Extraction of lipids and production of biodiesel from secondary tannery sludge by in situ transesterification

Alternative Methods for Biodiesel Cetane Number Valuation: A Technical Note

Biodiesel is an environmentally beneficial and clean energy source that may replace fossil fuels, which are detrimental to the environment and cannot be replenished. Therefore, the physicochemical parameters of biodiesel must be determined in order to verify its quality. The cetane number is a crucial dimensionless fuel property that gauges the fuel ignition quality in power diesel engines. A higher cetane number results in a shorter ignition delay time, and vice versa. Biodiesel's cetane number may fluctuate due to a variety of fatty acid compositions, including variations in carbon chain length and the degree of unsaturation. The cetane number generally increases with increasing saturation and chain length, while it decreases as chain length is reduced and degrees of unsaturation and branching increase. This is the main reason for why alkanes possess a higher cetane number than alkenes and aromatics. The standard protocols for evaluating the cetane number of biodiesel are ASTM D613 and ISO 5165 test techniques using a monocylindrical cetane engine. However, adhering to these conventional procedures is quite challenging and time-consuming, and the cetane number test result may also be affected by the presence of certain gases and fumes. As a result, many researchers are bothered with cetane number valuation, and occasionally they skip it due to a lack of other options. Consequently, the aim of this paper is to present a set of more straightforward and relevant alternative techniques that can be applied to predict the cetane number of biodiesel when engine-based measurement is not practical. The three techniques with their designed pictographic outlooks conferred in this article include color indicator titration, aniline point, and fatty acid composition-based methods. The reported values of these procedures meet the minimum cut point of the biodiesel cetane number required by ASTM D6751 (≥47) and exhibit minimal variation from the typical standard methods. Nevertheless, the above-mentioned techniques are not applicable to other alternative biofuels except biodiesel products because they have a direct implication on the characteristics of the fatty acid profiles of different oil precursors, such as carbon chain length, degree of saturation or unsaturation, and aromaticity, which make up monoalkyl esters.

Promoting sustainable management of hazardous waste-to-wealth practices: An innovative integrated DPSIR and decision-making framework

Sustainable valorization of tannery sludge (TS) is vital for achieving several sustainable development goals (SDGs) in the tannery industry. TS is considered a hazardous waste by-product posing a significant environmental challenge. However, TS can be utilized for energy or resource recovery by considering it as biomass and implementing the circular economy (CE) concept. Therefore, this study aims to develop an innovative DPSIR (Driver, Pressure, State, Impact, and Response) framework for promoting sustainable valorization of TS. Further, the study extends to quantify the importance of subjective DPSIR factors by offering interval-valued intuitionistic fuzzy number-based best worst method (IVIFN-BWM), which is relatively new in the literature and able to deal with the uncertainty, inconsistency, imprecise, and vagueness in the decision-making process. The study also investigates the most appropriate TS valorization technologies concerning identified DPSIR factors using a novel IVIFN-combined compromise solution (CoCoSo) approach. This research contributes to the literature by developing a comprehensive solution approach that combines the DPSIR framework, IVIFN-BWM, and IVIFN-CoCoSo method in addressing sustainability and resource recovery challenges for the tannery industry. The research findings highlight the potential of sustainable valorization of TS in reducing the waste amount and promoting sustainability and CE practices in the tannery industry. The findings indicated that response factors 'creation of national-level policies and awareness campaign' and 'facilitating financial support to adopt waste valorization technologies' received the highest priority among other DPSIR factors for managing and fostering sustainable valorization of TS. The IVIFN-CoCoSo analysis confirmed that the most promising TS valorization technology is 'gasification', which is followed by pyrolysis, anaerobic digestion, and incineration. The study's implications extend to policymakers, industrial practitioners, and researchers, who can leverage the research findings to develop more sustainable TS management practices in the tannery industry.

Assessment of thermokinetic behaviour of tannery sludge in slow pyrolysis process through artificial neural network

In the leather industry, tannery sludge is produced in large volume. This study investigated the thermal degradation behavior of tannery sludge using thermogravimetric analysis (TGA). The experiments were carried out in an inert atmosphere using nitrogen gas at varied heating rates of 5, 10, 20, and 40 °C/min in the temperature range of 30-900 °C. For the kinetic parameters calculation, three different models, Friedman, Kissinger-Akahira-Sunose (KAS) and the Ozawa-Flynn-Wall (OFW), were employed. The average activation energy E_a obtained from Friedman method, KAS, and the OFW were 130.9 kJ mol^-1, 143.14 kJ mol^-1, and 147.19 kJ mol^-1 respectively. Along with that experiment of pyrolysis was accomplished in fixed bed reactor at temperature of 400 °C. Biochar produced has a yield of about 71%. The analysis of gas chromatography-mass spectroscopy shows the different chemical compounds present in the bio-oil containing hydrocarbons (alkanes and alkenes), oxygen containing compounds (alcohols, aldehyde, ketones, esters carboxylic acids and the esters) and the nitrogen containing compounds. The kinetic assessment was complemented by frequency distribution of activation energy model (DAEM). In the pyrolysis of tannery sludge six pseudo-components were found to be involved. Furthermore, artificial neural network (ANN) was used to predict the activation energy from conversion, temperature, and the heating rate data. MLP-3-11-1 described well the conversion behavior of tannery sludge pyrolysis.

