Microwave Irradiation Time Research Articles

Microwave-assisted synthesis of silver nanoparticles using extract of unbaked cilembu sweet potato

Abstract Silver nanoparticle (AgNP) is one of attractive nanomaterials for biomedical applications, such as electroactive scaffold, antimicrobial treatment, anticancer therapy, and wound healing. Previously, AgNP was successfully synthesized using extract of Cilembu sweet potato (CSP) only if the extract was baked in oven at 120 °C for 60 minutes, which is an energy-intensive and time-consuming process. In this study, AgNPs was fabricated using unbaked extract of CSP with employing fast microwave heating instead of baking process. Microwave irradiation time were varied (0, 30, 60 and 90 seconds) to know the influence of microwave irradiation time on particles size and morphology of the obtained AgNPs. The obtained samples were evaluated using UV-Visible spectroscopy, dynamic light scattering and transmission electron microscopy to know the surface plasmon resonance characteristic, average particles size and morphologies of the obtained AgNPs respectively.

Investigation of Micro-Scale Damage and Weakening Mechanisms in Rocks Induced by Microwave Radiation and Their Associated Strength Reduction Patterns: Employing Meta-Heuristic Optimization Algorithms and Extreme Gradient Boosting Models

Microwave-assisted mechanical rock breaking represents an innovative technology in the realm of mining excavation. The intricate and variable characteristics of geological formations necessitate a comprehensive understanding of the interplay between microwave-induced rock damage and the subsequent deterioration in rock strength. This study conducted microwave irradiation damage assessments on 78 distinct rock samples, encompassing granite, sandstone, and marble. A total of ten critical parameters were identified: Microwave Irradiation Time (MIT), Microwave Irradiation Power (MIP), Longitudinal Wave Velocity prior to Microwave Treatment (LWVB), Longitudinal Wave Velocity post-Microwave Treatment (LWVA), Percentage Decrease in Longitudinal Wave Velocity (LWVP), Porosity before Microwave Treatment (PB), Porosity after Microwave Treatment (PA), Percentage Increase in Porosity (PP), and Uniaxial Compressive Strength following Microwave Treatment (UCSA). Utilizing the Pied Kingfisher Optimizer (PKO) alongside Extreme Gradient Boosting (XGBoost), we developed a PKO-XGBoost machine learning model to elucidate the relationship between UCSA and the nine additional parameters. This model was benchmarked against other prevalent machine learning frameworks, with Shapley additive explanatory methods employed to assess each parameter’s influence on UCSA. The findings reveal that the PKO-XGBoost model provides superior accuracy in delineating relationships among rock physical properties, microwave irradiation variables, microscopic attributes of rocks, and UCSA. Notably, PA emerged as having the most significant effect on UCSA, indicating that microwave-induced microscopic damage is a primary contributor to reductions in rock strength. Additionally, MR exhibited substantial influence; under identical microwave irradiation conditions, rocks with lower density demonstrated greater susceptibility to strength degradation. Furthermore, during microwave-assisted rock breaking operations, it is imperative to establish optimal MIT and MIP values to effectively diminish UCSA while facilitating mechanical cutting processes. The insights derived from this research offer a more rapid, cost-efficient approach for accurately assessing correlations between microwave irradiation parameters and resultant rock damage—providing essential data support for enhancing mechanical rock-breaking efficiency.

Microwave vacuum pyrolysis rapidly transforms bamboo into solid biofuel: Predicting fuel performances by response surface methodology

Microwave vacuum pyrolysis presents significant advantages in biochar refining and industrial upgrading. In this study, bamboo charcoal (BC) was produced rapidly by microwave vacuum pyrolysis, the microwave pyrolysis and conventional pyrolysis characteristics of bamboo were compared, and the potential of response surface methodology (RSM) to predict the fuel performances was investigated. The results indicated that microwave pyrolysis significantly reduced the heating time, and also effectively lowered the threshold of thermal decomposition reaction. Besides, as the microwave power and radiation time rose, the fixed carbon, ash, higher heating value, energy density, and fuel ratio of BCs increased, while the yield, H/C, O/C, volatile, and energy yield decreased. The quadratic models have high correlation coefficients for these characteristics, which can be used for the prediction of subsequent BCs production. When the microwave power was 1666 W and the radiation time was 13.3 min, the prepared BC exhibited the highest yield while maintaining a fixed carbon content of over 85 %. This research provided a green way for the transformation and upgrading of BCs industry, and also showed that the most cost-effective production strategy can be formulated through RSM.

