• Energy Research

En raison de la demande croissante de stockage d'énergie électrochimique, divers nouveaux matériaux d'électrode et de catalyse pour les supercondensateurs et les batteries rechargeables se sont développés au cours de la dernière décennie. La structure et les caractéristiques de ces matériaux catalytiques ont un effet majeur sur les performances du dispositif. Afin de réduire les coûts associés aux systèmes électrochimiques, des matériaux de catalyse sans métal peuvent être utilisés. Dans cette étude, des catalyseurs sans métal composés de nanotubes de carbone à parois multiples doublement dopés à l'azote (N) et au soufre (S) ont été synthétisés à l'aide d'une méthode hydrothermale simple et rentable en une seule étape. Les nanotubes de carbone ont servi de source de carbone, tandis que l'acide aminé l-cystéine et la thiourée ont agi comme éléments dopants. À la suite de la caractérisation physico-chimique, de nombreux défauts et une structure poreuse ont été notés, ainsi que l'insertion réussie de l'azote et du soufre dans le nanotube de carbone a été confirmée. Selon les tests de voltamétrie cyclique pour les échantillons doublement dopés en conditions alcalines, le catalyseur D-CNT2 présentait des potentiels d'apparition de -0,30 V supérieurs aux -0,37 V observés pour le catalyseur D-CNT3. Cela indique une réaction de réduction de l'oxygène accrue en raison des effets synergiques des hétéroatomes dans la structure et de la présence de sites chimiquement actifs. De plus, la capacité spécifique exceptionnelle du catalyseur D-CNT2 (214,12 F g-1 à des vitesses de balayage de 1 mV s-1) reflète la porosité effective du catalyseur proposé. Ces résultats mettent en évidence le potentiel des nanotubes de carbone doublement dopés N/S pour les applications électrocatalytiques, contribuant à une conversion d'énergie efficace. Debido a la creciente demanda de almacenamiento de energía electroquímica, en la última década se han desarrollado varios electrodos y materiales de catálisis novedosos para supercondensadores y baterías recargables. La estructura y las características de estos materiales catalíticos tienen un efecto importante en el rendimiento del dispositivo. Con el fin de reducir los costos asociados con los sistemas electroquímicos, se pueden emplear materiales de catálisis libres de metales. En este estudio, se sintetizaron catalizadores sin metales compuestos de nanotubos de carbono de pared múltiple dopados con nitrógeno (N) y azufre (S) utilizando un método hidrotérmico de una sola etapa sencillo y rentable. Los nanotubos de carbono sirvieron como fuente de carbono, mientras que el aminoácido l-cisteína y la tiourea actuaron como elementos dopantes. Como resultado de la caracterización fisicoquímica, se observaron muchos defectos y una estructura porosa, junto con la confirmación de la inserción exitosa de nitrógeno y azufre en el nanotubo de carbono. De acuerdo con las pruebas de voltametría cíclica para las muestras dopadas doblemente en condiciones alcalinas, el catalizador D-CNT2 exhibió potenciales de inicio de -0.30 V más altos que los -0.37 V observados para el catalizador D-CNT3. Esto indica una reacción de reducción de oxígeno mejorada debido a los efectos sinérgicos de los heteroátomos en la estructura y la presencia de sitios químicamente activos. Además, la capacitancia específica sobresaliente del catalizador D-CNT2 (214.12 F g-1 a velocidades de barrido de 1 mV s-1) refleja la porosidad efectiva del catalizador propuesto. Estos hallazgos destacan el potencial de los nanotubos de carbono doblemente dopados con N/S para aplicaciones electrocatalíticas, lo que contribuye a una conversión de energía eficiente. Due to the increasing demand for electrochemical energy storage, various novel electrode and catalysis materials for supercapacitors and rechargeable batteries have developed over the last decade. The structure and characteristics of these catalyst materials have a major effect on the device's performance. In order to lower the costs associated with electrochemical systems, electrochemical systems, metal-free catalysis materials can be employed. In this study, metal-free catalysts composed of nitrogen (N) and sulfur (S) dual-doped multi-walled carbon nanotubes were synthesized using a straightforward and cost-effective single-step hydrothermal method. Carbon nanotubes served as the carbon source, while l-cysteine amino acid and thiourea acted as doping elements. As a result of the physicochemical characterization, many defects and a porous structure were noted, along with the successful insertion of nitrogen and sulfur into the carbon nanotube was confirmed. According to the cyclic voltammetry tests for the dual-doped samples in alkaline conditions, the D-CNT2 catalyst exhibited onset potentials of -0.30 V higher than the -0.37 V observed for the D-CNT3 catalyst. This indicates enhanced oxygen–reduction reaction due to the synergistic effects of the heteroatoms in the structure and the presence of chemically active sites. Moreover, the outstanding specific capacitance of the D-CNT2 catalyst (214.12 F g-1 at scanning rates of 1 mV s-1) reflects the effective porosity of the proposed catalyst. These findings highlight the potential of N/S dual–doped carbon nanotubes for electrocatalytic applications, contributing to efficient energy conversion. نظرًا للطلب المتزايد على تخزين الطاقة الكهروكيميائية، تم تطوير العديد من مواد الإلكترود والحفز الجديدة للمكثفات الفائقة والبطاريات القابلة لإعادة الشحن على مدى العقد الماضي. لهيكل وخصائص هذه المواد الحفازة تأثير كبير على أداء الجهاز. من أجل خفض التكاليف المرتبطة بالأنظمة الكهروكيميائية، يمكن استخدام الأنظمة الكهروكيميائية ومواد الحفز الخالية من المعادن. في هذه الدراسة، تم تصنيع المحفزات الخالية من المعادن المكونة من النيتروجين (N) والكبريت (S) الأنابيب النانوية الكربونية متعددة الجدران ذات الإشابة المزدوجة باستخدام طريقة حرارية مائية مباشرة وفعالة من حيث التكلفة. كانت الأنابيب النانوية الكربونية بمثابة مصدر الكربون، في حين كان الحمض الأميني للسيستين والثيوريا بمثابة عناصر منشطات. نتيجة للتوصيف الفيزيائي الكيميائي، لوحظت العديد من العيوب والبنية المسامية، جنبًا إلى جنب مع الإدخال الناجح للنيتروجين والكبريت في الأنبوب النانوي الكربوني. وفقًا لاختبارات قياس الفولتية الدورية للعينات ثنائية المنشطات في الظروف القلوية، أظهر محفز D - CNT2 إمكانات بدء تبلغ -0.30 فولت أعلى من -0.37 فولت الملحوظة لمحفز D - CNT3. يشير هذا إلى تفاعل تقليل الأكسجين المعزز بسبب التأثيرات التآزرية للذرات غير المتجانسة في الهيكل ووجود مواقع نشطة كيميائيًا. علاوة على ذلك، تعكس السعة النوعية المتميزة للمحفز D - CNT2 (214.12 فهرنهايت ز-1 بمعدلات مسح تبلغ 1 مللي فولط ثانية-1) المسامية الفعالة للمحفز المقترح. تسلط هذه النتائج الضوء على إمكانات الأنابيب النانوية الكربونية ثنائية الإشابة N/S للتطبيقات الحفازة الكهربائية، مما يساهم في تحويل الطاقة بكفاءة.

