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Biodiesel (methyl esters) has been produced using numerous catalysts to enhance its quality and related productivity. Generally, the raw materials for biodiesel production and its catalysts significantly impact the produced biodiesel's quality. In addition, the heterogeneous catalysts are promising as catalysts in the transesterification for biodiesel production and can be used continuously during this production. In particular, these catalysts are essential for green biodiesel production because of their high activity, thermal stability, and reusability. Hence, several homogeneous and heterogeneous (acidic and alkaline) catalysts for biodiesel production, particularly the naturally derived heterogeneous catalysts, are reviewed in this article. Further, the different heterogeneous catalysts for biodiesel production have been studied extensively as replacements for the respective homogeneous catalyst. Specifically, this replacement is aimed at the simultaneous esterification and transesterification of the nonedible and low-cost biomasses under moderate conditions producing biodiesel. Moreover, this study analyzes biodiesel's impact and long-term performance in various applications. Finally, it also reports the advancements in biodiesel production in terms of the catalysts used in it and its processes to aid further developments in biodiesel production. [ABSTRACT FROM AUTHOR]

Fossil fuels are primary sources for energy production. Increased dependence on fossil fuels has resulted in increased environmental issues demanding alternative sources. Bioenergy is becoming a popular alternative energy source due to its positive environmental impact and the availability of renewable sources. However, the availability of renewable energy sources in the energy sector currently contributes to about 14%. Biofuels are preferred due to its sustainability, eco‐friendly approach, and low‐cost raw materials, making it an efficient technique for energy production. This article provides the fundamental and applied concepts for on conversion processes of biomass to biofuels, such as combustion, pyrolysis, fermentation, gasification, and anaerobic digestion along with their role in the green economy. Different physical characteristics of biomass resources are important and contribute to determining their potential for producing biofuels. Herein, LCA, its techno‐economic importance, and the role of biomass in green economy are explained. Varying compositions and properties of different types of biomass resources, including lignocellulosic feedstocks, agriculture and forest residue, municipal solid waste, food waste, and animal manure as potential biomass resources, have been discussed. The article explains the strengths and weaknesses of different thermochemical conversion techniques and their current input toward scalar applications and commercialization. [ABSTRACT FROM AUTHOR]

Introduction: In the present study, citrus pectin-stabilized copper/iron bimetallic nanoparticle (NP) catalyst has been used for the degradation of methylene blue (MB) dye in wastewater produced from the food industry. Methods: The P@Cu/Fe composites were synthesized by co-precipitation and the sol-gel methods. Results and discussion: The characterization of the composites was carried out using UV, FTIR, SEM, and XRD techniques, revealing that P1@Cu/FeNPs synthesized through co-precipitation had a particle size of 150-35 nm with an irregular spherical and hexagonal shape. P2@Cu/FeNPs, synthesized using the gel combustion method using triethylamine as fuel, proved to be a better nanocatalyst with spherical particles having a uniform structure and size distribution of 105-23 nm. The mean zeta potential value of P1@Cu/FeNPs was found to be between 0 and 5mv, showing the composite to be less stable and 13 mv for more stable P2@Cu/FeNPs. The degradation of MB by P1@Cu/FeNPs was recorded up to 23.57% after 35 min and the nanocomposite synthesized by the sol-gel method exhibited 97.28% degradation in 30 min. The P2@Cu/FeNPs performed the best degradation due to their synergistic impact. In essence, this research represents a step toward the synthesis of bimetallic NPs using a biomaterial (citrus pectin) with improved synergistic photocatalytic potential that can induce different features in nanomaterials. Pectin-functionalized NPs using different metals should be synthesized and tested for different catalytic applications. [ABSTRACT FROM AUTHOR]

Rapid growth in the global population and associated elevated reliance on modern technology has resulted in increased demand for energy consumption. This has resulted in an increased focus on the development and generation of advanced sustainable energy systems. The swift implementation of sustainable renewable energy resource utilization and improvement in their efficiency by the modification of current technologies are the possible solutions that gave rise to the emergence of geothermal technology as a potential alternative. Geothermal technology is a non-carbon renewable energy resource that could be utilized efficiently to fulfil the energy demands while mitigating the climate change threat. According to the surveyed literature, the global geothermal energy power plant installation capacity has reached 14.3 GWe to successfully implement this sustainable alternative. In order to have a successful and uninterrupted way forward, it is essential to evaluate the constraints both in terms of technicality and economic feasibility to establish an approved framework. Moreover, the governance and monitoring regarding the social and environmental impact alongside the legal challenges should also be addressed. The significant barriers include increased capital cost, site selection, superiority of resources at diverse levels of rock bottoms, and obstruction from nearby residents that need to be addressed appropriately. As a result, policymakers will continue to seek measure that have least negative impact on environment. [ABSTRACT FROM AUTHOR]

The occurrence of cellulose in wastewater is mostly due to the usage of lavatory tissue, anticipated to be about 30% of the produced domestic sewage. This makes the recovery of cellulosic substances from wastewater important as a resource valorization strategy. The cellulose recovery is highly recommended to be included in wastewater treatment plant (WWTPs), associated with the favorable environmental impression, flexible routes of application, and mature value chain. In the present review, a comprehensive map was drawn for the initial and transformational applications of cellulose in WWTPs. Typical microbial cultures found in wastewater, facilitating cellulose degradation in both aerobic and anaerobic cases were thoroughly reviewed. An outlook of commercialized technologies purposed for cellulose recovery has been provided, with prominence on rotating bed filter. The benefits of cellulose recovery from wastewater via various routes were also highlighted. [ABSTRACT FROM AUTHOR]

The use of biodiesel is a proactive measure that can be implemented to reduce emissions of greenhouse gases and other adverse environmental impacts. However, one of the major setbacks to biodiesel production is its relatively higher cost compared to petroleum diesel. The optimistic solution to this is valorization of biomasses like waste chicken fat (WCF) and clay for deriving non-edible oil and catalyst respectively. Herein, we report the synthesis of clay derived SiO2 catalyst impregnated with SrO, Bi2O3, CuO and CaO. The developed catalysts were characterized by FTIR, XRD, and SEM. XRD studies confirmed the successful impregnation of active metallic oxide on SiO2 support. Further, these catalysts were employed for biodiesel production from WCF, and SrO/SiO2 was found to be most effective and efficient catalyst for biodiesel production from WCF. Hence, SrO/SiO2 was adapted to optimize the different transesterification reaction parameters such as methanol to oil ratio, catalyst loading, reaction temperature and time. The optimized conditions for maximum biodiesel yield 98.9% were found to be 65 °C in 1 h with 12:1 methanol to oil ratio and 1 wt% catalyst loading. The biodiesel produced was also analyzed by GC-MS. The obtained biodiesel yield shows that clay can be a potential, and cost-effective, catalyst source to produce biodiesel from WCF. [ABSTRACT FROM AUTHOR]