Amalgamation and Optimization of FAEE Biodiesel Fuel from Croton macrostachyus hochst. ex Delile Seed oil Utilizing Solid Calcium Oxide-Chicken Eggshell Squander as a Heterogeneous Catalyst

Identification of better yielding nonedible feedstocks and process improvements with locally prepared chemicals is the way forward for improving biodiesel economic viability. Synthesis of fatty acid ethyl ester (FAEE) biodiesel from Croton macrostachyus hochst. ex delile (C. M.) seed oil is investigated through the transesterification method including oil extraction and CaO-chicken eggshell waste as a heterogeneous catalyst and ethanol, which has not yet been investigated earlier. The effects of catalyst load from 2% to 6% (w/w) of the weight of oil, ethanol to oil ratio from 9 : 1 to 12 : 1(v/v), reaction temperature from 60 to 80℃, and reaction time variation from 0.45 to 2 hr have been explored. The yield has been investigated, with the oil content of the C. M. seed being 46.85% realized through the solvent extraction route. The central composite design (CCD) using a design expert is employed to investigate the effects of different process parameters for biodiesel synthesis and to find the optimum conditions for maximizing the yield. The conversion to biodiesel via the calcium oxide-heterogeneous catalyzed transesterification route has achieved 91% yield under the optimum conditions. The optimum result predicted by the model is found to be 91.036% at a catalyst loading of 5.802 wt.%, reaction temperature of 76.117℃, a reaction time of 1.969 hr, and ethanol to oil molar ratio of 11.55 with a desirability value of 1.000. The FTIR spectrum confirms the composition and functional groups of synthesized biodiesel under optimum reaction conditions. Physicochemical properties of synthesized C. M. biodiesel are determined, and the results when compared with the biodiesel standard specifications are within the range prescribed. The result showed that C. M. could be a very viable feedstock for the biodiesel industry, which could be exploited as an alternative fuel source.