Comparing tensile, bending and interlaminar shear performance of GFRP composites fabricated using recovered and virgin glass fibers: Optimization of the microwave assisted chemical recycling technique

AbstractGlobal glass fiber reinforced plastic (GFRP) recycling provides an effective solution to the end‐of‐life wastes and industrial scrap, by which we can construct a closed‐loop system that reduces environmental impact while increasing sustainability. This study reports the tensile, flexural and shear properties of GFRP composites fabricated from reclaimed fibers from the waste GFRP. A hybrid recycling technique that is, microwave assisted chemical recycling has been used for recovering the glass fiber fabrics. The quantity of solvents (a mixture of 30% H2O2 and CH3COOH in 1:1 ratio) required (in mL/g) for degrading the polymer is optimized with respect to the amount of microwave irradiation time. The microwave irradiation duration was varied at constant power of 900 W for optimizing the quantity of solvent used. SEM analysis of both virgin and reclaimed fiber surfaces indicate an almost complete degradation of polymer from the waste composites. RGFE laminates, fabricated from reclaimed glass fiber fabrics, exhibited marginally higher tensile strength (7%–8%) and significant lower tensile modulus (~29%). On the other hand, RGFE composites demonstrated a greater strain to failure of ~44% compared to VGFE composites during tensile testing, consequently leading to a subsequent increase in tensile toughness by ~28%. The ILSS values obtained from SBS tests and storage modulus and loss factor curves from DMA tests showed almost similar values. SEM studies revealed the probable causes of failures of the samples for tensile and flexural tests.Highlights Hybrid recycling technique using microwave irradiation is optimized. Amount of solvent used is optimized by varying the irradiation times. Tensile and flexural strengths exhibit a marginal increase of 7%–8%. Significant rise in strain at failure by 44% and tensile toughness by 28%. Fractography studies have been performed for analyzing failures.

Experimental Study on Combined Microwave-Magnetic Separation-Flotation Coal Desulfurization.

In order to reduce the content of sulfur and ash in coal, improve the desulfurization and deashing rates, a combined experiment method of microwave magnetic separation-flotation was proposed for raw coal. The desulfurization and deashing rates of three experiment methods, namely, single magnetic separation, microwave magnetic separation, and microwave magnetic separation-flotation, were compared. Taking the microwave magnetic separation-flotation experiment method as the main line, the effects of the microwave irradiation time, microwave power, grinding time, magnetic field intensity, plate seam width, foaming agent dosage, collector dosage, and inhibitor dosage on desulfurization and deashing were discussed, and the mechanism of microwave irradiation on magnetic separation and flotation was revealed. The results show that under the conditions of a microwave irradiation time of 60 s, a microwave power of 80% of the rated power (800 W), a grinding time of 8 min, a plate seam width (the plate seam width of a magnetic separator sorting box) of 1 mm, a magnetic field intensity of 2.32 T, a foaming agent dosage of 90 g/t, a collector dosage of 2125 g/t, and an inhibitor dosage of 1500 g/t, the desulfurization and deashing effect is the best. The desulphurization rate is 76.51%, the sulfur removal rate of pyrite is 96.50%, and the deashing rate is 61.91%. Microwaves have the characteristic of selective heating, and the thermal conductivity of organic matter in coal is greater than that of mineral. Microwave irradiation can improve the reactivity of pyrite in coal, pyrolyze pyrite into high-magnetic pyrite, improve the magnetic properties, and improve the magnetic separation effect. Therefore, microwave irradiation plays a role in promoting magnetic separation. Through microwave irradiation, the positive and negative charges in coal molecules constantly vibrate and create friction under the action of an electric field force, and the thermal action generated by this vibration and friction process affects the structural changes in oxygen-containing functional groups in coal. With the increase in the irradiation time and power, the hydrophilic functional groups of -OH and -COOH decrease and the hydrophilicity decreases. Microwave heating evaporates the water in the pores of coal samples and weakens surface hydration. At the same time, microwave irradiation destroys the structure of coal and impurity minerals, produces cracks at the junction, increases the surface area of coal to a certain extent, enhances the hydrophobicity, and then improves the effect of flotation desulfurization and deashing. Therefore, after the microwave irradiation of raw coal, the magnetic separation effect is enhanced, and the flotation desulfurization effect is also enhanced.

