Min Reaction Time Research Articles

Production of highly antioxidant lignin nanoparticles from a hardwood technical lignin

Eucalypt kraft lignin isolated in a LignoBoost™ pilot plant was characterized by GC–MS, ICP-OES, DSC, HPSEC, 31P NMR, and HSQC 2D-NMR to be used without any further processing to produce lignin nanoparticles (LNPs) by nanoprecipitation. Tetrahydrofuran (THF) was used as a solvent, and water as a non-solvent. Microscopic analysis (TEM) showed that LNPs were regularly spherical with some hollow particles dispersed in-between, and sizes were tunable by changing the solvent dripping rate onto the non-solvent. LNP particle sizes had a bimodal distribution, with the largest population having an average apparent hydrodynamic diameter ranging from 105.6 to 75.6 nm. Colloidal dispersions of LNPs in water presented good stability in different dilutions without significant size changes upon storage at pH close to neutral for as long as 45 days. Zeta potentials around −40 mV were obtained for LNP suspensions at pH ranging from 7 to 9. The high carbohydrate content (circa 10 % on a dry basis, mostly xylans) of the lignin precursor did not interfere in LNP formation, whose antioxidant activity was expressive as demonstrated by the ABTS assay at pH 7.4, with an EC50 of 4.04 μg mL−1. Also, the Trolox® equivalent antioxidant capacity (TEAC) of LNPs reached 1.90 after 40 min reaction time.

Valorization of marine fishmeal industry oil as feedstock and calcined shrimp and crab shells as catalysts for production of biodiesels and evaluation of their fuel properties, engine combustion, performance and gas emission characteristics

The current investigation aims on valorization of marine fishmeal industry oil as alternate feedstock for biodiesel production using waste crustacean shell derived catalysts such as calcined shrimp shell (SSBD) at 1:12 oil-to-methanol molar ratio, 5 wt% catalyst dosage, 65 °C temperature, and 120 min reaction time and calcined crab shell (CSBD) at 1:9 oil-to-methanol molar ratio, 3 wt% catalyst concentration, 60 °C temperature and 60 min time, and validate their authenticity for application in diesel engine by evaluating engine performance, combustion, and gas emission characteristics. The SSBD and CSBD yield of 88.74 wt% and 87.47 wt% was obtained at 50 L biodiesel production. The fuel properties of SSBD and CSBD blends (B5, B20, and B50) ensured their application in diesel engine. The brake specific fuel consumption and brake thermal efficiency values for all SSBD and CSBD blends didn’t exhibit major deviation than diesel at 11.93 kW engine load, and ranged from 0.23 to 0.25 kg/kWh and 31.58–36.17%, respectively. Among all blends, the B50 blend of SSBD and CSBD reduced CO, CO2, and HC emissions up to 74.72% and 86.81%, 13.11% and 16.63%, and 35.09% and 58.54%, respectively. Overall, SSBD and CSBD produced using alternate novel feedstock and catalyst could pave way to meet energy demand and sustainable biodiesel production.

Upgrading Pyrolysis Bio-Oil through Esterification Process and Assessing the Performance and Emissions of Diesel-Biodiesel-Esterified Pyrolysis Bio-Oil Blends in Direct Injection Diesel Engines.