Introduction
Design for sustainability in the present context calls for decarbonization, distributed generation/production, and dematerialization, i.e., conservation of depletable materials. Biodiesel production from indigenous nonedible feedstocks holds promise to partially substitute a more signifcant share of fossil-based resources and mitigate the associated GHG emissions. However, to improve the economic viability of biodiesel, ways and means are to be explored, such as using locally available materials and alcohol including catalysts. Te potential of Croton megalocarpus [1] and Croton macrostachyus (C. M.) [2] have been explored to synthesize biodiesel fuel, and attributes like higher yield per hectare compared to Jatropha as well as the attractive cold fow properties of Biodiesel formed from these feedstocks have been highlighted. While it has been reported that the oil content of the seeds from both species is roughly the same, strategies intended to remunerate ecological execution and supportability of biofuels while further developing the transformation cycle to energize the arrangement of the more abundant and geologically broader feedstock supply could see second-generation items start to obscure the frstgeneration in the medium-to longer-term [2,3]. C. M. is one of the best raw materials for producing biodiesel as it is nonedible, occurs throughout tropical Africa and is one of the native trees in Ethiopia.
Nonedible oil such as C. M. oil can become a handy alternative raw material to produce biodiesel as a result of the massive demand for edible oils and also on account of food versus fuel competition.
As a result of its drought resistance and faster growth, a C. M., shown in Figure 2 as a plant and its seed, stays well-thought-out benefcial species used for changing water stream banks and tainted wasteland. Besides, due to the oil content of the seed and availability of feedstock for the synthesis of biodiesel, it can be a candidate for alternative fuel plants.
Several possible nonedible oil feedstocks were studied to synthesize biodiesel fuel in this backdrop, such as the castor and jatropha seed. In contrast, previous research based on C. M. seed oil has employed methanol and a homogeneous catalyst [1,2]. Despite the fact that the homogeneous basecatalyzed biodiesel creation processes are moderately quick and show high return, they are as yet not extremely costefective with petrodiesel ones due to the expense of unrefned substance utilized impetus that cannot be recuperated after the response [1,3]. Nevertheless, using a heterogeneous catalyst (CaO) ofers many benefts, for example, higher reaction, gentle response conditions, reusability, simple accessibility, and minimal expense [7][8][9][10][11]. Besides, previous studies have employed methanol as alcohol for biodiesel production, which is expensive and toxic relative to ethanol, now widely being produced from renewable sources in sugarbased distilleries, unlike the case of methanol. Large-scale cultivation, production, and related lipid recuperation are bound by various variables, particularly microalgae inferred biodiesel are seen as expected feedstocks for biofuel creation. Te economic feasibility of biodiesel yield is mainly afected by feedstock cost. Acid catalysts are cost-efective to produce biodiesel from the afordable feedstock. Cheap and useable catalysts reduce production costs and ameliorate productivity [4,5]. Supplanting petroleum derivative energies with biofuels, such as biodiesel created from sustainable natural material has the potential to decrease a few bothersome aspects of nonrenewable energy usage, including customary and ozone-harming substance poison outfows, modest asset decrease, and reliance on shaky unfamiliar providers. Interest in biofuels could likewise increase ranch pay. Ten again, in light of the fact that various biofuel feedstocks need land, water, and diferent assets, previous research suggests that biodiesel might bring about a few unwanted impacts [3]. Biodiesel synthesis includes two fundamental subprocesses specifcally oil extraction [12,13] cum cleansing [8,14] and transesterifcation [15]. Te yield of biodiesel produced through transesterifcation is impacted by a few interaction factors [16]. Te response is either inadequate or the yield is diminished signifcantly if the parameters are not optimized. Te decontamination interaction is the wet washing technique, which utilizes water or fermented water to refne the esters and dry washing, which also utilizes strong adsorbents or particle exchange pitches to purge unrefned biodiesel [9,10]. Furthermore, the RSM approach can be utilized to advance the biodiesel interaction parameters by soluble transesterifcation. While a few investigations revealed the improvement of biodiesel creation utilizing the RSM procedure, the streamlined utilization of RSM coordinated with the allure capability approach is inefectively known [11].
Biodiesel can't as of now be considered a serious contender to diesel fuel owing to the enormous distinction in their worldwide creation, with a high volume. It is not adequate for biodiesel to meet entire needs and necessities; it should likewise battle fnancially with fossil diesel at largescale creation [12]. According to the previous studies [17][18][19], the main factors infuencing biodiesel yield after transesterifcation are reaction temperature, alcohol to oil molar ratio, time of reaction, mixing intensity, and amount of catalyst loaded. Hence, in the present study, the production of biodiesel through the reaction of the C. M. seed oil with ethanol within the sight of a heterogeneous catalyst, CaO is investigated, and optimum biodiesel conversion is analyzed at the ideal mix of process variables such as ethanol to oil proportion, amount of catalyst loaded, time of reaction, and reaction temperature. Te properties of C. M. biodiesel are also tested similarly, contrasted, and suggested along with ASTM and EN standards. Reusability consideration led to the selection of chicken eggshell leftover as a heterogeneous catalyst to make the biodiesel process more economically viable and environmentally friendly.

Materials and Method
2.1. Site Description. Te C. M. seed samples used for the synthesis of Biodiesel are collected from Jimma, in the Oromia region, the largest city located in the southwestern part of Ethiopia. It has a latitude of 7°40′12″N and longitude of 36°49′48″E, with a height of 1780 m above sea level, which is appropriate for the growth of C. M. plants.

Materials and Equipment.
Te signifcant materials and equipment used during the experimental work are C. M. seed, waste chicken eggshell, ethanol, oven, grinder, measuring cylinder, mufe furnace, Soxhlet apparatus, rotary evaporator, bomb calorimeter, separating funnel, distilled water, phenolphthalein, water bath, heating mantle, digital balances, flter paper, bunsen burner, sodium hydroxide, potassium hydroxide beakers, water bath, and diferent sizes of conical fasks. All the other chemical compounds utilized are of analytical reagent grade.

C. M. Seeds Sample Preparation.
Seeds were crushed to rupture the cell wall and release the solute; see Figure 3. for direct contact with the solvent during the contact equilibrium process.

Extraction of C. M. Seed
Oil. Te dried seeds are squashed in a crushing mill with a constituent part size of less than 2.0 mm. Ten, the crushed C. M. seeds are packed into thimble and n-hexane of analytical grade as the solvent is set in the extraction unit at a dissolvable-to-the-solid ratio of 5 : 1 (v/w). Solvent to solid proportion is picked by their utilization according to their convention possibility in industrial scales and based on previously reported results and patent data [20].