Iron Removal from Low-Grade Pyrophyllite Ore by Microwave Irradiation and Dry Magnetic Separation

Owing to its unique properties, pyrophyllite is an economical alternative to many minerals in different applications. The presence of iron-bearing minerals in Saudi pyrophyllite hampers its industrial uses. The aim of this study was to examine the removal of iron from Saudi low-grade pyrophyllite ore using two approaches. The first approach involves dry high-intensity magnetic separation, whereas the second approach involves microwave pretreatment of the ore before dry magnetic separation. For the first approach, the studied operating parameters were roll speed; feed rate, field intensity, and feed particle size. For the alternative approach, microwave treatment followed by dry magnetic separation, the microwave irradiation time and the magnetic field intensity were studied. The results show that the combined microwave treatment and dry separation method could provide high-purity pyrophyllite for filler industries. Microwave irradiation for 30 min was optimal to change impurity phases (i.e., pyrite, hematite) into ferromagnetic phases in microwave-treated pyrophyllite samples. At a magnetic field intensity of 2000 Gauss, the 30 min microwave-irradiated pyrophyllite sample achieved an iron recovery of 11.2% in non-magnetic fractions, with a removal efficiency of 89% with an alumina recovery of 91.31%.

Eco-friendly and efficient extraction of phenolic compounds from Commiphora gileadensis bark using microwave-assisted extraction

Commiphora gileadensis (C. gileadensis) is a medicinal plant with a variety of biological activity; its bark has several therapeutic potentials, including the treatment of wounds, inflammatory diseases, and treating bacterial infections. This study utilized microwave-assisted extraction (MAE) to optimize the recovery and phenolic components of the ethanolic extracts of C. gileadensis bark. Different MAE process parameters (microwave power, irradiation time, sample/solvent ratio, extraction temperature, and solvent (ethanol) concentration) were studied for their impacts on the extraction process using One-Factor-At-a-Time (OFAT) method. The extracts were further characterized for the presence of different phytochemicals using Gas Chromatography-Mass Spectroscopy (FC-MS) and Fourier Transform Infrared Spectroscopy (FTIR) analyses. The experimental findings revealed that the maximum extraction yield, total phenolic content (TPC), and total flavonoid content (TFC) of the ethanolic extract of the of C. gileadensis bark using MAE process were 39.40 ± 0.47 w/w%, 166.41 ± 3.97 mg GAE/g d.w., and 52.83 ± 2.95 mg QE/g d.w., respectively. Furthermore, 30 phenolic constituents were discovered in the extract of C. gileadensis bark for the first time, and these compounds showed good in vitro antioxidant activity. Hence, MAE is a suitable technique for efficient and green extraction of different groups of phytochemicals of pharmaceutical importance from the bark of C. gileadensis.

Microwave Welding of Thermoplastic using Silicon Carbide Nanowhiskers as Susceptor: Effect of Heating Duration

