Optimization of novel pyrazolium ionic liquid catalysts for transesterification of bitter apple oil

In the present study, 4 different functionalized pyrazoliums based on sulfoalkyl-pyrazolium hydrogensulfate and alkylsulfo-alakylpyrazolium hydrogensulfate were explored to catalyze biodiesel production from bitter apple oil (BAO). The results demonstrated that a longer chains catalyst of 2-(4-sulfobutyl) pyrazolium hydrogensulfate (SBPHSO₄) exhibited the highest catalytic activity, which is attributed to its strong acidity. The highest yield of esters was up to 89.5% when the reaction was carried out under the conditions of 5.2 wt% of SBPHSO₄, molar ratio of methanol to BAO of 15:1, 170 °C, and 800 rpm for 6 h. These results demonstrated that ionic liquids offer a promising new type of pyrazolium catalyst for biodiesel production. The use of clean ionic liquids in preparing clean biodiesel could solve the drawbacks associated with using the old conventional catalysts and might be employed as an efficient catalyst for such relevance.     

Feasibility of honeycomb monolith supported sugar catalyst to produce biodiesel from palm fatty acid distillate (PFAD)

Carbon coated monolith was prepared by sucrose solution 65 wt.% via dip-coating method. Sulfonation of incomplete carbonized carbon coated monolith was carried out in order to synthesize solid acid catalyst. The textural structure characteristics of the solid acid catalyst demonstrated a low surface area and pore volume. Palm fatty acid distillate (PFAD), a by-product of palm oil refineries, was utilized as oil source in biodiesel production. The esterification reaction subjected to different reaction conditions was performed by using the sulfonated carbon coated monolith as heterogeneous catalyst. The sulfonation process had been performed by using vapour of concentrated H₂SO₄ that was much easier and efficient than liquid phase sulfonation. Total acidity value of carbon coated monolith was measured for unsulfonated sample (0.5 mmol/g) and sulfonated sample (4.2 mmol/g). The effect of methanol/oil ratio, catalyst amount and reaction time were examined. The maximum methyl ester content was 89% at the optimum condition, i.e. methanol/oil molar ratio (15:1), catalyst amount (2.5 wt.% with respect to PFAD), reaction time (240 min) and temperature 80 °C. The sugar catalyst supported on the honeycomb monolith showed comparable reactivity compared with the sugar catalyst powder. However, the catalyst reusability studies showed decrease in FFA% conversion from 95.3% to 68.8% after four cycles as well as the total acidity of catalyst dropped from the value 4.2 to 3.1 mmol/g during these cycles. This might be likely due to the leaching out of SO₃H group from the sulfonated carbon coated monolith surface. The leaching of active species reached a plateau state after fourth cycle.     

Studies on design of heterogeneous catalysts for biodiesel production

The production of biodiesel is gaining momentum with the ever increasing demand of the fuel. Presently, limited literature is available with respect to well designed solid heterogeneous catalyst for biodiesel production considering all the characteristics, process and operation parameters. Hence, a study was conducted to design effective heterogeneous catalyst for biodiesel production. Further, the significant impact of different catalysts, different feed stock, various reaction conditions such as temperature, methanol oil molar ratio, catalyst concentrations and stability/inactivation of the catalysts, are detailed out for transesterification process of biodiesel production. Based on the studies it can be concluded that well designed heterogeneous catalyst can yield high throughput of biodiesel.     

Sucrose-derived catalytic biodiesel synthesis from low cost palm fatty acid distillate

The current homogeneous acid catalyst for biodiesel product however, would lead to formation of many undesirable by-products that make the post treatment of the biodiesel to be difficult and costly. Thus, sucrose-derived solid acid catalyst was developed in the present study which aims to improve the esterification process and reduce the generation of waste. The physicochemical properties of the synthesized catalysts were studied by various techniques such as, BET surface area, X-ray diffraction (XRD), temperature programmed desorption of NH₃ (TPD-NH₃), scanning electron microscopy (SEM). Response surface methodology (RSM) with central composite design (CCD) is used to determine the optimum parameters for the catalytic reaction. The experimental results showed that the catalyst exhibited good catalytic activity in the transesterification of PFAD, providing maximum biodiesel yield of 94% at optimum parameters. The better catalytic activity of the aforementioned catalyst in the biodiesel reaction could be attributed to the presence of optimal number of catalytically active acid site density on its surface.     