The biosolids accumulation and biodegradation of domestic wastewater treatment plant (DWTP) sludge by filamentous fungi have been investigated in a batch fermenter. The filamentous fungi Aspergillus niger and Penicillium corylophilum isolated from wastewater and DWTP sludge was used to evaluate the treatment performance. The optimized mixed inoculum (A. niger and P. corylophilum) and developed process conditions (co-substrate and its concentration, temperature, initial pH, inoculum size, and aeration and agitation rate) were incorporated to accelerate the DWTP sludge treatment process. The results showed that microbial treatment of higher strength of DWTP sludge (4% w/w of TSS) was highly influenced by the liquid state bioconversion (LSB) process. In developed bioconversion processes, 93.8 g/kg of biosolids was enriched with fungal biomass protein of 30 g/kg. Enrichment of nutrients such as nitrogen (N), phosphorous (P), potassium (K) in biosolids was recorded in 6.2% (w/w), 3.1% (w/w) and 0.15% (w/w) from its initial values of 4.8% (w/w), 2.0% (w/w) and 0.08% (w/w) respectively after 10 days of fungal treatment. The biodegradation results revealed that 98.8% of TSS, 98.2% of TDS, 97.3% of turbidity, 80.2% of soluble protein, 98.8% of reducing sugar and 92.7% of COD in treated DWTP sludge supernatant were removed after 8 days of microbial treatment. The specific resistance to filtration (SRF) in treated sludge (1.4x10(12) m/kg) was decreased tremendously by the microbial treatment of DWTP sludge after 6 days of fermentation compared to untreated sample (85x10(12) m/kg).

