Valorization of Poultry Waste Oils Recovered from Water Treatment Through the Degumming–Transesterification Process to Produce Biodiesel

Abstract

The growing demand for chicken meat products has increased the amount of wastewater associated with their production; their treatment has increased the generation of sludge and oils trapped in the trap process treatment. This work presents a process for the valorization of this residual oil recovered through the production of biodiesel. An oil degumming process was applied, and the quality of the treated oil was evaluated. This was transesterified with alkaline conditions and a homogeneous catalyst (KOH); a 3^k experimental design was applied with two factors: the temperature at 50, 60, and 70 °C and the molar ratios of 5, 6, and 7 moles of methanol per mole of recovered chicken oil. The biodiesel quality parameters were evaluated based on the ASTM standard. The process achieved a yield of 90.2%. The biodiesel obtained met all the quality parameters; however, only the process conditions with a molar ratio of 6:1 and a temperature of 60 °C achieved a kinematic viscosity of 5.64 ± 0.15 mm² s⁻¹, meeting the limits of 1.9–6.0 mm² s⁻¹ of the ASTM regulation. The fluidity of this biodiesel in mixtures of 25, 50, and 75% v with petroleum diesel was also evaluated, and a better adjustment of the Bingham mixing rule model and rheological analysis revealed that the mixtures did not lose their Newtonian behavior. This allows for the application of this biodiesel in internal combustion engines, achieving the valorization of residual oil.

1. Introduction

Nowadays, global warming and climate change are among the greatest problems that society faces. This phenomenon is caused by the excessive generation of greenhouse gasses (GHGs), which accumulate in the Earth’s atmosphere, and due to excessive use of fossil fuels, it continues to increase [1]. Fossil fuels are not renewable, and they are the main source of primary energy employed in different industrial processes [2]. Another highly relevant environmental problem is the pollution of aquifers, which is derived from the high generation of liquid waste discharged without prior treatment. It has been reported that the poultry industry produces a great amount of wastewater, which is estimated to be around 140 tons of effluent for every 13,000 birds processed [3]. The main components of these sewage products are blood, urine, and fat [4]; so, wastewater has a huge potential for pollution.

To avoid the environmental problems caused by using fossil resources, the development of clean fuels derived from organic materials, also known as biofuels, has been studied [5].

Biofuels are generally more biodegradable, free of sulfur, and comprise non-toxic components when compared with traditional fuel sources. They can contribute to achieving goals 7 and 13 of the United Nations, which are affordable and clean energy and climate action, respectively [6]. In addition, it is estimated that the global demand for biofuels will rise from 41 to 53 billion liters by 2026.

Among biofuels, biodiesel has been extensively studied in the last decade. It is mainly composed of monoalkyl esters of fatty acids derived from the transesterification process of vegetable fats and oils [7], and it can represent an environmentally friendly substitute for traditional fossil fuels. The main waste sources for biodiesel production are agricultural and industrial residues, municipal and cooking waste, and animal fats/bone effluents [8]. The drainage system is typically used to dispose of used cooking oil because it is a difficult-to-treat waste. One liter of this effluent can contaminate up to 1000 L of water [9]; so, using it helps the environment and encourages the circular economy by creating a carbon cycle [10]. However, using biodiesel from these sources has drawbacks, such as low stability to oxidation and decreased cold fluidity because of an increase in viscosity [11].

For producing the biodiesel used in this study, chicken waste oils from the hot wash water of the chicken slaughtering areas were initially retained using a grease and oil trap, placed at the outlet of the wastewater treatment plant; then, by means of thermal treatment, the remaining water was evaporated, and the impurities present as large solids were eliminated in a suspension (for example, feces, feathers, or substrate remains) [12] via degumming [13]. Next, the captured fats were subjected to transesterification in a basic medium with which methyl esters of fatty acids, and finally, biodiesel and glycerin were obtained [14].

When waste oils with a high suspended particle content are used, a pretreatment procedure must be used to eliminate these non-lipid components, which reduces the transesterification reaction’s efficiency. In order to produce biodiesel, patent 382447 provides a novel pretreatment option that combines degumming and transesterification.

Transesterification is a key step during biodiesel production, and it is a commonly employed method for converting various types of waste into biodiesel. In general terms, triglycerides (fats/oils) are converted into fatty acid methyl esters (FAMEs) and glycerol by reacting them with an alcohol (typically methanol) with the help of a catalyst [15]. Particularly for feedstocks, such as waste oils and animal fats with a high free fatty acid content, hydrolysis followed by esterification, converts triglyceride to glycerol using water and catalysts like sulfuric acid or lipases.