Optimization of biodiesel production by alkali-catalyzed transesterification of used frying oil

Biodiesel as an alternative fuel for fossil diesel has many benefits such as reducing regulated air pollutants emissions, reducing greenhouse gases emissions, being renewable, biodegradable and non-toxic. In this study, used frying oil was applied as a low cost feedstock for biodiesel production by alkali-catalyzed transesterification. The design of experiments was performed using a double 5-level-4-factor central composite design coupled with response surface methodology in order to study the effect of factors on the yield of biodiesel and optimizing the reaction conditions. The factors studied were: reaction temperature, molar ratio of methanol to oil, catalyst concentration, reaction time and catalyst type (NaOH and KOH). A quadratic model was suggested for the prediction of the ester yield. The p-value for the model fell below 0.01 (F-value of 27.55). Also, the R² value of the model was 0.8831 which indicates the acceptable accuracy of the model. The optimum conditions were obtained as follows: reaction temperature of 65 °C, methanol to oil molar ratio of 9, NaOH concentration of 0.72% w/w, reaction time of 45 min and NaOH as the more effective catalyst. In these conditions the predicted and observed ester yields were 93.56% and 92.05%, respectively, which experimentally verified the accuracy of the model. The fuel properties of the biodiesel produced under optimum conditions, including density, kinetic viscosity, flash point, cloud and pour points were measured according to ASTM standard methods and found to be within specifications of EN 14214 and ASTM 6751 biodiesel standards.     

A summary of the available technologies for biodiesel production based on a comparison of different feedstock's properties

Biodiesel production is mainly done by carrying on the transesterification reaction while using refined oil, methanol and a homogeneous base catalyst. When using refined oil, a competition between oil for food and oil for fuel is then presented. Even more, the conventional technology has the disadvantage that the raw material has to be very pure, with no traces of other impurities. Otherwise, undesirable products will be produced decreasing the productivity of the process and making a large amount of waste treatment.Because of this, other technologies appear as possible sources for biodiesel production, mainly from refined oil, but also allowing less pure raw material to be used, such as waste oil, frying oil, soapstocks, and animal fats.In this work, a comparison of all these different raw materials, their physicochemical properties and how they can have an influence, and the magnitude of this phenomenon, in the biodiesel production will be presented and compared. Based on the previous analysis, a short summary of the technological possibilities to produce good quality biodiesel from low price raw material will be discussed with the aim of showing their advantages and disadvantages when using different feedstocks.     

Absorption kinetics of NO from simulated flue gas using Fe(II)EDTA solutions

The absorption of NO encountering flue gases in aqueous solutions of Fe(II)EDTA was determined using a semi-batch stirred tank with a plane gas–liquid interface at 50 °C. The concentrations of NO, SO₂ and O₂ in the feeding stream were 300–800 ppm, 500–2200 ppm and 0–20%, respectively. The pH value of the Fe(II)EDTA solutions varied from 3 to 11. The concentrations of Fe(II)EDTA were maintained between 0.01 and 0.05 M. Experiments were performed to evaluate the effect of operating parameters on the NO absorption rate, the reaction kinetics of the reactants in gas and liquid phases, and the effect of competition between various reactants on the mass transfer rate in the NO removal system. Results indicate that the average reaction rate constant is 3.70 × 10⁷ M⁻¹ s⁻¹. Adding NaOH does not increase the absorption capability of Fe(II)EDTA. The presence of O₂ decreases the NO absorption rate with Fe(II)EDTA. The absorption rate of NO with Fe(II)EDTA decreases at low concentrations of SO₂, but increases at high concentrations.     

Optimization of biodiesel production from the waste cooking oil using response surface methodology

In this research, transesterification of the waste cooking oil has been studied. Response surface methodology (RSM) based on Box–Behnken design was used to investigate the effects of the main operating parameters, including the methanol to oil molar ratio, catalyst concentration, and reaction temperature, on the biodiesel yield. The results revealed that the catalyst concentration is the most important parameter. The maximum biodiesel yield under the optimized conditions was 99.38 wt.%. Thermogravimetric analysis (TGA) was used for the determination of biodiesel conversion and the results were compared with that of gas chromatography (GC) analysis, showing a very small difference. Furthermore, an empirical quadratic equation has been presented to show the relation between biodiesel conversion and product viscosity.     

