Technical feasibility of biodiesel production from virgin oil and waste cooking oil: Comparison between traditional and innovative process based on hydrodynamic cavitation

Response surface optimization of a single-step castor oil-based biodiesel production process using a stator-rotor hydrodynamic cavitation reactor

In order to combat environmental pollution and the depletion of non-renewable fuels, feasible, eco-friendly, and sustainable biodiesel production from non-edible oil crops must be augmented. This study is the first to intensify biodiesel production from castor oil using a self-manufactured cylindrical stator-rotor hydrodynamic cavitation reactor. In order to model and optimize the biodiesel yield, a response surface methodology based on a 1/2 fraction-three-level face center composite design of three levels and five experimental factors was used. The predicted ideal operating parameters were found to be 52.51°C, 1164.8 rpm rotor speed, 27.43 min, 8.4:1 methanol-to-oil molar ratio, and 0.89% KOH concentration. That yielded 95.51% biodiesel with a 99% fatty acid methyl ester content. It recorded a relatively low energy consumption and high cavitation yield of 6.09 × 105 J and 12 × 10-3 g/J, respectively. The generated biodiesel and bio-/petro-diesel blends had good fuel qualities that were on par with global norms and commercially available Egyptian petro-diesel. The preliminary cost analysis assured the feasibility of the applied process.

Revealing the origins of vortex cavitation in a Venturi tube by high speed X-ray imaging

Hydrodynamic cavitation is useful in many processing applications, for example, in chemical reactors, water treatment and biochemical engineering. An important type of hydrodynamic cavitation that occurs in a Venturi tube is vortex cavitation known to cause luminescence whose intensity is closely related to the size and number of cavitation events. However, the mechanistic origins of bubbles constituting vortex cavitation remains unclear, although it has been concluded that the pressure fields generated by the cavitation collapse strongly depends on the bubble geometry. The common view is that vortex cavitation consists of numerous small spherical bubbles. In the present paper, aspects of vortex cavitation arising in a Venturi tube were visualized using high-speed X-ray imaging at SPring-8 and European XFEL. It was discovered that vortex cavitation in a Venturi tube consisted of angulated rather than spherical bubbles. The tangential velocity of the surface of vortex cavitation was assessed considering the Rankine vortex model.

Investigation of free fatty acid reduction from mixed crude palm oil using 3D-printed rotor-stator hydrodynamic cavitation: An experimental study of geometric characteristics of the inner hole

A continuous esterification process is employed to decrease the free fatty acid (FFA) concentration of FFA-rich mixed crude palm oil. Both optimal and recommended conditions are determined for the esterification reaction conditions and the geometry of the 3D-printed rotor design in the rotor-stator hydrodynamic cavitation reactor. This study is primarily concerned with the effect of the cavitation device configuration, especially the rotor design, on FFA reduction. Instead of conventional spherical or cylindrical drilled holes, a point angle cone-shaped hole is used to create cavities over the rotor surface. These point angles are adjusted to clarify their effect on FFA reduction. The response surface methodology is applied to determine the optimal concentrations of methanol and sulfuric acid, rotor speed, hole diameter and depth, and cone point angle. The recommended conditions are 20.8 wt% methanol, 2.6 wt% sulfuric acid, 3000 rpm, 5 mm hole diameter, 5 mm hole depth, and 110°, respectively. Under this configuration, the FFA content is reduced from 12.014 wt% to around 1 wt%. A maximum yield of 97.34 vol% esterified oil is obtained through a completed phase separation step, and 93.31 vol% pure oil is collected after the cleansing step. The recommended conditions result in reduced chemical usage, cheaper FFA reduction, and lower environmental impact. This creative rotor design effectively improves our understanding of the geometry of the cavitation device, thus enhancing the cavitation effect in industrial operations.

