A review on green trend for oil extraction using subcritical water technology and biodiesel production

A review on recent biodiesel intensification process through cavitation and microwave reactors: Yield, energy, and economic analysis

The use of biodiesel as a reliable and green energy source has grown over the past few years. Biodiesel is sustainable and biodegradable because it is only made from vegetable contents and waste cooking oil. Although biodiesel has many advantages over conventional fuels, there are still a lot of technological issues that need to be addressed during the production process. The yield of biodiesel produced using conventional methods is poor and the process is time-consuming. Process enhancements like cavitation and microwave have thus been developed to address this problem. Starting with a comparison to the conventional biodiesel process, this paper has reviewed the most recent developments in the increase of mixture and transfer of heat in these two reactors. This paper examined biodiesel improvement using microwave and cavitation reactors, including biodiesel yield, by meticulously reviewing and analyzing previous works. The production of biodiesel from various raw materials using a range of catalysts, energy requirements, as well as operating factors, activation energy, and constraints also have been discussed. Additionally, the economic analysis discusses the feasibility and cost-effectiveness of implementing these technologies on a commercial scale. Overall, this review provides valuable insights into the intensification of biodiesel production using cavitation and microwave reactors while considering both the technical and economic aspects.

Preliminary Studies on the Purification of Bleaching Earth from Slack Wax Residues in the Adsorption Refining by Low-Temperature Pyrolysis Process

The essence of the low-temperature pyrolysis process presented below is the processing of contaminated bleaching earth, resulting in a purified bleaching earth, high calorific oil with an average level of 45.5 MJ / kg and synthesis gas that can be used to heat the reactor. For research purposes, a proprietary low-pressure reactor with a system of direct cooling of hydrocarbon vapors was used. The main advantages of the presented method are the limitation of technological processes to a minimum and the ease of automation by reducing the entire cycle to one device.

Binary Linear Programming as a Tool of Cost Optimization for a Water Supply Operator

The problem of scheduling pumps is widely discussed in the literature in the context of improving energy efficiency, production costs, emissions, and reliability. In some studies, the authors analyze the available case studies and compare the results; others present their own computational methods. In the paper, a problem of pump scheduling in regular everyday operations of a water supply operator is considered. The issues of water production optimization and energy savings are part of the topic of sustainable development. The objective of the article is the minimization of the cost of electric power used by the pumps supplying water. It is achieved thanks to the variability of both the demand for water and the price of electric power during the day combined with the possibility of storing water. The formulation of an existing electric power cost optimization problem as a binary linear programming problem was improved. An essential extension of the above mathematical model, which enables more flexible management of the pump system, was also proposed. An example containing real-world input data was successfully solved using Microsoft Excel with a free OpenSolver add-in.

Prospects and Challenges of Microwave-Combined Technology for Biodiesel and Biolubricant Production through a Transesterification: A Review

Biodiesels and biolubricants are synthetic esters produced mainly via a transesterification of other esters from bio-based resources, such as plant-based oils or animal fats. Microwave heating has been used to enhance transesterification reaction by converting an electrical energy into a radiation, becoming part of the internal energy acquired by reactant molecules. This method leads to major energy savings and reduces the reaction time by at least 60% compared to a conventional heating via conduction and convection. However, the application of microwave heating technology alone still suffers from non-homogeneous electromagnetic field distribution, thermally unstable rising temperatures, and insufficient depth of microwave penetration, which reduces the mass transfer efficiency. The strategy of integrating multiple technologies for biodiesel and biolubricant production has gained a great deal of interest in applied chemistry. This review presents an advanced transesterification process that combines microwave heating with other technologies, namely an acoustic cavitation, a vacuum, ionic solvent, and a supercritical/subcritical approach to solve the limitations of the stand-alone microwave-assisted transesterification. The combined technologies allow for the improvement in the overall product yield and energy efficiency. This review provides insights into the broader prospects of microwave heating in the production of bio-based products.

Sustainability Outcomes of Green Processes in Relation to Industry 4.0 in Manufacturing: Systematic Review

Green processes are very important for the implementation of green technologies in production to achieve positive sustainability outcomes in the Industry 4.0 era. The scope of the paper is to review how conventional green processes as a part of Industry 4.0 provide sustainability outcomes in manufacturing. The paper is based on the methodology of systematic literature review through the content analysis of literary resources. Twenty-nine studies were included in our content analysis. The results show the main focus of current literature related to Industry 4.0, sustainability outcomes and green processes. The authors present a conceptual Sustainability Green Industry 4.0 (SGI 4.0) framework that helps to structure and evaluate conventional green processes in relation to Industry 4.0 and sustainability. The study summarizes which technologies (big data, cyber-physical systems, Industrial Internet of Things and smart systems) and green processes (logistics, manufacturing and product design) are important for achieving a higher level of sustainability. The authors found that the most often common sustainability outcomes are energy saving, emission reduction, resource optimalization, cost reduction, productivity and efficiency and higher economic performance, human resources development, social welfare and workplace safety. The study suggests implications for practice, knowledge and future research.

Green and Sustainable Separation of Natural Products from Agro-Industrial Waste: Challenges, Potentialities, and Perspectives on Emerging Approaches

New generations of biorefinery combine innovative biomass waste resources from different origins, chemical extraction and/or synthesis of biomaterials, biofuels, and bioenergy via green and sustainable processes. From the very beginning, identifying and evaluating all potentially high value-added chemicals that could be removed from available renewable feedstocks requires robust, efficient, selective, reproducible, and benign analytical approaches. With this in mind, green and sustainable separation of natural products from agro-industrial waste is clearly attractive considering both socio-environmental and economic aspects. In this paper, the concepts of green and sustainable separation of natural products will be discussed, highlighting the main studies conducted on this topic over the last 10 years. The principal analytical techniques (such as solvent, microwave, ultrasound, and supercritical treatments), by-products (e.g., citrus, coffee, corn, and sugarcane waste) and target compounds (polyphenols, proteins, essential oils, etc.) will be presented, including the emerging green and sustainable separation approaches towards bioeconomy and circular economy contexts.

Kinetic and Thermodynamics studies for Castor Oil Extraction Using Subcritical Water Technology

In this work both kinetic and thermodynamics of castor oil extraction from its seeds using subcritical water technique were studied. It was found that the extraction process followed two consecutive steps. In these steps, the oil was firstly extracted from inside the powder by diffusion mechanism. Then the extracted oil, due to extending the extraction time under high temperature and pressure, was subjected to a decomposition reaction following first order mechanism. The experimental data correlated well with the irreversible consecutive unimolecular-type first order mechanism. The values of both oil extraction rate constants and decomposition rate constants were calculated through non-linear fitting using DataFit software. The extraction rate constants were found to be 0.0019, 0.024, 0.098, 0.1 and 0.117 min(-1), while the decomposition rate constants were 0.057, 0.059, 0.014, 0.019 and 0.17 min(-1) at extraction temperatures of 240, 250, 260, 270 and 280°C, respectively. The thermodynamic properties of the oil extraction process were investigated using Arrhenius equation. The values of the activation energy, Ea, and the frequency factor, A, were 73 kJ mol(-1) and 946, 002 min(-1), respectively. The physicochemical properties of the extracted castor oil including the specific gravity, viscosity, acid value, pH value and calorific value were found to be 0.947, 7.487, 1.094 mg KOH/g, 6.1, and 41.5 MJ/Kg, respectively. Gas chromatography analysis showed that ricinoleic acid (83.6%) appears as the predominant fatty acid in the extracted oil followed by oleic acid (5.5%) and linoleic acid (2.3%).