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Flow-mode biodiesel production from palm oil using a pressurized microwave reactor

  • Seyed Mohammad Safieddin Ardebili , Xinyu Ge and Giancarlo Cravotto EMAIL logo
Published/Copyright: February 12, 2018
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Green Processing and Synthesis
From the journal Green Processing and Synthesis Volume 8 Issue 1

Abstract

The factors that influence microwave-assisted biodiesel production reactions have been analyzed in this investigation. The studied parameters included microwave (MW) power, irradiation time, and reactor pressure. The response surface method was used to optimize the reaction conditions. The conversion for the 6:1 methanol/oil molar ratio and 1% catalyst ranged from 68.4% to 96.71%. The optimized conditions were found to be 138 s of MW irradiation at 780 W and 7 bar pressure. The conversion at this point was 97.82%. Biodiesel yield increased at higher radiation times (90–130 s) and pressures (5–7 bar). Results show that MW power and irradiation time have significant effects at the 1% level, whereas pressure had significant effects at the 5% level on biodiesel production in this range. The major properties of the palm oil biodiesel produced herein have met the requirements of the EN 14214 methyl ester standard.

Keywords: biodiesel; flow process; microwave-assisted transesterification; pressurized microwave reactor; response surface method

1 Introduction

Energy is a basic need for humankind. Pollution from fossil fuels has led to global warming and climate change [1], [2]. Biodiesel is a methyl/ethyl ester produced from vegetable oils or animal fat, which can be used as fuel in diesel engines or thermal systems [3]. Biodiesel can be extracted from waste vegetable oils as well as from straight vegetable oils [4], [5].

We have compared classic biodiesel production by transesterification under conventional heating with processes in loop reactors, as assisted by ultrasound [6], [7], hydrodynamic cavitation [8], and continuous-flow microwaves (MW) [9], [10]. It was found that efficient heat and mass transfer and catalyst loading significantly influence the transesterification rate [11]. Hybrid reactors that combine acoustic cavitation and dielectric heating have therefore proven themselves to be highly efficient [12], [13].

MW heating significantly enhances transesterification, whereas volumetric heating provides several advantages, such as smaller reacting vessel, shorter reaction times, lower alcohol/oil ratios, and energy savings [13], [14], [15]. MW-assisted biodiesel production has been reported both under basic [16] and acid catalysis [17], but has also been carried out under heterogeneous catalysts [18] and in enzymatic processes [19]. Furthermore, fast conversions (94%) have been obtained in 30 s of irradiation (800 W) in a 9:1 molar ratio and oil/sodium hydroxide (1%) [20]. Several other studies have demonstrated the advantages of dielectric heating in waste oil transesterification [21], [22], [23], [24].

The economic aspects have been reported in another study; 3 min were required to produce 1:6 molar ratio biodiesel under 750 W MW exposure. In fact, the results showed that MW-assisted biodiesel production (as a fuel for power generators) is cost-effective [25]. The studied parameters included MW irradiation time, reaction time, and MW power. The response surface method (RSM) was used to optimize the reaction conditions [26], [27], [28], [29].

2 Materials and methods

2.1 Materials

Palm oil, supplied by Oilitalia Co. Ltd. (Italy), was used as the raw material for biodiesel production. The GC-MS analyses of palm oils are shown in Figure 1. Methanol (99.9%), potassium hydroxide flakes (85%), and n-heptanes were obtained from Sigma-Aldrich (Milan, Italy) and used without further purification.

Figure 1: Palm oil fatty acids profile.
Figure 1:

Palm oil fatty acids profile.

2.2 Equipment

The transesterification reaction was performed under MW irradiation using sodium methoxide as the catalyst. The catalyst solution was prepared using a magnetic stirrer. The experimental setup consisted of a continuous-flow MW reactor apparatus (Milestone FlowSynth). Figure 2 shows the setup that was used in this work.

Figure 2: Continuous-flow MW reactor for biodiesel production.
Figure 2:

Continuous-flow MW reactor for biodiesel production.

This system incorporated a variable-power MW oven that could control temperature, MW power, and pressure inside the reactor. The maximum working temperature of the system was 200°C. The reactor was equipped with a 250 ml cylindrical polytetrafluoroethylene vessel with an internal rotating mixer. The reaction mixture was pumped through the reactor. The maximum working pressure was 30 bar and the flow rate was 100 ml/min. The effects of MW power (200–1000 W), MW irradiation time (60–180 s), and reaction pressure (5–15 bar) were evaluated in this work.