Microbial Degradation and Value Addition to Food and Agriculture Waste

Food and agriculture waste (FAW) is a serious problem that is increasing globally. Wastage of raw materials or processed food due to various man-made activities is huge. This solid waste which is either being discarded by humans in their daily activities or an obligatory residue of agricultural processes is severely harming our environment. This becomes a major concern in densely populated agri-based countries, like India, China, and the USA. It is strongly debated that such issues need to be addressed very emphatically for sustainable development of ourselves and our surroundings. Lots of economic benefits can be obtained by reducing the food loss or converting the agricultural waste into useful products and these advantages can be in the form of better food security, reduced production cost, biodegradable products, and environment sustainability with cleaner options to reduce the ever-increasing global problem of garbage and waste management. Proper management of these substances can considerably lessen the risks to individual health. Reprocessing of waste is of great advantage as FAW has many components which may form an available resource to be converted to another useful product. Several approaches have been made for converting food waste into fruitful products. Bioconversion being the most prominent approach is helping us in a major way to overcome the problem of FAW. Microorganisms are at the forefront of this and have been extensively explored for their bioconversion potential. The present work focuses on the current state of food and agriculture waste and their valorization approaches. Through extensive literature review, we have highlighted and discussed the potential of microorganisms in bioconversion of waste, major types of functional ingredients derived during the process, and potential constraints in implementation of such state-of-the-art technology at industrial scale. The review also gives a brief technical overview of the conversion of waste products into energy generation and biofuels.

Recent advances in valorization of organic municipal waste into energy using biorefinery approach, environment and economic analysis

Researcher's all around works on a copious technique to lessen waste production and superintend the waste management for long-term socio-economic and environmental benefits. Value-added products can be produced from municipal waste by using holistic and integrated approaches. In this review, a detail about the superiority of the different methods like anaerobic digestion, biofuel production, incineration, pyrolysis and gasification were used for the conversion of municipal waste to feedstock for alternate energy and its economic- environmental impacts were consolidated. Most conversion techniques were environmentally friendly to manage municipal waste. The biological process was more economically feasible compare to the thermal process, for the reason thermal process required a large amount of capital investment and energy utilization. In the thermal process, gasification shows low emission, and pyrolysis shows low capital investment and economically feasible compare to other thermal processes. Waste to energy technology significantly reduced the emission and energy demand.

NaOH-Catalyzed Methanolysis Optimization of Biodiesel Synthesis from Desert Date Seed Kernel Oil

Biodiesel synthesis from non-edible vegetable oil via catalytic transesterification is one of the effective ways to replace petroleum-based fuels in the area of renewable energy development and is beneficial to environmental security. Therefore, this research investigates the optimization of process parameters (temperature, methanol to oil ratio, and NaOH catalyst dose) for the conversion of biodiesel from non-edible desert date (Balanites Aegyptiaca) seed kernel oil using the Box-Behnken experimental design of response surface methodology statistical analysis. Accordingly, the optimum values of reaction conditions, namely, a temperature of 60.5 °C, methanol to oil ratio of 6.7:1, and catalyst dose of 0.79 %wt, yielded 93.16% biodiesel. Fourier transform infrared spectroscopy analysis confirmed the cracking of a single glycerol backbone from the triglycerides and the substitution by methoxyl in the presence of a NaOH catalyst. The physicochemical properties of the biodiesel were investigated and compared with standards in terms of its density, viscosity, higher heating value, acid value, saponification value, cetane number, cloud point, pour point, and flash point, and the values are within the recommended standard limits of American Standard for Testing Material (ASTM D6751) and European Committee for Standardization (EN14214). Thus, the results revealed that homogeneous base catalysis of non-edible oil under optimum reaction conditions provides high yield of biodiesel.

Enhancement of biodiesel yield and characteristics through in-situ solvo-thermal co-transesterification of wet microalgae with spent coffee grounds

This study evaluated in-situ co-transesterification of wet spent coffee ground (SCG)/microalgae mixture for enhanced biodiesel production. SCG and microalgae showed lipid contents of 16.0 and 23.6 wt%, respectively. A total of 27 transesterification runs were performed using wet SCG:algae (1:1, w/w) at different temperatures, times, and solvent ratios. Box-Behnken quadratic model suggested 198 °C, 6 mL solvent g^-1 biomass, and reaction time of 132 min as the optimum conditions for maximum biodiesel yield. At different SCG/microalgae blend ratios, pure microalgae showed the highest biodiesel yield of 20.15 wt%. Increase of SCG ratio resulted in significant reduction in the biodiesel yield, reaching the lowest value of 11.2 wt% using pure SCG. On the other hand, SCG showed better biodiesel characteristics than microalgae regarding iodine value, cetane number, and oxidation stability. The present results confirmed that SCG-algae blend results in dual effect of enhancing biodiesel yield and quality, comparing to the individual transesterification.