Microwave welding is becoming more popular than conventional joining methods due to its advantages such as rapid and localised heating as well as applicable to components with complicated geometry. Previously reported susceptor, such as carbonaceous materials and conductive polymers, are toxic and the welding process involving these susceptors is time-consuming. Because of its exceptional microwave absorption and biocompatibility, silicon carbide nanowhiskers (SiCNWs) was employed as the microwave susceptor for microwave welding. Microwave welding in this study comprises of only three simple steps: SiCNWs suspension preparation, SiCNWs application and microwave heating. The weld strength of welded joint was then characterised using tensile test and energy dispersive x-ray spectroscopy equipped scanning electron microscopy (EDS-SEM) to study its mechanical properties and cross-section microstructure. The influence of microwave irradiation time was studied in this study, and it is found that the weld strength rose with the extension of microwave irradiation time, until a maximum weld strength of 1.61 MPa was achieved by 17 s welded joint. The development of SiCNWs reinforced PP nanocomposite welded joint layer is responsible for the enhanced weld strength. Prolonged heating duration may also result in flaws such as void formation at the welded joint, which subsequently lowered the weld strength to 0.60 MPa when the heating duration was extended to 20 s. In sum, a strengthen welded joint can be formed with rapid microwave heating under the proper control of heating duration.

Study on the characteristics and kinetics of microwave hot air combined drying of peanut pods

Drying is an important means to maintain the quality of peanut pods and reduce the risk of mildew. Microwave hot air combined drying is renowned for its efficacy, low-energy consumption, and superior processing quality, rendering it suitable for peanut pod drying. However, its efficacy hinges greatly on various parameters. To enhance drying efficiency and quality, the drying kinetics of peanut pods using microwave hot air combined drying equipment were investigated. Varying microwave power (1.2 kW, 2.4 kW, 3.6 kW), hot air temperature (30 °C, 35 °C, 40 °C, 45 °C), air velocity (0.4 m/s, 0.7 m/s, 1 m/s), and microwave radiation time (4 min, 6 min) were examined. Results indicated a decline in drying time, moisture ratio, and drying rate with increasing microwave power, hot air temperature, air velocity, and microwave radiation time. Peroxide and acid values complied with national standards. The Verma model exhibited optimal fitting. At 45 °C, peanut pod moisture diffusion coefficient was 3.022 × 10−9 m2 s−1, specific energy consumption at 30 °C was 5302 kJ/kg, and thermal efficiency was 42.6 %. The synergistic drying of peanut pods by microwave and hot air has a high moisture diffusion coefficient and thermal efficiency. The kinetic and energy analysis of the drying process can furnish some theoretical foundation for subsequent microwave hot air drying and equipment parameter adjustment.

Thermal fracturing of anthracite under low-energy microwave irradiation: An experimental study

Microwave-assisted coalbed methane (CBM) development is a very promising technology for engineering applications. The mechanism of the macro and micro thermal fracture of coal must be further discussed because of the thermal inhomogeneity of microwave caused by the heterogeneity and structural complexity of coal. In this study, the temperature, weight and P-wave velocity of anthracite were tested under low-energy microwave irradiation. The characteristics of fracture initiation, extension, and connectivity in coal after microwave irradiation were extracted from macroscopic and microscopic observations. Then the mechanisms of microwave thermal fracturing in anthracite were analyzed. The results showed that the temperature of anthracite under low-energy microwave irradiation varies asynchronously. The temperature distributions with high and low temperature partitions exhibit obvious bedding effects. The coal mass loss varies in stages with microwave irradiation time, first increasing slowly and then increasing dramatically above 500 °C. The P-wave velocity presents a decreasing trend with the increase of input microwave energy. Coal generates a complex fracture network at the micro and macro scales, with fractures expanding outwards in a divergent pattern. The nonuniformity of the temperature distribution promotes fracture development. It is related to the asynchronous heating caused by the mineral composition, water content, pore fracture structure, and electromagnetic field in coal. It is of great significance to improve the thermal fracturing efficiency by using the nonuniformity of microwave heat in the application of microwave-assisted CBM development.

Structural properties and low-temperature NH3-SCR activity of CeO2-MnOx mixed oxides catalyst in the microwave field

The NH3-SCR technology, based on CeO2-MnOx catalysts, is of great significance for NOx removal at low temperatures. Microwave irradiation, as an effective heating approach, can enhance the low-temperature NH3-SCR activity of catalysts. Herein, the structure-activity relationship of CeO2-MnOx oxides catalysts was explored under microwave irradiation. The MnOx catalyst and Ce-Mn(1:1) mixed oxide catalyst exhibited good low-temperature de-NOx performance in the microwave field. With the increase of microwave irradiation intensity and time, the structure and phase composition of MnOx material underwent significant changes. CeO2 played a key role in maintaining the structural stability of the Ce-Mn(1:1) catalyst. In addition, microwave irradiation affected the redox properties and acidity of the catalyst, regulating the catalytic performance. Suitable microwave operation conditions were conducive to increasing the number of acidic sites and enhancing the redox properties, which improved the low-temperature catalytic activity of the catalyst.