A 6:1 molar ratio and 1% catalyst loading were selected. The tests were primarily carried out under software-recommended conditions. All samples were then exposed to 6000 rpm of centrifugal motion for 5 min to separate the biodiesel phase. Methyl ester content (%) in biodiesel was measured using Equation 1. The free fatty acid content of samples was determined using methyl heptadecanoate and normal heptane solutions [22]:

(1)% of ME=∑A−AEIAEI×CEI×VEIm×100

ΣA=total peak area from the methyl ester on C14 to the one on C24

AEI= methyl heptadecanoate peak area

CEI=methyl heptadecanoate solution concentration (mg/ml)

VEI=methyl heptadecanoate solution volume (ml)

m=mass of the sample (mg).

The glycerin phase was separated from the biodiesel, which was then leached. All experimental conditions were investigated three times and mean values were entered into the software.

2.3 Experimental design

RSM is an effective statistical method used to study complex processes with no fully known mechanism. The relationship between independent variables and responses was determined using the central composite design with three replications. The central composite design provides the advantage of requiring fewer experiments [30]. Design Expert 7.0.0 was used for RSM data analysis purposes. This method was adopted due to the ease with which the catalyst content (%) could be selected. After carrying out the experiments and calculating reaction efficiency, the optimal points of the process were obtained by selecting the proper weights and variation ranges. The corresponding values were then evaluated by repeating the experiment at the recommended optimal point. After finding the optimum conditions, the effective parameters for the transesterification reaction were analyzed in this state. Biodiesel production efficiency was selected as the response parameter. Study variables and levels are presented in Table 1.

Table 1:

Independent variables for central composite design (CCD).

Codes factor levelsXiIndependent variable
−α−10+1+α
6090120150180X1MW irradation time (S)
2581114X2Pressure (bar)
2004006008001000X2MW power (W)

The operating pressure conditions are a continuation of those from Choedkiatsakul et al. [9], as the temperature maximum described in their article is related to the minimum pressure used in this investigation.

Once data were entered into the software, the second-order model was fitted to find the relationship between the response variable (biodiesel efficiency) and the independent variable. The general form of the second-order polynomial equation is expressed by Equation 2.

(2)Y=β0+∑i=1kβiXi+∑i=1kβiiXi2+∑i=1k∑j=i+1kβijXiXj+ε

where Y is the response (dependent variable), which is the biodiesel conversion percentage in this case, β0 is a constant, βi, βij, and βij are the linear and square coefficients and the mutual effect of parameters, respectively, whereas ε denotes the prediction error. Xi and Xj are the independent variables: MW irradiation time, pressure, and MW power in this case [31].

3 Results and discussion

3.1 Experimental design and statistical analysis

The effect that a number of parameters (namely, MW irradiation time, power, and reaction pressure) have on the transesterification reaction and the MW-assisted production efficiency of methyl esters has been investigated in this study. Twenty experiments with three replications were required to optimize the chemical parameters of the reaction, using RSM for three parameters at five levels. Table 2 presents the empirical results of the experiments. The conversion for 6:1 molar ratio and 1% catalyst ranged from 68.4% to 96.71%.

Table 2:

Central composite design for three-factor coded conditions.

RunStdMicrowave irradiation time (s)Pressure (bar)Power (W)Conversion (%)
11300−268.4
21600096.08
31700092.84
41400296.71
5811196.02
63−11−177.21
71−1−1−175.06
81900094.02
961−1194.05
10411−184.1
112000092.03
12110−2089.34
137−11192.81
145−1−1189.03
151500093.92
1621−1−182.79
171202096.18
181800094.71
199−20085.2
201020090.15

Analysis of variance (ANOVA) results show that the effects of MW irradiation time and power were significant at the 1% level of significance, as seen in Table 3. These significant effects indicate how important and effective the selected independent variables are for the experiments. ANOVA was selected to analyze the significant effects of the process variables on the response. As shown in the ANOVA table, the lack-of-fit test was nonsignificant for the study data. This indicates that the model predicted the data trends well [26].

Table 3:

ANOVA for coefficients of the RSM.

SourcedfSum of squareMean squareF valuep-Value
Model91134.19126.0221.67<0.0001
X1167.0467.0411.530.0068
X2132.6932.695.620.0392
X31747.61747.61128.57<0.0001
X2×X110.880.880.150.7058
X2×X115.105.100.880.3709
X2×X310.660.660.110.7440
X12183.5983.5914.370.0035
X2217.707.701.320.2767
X321242.14242.1441.64<0.0001
Residual1058.155.81
Lack of fit548.119.624.790.0552
Pure error510.042.0120.82<0.0001
Total191194.04125.9511.080.0076

  1. Significant values are boldface.

The statistical significance of both effects (power and irradiation time) suggest that the selected independent variables were effective in the experiments. Other reports have also mentioned the importance of these variables and also confirm the findings of this present study [20]. The polynomial second-order model for response prediction was obtained using multivariate regression analysis. Equation 3 is a polynomial second-order equation, based on the chosen variables, which was developed using the multiple regression analysis of empirical data.