Preparation, Characterization, and Evaluation of Emission and Performance Characteristics of Thumba Methyl Ester (Biodiesel)

Thumba oil with a higher triglyceride content can be a promising feed for synthesizing a fatty acid alkyl ester as an alternative to pure diesel. The current study investigates the emission and performance characteristics of thumba methyl ester (TME) in compression ignition (CI) engines corresponding to variable loads and compression ratios (CRs), respectively. TME was prepared at an optimized pressure of 5 bar by hydrodynamic cavitation. The properties of TME-diesel blends with varied volume percentages of biodiesel, such as 5, 10, 15, 20, and 25, denoted B5, B10, B15, B20, and B25, respectively, were compared to pure TME (100% biodiesel) and pure diesel (100%). The B20 biodiesel blend has been observed as the optimal one based on the lower emission composition and higher brake thermal efficiency. For B20 fuel, injection at 23° before the top dead center (TDC) and a CR of 18 resulted in the lowest brake specific fuel consumption of 0.32 kg/kW h and a maximum brake thermal efficiency of 36.5%. Using titanium dioxide nanoparticles in the pre-stage of TME manufacturing has ultimately reduced the nitrogen oxide, hydrocarbon, and carbon monoxide emissions. At a CR of 18 and advanced injection 23° before TDC for a CI engine, TME derived from thumba oil has the potential to be a viable diesel substitute.

Life cycle assessment of biodiesel production by using impregnated magnetic biochar derived from waste palm kernel shell

Biodiesel is renewable, biodegradable, biocompatible (non-toxic) and environmentally friendly, which emits less pollution than traditional fossil-based diesel, making it the most promising and ideal option. However, biodiesel is facing many current issues, mostly related to the utilisation of homogeneous catalytic technology, and this circumstance obstructs its potential development and advancement. Therefore, new pathways for biodiesel production need to be explored, and the aforementioned issues need to be addressed. Recently, a study was conducted on the impregnated magnetic biochar derived from a waste palm kernel shell (PKS) catalyst that can replace conventional catalysts due to its reusability property. Nevertheless, the environmental impacts of impregnated magnetic biochar derived from waste PKS catalyst for biodiesel production are yet to be studied. This study focuses on the evaluation of the life cycle assessment (LCA) of palm-based cooking oil for biodiesel production catalysed by impregnated magnetic biochar derived from waste PKS. Simapro was used in this study to evaluate the impact assessment methodologies. Case 1 (6.64 × 10² Pt) has contributed less to environmental impacts than Case 2 (1.83 × 10³ Pt). This indicates purchasing refined palm oil for biodiesel production may reduce environmental impacts by 64% compared to producing biodiesel from raw fruit bunches. In the midpoint assessment, the transesterification process was identified as the hotspot and marine aquatic ecotoxicity as the highest impact category with a value of 1.00 × 10⁶ kg 1,4-DB eq for 1 tonne of biodiesel produced. The endpoint results showed that Case 1 revealed the greatest impact on the transesterification process, with cumulative damage of 461 Pt. Scenario without processing the raw palm fruit bunches to obtained palm oil was better than Case 2. Further research should be conducted on life cycle cost and sensitivity analysis to evaluate the economic feasibility and promote sustainable biodiesel production.

Parametric study of glycerol and contaminants removal from biodiesel through solvent-aided crystallization

At present, biodiesel is known as an alternative fuel globally. It is also known that the purification of biodiesel before consumption is mandatory to comply with international standards. Commonly, purification using water washing generates a massive amount of wastewater with a high content of organic compounds that can harm the environment. Therefore, this study applied and tested a waterless method, i.e., the solvent-aided crystallization (SAC), to remove glycerol and other traces of impurities in the crude biodiesel. The parameters of coolant temperature, crystallization time, and stirring rate on the SAC system were investigated. It was discovered that with 14 °C coolant temperature, 300 RPM and higher cooling time result in the highest percentage of FAME up to 99.54%, which indicates that contaminants' presence is limited in the purified biodiesel. The use of 1-butanol as the solvent for crystallization process remarkably enhanced the separation and improved the higher biodiesel quality.