# Environmental Effect of Zinc Oxide Metal Nano Additives in Microalgae Biodiesel in Diesel Engine

Authors: M. Subbulakshmi; S. Srujana; ArifSenolSener; Mohammad A. Al Zubi; Ravi Kumar; Shanthi Natarajan; Tewodros Derese Gidebo
Journal: Journal of Nanomaterials
 (2023)

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## Abstract

We investigated how to extract energy from algal oil and convert it to biodiesel by transesterification in this study. In addition to performing engine performance tests with varying quantities of fuel mixture, parameters such as power, hourly torque consumption, specific consumption, and emissions of dioxide and monoxide were evaluated as an alternate solution to the pollution problem caused by fossil fuels. A 5.2 kW diesel engine powered the engine. The production of algal oil-based biodiesel was carried out effectively. The algal oil extraction procedure resulted in the production of biodiesel, which was then blended with commercial diesel in the amounts of 20, 40, and 60%. The engine performance testing revealed no statistically significant difference between the power and torque delivered by the various commercial diesel blends. Both hourly and particular consumption showed an increase of 15% and 20%, respectively, regarding commercial diesel consumption. However, the most significant advantage is the reduction in pollutant emissions, as demonstrated by the reduction in carbon dioxide emissions by more than 20% in any mixture of commercial diesel and biodiesel when compared to commercial diesel.


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## Body

## 1. Introduction

As a result of the increasing need for oil, biodiesel has emerged as a valuable source of energy and a viable alternative to the production of clean energy through the use of internal combustion engines, stoves, and other burners [1]. The growing use of biodiesel of the first generation in each country has occurred due to the introduction of policies that encourage the production and widespread use of this biofuel in the respective countries. In some countries, the growth of oil palm has been encouraged to manufacture biodiesel, which can be used to meet the demand for fuel in the creation of electricity [2]. In addition, it should be highlighted that first-generation biofuels have several drawbacks, including competition with crops for human consumption and the requirement of large amounts of water for their production. This results in a debate about food and fuels derived from these, which is a crucial point to consider when designing new policies in some countries. As a result, new alternatives and raw materials are being developed to address these issues; most of these initiatives are geared toward developing second-, third-, and fourth-generation biofuels derived from nonedible crops and other raw materials [3]. The manufacturing of biodiesel from these nonedible basic materials, as well as the use of this biodiesel, as a result, there is a disagreement over the food and fuel that can be gotten from these sources, which is an important matter to examine when new legislation is being drafted in some nations. Several authors from throughout the world have conducted substantial research into the performance of internal combustion engines [4]. A valuable review of the properties and performance of biodiesel derived from nonedible vegetable oils is available online. Numerous researchers looked examined raw materials such as rubber seed oil, cottonseed oil, jojoba oil, tobacco oil, flaxseed oil, and Jatropha as potential sources of raw materials, as well as other plants. For example, in some countries, the growth of oil palm has been promoted to manufacture biodiesel to meet the need for fuel in power generation [5]. In 2012, biodiesel from olive oil was created in one of these countries, the Philippines. In addition, it should be highlighted that first-generation biofuels have several drawbacks, including a rivalry with crops for human consumption and the high need for water during the cultivation process. As a result, there is a dispute regarding food and energy obtained from them, which is essential to address when developing new legislation in various jurisdictions. It was demonstrated that it is possible to produce biodiesel from algae oil while adhering to international environmental regulations and norms [6]. The researchers used a similar approach to generate biodiesel using an integrated catalytic process that included a composite membrane and sodium methoxide. This group of researchers concluded that it was possible to create this biofuel under optimal conditions with 98.1% of the total transesterification conversion rate. It is an important area of research in which various authors have contributed to recent years, and the use of biodiesel as a source of energy in internal combustion engines is one of them. Most of the research that has been conducted in recent years, however, has focused on the performance of internal combustion engines utilized in the transportation industry [7].