(3)Conversion (%)=93.39+2.05 X1+1.43 X2+6.84 X3− 1.83 X12−3.11 X32

Equation 3 suggests that palm oil conversion percentage has a linear second-order relationship with the selected parameters. Positive signs indicate synergic effects and negative signs denote antagonistic effects (i.e. negative effect on conversion percentage). The coefficient of correlation (R2=0.95) highlights the close relationship between the empirical results and those predicted by the model. These results were similar to those reported in previous studies [20], [32], [33].

According to the results, the effect of MW power on biodiesel production is higher than that of irradiation time and reaction pressure. The effect of reaction pressure on biodiesel production was significant (p<0.05). Increased pressure raised the boiling point of methanol. This helped to keep the methanol in a liquid state during the reaction. Increasing the pressure also slightly increased the number of molecules per volume unit, which in turn gave rise to more collisions. This contributed further to the reaction progress. According to Table 3, the second-order model is statistically significant (p<0.0001). Pressure-power, time-power, and time-pressure interactions were not significant. The RSM diagram of the dependent variable (reaction efficiency) against power and time variations displays contour lines and interactions in a three-dimensional (3D) presentation.

However, as shown in Figure 3B, efficiency initially improved and then declined with increasing pressure in the selected range. This is due to the reversibility of the reaction. It can be observed that the reaction efficiency increases initially (Figure 3A). However, the reaction tends to shift to the left side of the equilibrium, thus reducing the conversion at high MW irradiation time and power. These diagrams show that conversion decreased drastically at longer times, regardless of power level. This may be due to methanol evaporation and its removal from the reaction environment. The study’s findings are in complete agreement with the results in the literature [34].

Figure 3: (A) Two-dimensional (2D) and (B) 3D interaction between MW irradiation time and power on FAME conversion.
Figure 3:

(A) Two-dimensional (2D) and (B) 3D interaction between MW irradiation time and power on FAME conversion.

Several authors have reported that MW-assisted biodiesel production is effective due to the combination of exothermicity and the intrinsic properties of dielectric heating. It cannot be said with certainty which has the greatest effect. Nevertheless, the methanol involved in the reaction absorbed MW fairly well. The bipolar properties of methanol caused its molecules to rotate, when exposed to MW exposure, which led to a larger contact surface area between oil and alcohol molecules and thus a faster reaction [13], [15], [20], [35].

Results in Figure 4A indicate that the reagents are exposed to more irradiation at longer reaction times, which accordingly increases the effect of MW on the reaction environment. Transesterification is an equilibrium reaction, meaning that decreased amounts of reagents in the reaction environment lead to reserved reaction and decreases the conversion. Reaction efficiency initially increases and then decreases when irradiation time was extended. Glycerin and methanol are both polar and dissolve in each other, meaning that more methanol is dissolved when more glycerin is produced over a longer time period. This methanol is no longer available for the reaction, causing the reaction to revert to producing methanol, which decreases the total reaction efficiency (Figure 4B). The results indicate that there are a wide range of conditions under which efficiencies higher than 96%, which are required for producing standard biodiesel (Figures 3 and 4), can be reached. As shown in Figure 5A, the model predicted a reaction efficiency of 97% at 700 W MW power for 8 bar pressure under the central pressure point.

Figure 4: (A) 2D and (B) 3D interaction effect of MW irradiation time and pressure on FAME conversion.
Figure 4:

(A) 2D and (B) 3D interaction effect of MW irradiation time and pressure on FAME conversion.

Figure 5: (A) 2D and (B) 3D interaction effect of MW power and pressure on FAME conversion.
Figure 5:

(A) 2D and (B) 3D interaction effect of MW power and pressure on FAME conversion.

The optimized process occurred at 138 s of irradiation at 780 W under 7 bar pressure. The conversion at this point was 97.82%. An analysis on this optimal point showed a 96.08% conversion, which is slightly lower than the efficiency obtained (Figure 5B). Previous studies into the consecutive application of MW and ultrasound reported a process time of 30 min. Furthermore, the reported conversion percentage (98.8) and reaction time (30 min) in those studies were lower than those reported in this study [36]. Reaction time (2 min) was also shorter than in other similar studies (5, 4.5 and 6.5 min) [31], [37], [38].