Process optimization and method validation for efficient valorization of low- grade coal into humic substances

The exploration of low-grade coal resources and progress in the extraction method of humic substances are the core aims of this study. Ultrasonic and microwave assisted alkali extractions were compared with conventional shake flask alkali extraction to trace the efficiency of the extraction of humic substances from a wide range of coal samples. Among the seven coal samples collected from coal mines in Chakwal district, Pakistan, the observed humification index values ranged from 1.22 to 1.35 for humic acids, and from 5.0 to 6.9 for fulvic acids. This indicates high ratio of polycondensed aromatic moieties. The coal sample with the highest humic content was used to assess extraction methods targeted to humic substances. The extractions supported with microwave and ultrasound, when compared to shake flask extraction, increased the yield in 6.3 % and 3.2 % for humic acids, and just under 1 % for fulvic acids along with 4 times reduction in extraction time. The highest recoveries of humic acids (39.2 ± 0.9 %) and fulvic acids (9.1 ± 0.3 %) were obtained with a microwave assisted alkali extraction using KOH (0.1 M)-urea (0.5 M) (4:1, v/v) solution, and microwave irradiation time 180 s. In general, the optimised method improved the humic and fulvic acids extraction yield up to 10.8 % and 4.4 %, respectively. Furthermore, the Yates model was well suited for predicting the efficiency of the study extractions.

Development and validation of an efficient approach for extracting essential oil, scutellarin, and rosmarinic acid from Perilla frutescens leaves using vacuum microwave-mediated rotary hydrodistillation and extraction in situ and a choline amino acid ionic liquid

In this study, an efficient vacuum microwave-mediated rotary hydrodistillation and extraction in situ (VMRHDE) device was used for extracting essential oil, scutellarin, and rosmarinic acid from Perilla frutescens leaves with choline amino acid ionic liquid solution. The extracted products were then analyzed through GC–MS and HPLC. The optimal parameters were determined through a Doehlert design matrix and desirability function, resulting in the use of 10 % choline glutamate ionic liquid ([Ch][Glu]), a liquid–solid ratio of 15 mL/g, a microwave irradiation time of 20 min, a microwave irradiation power of 540 W, and a rotary speed of 24 r/min. Under optimal operating conditions, the yields of essential oil, scutellarin, and rosmarinic acid were 0.41 % ± 0.02 %, 0.39 % ± 0.01 %, and 0.36 % ± 0.01 %, respectively. GC–MS analysis revealed that adding [Ch][Glu] significantly increased the content of perilla aldehyde and oxygenates in the essential oils. Methodological validation confirmed that the established method met the detection requirements, with recoveries of 99.20 % for scutellarin and 99.83 % for rosmarinic acid, demonstrating high accuracy. The linear relationship of scutellarin and rosmarinic acid was good in the concentration range, with R2 values of 0.9999 for both.

Enhanced NO2 gas response of ZnO–Ti3C2Tx MXene nanocomposites by microwave irradiation

ZnO–Ti3C2Tx MXene nanocomposites with varying MXene contents (0.5, 1, 2, and 5 wt%) were synthesized for NO2 detection, and the impact of microwave (MW) irradiation time (1–8 min) on NO2 response was explored. It was observed that the sensor containing 2 wt% Ti3C2Tx MXene, irradiated for 5 min, indicated the best response of 42.65 to NO2 (10 ppm) at 300°C. Additionally, the optimal gas sensor demonstrated long-term stability (over six months), and reproducibility. The boosted NO2 response was ascribed to the creation of ZnO–MXene Schottky barriers, an increase in oxygen vacancies due to MW irradiation, a large surface area of the nanocomposite sensor, and the presence of surface groups on MXene. We confirmed the promising effects of MW irradiation in enhancing gas sensing, showcasing it as a cost-effective and readily available technique.