## 2. Materials and Method

### 2.1. Biodiesel Production

According to the FAO, the process begins with extracting algae oil using heating operations that yield around 10 liters of oil. A sample of this oil is used for acidity analysis. When free fatty acids are present in a triglyceride, its acidity is indicated by its acid number (acidity number). It is necessary to titrate using potassium hydroxide, and the acidity is measured using an index known as the acid number. The acid number of the oil will be determined through this analysis; if it finds a value that is not greater than 5, it will be possible to work without problems; acidity index values greater than 5 are not recommended for the production of biodiesel due to the high acid number; however, the use of this is recommended for other products other than biodiesel production. For the acidity test, 5 grams of sample was weighed and diluted with 50 mL of ethyl alcohol neutralized at 50°C before being placed in an Erlenmeyer flask with a few drops of phenolphthalein and then titrated with potassium hydroxide solution 0.1 N [8]. Figure 1 shows the transesterification process.Figure 1
Transesterification process.Biodiesel is a mixture of monoalkyl esters of long-chain fatty acids derived from renewable lipids such as vegetable and animal oils and obtained by the transesterification process. The procedure consisted of pouring the ten liters of algae oil into a container; then, methanol 20% (v/v) was added about the amount of sample. The amount of catalyst was calculated by adding an excess depending on the acid number. KOH (potassium hydroxide) was taken as 8 grams. The catalyst was mixed with methanol (methoxide), the methoxide mixture was added to the sample, and the mixture was mixed at 50-60°C for approximately 2 hours. The glycerin was decanted and separated, and then, 3 to 4 washes with water (20-30% (v/v) depending on the yield of biodiesel) were carried out, followed by drying and filtering [9]. The separation of glycerol from biodiesel is shown in Figure 2.Figure 2
The separation of glycerol from biodiesel.


### 2.2. Fuel Samples

Figure3 shows photographs of the biodiesel mixes in nanoparticles. It was created by mixing 20% biodiesel and 80% diesel on a volumetric basis in a magnetic stirrer to create the C. vulgaris algal methyl ester blend (B20), which was then tested. As previously reported, ZnO nanoparticles were also disseminated into B20 fuel test samples at dose levels of 50 and 100 parts per million (ppm) using an ultrasonicator. This experiment employed B20, B20+50 ppm ZnO, and B20+100 ppm ZnO as the starting materials. To measure the qualities of these fuels, we used ASTM D 6751, a standard procedure for testing fuel parameters [10]. The properties of fuel blends are shown in Table 1.Figure 3
Biodiesel mixes in nanoparticles.Table 1
Properties of different fuel blends.
S. noPropertiesDiesel (D100)Algae methyl ester (B20)B20+50 ppm of ZnOB20+100 ppm of ZnO1Kinetic viscosity, cSt5.666.126.182Density, kg/m38908888938963Calorific value, MJ/kg39.5404141.64Flashpoint, °C96921281375Fire point, °C115118136151


### 2.3. Experimental Set-Up

The engine used for the experimental analysis was a one-cylinder four-stroke CI engine (Make: Kirloskar, TV1 model engine with overhead valves controlled by pushrods) with a water-cooled system, which was employed for the experiments. The engine can provide 5.2 kW of output power at 1500 rpm when operating at full load. The fuel injection pressure and timing were maintained at 23° before TDC and 210 bar, respectively, by the manufacturer’s recommendations. The coolant was circulated through the water jackets in the cylinder, and the temperature of the coolant was maintained at 80°C throughout the process. To measure the in-cylinder pressure, a piezoelectric transducer was flush-mounted on the cylinder head of the engine. The engine was equipped with an eddy current dynamometer, which measured torque. The experimental set-up is schematically depicted in Figure4, which illustrates the schematic diagram. The engine specification is shown in Table 2.Figure 4
Experimental set-up.Table 2
Engine specification.
Engine typeMake Kirloskar 1 cylinder, 4 stroke water-cooled, diesel (computerized), modified to VCR engineModelTV1Bore diameter87.50 mmStroke110.00 mmCombustion principleCompression ignitionEngine capacity661 ccPeak pressure77.5 kg/cm2Power5.2 kW at 1500 rpmDynamometerEddy current dynamometer cooled by water includes a loading unitAirboxFabricated by MS including an orifice meter and U-tube manometerFuel tankMaximum capacity of 15 liters including metering columnPiezoelectric sensorRange 345 bar, including no noise cableEncoder1 degree resolution, 5500 RPM speed including TDC pulseData acquisition systemNI USB-6210, 250 kb/s, bit-16Digital voltmeter0-200 mV range mounted on panelTemperature detectorRTD type, K-type thermocouple, and PT100Load indicator0-50 kg range, digital typeLoad sensorStrain gauge with 0-50 kg rangeDirection of rotationClockwise (looking from flywheel end side)Idle speed range750 rpm to 2000 rpmMin. running speed1200 rpmFuel timing for the engine230 BTDCValve clearanceAt inlet 0.18 mmValve clearanceAt exhaust 0.20 mmBumping clearance0.046 inch to 0.052 inchBMEP at 1500 rpm6.35 kg/cm2Lubricating oil pumpGear typeLub. oil pump6.50 lit/min