The physical characteristics of the fatty acid methyl esters (FAME) produced from rapeseed and waste oil are compared and contrasted with those of palm oil in Table 4. All the specifications mentioned are then compared with EN 14214 biodiesel standards. The results show that palm methyl esters meet EN 14214 requirements for biodiesel. Viscosity plays an important role in the typicality of the performance of diesel engine [41]. There are reports on the properties, including viscosity, specific gravity, cetane number, iodine value, and freezing point of the different possible sources for biodiesel, the results of which show that kinematic viscosity ranged between 4 and 5 mm2/s [39], whereas the specific gravity of the methyl esters varied between 0.873 and 0.883. The palm oil in the present work was within the range of parameters that other researchers have obtained [39], [42]. Comparing the results reported in Table 4 with the other results [43], it can be concluded that biodiesel produced from palm oil has a higher viscosity than others. The kinematic viscosity of palm oil was lower than that of waste oil but higher than rapeseed oil. According to Table 4, rapeseed oil had the highest density, whereas waste oils have the lowest density. The results in the Table 4 also showed that the flash point of palm oil is higher than the others and that the kinematic viscosity of palm oil is lower than that of waste oil and higher than rapeseed oil. In Table 4, rapeseed oil has the highest density, whereas the lowest density belongs to waste oil.

Table 4:

Comparison of biodiesel produced from palm oil, rapeseed oil, and waste oil.

SpecificationsStandard method of testWaste oil [39]Rapeseed oil [40]Palm oil [9]Unit
Flash pointASTM D92176170179°C
Kinematic viscosityASTM D4454.734.014.62mm2/s
DensityASTM D129880900–930860kg/m3

3.2 Validation experiments

In this study, the conditions of the transesterification reaction under MW irradiation have been studied to optimize biodiesel production efficiency. RSM analyses predicted the optimal point for 96.82% efficiency as follows: 138 s MW irradiation, 7 bar pressure, and 780 W power. Experiments were performed at the RSM-predicted optimal points. Reaction efficiency was 96.71%, which is slightly lower than the model-predicted value. However, this error, which may have been caused by instruments or the operator, was acceptable according to the ANOVA table and significance (p<0.05).

4 Conclusions

RSM has been used to optimize the transesterification reaction conditions for palm oil under MW irradiation. RSM was used to optimize the transesterification reaction conditions for palm oil, which was exposed to pressure and MW irradiation. The MW heating effect had a significant effect on the conversion, which was improved by the ionic rotation phenomenon and dipole rotation. Results suggest that MW power and irradiation time have a significant influence on biodiesel production, at the 1% level, whereas pressure had significant effects at the 5% level. Our findings suggest that there are a wide range of experimental conditions under which 96% efficiency for palm oil transesterification can be achieved. Moreover, increased power and longer irradiation times initially drive the reaction toward producing methyl esters before reaching the optimal point, after which reaction efficiency decreases due to reaction reversibility. The reaction time (138 s; 96.71% yield) was considerably shorter than in conventional processes (1 h) and sonochemical methods (5 min) [7]. In this work, the total energy consumption (measuring by plug-in meter) for FAME preparation in a pressurized, flow-microwave reactor, was much lower than in conventional processes at 0.88 MJ/l [DMH pump (0.64 MJ/l), dielectric heating and mechanical stirrer (0.24 MJ/l)] vs. 1.92 MJ/l (400 W heating and mechanical stirrer for 40 min). Biodiesel from all samples fully complied with ASTM D6751 recommendations.

Acknowledgements

This work was supported by the University of Turin (fondi ricerca locale ex-60% 2015). The authors also wish to thank the Shahid Chamran University of Ahvaz for supporting part of this investigation.

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Received: 2017-08-03
Accepted: 2017-12-14
Published Online: 2018-02-12
Published in Print: 2019-01-28

©2019 Walter de Gruyter GmbH, Berlin/Boston

This work is licensed under the Creative Commons Attribution 4.0 Public License.