This research aimed to evaluate the performance and emissions of direct injection diesel engines using blends of diesel-biodiesel-esterified pyrolysis bio-oil (D-B-EPB). The pyrolysis process was employed to produce pyrolysis bio-oil (PBO) from solid biomass obtained from fresh palm fruits. Furthermore, a simple and effective esterification process was used to upgrade the PBO. The methyl ester (ME) purity of EPB production was studied to optimize three independent variables: methanol (14.8-65.2 wt %), sulfuric acid (1.6-18.4 wt %), and reaction time (16-84 min) using the response surface methodology. The actual experiment yielded a ME purity of 72.73 wt % under the recommended conditions of 40.3 wt % methanol, 13.0 wt % sulfuric acid, 50 min reaction time, 60 °C reaction temperature, and 300 rpm stirrer speed. Additionally, the stability and phase behaviors of D-B-EPB blends were analyzed by using a ternary phase diagram to determine the potential blending proportion. The results revealed that a fuel blend consisting of 30 wt % diesel, 60 wt % biodiesel, and 10 wt % EPB (D30B60EPB10) met the density and viscosity requirements of diesel standards. This D30B60EPB10 blend was subjected to performance and emission tests in diesel engines at various speeds ranging from 1100 to 2300 rpm and different engine loads of 25, 50, and 75%. In terms of performance analysis, the brake thermal efficiencies of biodiesel and D30B60EPB10 were 7.19 and 3.88% higher than that of diesel, respectively. However, the brake-specific fuel consumption of the D30B60EPB10 blend was 6.60% higher than that of diesel due to its higher density and viscosity and lower heating value compared with that of diesel. In the emission analysis, the D30B60EPB10 blend exhibited performance comparable to diesel while being more environmentally friendly, reducing carbon monoxide, carbon dioxide, nitrogen oxide, and smoke opacity by 8.73, 30.13, 37.55, and 59.75%, respectively. The results of this study suggest that the D-B-EPB blend has the potential to serve as a viable biofuel option, reducing the proportion of diesel in blended fuel and benefiting farmers and rural communities..

Synthesis of AgFeO2 delafossite catalyst and its application for photo-degradation of dye present in solution

The present work highlights the physicochemical properties of a series of novel silver ferric oxide (AgFeO2) delafossite nanoparticles while employing them as photocatalysts under visible light irradiation. The first sample was synthesized by a facile co-precipitation route (AFO-0) while the second and third samples were prepared at a constant hydrothermal temperature (180 °C) with varying reaction time of 2 h (AFO-2) and 8 h (AFO-8) and all three samples were subjected to visible light irradiation to photo-degrade Malachite Green (MG) dye. The crystalline structure, morphology, functional groups, elemental analysis, and optical property was conducted by their respective characterization techniques. The size of nanocrystals increased with the hydrothermal time and the average particle size of AFO-0, AFO-2 and AFO-8 were 87.7 nm, 154 nm, and 209.3 nm respectively, with AFO-8 exhibiting prominent hexagonal flake-like morphology. The direct band gap of AFO-0, AFO-2 and AFO-8 were 2.74 eV, 2.53 eV and 2.11 eV respectively and the Urbach energy was 0.20 eV, 0.217 eV and 0.254 eV respectively. The photo generated charge isolation efficiency of the samples was conducted where charge recombination sequence was of the order: AFO-8<AFO-2<AFO-0. The sample AFO-8 exhibited the optimum performance which resulted in excellent degradation of MG under visible light irradiation based on all the batch study experiments using solution pH, comparative analysis, catalyst dose, initial pollutant concentration as parameters. Finally, the optimum conditions at which AFO-8 degraded 97 % of MG were: 80 mg catalyst dose, pH 8, 20 mg L−1 (100 mL) MG, 90 min reaction time, 30 °C temperature and 130 rpm agitation speed. As per the quenching tests, the OH° and O2°− radicals were the governing reactive species that were responsible for degrading MG.

Microwave-assisted acidic hydrolysis of phytate from rye bran – Experimental procedure and model prediction

Phytate is an abundant phosphorus (P) compound in plant material, which cannot be taken up by monogastric animals but is to a significant part released into the environment with excreta. In order to make use of cereals' phytate content, phytate hydrolysis by microwave-assisted thermal treatment of an acidic rye bran extract into inorganic phosphate was investigated experimentally and by modelling for process application. A phytate conversion of 98.5% could be achieved at 200 °C and 15 min reaction time and showed to be highly dependent on the temperature by a sigmoidal correlation. Treatment time showed its main influence in the mid temperature range (between 150 and 180 °C), thus didn't play a role anymore at beginning hydrolysis and towards full conversion. A mathematical quartic model represented phytate conversion with an optimum at harshest examined conditions and allows for predictions of the hydrolysis within the parameter range investigated. A kinetic model gives parameters of reaction order 0.68 and an activation energy of 118.7 kJ/mol with the option to predict phytate hydrolysis beyond the investigated parameter range and for varying input concentration. Equal liberation of all six phosphate groups from phytate is mechanistically suggested. Both model approaches show comparable results.