## 2.1. Biodiesel Production

According to the FAO, the process begins with extracting algae oil using heating operations that yield around 10 liters of oil. A sample of this oil is used for acidity analysis. When free fatty acids are present in a triglyceride, its acidity is indicated by its acid number (acidity number). It is necessary to titrate using potassium hydroxide, and the acidity is measured using an index known as the acid number. The acid number of the oil will be determined through this analysis; if it finds a value that is not greater than 5, it will be possible to work without problems; acidity index values greater than 5 are not recommended for the production of biodiesel due to the high acid number; however, the use of this is recommended for other products other than biodiesel production. For the acidity test, 5 grams of sample was weighed and diluted with 50 mL of ethyl alcohol neutralized at 50°C before being placed in an Erlenmeyer flask with a few drops of phenolphthalein and then titrated with potassium hydroxide solution 0.1 N [8]. Figure 1 shows the transesterification process.Figure 1
Transesterification process.Biodiesel is a mixture of monoalkyl esters of long-chain fatty acids derived from renewable lipids such as vegetable and animal oils and obtained by the transesterification process. The procedure consisted of pouring the ten liters of algae oil into a container; then, methanol 20% (v/v) was added about the amount of sample. The amount of catalyst was calculated by adding an excess depending on the acid number. KOH (potassium hydroxide) was taken as 8 grams. The catalyst was mixed with methanol (methoxide), the methoxide mixture was added to the sample, and the mixture was mixed at 50-60°C for approximately 2 hours. The glycerin was decanted and separated, and then, 3 to 4 washes with water (20-30% (v/v) depending on the yield of biodiesel) were carried out, followed by drying and filtering [9]. The separation of glycerol from biodiesel is shown in Figure 2.Figure 2
The separation of glycerol from biodiesel.


## 2.2. Fuel Samples

Figure3 shows photographs of the biodiesel mixes in nanoparticles. It was created by mixing 20% biodiesel and 80% diesel on a volumetric basis in a magnetic stirrer to create the C. vulgaris algal methyl ester blend (B20), which was then tested. As previously reported, ZnO nanoparticles were also disseminated into B20 fuel test samples at dose levels of 50 and 100 parts per million (ppm) using an ultrasonicator. This experiment employed B20, B20+50 ppm ZnO, and B20+100 ppm ZnO as the starting materials. To measure the qualities of these fuels, we used ASTM D 6751, a standard procedure for testing fuel parameters [10]. The properties of fuel blends are shown in Table 1.Figure 3
Biodiesel mixes in nanoparticles.Table 1
Properties of different fuel blends.
S. noPropertiesDiesel (D100)Algae methyl ester (B20)B20+50 ppm of ZnOB20+100 ppm of ZnO1Kinetic viscosity, cSt5.666.126.182Density, kg/m38908888938963Calorific value, MJ/kg39.5404141.64Flashpoint, °C96921281375Fire point, °C115118136151