Refinery wastewater degradation with titanium dioxide,zinc oxide,and hydrogen peroxide in a photocatalytic reactor

This paper presents the photo-catalytic degradation of real refinery wastewater from National Refinery Limited (NRL) in Karachi, Pakistan, using TiO₂, ZnO, and H₂O₂. The pretreatment of the refinery effluent was carried out on site and pretreated samples were tested at 32–37 °C in a stirrer bath reactor by using ultra-violet photo oxidation process. The degradation of wastewater was measured as a change in initial chemical oxygen demand (COD) and with time. Optimal conditions were obtained for catalyst type, and pH. The titanium dioxide proved to be very effective catalysts in photo-catalytic degradation of real refinery wastewater. The maximum degradation achieved was 40.68% by using TiO₂ at 37 °C and pH of 4, within 120 min of irradiations. When TiO₂ was combined with H₂O₂ the degradation decreased to 25.35%. A higher reaction rate was found for titanium dioxide. The results indicate that for real refinery wastewater, TiO₂ is comparatively more effective than ZnO and H₂O₂. The experiments indicated that first-order kinetics can successfully describe the photo-catalytic reaction. The ANOVA results for the model showed satisfactory and reasonable adjustment of the second-order regression model with the experimental data. The ANOVA results also showed that pH is significant than reaction time and catalyst dosage of TiO₂; and in case of ZnO, reaction time is significant than pH and catalyst dosage. This study proves that real refinery wastewater reacts differently than synthetic refinery wastewater, oil field produced water or oil water industrial effluent.     

Flash point of biodiesel/glycerol/alcohol mixtures for safe processing and storage

Mixtures of biodiesel, glycerol, and ethanol/methanol are commonly processed and stored in biodiesel production. In this work, non-ideal models are used to calculate the Flash Points (FPs) of binary and ternary mixtures, using data available from different feedstocks. Despite the fact that biodiesel is considered safer than common diesel fuels, results show a synergistic effect of biodiesel/methanol and biodiesel/ethanol mixtures, resulting in a reduction of the flash point of mixtures to values lower than the ones of pure compounds. Most soluble ternary mixtures were found flammable, the only exception being mixtures with a relatively lower alcohol content (45% mol. ethanol or 42% methanol) at temperature lower than 303 K. Accidental increase in temperature can cause domino effect, due to the higher solubility and the formation of new flammable ternary mixtures.     

Synthesis of Bio-Diesel and Bio-Lubricant by Transesterification of Vegetable Oil with Lower and Higher Alcohols Over Heteropolyacids Supported by Clay (K-10)

The use of different lower and higher alcohols viz; methanol, ethanol, n-propanol and n-octanol, for the synthesis of methyl, ethyl, propyl and octyl fatty acid esters by transesterification of vegetable oil (triglycerides) with respective alcohols also known as ‘Bio-diesel’ and ‘Bio-lubricants’ was studied in detail. The reactions were carried out in a batch process. The activity with different supports like clay (K-10), activated carbon, ZSM-5, H-beta and TS-1 were compared. The superacids (heteropolyacids, HPA) viz; Dodeca-Tungstophosphoric acid [H₃PO₄·12 WO₃·xH₂O] (TPA) and Dodeca-Molybdo phosphoric acid ammonium salt hydrate [H₁₂Mo₁₂N_3-O₄₀P + aq] (DMAA) was used to increase the acidity and so the activity by loading on the most active support viz; clay (K-10). These HPA loaded on clay as a catalyst was used for the following study: effect of percent HPA loading on clay, effect of different vegetable oils, effect of different alcohols on the triglyceride conversion based on glycerol formation and selectivity based on alkyl esters formation. The data is compared at the best-optimized identical set of operating reaction conditions: 170 °C, 170 rpm, catalyst loading: 5% (w/w of reaction mixture), molar ratio (oil: alcohol): 1:15 and time on stream of 8 h. The generated data is also evaluated based on the reported one.     

生物柴油产业链分析

生物柴油是指由植物油、动物油脂等制备得到的单烷烃酯类。它是一种环境友好、清洁排放的燃料,因此是非常理想的石油柴油替代燃料。本文从生物柴油产业链中的原料来源、生产工艺、产品应用以及其效益等方面对这种新型的清洁燃料进行了简单介绍。总之,生物柴油是一种很有发展前景的生物质燃料。     

Disintegration of waste activated sludge by different applications of Fenton process

Oxidative disintegration of municipal waste activated sludge (WAS) using conventional Fenton (Fe²⁺ + H₂O₂, CFP) and Fenton type (Fe⁰ + H₂O₂, FTP) processes was investigated and compared in terms of the efficiency of sludge disintegration and enhancement of anaerobic biodegradability. The influences of different operational variables namely sludge pH, initial concentration of Fe²⁺ or Fe⁰, and H₂O₂ were studied in detail. The optimum conditions have been found as catalyst iron dosage = 4 g/kg TS, H₂O₂ dosage = 40 g/kg TS and pH = 3 within 1 h oxidation period for both CFP and FTP. Kinetics studies were performed under optimal conditions. It was determined that the sludge disintegration was happened in two stages by both processes: rapid and subsequent slow disintegration stages and rapid sludge disintegration stage can be described by a zero-order kinetic model. The effects of oxidative sludge disintegration under the optimum conditions on anaerobic digestion were experienced with biochemical methane potential (BMP) assay in batch anaerobic reactors. Total methane production in the CFP and FTP pre-treated reactors increased by 26.9% and 38.0%, relative to the untreated reactor (digested the raw WAS). Furthermore, the total chemical oxygen demand reductions in the pre-treated reactors were improved as well.     