By exploiting the potential of waste sources, the critical issue of waste management can be solved contributing to circular and sustainable bioenergy production. Three temperatures and three molar ratios were evaluated through a degumming process, and a 3k experimental design with two factors. The current work suggests employing oils recovered from contaminated water in the poultry industry to produce second-generation biodiesel and prevent waste oil from producing greenhouse gasses or polluting water. Additionally, the prediction of viscosity utilizing mixing rules and the interaction between the produced biodiesel’s viscosities and petroleum diesel was assessed. The performance of this emerging raw material was evaluated, as well as the quality of the biodiesel obtained, which offers tools for the prediction of viscosity, which is important for its employment for internal combustion systems.

2. Materials and Methods

2.1. Sampling and Physicochemical Characterization of Chicken Oil

A poultry processing plant in the central area of Veracruz state provided the recovered residual chicken oil (RCO) that was utilized. This sample was taken from the chicken processing plant’s fat and oil trap, and its quality was evaluated by physicochemical characterization.

Using methods established by the Mexican regulations for each parameter, quality evaluations were performed on the RCO (

Table 1. Standards used for oil characterization.

Parameter	Method	References
Density	Gravimetric	[16]
Melting point	Thermal	[17]
Humidity	Gravimetric	[18]
Refractive index	Refractometric	[19]
Acidity index	Volumetric	[20]
Saponification index	Volumetric	[21]

), in order to determine whether a treatment was necessary before the transesterification process to homogenize the quality of the raw material. Oil characterization is helpful when it comes from a residual origin.

2.2. Degummed Oil Process

The quality of the RCO sample needed to be improved and homogenized prior to the transesterification reaction using the degumming process in order to be used as a raw material in the manufacturing of the biodiesel. For every 150 g of RCO, degumming involved add 1.5 g of sodium bicarbonate and 20.8 mL of water. After being heated to 100 °C for an hour with magnetic stirring, the resultant liquid was moved to a separatory funnel to cool.

The degumming procedure was carried out according to the method indicated in patent number 382447 developed by Hernández-Aguilar and Cobos-Murcia [13]. Once the process was finished, the treated residual oil was characterized according to the parameters in Table 1.

2.3. Transesterification

The degummed and characterized oil was subjected to homogeneous transesterification with potassium hydroxide as a catalyst, and 5, 6 and 7 moles of methanol per mole of oil 1% w/w catalyst were used. The methoxide used for homogeneous catalysis was prepared by dissolving 0.1 g of KOH in 30, 35.5, or 42 mL of methanol according to the molar ratio of alcohol to oil.

Using a hotplate with magnetic stirrer, the degummed RCO was heated to 50, 60, and 70 °C in a three-mouth flask. One of the flask mouths was filled with a condenser, and the other two flask inlets were equipped with pH and temperature sensors. The catalyst was added to the flask containing the RCO and heated for ninety minutes once the temperature was attained. In order to separate the glycerine and monoalkyl esters into two distinct phases, the final reaction’s solution was put in a separatory funnel and left to stand for 24 h. A separatory funnel was used to separate the glycerin from the esters, and a Büchi rotary evaporator (Büchi mod. R-100, Barcelona, Spain) was used to evaporate the remaining methanol.

To evaluate the results, a 3^k experimental design was used, in which the factors were the temperature (50, 60, and 70 °C) and molar ratio (5, 6, and 7 moles of methanol per mole of oil). The data obtained were plotted and processed with NCSS^® 2024 software.

2.4. Identification of Esters by Chromatography

The characterization of the fatty acid methyl ester (FAME) profile was performed via a Thermo Scientific^® model Trace 1310 gas chromatograph with a 30 m × 0.25 mm × 0.25 µm TG-WAXMS column adapted to a Thermo Scientific^® ISQ^® 7000 single quadrupole mass spectrometer (Thermo Fisher Scientific, Waltham, MA, USA). The operating conditions of the gas chromatograph were as follows: 280 °C injection temperature, 110 °C column temperature, helium as the carrier gas, 15 kPa pressure, split injection method, ratio: 1:15. The operating conditions of the spectrometer were as follows: 280 °C interface temperature, 200 °C ion source temperature, 45–450 mass-charge ratio scan range, and 15-s scan interval.

2.5. Quality Tests of the Obtained Biodiesel

The biodiesel resulting from the transesterification process was analyzed according to the international standards indicated in

Table 2. Parameters and standards used in the analysis of biodiesel.