Facile Production of Biodiesel from Candlenut Oil (&lt;i&gt;Aleurites moluccana&lt;/i&gt; L.) Using Photocatalytic Method by Nano Sized-ZnO Photocatalytic Agent Synthesized via Polyol Method

Biodiesel production from non-edible oil is an alternative way to reduce edible oil dependency and reduce the competition for feed and food. Candlenut oil (Aleurites moluccana L.) is one of the non-edible oils which can be used as feedstock for biodiesel production since they have a high oil content. Herein, the biodiesel production from candlenut oil has been conducted using zinc oxide (ZnO) synthesized by the polyol method. Polyol methods facilitated the formation of ZnO nanoparticles with various shapes, including spherical, rod, and hexagonal. Besides, ZnO showed a mesoporous characteristic, facilitating the conversion of fat fatty acid to fatty acid methyl ester (FAME) of 61%. Increasing ZnO dosage led to enhancing the FAME yield. Similarly, the FAME yield was also improved by increasing the reaction time. The results of esterification of candlenut oil and methanol yielded 70.76% FAME with 2% nano-ZnO polyol catalyst at 180 min reaction time at room temperature whilst being stirred constantly at 400 rpm. A good FAME conversion using ZnO at room temperature provides good information to produce biodiesel with a simple method. Apart from that, photocatalytic promoted transesterification at room temperature, which is beneficial for reducing energy consumption.

Rapid Biomolecular Trifluoromethylation Using Cationic Aromatic Sulfonate Esters as Visible-Light-Triggered Radical Photocages.

Described here is a photodecaging approach to radical trifluoromethylation of biomolecules. This was accomplished by designing a quinolinium sulfonate ester that, upon absorption of visible light, achieves decaging via photolysis of the sulfonate ester to ultimately liberate free trifluoromethyl radicals that are trapped by π-nucleophiles in biomolecules. This photodecaging process enables protein and protein-interaction mapping experiments using trifluoromethyl radicals that require only 1 s reaction times and low photocage concentrations. In these experiments, aromatic side chains are labeled in an environmentally dependent fashion, with selectivity observed for tryptophan (Trp), followed by histidine (His) and tyrosine (Tyr). Scalable peptide trifluoromethylation through photodecaging is also demonstrated, where bespoke peptides harboring trifluoromethyl groups at tryptophan residues can be synthesized with 5-7 min reaction times and good yields.

Fabrication of a novel gas diffusion electrode (g-C3N4/CB/PTFE-GF) for electro-Fenton treatment of amaranth dye

It is of great importance to find suitable electrode materials to degrade dyes wastewater in electro-Fenton system. In this work, a novel gas diffusion electrode (g-C3N4/CB/PTFE-GF) was prepared by modified with graphitic carbon nitride (g-C3N4), carbon black (CB) and polytetrafluoroethylene (PTFE) on the surface of graphite felt (GF). According to the production of H2O2, the performance of g-C3N4/CB/PTFE-GF is significantly higher than GF electrode and CB/PTFE gas diffusion electrode, while optimum preparation parameters were determined, i.e. the mass ratio of g-C3N4 to CB = 1:1, PTFE = 2 mL, calcination temperature = 350 °C. Physicochemical analysis indicated the introduction of g-C3N4 and the presence of CC increase current efficiency and the activity of 2e− ORR process and electrocatalysis, thereby promoting H2O2 generation. The single and combined effects of the current density, pH, Fe2+ concentration, initial amaranth concentration, and reaction time on amaranth degradation were further investigated. Based on the optimization of response surface methodology, amaranth removal efficiency of 96.98 % was achieved with the following condition: 200 mg/L initial amaranth concentration, 4 mA/cm2 current density, 3.0 pH, 0.1 mM Fe2+ concentration, and 70 min reaction time. The g-C3N4/CB/PTFE-GF electrode possessed excellent stability and recyclability, as revealed by amaranth removal efficiency of >89 % after ten consecutive cycles. A potential amaranth degradation pathway was proposed based on the quenching test, UV–vis spectra, and HPLS-MS. In this study, a novel gas diffusion electrode with high performance and stability is provided for the treatment of refractory dye wastewater by electro-Fenton oxidation.

