Two-stage continuous production process for fatty acid methyl ester from high FFA crude palm oil using rotor-stator hydrocavitation

Effect of the arrangement of cavitation generation unit on the performance of an advanced rotational hydrodynamic cavitation reactor

Hydrodynamic cavitation (HC) is widely considered a promising process intensification technology. The novel advanced rotational hydrodynamic cavitation reactors (ARHCRs), with considerably higher performance compared with traditional devices, have gained increasing attention of academic and industrial communities. The cavitation generation unit (CGU), located on the rotor and/or stator of an ARHCR, is utilized to generate cavitation and consequently, its geometrical structure is vital for the performance. The present work studied, for the first time, the effect of the arrangement of CGU on the performance of a representative ARHCR by employing computational fluid dynamics based on the "simplified flow field" strategy. The effect of CGU arrangement, which was neglected in the past, was evaluated: radial offset distance (c), intersection angle (ω), number of rows (N), circumferential offset angle (γ), and radial spacing (r). The results indicate that the CGU, with an arrangement of a low ω and moderate c, N, γ, and r, performed the highest cavitation efficiency. The corresponding reasons were analyzed by combining the flow field and cavitation pattern. Moreover, the results also exposed a weakness of the "simplified flow field" strategy which may induce the unfavorable "sidewall effect" and cause false high-pressure region. The findings of this work may provide a reference value to the design of ARHCRs.

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.

Hydrodynamic cavitation-assisted preparation of porous carbon from garlic peels for supercapacitors

Hydrodynamic cavitation (HC), which can effectively induce sonochemical effects, is widely considered a promising process intensification technology. In the present study, HC was successfully utilized to intensify the alkali activation of GPs for SCs, for the first time. Five BDCMs were synthesized following the method reported in the literature. For comparison, four more BDCMs with HC-treated, among which a sample was further doped with nitrogen during the HC treatment, were prepared. Then all the samples were compared from microscopical characteristics to electrochemical performance as SCs materials. The morphology study demonstrated that the HC treatment had created many defects and amorphous carbon structures on the GP-based BDCMs, with the highest SSA reaching 3272 m²/g (1:6-HCGP), which 32 folded that of the Raw carbon sample's. The HC treatment also intensified the N-doping process. XRD and XPS results manifested that the N content had been increased and consequently changed the electronic structure of the carbon atoms, leading to the increase of specific capacitance (1:6-HCGP+N-based SC, 227 F/g at 10 A/g). The cycle performance proved that the GP-based BDCMs have long-term stability, indicating that the HC-treated BDCMs were good choices for energy storage technologies. Compared with the ultrasound-assisted method, which may have a high energy density, the HC-assisted method enables high production and energy efficiency. This work is a first time attempt towards the industrial application of HC method in energy-related materials synthesis and encourages more in-depth studies in the future.

Effects of static mixers on continuous methyl ester production: comparing four types of 3D-printed mixing elements

Four types of 3D-printed static mixer were employed in the continuous transesterification process to examine the pressure drop and mixing intensity. Methanol, KOH, and mixer length were also optimized using RSM to obtain the highest biodiesel purity.

Continuous Double-Step Esterification Production of Palm Fatty Acid Distillate Methyl Ester Using Ultrasonic Tubular Reactor

Double-step esterification to produce biodiesel from palm fatty acid distillate (PFAD) was performed by utilizing an ultrasound clamp reactor. Six pairs of ultrasonic clamps were attached to the left and right sides of the stainless-steel tube, and each pair was separated 100 mm apart from each other. Therefore, a total of 12 units of ultrasound clamps distributed 4800 W maximum power (12 × 400 W) throughout the continuous reactor by an ultrasonic generator. To optimize each step of the continuous esterification process for producing methyl ester from PFAD, a response surface methodology was used. The final 93.32 wt % methyl ester purity was attained under a double-step esterification process. For the first step, a 3.75:1 molar ratio of methanol to PFAD (46.4 vol % methanol), 6.6 vol % sulfuric acid, and 400 mm length of ultrasound clamp at 25 L/h PFAD flow rate for converting the PFAD to 60.24 wt % methyl ester were recommended. For the second step, the esterification was repeated under a molar ratio of methanol to the first esterified oil of 2.87:1 (61.6 vol % methanol), 5.6 vol % of sulfuric acid, and 400 mm length of ultrasound clamp at 25 L/h esterified oil flow rate. The ultrasonic clamp reactor achieved high yields of esterified oil and the crude biodiesel in a relatively short residence period of 32 s. To determine the product yields of a double-step esterification process, the maximum yields were 103.9 wt % first esterified oil, 107.6% crude biodiesel, and 98 wt % purified biodiesel when calculated on the basis of 100 vol % initial PFAD. The average energy consumed in the production of double-step esterification biodiesel was 0.05796 kWh/L. Therefore, this current approach has a high potential for producing biodiesel with less energy and requires less time to convert the PFAD to a high purity of methyl ester.