AbstractThe present generation of nutrient rich waste streams within the food and hospitality industry is inevitable and remained a matter of concern to stakeholders. Three white rot fungal strains were cultivated under submerged state bioconversion (SmB). Fermentable sugar conversion efficiency, biomass production and substrate utilization constant were indicators used to measure the success of the process. The substrates – banana peel (Bp), pineapple peel (PAp) and papaya peel (Pp) were prepared in wet and dried forms as substrates. Phanerochaete chrysosporium (P. chrysosporium), Panus tigrinus M609RQY, and RO209RQY were cultivated on sole fruit wastes and their composites. All fungal strains produced profound biomass on dry sole wet substrates, but wet composite substrates gave improved results. P. tigrinus RO209RQY was the most efficient in sugar conversion (99.6%) on sole substrates while P. tigrinus M609RQY was efficient on composite substrates. Elevated substrate utilization constant (Ku) and biomass production heralded wet composite substrates. P. chrysosporium was the most performing fungal strain for biomass production, while PApBp was the best composite substrate.

A laboratory-scale study of bioconversion of local lignocellulosic material, oil palm biomass (OPB) was conducted by evaluating the enzyme production through microbial treatment in solid state bioconversion (SSB). OPB in the form of empty fruit bunches (EFB) was used as a solid substrate and treated with the white-rot fungus, Phanerochaete chrysosporium, to produce ligninase. The results showed that the highest ligninase activity of 400.27 U/liter was obtained at day 12 of fermentation. While the optimum study indicated the enzyme production of 1472.8 U/liter with moisture content of 50%, 578.7 U/liter with 10% v/w of inoculum size, and 721.8 U/liter with co-substrate concentration of 1% (w/w) at days 9, 9 and 12 of fungal treatment, respectively. The parameters glucosamine and reducing sugar were observed to evaluate the growth and substrate utilization in the experiment.

Cellulase production was carried out by solid state bioconversion (SSB) method using rice straw, a lignocellulosic material and agricultural waste, as the substrate of three Trichoderma spp. and Phanerochaete chrysosporium in lab-scale experiments. The results were compared to select the best fungi among them for the production of cellulase. Phanerochaete chrysosporium was found to be the best among these species of fungi, which produced the highest cellulase enzyme of 1.43 IU/mL of filter paper activity (FPase) and 2.40 IU/mL of carboxymethylcellulose activity (CMCase). The "glucosamine" and "reducing sugar" parameters were observed to evaluate the growth and substrate utilization in the experiments. In the case of Phanerochaete Chrysosporium, the highest glucosamine concentration was 1.60 g/L and a high concentration of the release of reducing sugar was measured as 2.58 g/L obtained on the 4th day of fermentation. The pH values were also recorded. The range of the pH was about 5.15 to 5.56 in the case of Phanerochaete Chrysosporium.