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  39. A highly efficient and multifunctional biomass supporting Ag, Ni, and Cu nanoparticles through wetness impregnation for environmental remediation
  40. Simple one-pot green method for large-scale production of mesalamine, an anti-inflammatory agent
  41. Relationships between step and cumulative PMI and E-factors: implications on estimating material efficiency with respect to charting synthesis optimization strategies
  42. A comparative sorption study of Cr3+ and Cr6+ using mango peels: kinetic, equilibrium and thermodynamic
  43. Effects of acid hydrolysis waste liquid recycle on preparation of microcrystalline cellulose
  44. Use of deep eutectic solvents as catalyst: A mini-review
  45. Microwave-assisted synthesis of pyrrolidinone derivatives using 1,1’-butylenebis(3-sulfo-3H-imidazol-1-ium) chloride in ethylene glycol
  46. Green and eco-friendly synthesis of Co3O4 and Ag-Co3O4: Characterization and photo-catalytic activity
  47. Adsorption optimized of the coal-based material and application for cyanide wastewater treatment
  48. Aloe vera leaf extract mediated green synthesis of selenium nanoparticles and assessment of their In vitro antimicrobial activity against spoilage fungi and pathogenic bacteria strains
  49. Waste phenolic resin derived activated carbon by microwave-assisted KOH activation and application to dye wastewater treatment
  50. Direct ethanol production from cellulose by consortium of Trichoderma reesei and Candida molischiana
  51. Agricultural waste biomass-assisted nanostructures: Synthesis and application
  52. Biodiesel production from rubber seed oil using calcium oxide derived from eggshell as catalyst – optimization and modeling studies
  53. Study of fabrication of fully aqueous solution processed SnS quantum dot-sensitized solar cell
  54. Assessment of aqueous extract of Gypsophila aretioides for inhibitory effects on calcium carbonate formation
  55. An environmentally friendly acylation reaction of 2-methylnaphthalene in solvent-free condition in a micro-channel reactor
  56. Aegle marmelos phytochemical stabilized synthesis and characterization of ZnO nanoparticles and their role against agriculture and food pathogen
  57. A reactive coupling process for co-production of solketal and biodiesel
  58. Optimization of the asymmetric synthesis of (S)-1-phenylethanol using Ispir bean as whole-cell biocatalyst
  59. Synthesis of pyrazolopyridine and pyrazoloquinoline derivatives by one-pot, three-component reactions of arylglyoxals, 3-methyl-1-aryl-1H-pyrazol-5-amines and cyclic 1,3-dicarbonyl compounds in the presence of tetrapropylammonium bromide
  60. Preconcentration of morphine in urine sample using a green and solvent-free microextraction method
  61. Extraction of glycyrrhizic acid by aqueous two-phase system formed by PEG and two environmentally friendly organic acid salts - sodium citrate and sodium tartrate
  62. Green synthesis of copper oxide nanoparticles using Juglans regia leaf extract and assessment of their physico-chemical and biological properties
  63. Deep eutectic solvents (DESs) as powerful and recyclable catalysts and solvents for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones
  64. Biosynthesis, characterization and anti-microbial activity of silver nanoparticle based gel hand wash
  65. Efficient and selective microwave-assisted O-methylation of phenolic compounds using tetramethylammonium hydroxide (TMAH)
  66. Anticoagulant, thrombolytic and antibacterial activities of Euphorbia acruensis latex-mediated bioengineered silver nanoparticles
  67. Volcanic ash as reusable catalyst in the green synthesis of 3H-1,5-benzodiazepines
  68. Green synthesis, anionic polymerization of 1,4-bis(methacryloyl)piperazine using Algerian clay as catalyst
  69. Selenium supplementation during fermentation with sugar beet molasses and Saccharomyces cerevisiae to increase bioethanol production