Using a New Fe3O4@CPAM Magnetic Flocculant and Microwave to Demulsify Heavy Oil-in-Water Emulsions.

In this study, cationic polyacrylamide (CPAM)-coated magnetic nanoparticles (MNPs) Fe3O4@CPAM were synthesized for treating heavy O/W emulsions. This Fe3O4@CPAM was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM) techniques, and its synergistic performances with microwaves were evaluated in detail with respect to the microwave radiation power, radiation time, and magnetic nanoparticle concentration. On this basis, the distribution of oil droplets and the wettability and chargeability of magnetic nanoparticles were measured without or with microwave radiation using biomicroscopy, contact angle measurement instrument, and a ζ-potential analyzer, thus revealing the synergistic demulsification mechanism between microwave and magnetic nanoparticles. The results showed that excessively high or low microwave radiation parameters had an inhibitory effect on the magnetic nanoparticle demulsification, and microwave promoted the magnetic nanoparticle demulsification only when the radiation parameters were in the optimal range. In addition, the water separation rate showed an increasing and then decreasing trend with the increase of magnetic nanoparticles concentration, with or without microwave action. As an example, the water separation rate of the emulsion for 1 h was 21.34% when the Fe3O4 concentration was 175 mg/L without microwave action, while it increased to 55.56% with microwave action. In contrast, when the concentration of Fe3O4@CPAM was 175 mg/L, the water separation rate was 42.86% without microwave radiation, while it was further increased to 77.38% under microwave radiation. These results indicate that magnetic nanoparticles and their complexes significantly affect the water separation process under different conditions. There is a more obvious coupling synergistic effect between Fe3O4@CPAM and microwave. This was due to the lower absolute potential of Fe3O4@CPAM and its higher hydrophobicity.

Citric acid-glycerol-based NADES for microwave-assisted extraction enhances the polyphenols level of Eleutherine bulbosa mill. Urb. Bulbs

Natural deep eutectic solvent combined with Microwave-assisted extraction (MAE) is considered as a potential green substitute for conventional extraction methods because of its selectivity and shorter extraction time. Eleutherine bulbosa Mill Urb. (E. bulbosa) bulbs, is renowned for having a high concentration of bioactive substances, primarily phenolics compounds with various therapeutic characteristics. This study aims to increase the level of total phenolics content (TPC) in E. bulbosa bulbs extract by applying a citric acid-glycerol (CA-Gly)-MAE and to optimize its extraction conditions using response surface methodology-based box-behnken design. In this study, we extracted dried samples under various conditions including microwave irradiation time and power, solid–liquid, sample-solvent ratio, and CA-Gly ratio. The measurements of TPC value were done spectrophotometrically and gallic acid was used as standard reference. The recommended optimum conditions were at 50% microwave power for 15 minutes, ratio of 1:14 g/ml, and CA-Gly ratio of 1:1 g/g, resulting in a predicted TPC value of 74.749 ± 3.716 mg GAE/g DW extract. Confirmation experiments were conducted using the recommended optimal extraction parameters, and the obtained TPC value was 84.653 ± 0.918 mg GAE/g DW extract. Our result demonstrates the potential of the CA-Gly-MAE for obtaining a higher yield of polyphenols from E. bulbosa bulbs.

A novel semi-continuous preparation mode of ultra-low density thermoplastic polyurethane foam