Evaluation of beech for production of bio-char,bio-oil and gaseous materials

Evaluation of Oriental beech (Fagus orientalis L.) was investigated with aspect of thermo-chemical conversion to obtain bio-char, bio-oil and gaseous. When the pyrolysis temperature increased, the bio-char yield decreased. A high temperature and smaller particles increase the heating rate resulting in a decreased bio-char yield. The bio-char obtained are carbon rich, with high heating value and relatively pollution-free potential solid biofuel. The liquefaction yield sharply increased with increasing the temperature near critical temperature and after that. In the pyrolysis, increases of liquid yields are considerably sharply for all of the samples with increasing of pyrolysis temperature from 690 K to 720 K. The beechnut oil was converted to biodiesel in supercritical methanol without using the catalyst. Experiments have been carried out in an autoclave at 493, 523 and 593 K, and with molar ratios of 1:6–1:40 of the oil to methanol. The yield of alkyl ester increased with increasing the molar ratio of oil to alcohol.     

A multi-criteria approach to screening alternatives for converting sewage sludge to biodiesel

The search for cheaper feedstock for use in the production of biofuels such as biodiesel has turned attention to various forms of waste products including animal fats, waste oils and now lipids in sludge. With the potential of obtaining sludge at a reduced cost, free, or possibly with incentives, sewage sludge is being investigated as a potential feedstock for biofuel production. For the extraction of oils from the sewage sludge and the subsequent processing, there are various alternatives that should be designed, analyzed, and screened. In developing and screening these alternatives, it is necessary to have a consistent basis for comparing alternatives based on key criteria. While most of the design studies focus on techno-economic criteria, it is also important to include safety metrics in the multi-criteria analysis. In this work, a detailed economic analysis and a safety evaluation are performed on a process involving extraction of triglycerides and fatty acids, pre-treatment of fatty acids (direct conversion to biodiesel), and transesterification of triglycerides to biodiesel. Four solvents, toluene, hexane, methanol and ethanol, are individually used in the extraction process. The resulting triglycerides and fatty acids from each extraction are modeled in the pre-treatment process. ASPEN Plus software is used to simulate the detailed process. Economic analysis is performed using ASPEN ICARUS, and scale-up of a previously analyzed process is used to estimate the cost of the biodiesel portion of the process. A new safety metric (referred to as the Safety Index “SI”) is introduced to enable comparison of the various solvent extraction processes. The SI is based on solvent criteria as well as process conditions. A case study is presented to demonstrate the insights and usefulness of the developed approach. The results of the techno-economic analysis reveal that of the four solvents used for the initial extraction, hexane and toluene were least costly (2.89 and 2.79 $/gal, respectively). Conversely, the safety analysis utilizing the SI reveals that methanol and ethanol are the safer solvent options. The issue of cost/safety tradeoffs is also discussed.     

Anaerobic digestion modeling of the main components of organic fraction of municipal solid waste

The organic fraction of municipal solid waste (OFMSW) is composed of several heterogeneous organic and inorganic wastes. The diversity of composition, the high volatile solid content and the biodegradable material that this waste offers make it quite an interesting option for anaerobic digestion (AD). Depending on the substrate composition, the biological degradation and kinetics of the AD could vary. Biochemical methane potential (BMP) tests are used as a tool to evaluate the methane production of several fractions of OFMSW, in order to study the influence of each fraction in the final mixture. The kinetic parameters of methane curves and the prediction of final productions are studied by different approaches to model equations using linear, exponential, logistic and Gaussian models. The analyses of the fractions indicate that organic substrates such as meat/fish which are in a small proportion in the final mixture, obtain major productivities (291 ± 3 mlCH₄/gVS), however others such as paper (217 ± 5 mlCH₄/gVS) could have their productivity enhanced due to their high VS present in the final mixture. Both the Gomperzt and the first order model fit reasonably with all the fractions, although substrates with lag phase adjust only to the Gompertz model explaining 99% of the experimental results.     