## 2.3. Experimental Set-Up

The engine used for the experimental analysis was a one-cylinder four-stroke CI engine (Make: Kirloskar, TV1 model engine with overhead valves controlled by pushrods) with a water-cooled system, which was employed for the experiments. The engine can provide 5.2 kW of output power at 1500 rpm when operating at full load. The fuel injection pressure and timing were maintained at 23° before TDC and 210 bar, respectively, by the manufacturer’s recommendations. The coolant was circulated through the water jackets in the cylinder, and the temperature of the coolant was maintained at 80°C throughout the process. To measure the in-cylinder pressure, a piezoelectric transducer was flush-mounted on the cylinder head of the engine. The engine was equipped with an eddy current dynamometer, which measured torque. The experimental set-up is schematically depicted in Figure4, which illustrates the schematic diagram. The engine specification is shown in Table 2.Figure 4
Experimental set-up.Table 2
Engine specification.
Engine typeMake Kirloskar 1 cylinder, 4 stroke water-cooled, diesel (computerized), modified to VCR engineModelTV1Bore diameter87.50 mmStroke110.00 mmCombustion principleCompression ignitionEngine capacity661 ccPeak pressure77.5 kg/cm2Power5.2 kW at 1500 rpmDynamometerEddy current dynamometer cooled by water includes a loading unitAirboxFabricated by MS including an orifice meter and U-tube manometerFuel tankMaximum capacity of 15 liters including metering columnPiezoelectric sensorRange 345 bar, including no noise cableEncoder1 degree resolution, 5500 RPM speed including TDC pulseData acquisition systemNI USB-6210, 250 kb/s, bit-16Digital voltmeter0-200 mV range mounted on panelTemperature detectorRTD type, K-type thermocouple, and PT100Load indicator0-50 kg range, digital typeLoad sensorStrain gauge with 0-50 kg rangeDirection of rotationClockwise (looking from flywheel end side)Idle speed range750 rpm to 2000 rpmMin. running speed1200 rpmFuel timing for the engine230 BTDCValve clearanceAt inlet 0.18 mmValve clearanceAt exhaust 0.20 mmBumping clearance0.046 inch to 0.052 inchBMEP at 1500 rpm6.35 kg/cm2Lubricating oil pumpGear typeLub. oil pump6.50 lit/min


## 3. Result Analysis

Statistically, general and mixed linear models were made using fuel type and load as factors with all the data. To analyze the assumption of errors with normal distribution, the normality was analyzed using the Shapiro-France test for each parameter of all the measured variables.


## 4. Performance Analysis

### 4.1. Power Test

Each type of fuel mixture is represented in Figure5, with the power developed by the engine operating at a fixed speed of 3600 rpm and four variable loads increased by 25% for each type of fuel mixture being used as a baseline. The power developed by the mixture B20+100 ppm ZnO is being used as a reference. The power values for each type of mixture differ by an average of 0.01 kw, indicating that there is no significant change in this operational feature compared to the base power. Figure 5 depicts the results for each load applied to the engine and for each of the various blends. The power does not change about the power deemed to be the base (B20). In the same way, the power increases as the load increases, demonstrating the distinctive line that is commonly observed [11].Figure 5
Variation of power vs. load.


### 4.2. Torque Test

Figure6 shows that the engine torque values are practically the same for each load group and each type of mixture, showing an increasing trend practically linear as the load increases. The figure shows that the types of fuel do not influence the result of the engine torque [1]. This corresponds to each load imposed on the engine, and its tendency is growing as the imposed load grows (B20+100 ppm ZnO), as shown by the trend line.Figure 6
Variation of torque vs. load.


### 4.3. Consumption Test

The results of Figure7 show that in commercial fuel, the hourly consumption is lower than the consumption with the mixtures almost in the entire range of load [12]. This increased consumption in the mixture of commercial fuel with algae biodiesel is due to a kind of compensation due to the lower calorific value of biodiesel compared to B20. Figure 7 shows the trend that the hourly consumption curve has with any of the mixtures used depending on the loads adjusting to the expected characteristic [13]. The minimum hourly consumption is given with a biodiesel mixture. The consumption is lower for all types of fuel.Figure 7
Variation of hourly consumption vs. load.