Short-Loop Recycling of Nd-Fe-B Permanent Magnets: A Sustainable Solution for the RE2Fe14B Matrix Phase Recovery.

The green transition initiatives and exploitation of renewable energy sources require the sustainable development of rare earth (RE)-based permanent magnets prominent technologies like wind turbine generators and electric vehicles. The recycling of RE-based permanent magnets is necessary for the future supply of critical rare-earth elements. The short-loop recycling strategies to directly reprocess Nd-Fe-B magnet waste are economically attractive and practical alternatives to conventional hydro- and pyrometallurgical processes. This study focuses on the development of a procedure to extract the (Nd, Pr)2Fe14B hard-magnetic phase from sintered Nd-Fe-B magnets. The extraction is achieved through preferential chemical leaching of the secondary, RE-rich phases using 1 M citric acid. Before the acid treatment, the magnets were pulverized through hydrogen decrepitation (HD) to increase the material's surface-to-volume ratio. The as-pulverized Nd-Fe-B powder was subsequently exposed to a 1 M citric acid solution. The effect of leaching time (5-120 min) on the phase composition and magnetic properties was studied. The results of the microstructural (SEM) and compositional (ICP-MS) analyses and the study of thermal degassing profiles revealed that the RE-rich phase is preferentially leached within 5-15 min of reaction time. Leaching of the secondary phases from the magnet's multi-phase microstructure is governed by the negative electrochemical potential of Nd and Pr. The extraction of (Nd, Pr)2Fe14B grains by the proposed acid leaching approach is compatible with the existing hydrogen processing of magnetic scrap (HPMS) technologies. The use of mild organic acid as a leaching medium makes the leaching process environmentally friendly, as the leaching medium can be easily neutralized after the reaction is completed.

Integrated oxidative-adsorptive desulfurization of model and real fuel oils over a Zn-impregnated hydroxyapatite-activated carbon (Zn/HA-AC) composite

Herein, a Zn-impregnated hydroxyapatite-activated carbon (Zn/HA-AC) composite catalyst was fabricated and was, in turn, applied for the desulfurization of a model and real oil samples via the integrated adsorptive-oxidative desulfurization strategy. Activity results revealed that Zn/HA and AC (25:75) realized 76.7% dibenzothiophene (DBT) adsorptive desulfurization at 50 °C in 60 min reaction time at an adsorbent dose of 0.14 g/20 mL of feed. Zn/HA-AC(25:75) composite catalyst was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray analysis, and scanning electron microscopy analysis. In the oxidative desulfurization (ODS) combined with adsorptive desulfurization experiments, under the optimum conditions of 45 oC temperature for 60 min and a catalyst dose of 0.1 g/20 mL of feed using H2O2 and HCOOH, Zn/HA-AC (25:75) achieved 93% DBT conversion. Under these optimized experimental parameters, the adsorptive desulfurization and catalytic ODS performance (% DBT conversion) of Zn/HA-AC (25:75) for real gasoline, kerosene, and diesel oil reached 18, 31 and 15%, and 31.66, 55.31 and 11.19%, respectively. Contrary to this, under the integrated catalytic-oxidative-adsorptive experiments, the desulfurization performance of Zn/HA-AC (25:75) for gasoline, kerosene, and diesel oil reached 61, 41, and 34%, respectively.