Parameter	Method	References
Density	Gravimetric	[22]
Cloud point	Temperature	[23]
Flash point	Temperature	[24]
Refractive index	Refractometric	[25]
Acid number	Volumetric	[26]
Residual carbon	Gravimetric	[27]
Kinematic viscosity	Ubbelohde	[28]

to verify the quality of the obtained product.

2.6. Evaluation of Mixing Patterns in Kinematic Viscosity

Five models of mixing rules were evaluated for the prediction of the viscosity of the obtained biodiesel’s mixture with petroleum diesel; the diesel supplier was Pemex, which indicated that its composition included n-alkanes, iso-alkanes, cycloalkanes, and aromatics. With distillation temperatures between 150 and 400 °C, its physicochemical characteristics were as follows: auto-ignition temperature (°C): 254–285 °C, solubility in water @ 20 °C (g/100 mL): 0.0005, density (g/m³): 0.87–0.95, lower–upper explosive limits: 0.6–6.5, physical state: liquid and kinematic viscosity @ 40 °C (mm²/s): 1.9–4.1 [29].

Each model indicates the type of interaction between the concentration and property.

Table 3. Models of studied mixing rules.

Model Mix Rule	Equation	References
Newton	$$v_{blend}=x_{v1}·v_1+x_{v2}·v_2$$ (1)	[31]
Arrhenius	$$log{v}_{blend}=x_{v1}·log{v}_1+x_{v2}·log{v}_2$$ (2)	[32]
Bingham	$${\displaystyle \frac{1}{v_{blend}}}={\displaystyle \frac{x_{v1}}{v_1}}+{\displaystyle \frac{x_{v2}}{v_2}}$$ (3)	[33]
Cragoe	$${\displaystyle \frac{1}{\ln \left(2000·v_{blend}\right)}}={\displaystyle \frac{x_{v1}}{\ln \left(2000·v_1\right)}}+{\displaystyle \frac{x_{v2}}{\ln \left(2000·v_2\right)}}$$ (4)	[34]
Kendall and Monroe	$$v_{blend}^{1/3}=\left(x_{v1}·v_1^{{\displaystyle \raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}\right)+\left(x_{v2}·v_2^{{\displaystyle \raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}\right)$$ (5)	[35]

where $v_{blend}$ viscosity of the blend. $v_1$ biodiesel viscosity. $x_{v1}$ biodiesel concentration. $x_{v2}$ diesel concentration. $v_2$ biodiesel viscosity.

shows the rules used to evaluate the correlation coefficient to determine the fitting of the model with respect to the experimental data. These rules are the most used to evaluate fluidity changes in mixed fluids [30].

2.7. Rheological Analysis of Biodiesel and Petrodiesel Mixtures

After the quality analysis of the biodiesel, a series of mixtures with the newly produced biodiesel were carried out. Two liters of commercial diesel were used, and 5 samples of 100 mL each were made, which were identified according to the percentage by volume of biofuel in the mixture. The proposed mixtures were the following: 75, 50, and 25% v/v, and the rheology of the biodiesel and pure diesel was also evaluated.

A Brookfield^® DV2T rotational viscometer (Brookfield, WI, USA) equipped with a ULA LV-1 needle and a Brookfield^® ULA adapter with a temperature control jacket connected to a water recirculating thermostatic bath was used. The determinations were made at 40 °C, with speeds of 10 to 200 rpm in 10 rpm intervals. With GraphPad Prism^® 9 software, the data obtained from the biodiesel blends were adjusted to Newton’s rheological model, denoted by Equation (6):

$$\tau =\eta · \gamma ,$$

(6)

where $\tau$ is the shear force in Pa, $\eta$ is the index of the flow behavior (Pa·s), and $\gamma$ is the strain rate in s ⁻¹ [36].

3. Results and Discussion

3.1. Physicochemical Evaluation of the Residual Oil Removal Process

Separation with a distinct interface between the clean oil (lower part) and the contaminants in the form of yellow foam (upper part) was achievable at the conclusion of the degumming process as shown in Figure 1. The mixture was separated by centrifugation at 3000 rpm and subsequently transferred into a clean and dry bottle.

Table 4. Results of the physicochemical characterization of crude and degummed oil.