Continuous production of nanoemulsion for skincare product using a 3D-printed rotor-stator hydrodynamic cavitation reactor

In this study, nanoemulsions for skincare products were continuously produced using a hydrodynamic cavitation reactor (HCR) designed with a rotor and stator. The key component of this research is the utilization of a 3D-printed rotor in a HCR for the production of an oil-in-water nanoemulsion. Response surface methodology was used to determine the process conditions, such as speed of the rotor, flow rate, as well as, Span60, Tween60, and mineral oil concentrations, for generating the optimal droplet size in the nanoemulsion. The results showed that a droplet size of 366.4 nm was achieved under the recommended conditions of rotor speed of 3500 rpm, flow rate of 3.3 L/h, Span60 concentration of 2.36 wt%, Tween60 concentration of 3.00 wt%, and mineral oil concentration of 1.76 wt%. Moreover, the important characteristics for consideration in skincare products, such as polydispersity index, pH, zeta potential, viscosity, stability, and niacin released from formulations, were also assessed. For the niacin release profile of emulsion and nanoemulsion formulations, different methods, such as magnetic stirring, ultrasound, and hydrodynamic cavitation, were compared. The nanoemulsion formulations provided a greater cumulative release from the formulation than the emulsion. Particularly, the nanoemulsion generated using the HCR provided the largest cumulative release from the formulation after 12 h. Therefore, the present study suggests that nanoemulsions can be created by means of hydrodynamic cavitation, which reduces the droplet size, as compared to that generated using other techniques. The satisfactory results of this study indicate that the rotor-stator-type HCR is a potentially cost-effective technology for nanoemulsion production.

Optimization of Continuous FAME Production in High-Performance Bumpy Surface Rotor Reactor under Theoretical Molar Ratio by Response Surface Methodology

The continuous production of fatty acid methyl ester (FAME) from waste cooking oil (WCO) via transesterification was carried out under theoretical methanol to oil molar ratio using a high-performance bumpy surface rotor reactor (BSRR). Three types of rotors with different area fractions (A_F) of 6.9%, 13.8% and 27.6% were used to equip the BSRR. The selection of the highest performance rotor was compared by factorial experiments. Absolute methanol with 99.9 vol% purity was used as the reactant and potassium hydroxide with 90 wt% purity was used as the base catalyst. Response surface methodology (RSM) was applied to design the experiments and predict the optimal conditions. The three variables in RSM were 0.58-1.43 wt% potassium hydroxide concentration [KOH], 2160-3840 rpm rotor speed, and 1.38-4.74 L/min flow rate. The performance was the specific energy consumption (SEC). The highest performance rotor was A_F27.6%. In the first step, the transesterification process was performed using [KOH] 1.5 wt%, a rotor speed of 3000 rpm and a flow rate of 2.027 L/min to produce 98.6 wt% FAME and using SEC at 12.5 W h/kg. In the second step, RSM predicted the optimal condition of [KOH] 1.016 wt%, rotor speed 2910 rpm, flow rate 2.134 L/min and FAME content 97.3 wt%. The actual FAME content averaged 97.16 wt%. The biodiesel properties complied with the EN 14214 standard. This biodiesel production can reduce the cost of methanol by one-half and the cost of KOH by one-third. The energy consumption is only 0.012 kW・h/kg, so the methanol recovery process is not necessary. It has low KOH residue, so washing with water is superfluous and uses minimal energy, which can reduce a lot of costs. The high flow rate of 128 L/h can be used to scale up commercial production.