Recycling of valuable chemicals through the catalytic decomposition of phenol tar in cumene process

The base catalyst LZ-2, which was the mixture of CaO and Na–NaOH/Al₂O₃·3H₂O, was chosen for the decomposition of phenol tar to generate valuable chemicals. The selectivity of LZ-2 for dimethyl phenyl carbinol, α-methyl styrene dimer and cumenyl phenol was 100%, 100% and 98%, respectively. Under the optimum operating conditions of catalyst 2.5 wt%, operating temperature 603.15 K and decomposition time 3.5 h, decomposition ratios of cumenyl phenol and dimethyl phenyl carbinol were 98.7% and 99.97%, respectively. In addition, the experimental repeatability demonstrated that the total yield of valuable chemicals still reached 90.1% after the catalyst being used five times. Mass and energy balance indicated that the catalytic decomposition was a high potential for the recycling of chemicals from phenol tar.     

Inherently Safer Design for low-temperature process during depressurization: An industrial case study

The exploitation of a low-quality gas field with high CO₂ concentration is more viable through liquid CO₂ produced from cryogenic distillation technology. Despite the bright potential of the technology, there are deficiencies in handling high concentration of CO₂ at low temperature and high pressure during the blowdown condition. This study focuses on the CO₂ blowdown at a cryogenic pilot plant designed to manage high concentrations of CO₂ in the feed gas, high pressures, and low temperatures. A comprehensive design review and risk assessment using Inherent Safer Design (ISD) indexes were carried out in this study. The ISD was performed to identify the current risk level, and the critical parameters that may cause solid CO₂ formation in the piping or equipment as well as to identify mitigation measures to avoid the temperature to drop below the CO₂ freezing point during blowdown. The present findings confirmed that the initial pressure and temperature, as well as CO₂ concentration are key parameters towards significant impact on blowdown conditions. Therefore, the reduction of the feed gas pressure from 80 bar to 70 bars has minimized the Joule Thomson (JT) effect during blowdown and avoided the CO₂ solid formation in the system. Moreover, the relocation of the blowdown valve at the downstream heater resulted in a higher final temperature above the CO₂ freezing point. The ISD indexes confirmed that the cryogenic facilities are inherently safer during blowdown with the mitigation measures adopted.     

High nitrite accumulation and strengthening denitrification for old-age landfill leachate treatment using an autocontrol two-stage hybrid process

An autocontrol two-stage hybrid process was developed to treat landfill leachate. Biological nitrogen removal with nitrification and denitrification via nitrite pathway was split into two stages. The first stage was designed for the high nitrite accumulation and was composed of two hybrid bed reactors (Hybrid I and Hybrid II) and a coagulation–flocculation reactor having effective volumes of 120 L and 80 L, respectively. The second stage was designed for strengthening denitrification and included a single 80 L reactor. The carriers of the hybrid bed reactors were composed of fixed multiple flexible carriers and suspended particle carriers. Dissolved oxygen (DO), pH value, oxidation–reduction potential (ORP) and temperature were used as online fuzzy control parameters of the automatic control system. The concentration of nitrite in Hybrid I and Hybrid II could reach 411 mg L⁻¹ and 604 mg L⁻¹, respectively. Ammonia removal has reached maximal rates of 0.061 kgNH₄⁺-N (m³ h)⁻¹ and 0.041 kgNH₄⁺-N (m³ h)⁻¹, respectively. A maximum nitrite removal rate of 0.211 kgNO₂⁻-N (m³ h)⁻¹ was observed during the strengthening denitrification. The running time of one cycle was not fixed and was actually controlled by the system. The results indicated that the running period was more closely related to influent ammonia concentration than influent COD concentration. The aeration times could be shortened and the energy could be saved. The autocontrol two-stage hybrid process is therefore an economical and effective way for landfill leachate treatment.     

Is biochar or straw-bale construction a better carbon storage from a life cycle perspective?

Biochar has been presented as a key technology for avoiding dangerous climate change. Pyrolysis converts part of the biomass feedstock into a gaseous fraction, which can be used for energy production. The remaining fraction is char, which is highly stable and resistant to biodegradation. When char is added to soil it increases carbon storage, reduces emissions and improves soil quality. Agricultural residues such as straw, stover and hulls are seen as the most accessible raw material. These residues could also be used as insulation in passive energy housing. Straw bale construction is a relatively simple technology, which has been applied for decades. It can store the carbon of the straw material into walls structures and in the process provides energy efficient housing. The climate benefits from improved energy efficiency depend on local conditions and energy production forms. In this study life cycle assessment was used to compare the climate impacts of biochar production and straw bale construction. On a life cycle perspective, straw bale construction results in higher net carbon storage than biochar production (3.3 t CO₂eq vs. 0.9 t CO₂eq/t of straw). However the result was found to be highly dependent on the assumptions on the overall energy efficiency of the replaced building stock.