Parameter	Crude	Degummed	Reference
Density (g mL−1)	0.9224 $\pm$ 0.0035	0.9091 $\pm$ 0.002	0.876	[37]
Melting point (°C)	10 $\pm$ 0.5	8 $\pm$ 0.5	3	[40]
Humidity (% w/w)	0.0177 $\pm$ 0.0002	0.0256 $\pm$ 0.0002	0.31	[41]
Refractive index (N/A)	1.5856 $\pm$ 0.0001	1.5856 $\pm$ 0.0001	1.459	[43]
Acid number (% AGL)	4.891 $\pm$ 0.004	1.397 $\pm$ 0.002	2.77	[37]
Saponification index (mg KOH g−1)	192.384 $\pm$ 0.004	246.373 $\pm$ 0.003	182.5	[44]

presents the results of the crude and degummed oil, as well as the values reported by other authors. The density of the sample used in the present study was slightly larger than that reported by Tejada-Tovar et al. [37], leading to a phase separation of the oil present in the wastewater [38]. The melting point, which represents the temperature change from the solid state to the liquid state of oil [39], was lower in the degummed oil but higher than the value reported by Sotero Solís et al. [40]; the difference can be attributed to the nature of the sample, since that author used hydrogenated chestnut fat. The content of short-chain fatty acids contributes to the decrease in the melting point [41], as the short chains increase the fluidity of the fatty acids [42], while the humidity results confirmed the small amount of water present in the sample.

The refractive index was similar in the crude and degummed oil; however, it was slightly higher than the findings of Murcia Ordoñez et al. [44]. This variable is an indicator of the purity of the oil, and its increase is associated with the saturation or chain length of the fatty acids present [45].

Finally, the decrease in acidity in the degummed sample was remarkable; usually values lower than 4% acidity are suitable for transesterification, since the acidity prevents oils from saponifying and forming soaps in a parallel reaction [37], thus reducing the performance of the transesterification reaction. However, more potassium hydroxide was needed to produce saponification in the degummed oil, indicating the presence of short-chain fatty acids in the leftover chicken oil [46], as supported by the measured melting point.

3.2. Identification of Fatty Acid Methyl Ester by Chromatography

The FAMEs found in the biodiesel produced from the residual chicken oil are shown in

Table 5. FAME profile of recovered chicken oil.

Retention Time	Fatty Acid	Specie	Biodiesel Sample (% w/w)	Biodiesel from Skin Chicken Oil (% w/w) [47]	Biodiesel from Rendered Chicken Oil (% w/w) [48]
19.17	Methyl myristate	14:0	2	0.53	0
21.6	Methyl palmitate	16:0	15.92	23.52	26.03
21.89	Methyl palmitoleate	16:1	19.34	4.18	7.03
25.77	Methyl stearate	18:0	16.26	6.11	13.97
24.21	Methyl oleate	18:1	5.42	34.78	37.73
23.94	Methyl linoleate	18:2	36.01	28.23	14.4
ND	Methyl linolenate	18:3	0	2.37	0
26.26	Methyl 11(Z),14(Z)-Eicosadienoate	21:2	1.86	0	0
26.2	Omega-3 arachidonic acid methyl ester	21:4	3.18	2.4	0
	Saturated		34.18	30.16	40
	Unsaturated		65.81	69.56	59.16
	Sat/Unsat Ratio		99.99	99.72	99.16
		Sat/Unsat	0.519373955	0.43358252	0.676132522

. The saturated fatty acids present were palmitate (15.92%), myristate (2%), and stereate (16.26%), which represented 34.18% of the total FAMEs; the other part (65.81%) contained unsaturated compounds such as oleate (5.42%), palmitoleate (19.34%), eicosadienoate (1.86%), arachidonic acid (3.18%), and linoleate (36.01%).

The FAME profile of chicken skin fat biodiesel as assessed by Feddern et al. [47] is quite similar to that of the RCO-based biodiesel. Abraham et al.’s [48] analysis of rendered chicken oil biodiesel, however, showed some variations; this biodiesel does not contain methyl myristate, methyl linolenate, methyl 11 (Z), 14 (Z)-eicosadienoate, or arachidonic acid. The only methyl ester absent from the sample used was linolenate.

The FAMEs shown in Figure 2 have a direct influence on the production of biodiesel; due to their impact on the product’s stability and usefulness, the high percentage of unsaturated fatty acids, especially linoleate and palmitoleate, is significant. Oxidative stability is a key factor that affects the quality and shelf life of biodiesel, and unsaturated fatty acids, despite being beneficial in certain contexts, are more prone to oxidation than saturated fatty acids. In this case, the high presence of linoleate and oleate introduces double bonds that make biodiesel less stable in the long term, which can result in the formation of unwanted compounds such as polymers. These compounds can affect both engine performance and fuel efficiency.