Chicken Eggshell Waste Catalyst Preparation.
Te eggshell is washed using refned water to eliminate impurities and afterward dried in an oven (105°C, 24 h). Te sample is squashed in agate mortar hardware into fne particles (0.25-2 mm). Te fne particles are then calcined in a mufe furnace at a temperature of 900°C for 2 hours to dispense any type of carbon and get the total transformation from CaCO 3 to CaO. Te debris then is utilized as a heterogeneous base catalyst in the development of ethyl ester. Te whole sequential process is highlighted in Figure 4.    Table 1 and two center points are used with a central composite design (CCD). Te CCD was applied for carrying out the optimization studies to maximize the yield of biodiesel in the transesterifcation method. Experimental values of converting the C. M. seed oil to biodiesel at the design points at diferent parameters are obtained, and from those values, the yield is determined and recorded.

Seed Preparation.
Te collected seeds are separated from the chaf and other impurities and then weighed before drying to remove the excess moisture. Te moisture content for the three samples characterized is 7.366%, 5.425%, and 4.22%, respectively, and the average moisture content is obtained as 5.67% w/w, which is in the acceptable range for oil extraction [21].

Oil Extraction.
Extraction of C. M. seed oil is carried out using heating and solvent extraction methods. From 100 g of purifed seed, 19.8 g oil is found, which shows 19.8% (w/w) of C. M. seed oil is extracted using heating methods while from 100 g of purifed seed, 46.85 g oil is found, which shows 46.85%(w/w) of C. M. seed oil is extracted using solvent extraction. Te properties of the seed oil in comparison with others are indicated in Table 2.

Physicochemical Properties of the Chicken Eggshell Ash.
Tis study inspected the chemical composition of waste chicken eggshells before and after calcination via XRD investigation. Figure 5 shows the chemical structure before and after calcination; the eggshells became totally white for all intents, which shows that calcium carbonate got away and the item just became calcium oxide.

Te Efect of the Catalyst Load.
Catalyst load is seen to infuence the biodiesel yield up to a specifc concentration positively. Beyond this concentration, the biodiesel yield diminished with an increase in CaO concentration. Tis can be attributed to the fact that the amount of available catalytic active surface is crucial for shifting the reaction equilibrium forward and ethanol in the reaction mixture [29]. Ash content % 0.73 --8 Iodine value gI 2 /100 g 64.0 73 65 20.3-93.9 * * * Adopted from [19]. * * Adopted from [23]. * Adopted from [24].  International Journal of Analytical Chemistry

Statistical Investigation of the Experimental Results.
Te statistical investigation of the model has been performed to assess the analysis of variance (ANOVA). It is utilized to produce surface plots, utilizing the ftted equation obtained from the regression analysis, holding one of the autonomous variables as constant. Te central composite design (CCD) predicts values and variables that lead to accomplishing a high yield of biodiesel in actual terms. Te transesterifcation process response is used to develop a numerical model that correlates the yield of FAEE to the transesterifcation interaction factors investigated. Te Design-Expert version 11 software (Stat-Ease Inc., Minneapolis, USA) has been utilized for the regression study of the experimental data and valuation of the statistical signifcance of the equation developed.
Te typical model equation that links the response (% yield of FAEE) to the transesterifcation process factors in terms of the coded factors is given by the following equation: where, A-a reaction temperature, B-ethanol to oil ratio, Creaction time, and D-catalyst load. A.B., A.C., A.D., and B.C. are interaction efects.