  70. Biosynthetic potential assessment of four food pathogenic bacteria in hydrothermally silver nanoparticles fabrication
  71. Investigating the effectiveness of classical and eco-friendly approaches for synthesis of dialdehydes from organic dihalides
  72. Pyrolysis of palm oil using zeolite catalyst and characterization of the boil-oil
  73. Azadirachta indica leaves extract assisted green synthesis of Ag-TiO2 for degradation of Methylene blue and Rhodamine B dyes in aqueous medium
  74. Synthesis of vitamin E succinate catalyzed by nano-SiO2 immobilized DMAP derivative in mixed solvent system
  75. Extraction of phytosterols from melon (Cucumis melo) seeds by supercritical CO2 as a clean technology
  76. Production of uronic acids by hydrothermolysis of pectin as a model substance for plant biomass waste
  77. Biofabrication of highly pure copper oxide nanoparticles using wheat seed extract and their catalytic activity: A mechanistic approach
  78. Intelligent modeling and optimization of emulsion aggregation method for producing green printing ink
  79. Improved removal of methylene blue on modified hierarchical zeolite Y: Achieved by a “destructive-constructive” method
  80. Two different facile and efficient approaches for the synthesis of various N-arylacetamides via N-acetylation of arylamines and straightforward one-pot reductive acetylation of nitroarenes promoted by recyclable CuFe2O4 nanoparticles in water
  81. Optimization of acid catalyzed esterification and mixed metal oxide catalyzed transesterification for biodiesel production from Moringa oleifera oil
  82. Kinetics and the fluidity of the stearic acid esters with different carbon backbones
  83. Aiming for a standardized protocol for preparing a process green synthesis report and for ranking multiple synthesis plans to a common target product
  84. Microstructure and luminescence of VO2 (B) nanoparticle synthesis by hydrothermal method
  85. Optimization of uranium removal from uranium plant wastewater by response surface methodology (RSM)
  86. Microwave drying of nickel-containing residue: dielectric properties, kinetics, and energy aspects
  87. Simple and convenient two step synthesis of 5-bromo-2,3-dimethoxy-6-methyl-1,4-benzoquinone
  88. Biodiesel production from waste cooking oil
  89. The effect of activation temperature on structure and properties of blue coke-based activated carbon by CO2 activation
  90. Optimization of reaction parameters for the green synthesis of zero valent iron nanoparticles using pine tree needles
  91. Microwave-assisted protocol for squalene isolation and conversion from oil-deodoriser distillates
  92. Denitrification performance of rare earth tailings-based catalysts
  93. Facile synthesis of silver nanoparticles using Averrhoa bilimbi L and Plum extracts and investigation on the synergistic bioactivity using in vitro models
  94. Green production of AgNPs and their phytostimulatory impact
  95. Photocatalytic activity of Ag/Ni bi-metallic nanoparticles on textile dye removal
  96. Topical Issue: Green Process Engineering / Guest Editors: Martine Poux, Patrick Cognet
  97. Modelling and optimisation of oxidative desulphurisation of tyre-derived oil via central composite design approach
  98. CO2 sequestration by carbonation of olivine: a new process for optimal separation of the solids produced
  99. Organic carbonates synthesis improved by pervaporation for CO2 utilisation
  100. Production of starch nanoparticles through solvent-antisolvent precipitation in a spinning disc reactor
  101. A kinetic study of Zn halide/TBAB-catalysed fixation of CO2 with styrene oxide in propylene carbonate
  102. Topical on Green Process Engineering
https://doi.org/10.1515/gps-2017-0116
Keywords for this article
biodiesel; flow process; microwave-assisted transesterification; pressurized microwave reactor; response surface method
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BY 4.0