Soil acidity is a major problem of agriculture in many parts of the world. Soil acidity causes multiple problems such as nutrient deficiency, elemental toxicity and adverse effects on biological characteristics of soil, resulting in decreased crop yields and productivity. Although a number of conventional strategies including liming and use of organic and inorganic fertilizers are suggested for managing soil acidity but cost-effective and sustainable amendments are not available to address this problem. Currently, there is increasing interest in using biochar, a form of biomass derived pyrogenic carbon, for managing acidity while improving soil health and fertility. However, biochar varies in properties due to the use of wide diversity of biomass, variable production conditions and, therefore, its application to different soils can result in positive, neutral and or negative effects requiring an in-depth understanding of biochar-acid soil interactions to achieve the best possible outcomes. Here, we present a comprehensive synthesis of the current literature on soil acidity management using biochar. Synthesis of literature showed that biochars, enriched with minerals (i.e., usually produced at higher temperatures), are the most effective at increasing soil pH, basic cation retention and promoting plant growth and yield. Moreover, the mechanism of soil acidity amelioration with biochar amendments varies biochar types, i.e., high temperature biochars with liming effects and low temperature biochars with proton consumption on their functional groups. We also provide the mechanistic interactions between biochar, plant and soils. Altogether, this comprehensive review will provide guidelines to agricultural practitioners on the selection of suitable biochar for the reclamation of soil acidity.

Production of biogas is based on anaerobic digestion of different renewable raw materials including human, animal, agricultural, industrial, and municipal wastes. In addition to methane content, biogas contains carbon dioxide along with water vapor, hydrogen sulfide, ammonia, and depending on the raw materials siloxane can be present. Thus, different purification and upgrading strategies are necessary in order to enhance the methane content; this review presents some of the upgrading technologies for practical removal of major contaminants in biogas. Recent development in membrane technology with high selectivity and permeability could serve as a boost in search for the most efficient biogas upgrading process capable of meeting the requirements for its use in vehicle fuel as well as incorporation in the natural gas grid. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1512–1520, 2015

Abstract In recent years, biodiesel has attracted significant attention from researchers, governments, and industries as a renewable, biodegradable, and non-toxic fuel. However, several feedstocks have been proven impractical or infeasible because of their extremely high cost due to their usage primarily as food resources. Waste cooking oil (WCO) is considered the most promising biodiesel feedstock despite its drawbacks, such as its high free fatty acid (FFA) and water contents. This review paper provides a comprehensive overview of the pre-treatment and the usage of WCO for the production of biodiesel using several methods, different types of reactors, and various types and amounts of alcohol and catalysts. The most common process in the production of biodiesel is transesterification, and using a methanol–ethanol mixture will combine the advantages of both alcohols in biodiesel production. In addition, this paper highlights the purification and analysis of the produced biodiesel, operating parameters that highly affect the biodiesel yield, and several economic studies. This review suggests that WCO is a promising feedstock in biodiesel production.

The purpose of this study was to evaluate the feasibility of producing bioethanol from palm-oil mill effluent generated by the oil-palm industries through direct bioconversion process. The bioethanol production was carried out through the treatment of compatible mixed cultures such as Thrichoderma harzianum, Phanerochaete chrysosporium, Mucor hiemalis, and yeast, Saccharomyces cerevisiae. Simultaneous inoculation of T. harzianum and S. cerevisiae was found to be the mixed culture that yielded the highest ethanol production (4% v/v or 31.6 g/l). Statistical optimization was carried out to determine the operating conditions of the stirred-tank bioreactor for maximum bioethanol production by a two-level fractional factorial design with a single central point. The factors involved were oxygen saturation level (pO(2)%), temperature, and pH. A polynomial regression model was developed using the experimental data including the linear, quadratic, and interaction effects. Statistical analysis showed that the maximum ethanol production of 4.6% (v/v) or 36.3 g/l was achieved at a temperature of 32 degrees C, pH of 6, and pO(2) of 30%. The results of the model validation test under the developed optimum process conditions indicated that the maximum production was increased from 4.6% (v/v) to 6.5% (v/v) or 51.3 g/l with 89.1% chemical-oxygen-demand removal.