Te Efect of Interaction of Process Variables on Percentage Yield of FAEE.
Te process factors have signifcant interaction efects except for ethanol's molar ratio to oil with catalyst load interaction. Te interaction result between ethanol to oil ratio and reaction time has a signifcant (p < 0.0001) result on the biodiesel yield, followed by response temperature and catalyst loading, the reaction temperature and reaction time, reaction temperature, and ethanol to oil proportion in that order, respectively. Te results obtained are presented in Figures 6-9.
As observed from Figure 6, the reaction temperature and reaction time have small interactions prior to 70°C and they have positive efects on the yield of biodiesel at 4% catalyst loading until the ethanol to oil ratio reaches 10.5 : 1. But, beyond 10.5 : 1 ethanol to oil ratio and at fxed catalyst loading, the yield of biodiesel slightly decreases due to the fact that emulsion is formed. Figure 7 shows the efect of reaction temperature and ethanol to oil ratio on biodiesel yield when the catalyst concentration is 4%. As the temperature of the reaction is increased, at lower oil to molar ratio the yield of biodiesel is also increased. Te biodiesel yield also increases as the ethanol to oil ratio increases up to an optimal level and decreases thereafter.
As can be inferred from Figure 8, upon increasing the catalyst loading from 2 to 6% with an increase of reaction temperature from 60 to 80°C, the yield of biodiesel increased substantially. Beyond this ratio, the yield of biodiesel seems to gradually decrease. Te highest yield was obtained at an ethanol to oil ratio of 10.5 : 1, reaction time of 1.375 hr, and at a reaction temperature of 70°C with 4% catalyst loading.
As indicated in Figure 9, there is an interaction efect between reaction time and ethanol to oil ratio. It can be seen that with the reaction time rising, the FAEE yield generally decreases. Te reason is that as the reaction time increases ethanol to oil ratio tends to decrease on account of conversion.

Optimization of Interaction
Variables. Te enhancement of process factors inside the chosen ranges for the maximum change from the oil to FAEE is carried out. Te optimum outcome predicted by the model is found as 91.036% at a catalyst loading of 5.802 wt.%, reaction temperature of 76.117℃, a reaction time of 1.969 hr, and ethanol to oil molar ratio of 11.55 with a desirability value of 1.000. Te improved optimization result also reveals a similar outcome as the ANOVA output. Te predicted (91.036%) and experimental output (91%) values of (biodiesel yield) under the optimum circumstances are in excellent agreement. In other cases, the minimal deviation, i.e., 0.036%, among the predicted and experimental values of % (biodiesel yield) indicates that the typical equation is suitable and adequate to forecast the biodiesel yield from the process using C. M. seed oil, ethanol, and CaO-chicken eggshell waste derived as a heterogeneous catalyst via the transesterifcation reaction process in the range of variables investigated. A comparison of the C. M. seed oil-based biodiesel properties from this study is presented in Table 3 against those of WCO biodiesel.

Analysis of FTIR for C. M. Derived Biodiesel
Characterization. FTIR has been carried out to characterize the biodiesel produced in this study from C. M. seed oil. Te spectrum obtained are shown and analyzed in Figure 10. Te frm peaks at 1745 cm −1 (C�O ester) and 1161 cm −1 (C-O ester) that are available inside the range are allotted to carbonyl functional groups; these two functional groups afrm the presence of ethyl esters and are accredited to biodiesel, and this perception is in accordance with the experimental data reported in [17,31,32]. Te observed dominant peaks represent the triglyceride functional group, which is the major component of the C. M. biodiesel. Besides, comparing the properties of biodiesel produced in this study with those specifed by international standards is illustrated in Table 4. As perceived in the table, most of the physicochemical properties of the C. M. seed oil biodiesel are in good agreement with international standard prescriptions.

Conclusion
In this study, the synthesis and optimization of biodiesel from C. M. seed oil using calcium oxide-chicken eggshell waste as a heterogeneous catalyst are investigated. Te experimental oil yield obtained from washed and dried C. M. seed oil using the solvent extraction route is 46.85% (w/w), whereas using the heating method is 19.8% (w/w). Degumming is seen to be sufcient to reduce the FFA level. Te biodiesel extracted using the transesterifcation method is characterized, and the yield from the experiments conducted has been examined by employing the design-expert software for optimizing the process yield. Te process variables revealed a signifcant interaction efect on the FAME yield based on the experimental results obtained. Reaction time and reaction temperature have a more profound efect on the FAEE yield than other process variables such as catalyst loading and ethanol to oil ratio.   International Journal of Analytical Chemistry out in the future to synthesize biodiesel at a larger scale that could have positive impacts and will generate new jobs for the poorest of local communities.

Data Availability
Te data used to support the fndings of this study are included within the article.

Conflicts of Interest
Te authors declare that they have no conficts of interest in this paper.