Articles in the same Issue

  1. Regular Articles
  2. Studies on the preparation and properties of biodegradable polyester from soybean oil
  3. Flow-mode biodiesel production from palm oil using a pressurized microwave reactor
  4. Reduction of free fatty acids in waste oil for biodiesel production by glycerolysis: investigation and optimization of process parameters
  5. Saccharin: a cheap and mild acidic agent for the synthesis of azo dyes via telescoped dediazotization
  6. Optimization of lipase-catalyzed synthesis of polyethylene glycol stearate in a solvent-free system
  7. Green synthesis of iron oxide nanoparticles using Platanus orientalis leaf extract for antifungal activity
  8. Ultrasound assisted chemical activation of peanut husk for copper removal
  9. Room temperature silanization of Fe3O4 for the preparation of phenyl functionalized magnetic adsorbent for dispersive solid phase extraction for the extraction of phthalates in water
  10. Evaluation of the saponin green extraction from Ziziphus spina-christi leaves using hydrothermal, microwave and Bain-Marie water bath heating methods
  11. Oxidation of dibenzothiophene using the heterogeneous catalyst of tungsten-based carbon nanotubes
  12. Calcined sodium silicate as an efficient and benign heterogeneous catalyst for the transesterification of natural lecithin to L-α-glycerophosphocholine
  13. Synergistic effect between CO2 and H2O2 on ethylbenzene oxidation catalyzed by carbon supported heteropolyanion catalysts
  14. Hydrocyanation of 2-arylmethyleneindan-1,3-diones using potassium hexacyanoferrate(II) as a nontoxic cyanating agent
  15. Green synthesis of hydratropic aldehyde from α-methylstyrene catalyzed by Al2O3-supported metal phthalocyanines
  16. Environmentally benign chemical recycling of polycarbonate wastes: comparison of micro- and nano-TiO2 solid support efficiencies
  17. Medicago polymorpha-mediated antibacterial silver nanoparticles in the reduction of methyl orange
  18. Production of value-added chemicals from esterification of waste glycerol over MCM-41 supported catalysts
  19. Green synthesis of zerovalent copper nanoparticles for efficient reduction of toxic azo dyes congo red and methyl orange
  20. Optimization of the biological synthesis of silver nanoparticles using Penicillium oxalicum GRS-1 and their antimicrobial effects against common food-borne pathogens
  21. Optimization of submerged fermentation conditions to overproduce bioethanol using two industrial and traditional Saccharomyces cerevisiae strains
  22. Extraction of In3+ and Fe3+ from sulfate solutions by using a 3D-printed “Y”-shaped microreactor
  23. Foliar-mediated Ag:ZnO nanophotocatalysts: green synthesis, characterization, pollutants degradation, and in vitro biocidal activity
  24. Green cyclic acetals production by glycerol etherification reaction with benzaldehyde using cationic acidic resin
  25. Biosynthesis, characterization and antimicrobial activities assessment of fabricated selenium nanoparticles using Pelargonium zonale leaf extract
  26. Synthesis of high surface area magnesia by using walnut shell as a template
  27. Controllable biosynthesis of silver nanoparticles using actinobacterial strains
  28. Green vegetation: a promising source of color dyes
  29. Mechano-chemical synthesis of ammonia and acetic acid from inorganic materials in water
  30. Green synthesis and structural characterization of novel N1-substituted 3,4-dihydropyrimidin-2(1H)-ones
  31. Biodiesel production from cotton oil using heterogeneous CaO catalysts from eggshells prepared at different calcination temperatures
  32. Regeneration of spent mercury catalyst for the treatment of dye wastewater by the microwave and ultrasonic spray-assisted method
  33. Green synthesis of the innovative super paramagnetic nanoparticles from the leaves extract of Fraxinus chinensis Roxb and their application for the decolourisation of toxic dyes
  34. Biogenic ZnO nanoparticles: a study of blueshift of optical band gap and photocatalytic degradation of reactive yellow 186 dye under direct sunlight
  35. Leached compounds from the extracts of pomegranate peel, green coconut shell, and karuvelam wood for the removal of hexavalent chromium
  36. Enhancement of molecular weight reduction of natural rubber in triphasic CO2/toluene/H2O systems with hydrogen peroxide for preparation of biobased polyurethanes
  37. An efficient green synthesis of novel 1H-imidazo[1,2-a]imidazole-3-amine and imidazo[2,1-c][1,2,4]triazole-5-amine derivatives via Strecker reaction under controlled microwave heating
  38. Evaluation of three different green fabrication methods for the synthesis of crystalline ZnO nanoparticles using Pelargonium zonale leaf extract
  39. A highly efficient and multifunctional biomass supporting Ag, Ni, and Cu nanoparticles through wetness impregnation for environmental remediation
  40. Simple one-pot green method for large-scale production of mesalamine, an anti-inflammatory agent
  41. Relationships between step and cumulative PMI and E-factors: implications on estimating material efficiency with respect to charting synthesis optimization strategies
  42. A comparative sorption study of Cr3+ and Cr6+ using mango peels: kinetic, equilibrium and thermodynamic
  43. Effects of acid hydrolysis waste liquid recycle on preparation of microcrystalline cellulose
  44. Use of deep eutectic solvents as catalyst: A mini-review
  45. Microwave-assisted synthesis of pyrrolidinone derivatives using 1,1’-butylenebis(3-sulfo-3H-imidazol-1-ium) chloride in ethylene glycol
  46. Green and eco-friendly synthesis of Co3O4 and Ag-Co3O4: Characterization and photo-catalytic activity
  47. Adsorption optimized of the coal-based material and application for cyanide wastewater treatment
  48. Aloe vera leaf extract mediated green synthesis of selenium nanoparticles and assessment of their In vitro antimicrobial activity against spoilage fungi and pathogenic bacteria strains
  49. Waste phenolic resin derived activated carbon by microwave-assisted KOH activation and application to dye wastewater treatment
  50. Direct ethanol production from cellulose by consortium of Trichoderma reesei and Candida molischiana