Moreover, the content of methyl esters of saturated fatty acids, mainly stearate and palmitate, contributes to the viscosity of biodiesel. Since biodiesel can solidify at room temperature, saturated fatty acids have a tendency to increase viscosity and the freezing point, which can be troublesome in cold locations [49]. However, this higher proportion of saturated fat also improves the thermal stability, which makes biodiesel more resistant to decomposition by heat during its employment. The mixed profile of FAMEs with 65.81% of unsaturations in the biodiesel from chicken waste oil offer a balance between stability and performance; therefore, improving the durability and efficiency of biodiesel without compromising its properties would be possible [50].

3.3. Statistical Analysis of the Production and Quality of Biodiesel

The yield obtained in the production of biodiesel from the RCO recovered from the treatment of wastewater from the poultry processing plant was more than 80%, and according to the statistical analysis of the experimental design, the temperature (p = 0.0309) had a significant effect on the efficiency. Specifically, the oil:methanol molar ratio was not significant (p = 0619); however, the interaction (p = 0.0024) of both factors was decisive in obtaining the maximum conversion of this experiment reaching 90.2 ± 0.7%, as shown in Figure 3. This value was slightly higher than that reported in the production of biodiesel from chicken fat, which reached 89% [51]. The control experiment in which the oil was transesterified without degumming had a yield of 75%; this increase in efficiency can be attributed to the nontransesterable materials removed during the degumming process, which limited the performance of the process.

The samples obtained with this experimental design achieved the following quality indicators: the density was 0.874 ± 0.002 g mL⁻¹, indicating a significant effect on the temperature (p = 0.0022) and molar relationship (p = 0.00002). These data are close to those of the biodiesel obtained from chicken waste, which showed a density of 0.872 g mL⁻¹ [52]. All the experiments complied with the ASTM D6751-09, which establishes limits of 0.86 to 0.9 g mL⁻¹.

The average cloud point for the biodiesel samples was 4.26 ± 2.58 °C, and it should be reported as indicated by ASTM D6751-09. The result was in accordance with the biodiesel produced from waste chicken fat oil, which presented a cloud point of 6.3 ± 2.37 [53]. This parameter was influenced by the molar ratio (p = 0.00002). The temperature factor (p = 0.71309) and the interaction (p = 0.79696) did not have a significant effect on this quality parameter.

The average flash point (F.P.) obtained by the samples was 179.33 ± 5.09 °C; this value agrees with the ASTM D6751-09 standard, which establishes a minimum limit of 130 °C. The F.P. value obtained was higher than that of the biodiesel obtained from waste chicken fat oil, which presented an F.P. of 171 ± 2.51 °C. This quality parameter was significantly affected by the process temperature (p = 0.015) and the molar ratio (p = 0.012).

In this study, refractive index values of 1.445–1.451 were obtained, which comply with ASTM D6751-09, which specifies a maximum value of 1.479. The molar ratio (p = 0.0035) significantly affects the refractive index. This parameter was similar to that presented with biodiesel and diesel blends with refractive indices in a range of 1.445–1.475 [54].

The molar ratio (p = 0.6944) and the process temperature (p = 0.6944) did not affect the obtained acid number (0.26 ± 0.116 mg KOH g⁻¹). The biodiesel produced by this process is within the permissible limits of the ASTM D6751-12 regulation, which indicates 0.50 mg KOH g⁻¹; other biodiesels produced with chicken oils obtained 0.69 mg KOH g⁻¹ [55].

The value of the carbon residue was 0.0341 ± 0.001% w/w; the factor that most influenced the carbon residue was temperature (p = 0.002). The molar relationship (p = 0.8190) and the interaction (p = 0.0565) had no significant effect. These experiments showed values below the specification of the regulation ASTM D6751-09, which indicates an upper limit of 0.050 % w/w.

The viscosity was significantly affected by the factors of temperature (p = 0.01125) and molar ratio (0.00186), without a significant effect on the interaction. Figure 4 shows that only the experiments performed at a temperature of 60 °C and a molar ratio of 6:1 obtained a viscosity of 5.64 ± 0.15 mm² s⁻¹; only these process conditions comply with the limits established by the ASTM D6751-09 regulation of 1.9–6.0 mm² s⁻¹ for this parameter quality. Other works using different sources of chicken oil reported similar values ranging from 2.6 to 5.8 mm² s⁻¹. The high viscosity of biodiesel made from animal fats hinders fuel atomization and vaporization, which directly affects engine combustion and lowers engine efficiency. As a result, the engine needs to be closely monitored to meet regulations and prevent these issues. In addition, it is critical to examine how diesel and biodiesel interact to guarantee that the mixture works as biofuel [56].