## 4.1. Power Test

Each type of fuel mixture is represented in Figure5, with the power developed by the engine operating at a fixed speed of 3600 rpm and four variable loads increased by 25% for each type of fuel mixture being used as a baseline. The power developed by the mixture B20+100 ppm ZnO is being used as a reference. The power values for each type of mixture differ by an average of 0.01 kw, indicating that there is no significant change in this operational feature compared to the base power. Figure 5 depicts the results for each load applied to the engine and for each of the various blends. The power does not change about the power deemed to be the base (B20). In the same way, the power increases as the load increases, demonstrating the distinctive line that is commonly observed [11].Figure 5
Variation of power vs. load.


## 4.2. Torque Test

Figure6 shows that the engine torque values are practically the same for each load group and each type of mixture, showing an increasing trend practically linear as the load increases. The figure shows that the types of fuel do not influence the result of the engine torque [1]. This corresponds to each load imposed on the engine, and its tendency is growing as the imposed load grows (B20+100 ppm ZnO), as shown by the trend line.Figure 6
Variation of torque vs. load.


## 4.3. Consumption Test

The results of Figure7 show that in commercial fuel, the hourly consumption is lower than the consumption with the mixtures almost in the entire range of load [12]. This increased consumption in the mixture of commercial fuel with algae biodiesel is due to a kind of compensation due to the lower calorific value of biodiesel compared to B20. Figure 7 shows the trend that the hourly consumption curve has with any of the mixtures used depending on the loads adjusting to the expected characteristic [13]. The minimum hourly consumption is given with a biodiesel mixture. The consumption is lower for all types of fuel.Figure 7
Variation of hourly consumption vs. load.


## 5. Emission Analysis

### 5.1. CO Emission Test

Figure8 shows that the values of the emissions both in a low load or high load close to the maximum power increase its emission of CO [14]. According to the theory, the scarcity of oxygen produces an increase in CO. It means that the richness of the fuel is greater than the ratio of the fuel-air mixture [13]. In Figure 8, it can see that in the range of operation, the CO emission is lower for any mixture, also being the mixture with B20+100 ppm ZnO has lower emissions than B20 [15].Figure 8
Variation of CO vs. load.


### 5.2. CO2 Emission Test

From the data shown in Figure9, it is observed that the emission of CO2 increases proportionally to the increase in all loads. In the case of fuel mixed with algae biodiesel, these figures drop considerably reduction of 20% to 25% in CO2 emissions in general [16]. In Figure 9, it can see that the CO2 emission for each load to which it is subjected to the engine with B20. The highest proportion of CO2 in general is for the mixture of B20 blend [17]. It can ensure that the mixture of B20+100 ppm ZnO considerably reduces this greenhouse gas emission.Figure 9
Variation of CO2 vs. load.


## 5.1. CO Emission Test

Figure8 shows that the values of the emissions both in a low load or high load close to the maximum power increase its emission of CO [14]. According to the theory, the scarcity of oxygen produces an increase in CO. It means that the richness of the fuel is greater than the ratio of the fuel-air mixture [13]. In Figure 8, it can see that in the range of operation, the CO emission is lower for any mixture, also being the mixture with B20+100 ppm ZnO has lower emissions than B20 [15].Figure 8
Variation of CO vs. load.


## 5.2. CO2 Emission Test

From the data shown in Figure9, it is observed that the emission of CO2 increases proportionally to the increase in all loads. In the case of fuel mixed with algae biodiesel, these figures drop considerably reduction of 20% to 25% in CO2 emissions in general [16]. In Figure 9, it can see that the CO2 emission for each load to which it is subjected to the engine with B20. The highest proportion of CO2 in general is for the mixture of B20 blend [17]. It can ensure that the mixture of B20+100 ppm ZnO considerably reduces this greenhouse gas emission.Figure 9
Variation of CO2 vs. load.


## 6. Conclusion

Algae oil represents an important source of input to be used in biodiesel production due to a large amount of consumption at the national level and world. Biodiesel made from algal oil is a third- or fourth-generation renewable fuel that does not impact food security. Using algal oil as a biodiesel raw material discharges a lower rate of harmful gases into the atmosphere. The energy capacity of algae oil biodiesel is higher than that of commercial diesel. The mechanical effects of blended biodiesel with ZnO nano additives are similar to those of commercial diesel, increasing power, and reduced emission than B20.



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*Source: 1051117-2023-02-17.xml*