  51. Agricultural waste biomass-assisted nanostructures: Synthesis and application
  52. Biodiesel production from rubber seed oil using calcium oxide derived from eggshell as catalyst – optimization and modeling studies
  53. Study of fabrication of fully aqueous solution processed SnS quantum dot-sensitized solar cell
  54. Assessment of aqueous extract of Gypsophila aretioides for inhibitory effects on calcium carbonate formation
  55. An environmentally friendly acylation reaction of 2-methylnaphthalene in solvent-free condition in a micro-channel reactor
  56. Aegle marmelos phytochemical stabilized synthesis and characterization of ZnO nanoparticles and their role against agriculture and food pathogen
  57. A reactive coupling process for co-production of solketal and biodiesel
  58. Optimization of the asymmetric synthesis of (S)-1-phenylethanol using Ispir bean as whole-cell biocatalyst
  59. Synthesis of pyrazolopyridine and pyrazoloquinoline derivatives by one-pot, three-component reactions of arylglyoxals, 3-methyl-1-aryl-1H-pyrazol-5-amines and cyclic 1,3-dicarbonyl compounds in the presence of tetrapropylammonium bromide
  60. Preconcentration of morphine in urine sample using a green and solvent-free microextraction method
  61. Extraction of glycyrrhizic acid by aqueous two-phase system formed by PEG and two environmentally friendly organic acid salts - sodium citrate and sodium tartrate
  62. Green synthesis of copper oxide nanoparticles using Juglans regia leaf extract and assessment of their physico-chemical and biological properties
  63. Deep eutectic solvents (DESs) as powerful and recyclable catalysts and solvents for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones
  64. Biosynthesis, characterization and anti-microbial activity of silver nanoparticle based gel hand wash
  65. Efficient and selective microwave-assisted O-methylation of phenolic compounds using tetramethylammonium hydroxide (TMAH)
  66. Anticoagulant, thrombolytic and antibacterial activities of Euphorbia acruensis latex-mediated bioengineered silver nanoparticles
  67. Volcanic ash as reusable catalyst in the green synthesis of 3H-1,5-benzodiazepines
  68. Green synthesis, anionic polymerization of 1,4-bis(methacryloyl)piperazine using Algerian clay as catalyst
  69. Selenium supplementation during fermentation with sugar beet molasses and Saccharomyces cerevisiae to increase bioethanol production
  70. Biosynthetic potential assessment of four food pathogenic bacteria in hydrothermally silver nanoparticles fabrication
  71. Investigating the effectiveness of classical and eco-friendly approaches for synthesis of dialdehydes from organic dihalides
  72. Pyrolysis of palm oil using zeolite catalyst and characterization of the boil-oil
  73. Azadirachta indica leaves extract assisted green synthesis of Ag-TiO2 for degradation of Methylene blue and Rhodamine B dyes in aqueous medium
  74. Synthesis of vitamin E succinate catalyzed by nano-SiO2 immobilized DMAP derivative in mixed solvent system
  75. Extraction of phytosterols from melon (Cucumis melo) seeds by supercritical CO2 as a clean technology
  76. Production of uronic acids by hydrothermolysis of pectin as a model substance for plant biomass waste
  77. Biofabrication of highly pure copper oxide nanoparticles using wheat seed extract and their catalytic activity: A mechanistic approach
  78. Intelligent modeling and optimization of emulsion aggregation method for producing green printing ink
  79. Improved removal of methylene blue on modified hierarchical zeolite Y: Achieved by a “destructive-constructive” method
  80. Two different facile and efficient approaches for the synthesis of various N-arylacetamides via N-acetylation of arylamines and straightforward one-pot reductive acetylation of nitroarenes promoted by recyclable CuFe2O4 nanoparticles in water
  81. Optimization of acid catalyzed esterification and mixed metal oxide catalyzed transesterification for biodiesel production from Moringa oleifera oil
  82. Kinetics and the fluidity of the stearic acid esters with different carbon backbones
  83. Aiming for a standardized protocol for preparing a process green synthesis report and for ranking multiple synthesis plans to a common target product
  84. Microstructure and luminescence of VO2 (B) nanoparticle synthesis by hydrothermal method
  85. Optimization of uranium removal from uranium plant wastewater by response surface methodology (RSM)
  86. Microwave drying of nickel-containing residue: dielectric properties, kinetics, and energy aspects
  87. Simple and convenient two step synthesis of 5-bromo-2,3-dimethoxy-6-methyl-1,4-benzoquinone
  88. Biodiesel production from waste cooking oil
  89. The effect of activation temperature on structure and properties of blue coke-based activated carbon by CO2 activation
  90. Optimization of reaction parameters for the green synthesis of zero valent iron nanoparticles using pine tree needles
  91. Microwave-assisted protocol for squalene isolation and conversion from oil-deodoriser distillates
  92. Denitrification performance of rare earth tailings-based catalysts
  93. Facile synthesis of silver nanoparticles using Averrhoa bilimbi L and Plum extracts and investigation on the synergistic bioactivity using in vitro models
  94. Green production of AgNPs and their phytostimulatory impact
  95. Photocatalytic activity of Ag/Ni bi-metallic nanoparticles on textile dye removal
  96. Topical Issue: Green Process Engineering / Guest Editors: Martine Poux, Patrick Cognet
  97. Modelling and optimisation of oxidative desulphurisation of tyre-derived oil via central composite design approach
  98. CO2 sequestration by carbonation of olivine: a new process for optimal separation of the solids produced
  99. Organic carbonates synthesis improved by pervaporation for CO2 utilisation
  100. Production of starch nanoparticles through solvent-antisolvent precipitation in a spinning disc reactor
  101. A kinetic study of Zn halide/TBAB-catalysed fixation of CO2 with styrene oxide in propylene carbonate
  102. Topical on Green Process Engineering
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