3.4. Evaluation of Biodiesel Blending Models with Petroleum Diesel

The mixing rules models performed well in terms of the viscosity prediction and they showed a good fit. Newton’s rule yielded a correlation coefficient (R²) of 0.8939, the Arrhenius model yielded a coefficient (R²) of 0.9348, the mixing rule Cragoe’s model yielded a score of 0.9399, and the Kendall and Monroe model yielded a score of 0.9242. Figure 5 indicates that Bingham’s rule achieved a correlation coefficient (R²) of 0.945, which is consistent with the published data, where this model had a correlation coefficient (R²) of 0.9959 and had the best performance among different biodiesels [57]. This mathematical model is the best option for predicting the viscosity of biodiesel mixtures obtained from fatty residues with petroleum diesel, ensuring fluidity and avoiding engine problems.

3.5. Rheological Evaluation of Biodiesel Blends with Petroleum Diesel

The linearity of each rheological monitoring, shown in the rheogram in Figure 6, indicates that the biodiesel and petroleum diesel blends have Newtonian behavior, since they contain long-chain fatty acids [58]. For this reason, this rheological model was employed in this research.

The rheological characteristics of the biodiesel blends are displayed in

Table 6. Results of the rheological analysis of biodiesel blends.

Biodiesel Concentration (% v/v)	Dynamic Viscosity (Pa·s)	Equation	R2
100	0.004903	$\tau =0.004903\gamma$	0.9904
75	0.004065	$\tau =0.004065\gamma$	0.9999
50	0.003389	$\tau =0.003389\gamma$	0.9994
25	0.002790	$\tau =0.002790\gamma$	0.9994
0	0.002322	$\tau =0.002322\gamma$	0.9993

; as the biodiesel concentration drops, the viscosity falls. The correlation coefficients (R²) higher than 0.99 confirm that the rheological behavior was not modified by the interaction of the two fluids at any concentration, following a Newtonian behavior, and the dynamic viscosity levels of biodiesel indicate a high conversion of oils into methyl groups. According to the reports that were published by Borges et al., viscosity levels from 0.004 to 0.005 Pa·s indicate yields between 85 and 95% [59].

The viscosity levels of the mixture ensure that this product will not have flow problems in its utilization as a biofuel. In addition, it has a high volumetric modulus and viscosity, resulting in a lower compressibility; so, the pressure response in the fuel injection system is more accurate. A higher viscosity helps reduce losses during the fuel injection process, making it beneficial to spray early. High viscosity values also reduce engine power and relieve stress vibration [60].

4. Conclusions

The RCO from the poultry processing wastewater treatment process proved to be a raw material with technical feasibility to produce biodiesel with an efficiency greater than 90%, complying with the ASTM D6751-09 regulations and a FAME profile with 34.18% w/w saturated and 65.81% w/w unsaturated.

A reaction temperature of 60 °C and a methanol-to-oil molar ratio of 6:1 are the process parameters that provide a biodiesel that meets the ASTM criteria. The viscosity parameter was only met by these conditions. The Bingham mixing model showed the highest correlation coefficient for predicting the viscosity of biodiesel blends obtained with petroleum diesel, and the kinematic value obtained was 5.64 ± 0.15 mm² s⁻¹.

The rheological behavior of the biodiesel and petroleum diesel blends showed that the interaction of the biodiesel produced does not modify the Newtonian rheological behavior of the biodiesel blends.

Since improper disposal of oily waste has a significant negative impact on water bodies, removing 1 liter of grease can help prevent 10,000,000 L of water from becoming contaminated. For this reason, it is necessary to scale up this technology to look for its possible implementation in transport systems. This could reduce at least 5% of the non-neutral CO₂ emissions of these transport devices, increase the poultry industry’s energy sources, and reduce its dependence on fossil fuels.

With a shared global goal of effectiveness and sustainability, more work must be conducted to optimize the biodiesel production process using the methodology of this article and investigate ways to increase efficiency focusing on biodiesel production integration with the principles of the circular economy.

5. Patents

Hernández-Aguilar, E., JA Cobos-Murcia. 2021. Proceso para tratamiento de grasas residuales (Mexican Patent No. 382447). Instituto Mexicano de la Propiedad Industrial.