Diazinon and MCPA photo-reduction with sulfite excitation under UV irradiation and reducing agents’ generation

Diazinon (DIZ) and 4-Chloro-2-methylphenoxyacetic acid (MCPA) herbicide and widely used in agricultural lands. Present study investigates diazinon and 4-chloro-2-methylphenoxyacetic acid photo-reduction via UV/Sulfite (US) in as Advanced Reduction Processes (ARP). The ideal pH was Molar ratio of sulfite: DIZ or MCPA 1:1 and, 20 min reaction time, and pH 9, in which about 100 % reduction of DIZ and MCPA with a concentration of 10 mg L−1 was achieved and the optimal conditions were considered. Kinetic investigation increasing DIZ and MCPA concentration from 5 to 20 mgL−1, kobs increase about from 0.151 to 0.234 for DIZ and from 0.231 to 0.589 min−1. Also, reaction rate (robs) increases about from 0.755 to 4.68 for DIZ and from 1.155 to 11.78 mg L−1.min. The amount of energy consumption in DIZ solution increased from 5 to 20, respectively, from 0.73 to 2.37, and in the reduction of MCPA from 0.47 to 1.49 kWh per cubic meter. According to experiments performed in 30 min with the US process, COD levels were reduced by about 46 % of both pollutants. It is important to note that the BOD/COD ratio rose from about 0.20 to 0.48 after 30 min. Since the index of biodegradability has grown high, it can be concluded that non-biodegradable COD (NBDCOD) convert to biodegradable COD (BDCOD) and toxicity is lower than of before of treatment. This study has been very suggesting that the UV/sulfite method produces effluent with a non-toxic and ecologically beneficial manner by biological treatment or discharge directly in environment.

Evaluating compost for hydrogen and methane rich gas production via supercritical water gasification

The compost produced from organic wastes (MSW, city market’s wastes and wood dust) was selected to be processed via supercritical water gasification (SCWG) in order to produce gas product consisting of hydrogen and methane mainly. The effects of parameters such as temperature, reaction time and KOH as an additive were determined and around 55 vol.% of H2 and CH4 in the gas product was found after 30 min reaction time together with KOH, at 500 oC. The red mud catalysts did not improve the gasification yields even though they increased the calorific value of the product gas.

Biosynthesis of Silver Nanoparticles Using Garcinia cowa Aqueous Leaf Extract and Their Antifungal Activity Against Durian Dieback Pathogen

Silver nanoparticles (AgNPs) were synthesized under different pH and reaction time using the Garcinia cowa aqueous leaf extract. The formation, crystal structure and morphology of synthesized AgNPs were investigated using UV-Vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. The UV-Vis result indicated that the AgNPs were synthesized using Garcinia cowa aqueous leaf extract at all pH conditions within 10 min. The synthesis of AgNPs was signifi cantly affected by pH condition which was shown by the TEM micrographs. The particle sizes of AgNPs were in a nano-sized range; 6.30 ± 3.52 nm for pH 4, 3.87 ± 2.51 nm for pH 7 and 13.97 ± 11.84 nm for pH 10. Furthermore, the AgNPs prepared in pH 4, pH 7 and pH 10 (120 min reaction time) at different concentrations were assessed for their antifungal activity against durian dieback pathogen. It was found that the 800 mL/L of AgNPs prepared at pH 7, the smallest particle size and good dispersion, showed the highest inhibition mycelial growth at 47.33%, whereas the larger nanoparticles prepared at pH 4 and pH 10 conditions showed lower inhibition of mycelial growth at 43.22% and 32.55%, respectively.

