, MFC-Fenton process, etc., developed to obtain high removal efficiency and bioelectricity production simultaneously have been discussed. Further, this review assessed the influence of factors, such as nature of electrode catalysts, organic pollutants, electrolyte, microbes and operational conditions, on the performance of pristine and hybrid MFC reactors in terms of pollutant removal efficiency and power generation simultaneously. Moreover, the limitations and future research directions of MFCs for wastewater treatment have been discussed. Finally, a conclusive summary of the findings has been outlined.

Abstract Sodium salt of sulfonated styrene (SS) was polymerized in situ within the polymeric blend of PVdF- co -HFP/Nafion. The electrical efficiency of this cross-linked semi interpenetrating network membranes were evaluated for its potential application as a polymer electrolyte membrane in direct methanol fuel cell (DMFC). The characteristic aromatic peaks obtained in the FT-IR spectra confirmed the successful incorporation of SS within the polymeric blend. X-ray diffraction analyses were conducted to determine the presence of crystalline and amorphous domains within the structure of the blend membrane. Water uptake measurements at room temperature indicate that above a threshold value of 20 wt% of incorporated SS (S-20), water uptake of the semi-IPN membranes increases up to 24%, with an IEC value equal to Nafion, i.e. 0.8 meq g −1 . The maximum current density was recorded to be 120 mA cm −2 at 0.2 V, with a cell efficiency (power density) of 24 mW cm −2 at 60 °C. In addition, proton conductivity and methanol permeability test results indicate that the prepared membrane S-20 is comparable to that of Nafion-117 membrane.

Abstract Sulfonation of PVdF-co-HFP was conducted by treating the copolymer with chlorosulfonic acid. The efficiency of this sulfonated copolymer towards application as a polymer electrolyte membrane in direct methanol fuel cell (DMFC) was evaluated. For this purpose, we determined the thermal stability, water uptake, ion exchange capacity (IEC), methanol crossover, and proton conductivity of the prepared membranes as functions of duration and degree of sulfonation. The characteristic aromatic peaks obtained in the FT-IR spectra confirmed the successful sulfonation of PVdF-co-HFP. The effect of sulfonation on the semi-crystalline nature of pure PVdF-co-HFP was determined from XRD analysis. Water uptake results indicated that a sulfonation time of 7 h produced maximum water uptake value of about 20%, with a corresponding IEC and proton conductivity values of about 0.42 meq g−1 and 0.00375 S cm−1 respectively. The maximum current density was recorded to be 30 mA cm−2 at 0.2 V potential.