Highly efficient polystyrene / Fe2O3-Al2O3 heterojunction photocatalyst for non-oxidative DBT desulfurization at visible light irradiation

Non-oxidative photo-desulfurization of Dibenzothiophene (DBT) was studied using pure Fe2O3-Al2O3 and its sub-driven nanocomposites with polystyrene (PS). The incorporation of inorganic composite with PS was done through two routes. In the first one, particles of PS were ex-situ coupled with those of Fe2O3-Al2O3 nanocomposite via using ultrasonic waves while in the second the inorganic nanocomposite was in-situ added in the aqueous phase during PS preparation stage. Proper analytical techniques were employed to determine the physicochemical properties of the prepared structures. The impact of PS content (10–50%), in the prepared composites, on the sulfur removal efficiency was investigated and optimum operating conditions were optimized. The photocatalyst which contained 30% PS and was prepared via ex-situ route (denoted as px30/NC70) could exhibit a maximum sulfur removal 94.9%. On the other side, the photocatalyst which had same composition but was prepared via in-situ technique (labeled as pi30/NC70) could reveal less desulfurization activity, particularly 84%. The increased performance by px30/NC70 over the other photocatalyst could be referred to the differences in their textural properties. The prior-stated sulfur removal percentages were detected at 1 g/L (catalyst dose), 500 W (power of light source) and 30 min (reaction time) as optimum operating conditions. The noticed desulfurization exploit by px30/NC70 was found to be eight-fold higher than that of Fe2O3-Al2O3.

Fabrication of new composite NCuTiO2/CQD for photocatalytic degradation of ciprofloxacin and pharmaceutical wastewater treatment: degradation pathway, toxicity assessment

In this research, the photocatalytic degradation of CIP from aqueous solutions using CQD decorated on N-Cu co-doped titania (NCuTCQD) was made during two synthesis steps by sol–gel and hydrothermal methods. The fabricated catalysts were analyzed using various techniques, including XRD, FT-IR, BET, FESEM, EDX, and DRS. The results showed that N and Cu atoms were doped on TiO2 and CQD was well deposited on NCuT. The investigation of effective operational parameters demonstrated that the complete removal of ciprofloxacin (CIP: 20 mg/L) could be achieved at pH 7.0, NCuTCQD4wt%: 0.8 g/L, and light intensity: 100 mW/cm2 over 60 min reaction time. The O2•– and OH˙ radicals were identified as the primary reactive species during the decontamination process. The synthesized photocatalyst could be recycled after six consecutive cycles of CIP decomposition with an insignificant decrease in performance. Pharmaceutical wastewater was treated through the optimum degradation conditions which showed the photocatalytic degradation eliminated 89% of COD and 75% of TOC within 180 min. In the effluent toxicity evaluation, the EC50 values for treated and untreated pharmaceutical wastewater increased from 62.50% to 140%, indicating that the NCuTCQD4wt%/Vis system can effectively reduce the toxic effects of pharmaceutical wastewater on aquatic environments.

Rugulopteryx okamurae: Effect of hydrothermal acid pretreatment on the saccharification process

The biological invasion caused by the invasive macroalga Rugulopteryx okamurae is causing increasing concern in southern Europe. To reduce its impact, this brown alga can be treated from a biorefinery approach. In this study, the macroalga is used as raw material to obtain fermentable sugars, which can be converted into high value-added products. The alga was exposed to hydrothermal and hydrothermal acid pretreatment and the pretreated biomass was used for enzymatic hydrolysis, achieving a hydrolysate with a reducing sugar concentration of almost 25 g/L (49.2% more than with non-pretreated alga). In addition, the combined severity factor was calculated to identify the best pretreatment conditions, finding the optimum in those pretreatments performed with 0.2 N HCl concentration and 15 min reaction time. Based on the results, it would be interesting to carry out new studies using the saccharified medium obtained under optimal conditions to obtain value-added compounds by fermentation.

Fuel production from liquefaction of polypropylene in n-hexane solvent

The excessive generation of plastic waste has become a major threat to the environment. Petroleum-based plastics, however, provided the opportunity for its re-conversion into fuel oil. In this study, polypropylene plastic was liquefied to produce liquid fuels in the presence of n-hexane solvent. The study was performed in a batch reactor at temperatures between 350 and 400 °C, reaction times between 0 and 150 min, and solvent-to-plastic mass ratios between 0:1–5:1. The effect of the different parameters was evaluated based on its yield amount and fuel quality. The results showed that the highest oil yield of 88.2 wt% was obtained at a temperature of 400 °C. A comparable oil yield of 88.0 wt% was also obtained at 150 min reaction time. The characterization results showed that the oil had density, viscosity and calorific value similar to the conventional gasoline. The GC–MS analysis showed that the oil was dominated by alkanes, alkenes and alcohol compounds with carbon numbers C6-C20, which is within the range of gasoline, kerosene and diesel fuel. In addition, the production of oil from the liquefaction of plastic could serve as an alternative source to the depleting fuel as well as increase the value of plastics, leading to fewer environmental problems caused by plastic waste.

Optimization of water removal from oil by eggplant stems using response surface methodology

Eggplant stems are among the most produced organic wastes. Unfortunately, the burning and irregular storage of eggplant stems outdoors causes both global air pollution and environmental pollution. Environmental impacts can be minimized by recycling eggplant stems, turning them into valuable products and using them as valuable additives. In this study, the water-binding capacity (WBC) and water-binding capacity in oil (WBCO) potential of eggplant stems was investigated. In the first step, optimization of the alkaline treatment of eggplant stems was carried out. Alkaline treatment optimization parameters such as sodium hydroxide (NaOH) concentration (0.050, 0.125 and 0.200 M), temperature (20, 40 and 60°C) and reaction time (30, 90 and 150 min) were investigated using response surface methodology. In the second stage, WBC and WBCO tests of eggplant stems were carried out. According to the experimental results, capacity efficiencies of 30.64 and 98.20% were obtained for WBC and WBCO, respectively, at 0.125 M sodium hydroxide concentration, 60°C temperature and 150 min reaction time. In addition, eggplant stems demonstrated the ability to retain water effectively for up to five cycles. The high WBC of eggplant stems in oil after alkali treatment showed that they could be a suitable and inexpensive candidate for use in biodiesel purification and methane production.

Homogenizer-intensified amidation of free fatty acids in waste cooking oil for biodiesel production

Biodiesel production from waste cooking oil is a viable alternative both to satisfy renewable energy demand and utilize a low-cost feedstock. However, a preparatory procedure is required to reduce free fatty acid contained in waste cooking oil to a specific value which is time- and energy-extensive. Herein, a fast and non-catalytic amidation reaction performs at room temperature is established as an alternative method to reduce the free fatty acid level. The effect of the molar ratio of waste cooking oil to monoethanolamine, reaction time and rotational speed of homogenizer were investigated on the conversion of free fatty acid to alkanolamide compounds. The highest conversion of 95.9 ± 0.02% was achieved in presence of a molar ratio of 1:1.5, reaction time of 0.5 min and rotational speed of 5000 rpm. Further, a homogenizer was used to facilitate the transesterification reaction using an alkaline catalyst at room temperature. The conversion of waste cooking oil to biodiesel of 91.4 ± 0.2% was achieved after 5 min of reaction time. In terms of processing parameters, the non-catalytic amidation and alkaline base catalytic transesterification reaction assisted by a homogenizer device is a time-saved process as it could save 92% and 94% of reaction time compared to one- and two-steps method and was performed in ambient condition.

Facile recyclable process of high-quality single layer graphene oxide via waste graphite anode scrap

Here we report a facile reusable method for graphene oxide (GO) from the oxidation of waste graphite anode scrap (WGAS), which was synthesized by Couette–Taylor flow reactor. The toroidal motion of fluids generated by the mechanical and structural specificity of the reactor increased the intercalation rate and oxidation efficiency of the WGAS, resulting in high production yield (95 ± 1%) of GO within 90 min reaction time. In addition, the as-synthesized GO nanosheets were extensively characterized using a variety of techniques, which allowed the identification of two-dimensional monolayers (∼1.3 nm) and successfully functionalized high-quality graphene oxides. Our approach of the high-efficiency oxidation and exfoliation of recycled GO with WGAS may find potential application in numerous industrial fields, such as catalysis and electrodes in energy conversion and storage systems, and conductive materials in electronic devices.