The production of elastomer foam commonly faces challenges like low production efficiency, limited controllability, uneven foaming, and inherent shrinkage characteristics, especially in manufacturing thick foam sheets. Addressing these, this study introduces innovative “semi-continuous foaming with ultra-low-pressure” (SFU) strategy that integrates low-temperature gas-locking, conduction-microwave heating, and N2-assisted gas-exchange, aimed at optimizing the entire process of TPU foam production, from manufacturing and storage to post-processing. The low-temperature gas-locking scheme realizes semi-continuous preparation of elastomer foam; the conduction-microwave heating scheme significantly improves the heating speed and uniformity; and the N2-assisted gas exchange scheme prevents elastomer foam shrinkage, facilitating the creation of high expansion ratio foam. This process offers the flexibility to adjust initial cell sizes (5–30 μm after shrinkage) and expansion ratios (1–24 times) by manipulating parameters such as microwave radiation time, power, and saturation time. Furthermore, the foam was prepared under ultra-low pressure (<7 MPa), resulting in a final expansion exceeding 14.2 times TPU thick sheet (5 mm thickness before foaming) foam with excellent resilience (energy loss coefficient ∼ 10 % and ball resilience ∼ 68.8 %). This study explores the mechanism by which TPU can self-absorb during microwave heating and extends this process to TPU materials with varying thicknesses (16.5 mm thickness before foaming) and chain compositions, as well as different types of elastomeric materials or materials with elastomer-like properties (e.g., PBAT, etc.). The SFU strategy not only significantly reduces energy and gas consumption but also steers the technological advancement of foam production towards a greener and more sustainable future.

Agricultural waste-based microporous catalysts for oxidative desulfurization of highly sour heavy gas oil

In recent years, the use of abundant and low-cost biomaterials such as agricultural wastes in the preparation of activated carbon has been receiving a lot of attention. Besides, the conventional middle and heavy fuel cuts require a substantial and cost-effective sweetening process because sulfur in transportation fuel was found as one of the main causes of air pollution. The present work explored the preparation and characterization of microporous activated carbon (AC) catalysts prepared from olive stone by tubular furnace (Fe/AC1) and microwave (Fe/AC2) heating methods using H3PO4 (85 wt%) as chemical activating agents. The kinetics of the oxidative desulfurization process (ODS) of a highly sour diesel fuel (sulfur content = 7361 ppm) was determined. The effect of the heating method on the texture and morphological structure, surface area, and surface chemistry of the carbons produced was investigated. Fe/AC1 was prepared in a horizontal tabular furnace at 650 °C calcination temperature and 90 min residence time under a nitrogen atmosphere, while Fe/AC2 was performed in a microwave reactor with 565 W and 7 min microwave power and irradiation time respectively. The catalysts were characterized by N2- adsorption-desorption, SEM-EDX, FTIR, XRD, XRF, TGA, PSD, and elemental analysis. It was found that the use of a tubular furnace for heating the olive seeds resulted in a higher surface area and yield. Also, the characterizations of the Fe/AC1 catalyst showed that it has a large surface area of 1175 m2/g and micropore volume of 0.6954 cm3/g whereas Fe/AC2 had a surface area of 854 m2/g and micropore volume of 0.6936 cm3/g. Moreover, SEM-EDX results indicated that Fe/AC1 was dispersed uniformly better than Fe/AC2. Also, TGA/DTA results revealed better results for Fe/AC1 than Fe/AC2 making it favorable in ODS experiments. The difference in texture and chemical properties is caused by the heating methods. The desulfurization removal was investigated under different temperatures (80, 90, 100, 110 °C) and reaction time (30–90 min). The kinetics of the ODS were conducted over the efficient Fe/AC1 catalyst prepared. It was shown that the ODS reaction followed pseudo-first-order kinetics with a fairly low activation energy over the catalyst was 40.71 kJ/mol.

Liquid activated carbon (LAC) – Enhanced microwave remediation of PAH – Contaminated soils

A new Liquid Activated Carbon (LAC)-enhanced microwave (MW) treatment was studied in the remediation of PAH-contaminated soils. The role of different doses of LAC was studied at the bench-scale varying MW input and irradiation times. Laboratory transport tests were also designed to assess the potential mobility of LAC suspensions in unsaturated porous media under the effect of gravity, thus simulating field application via ground flooding and gravity-driven percolation.The main results revealed that the LAC can significantly increase the MW electric field absorbing performance of the irradiated medium, leading to very high soils temperatures up to ∼1100 °C within 3-min irradiation time (LAC 10%). This resulted in largely shortened PAH removal kinetics. A LAC dose of 5% led to a total PAH removal in 5 min, whereas the maximum dose of 5% shorted this time to 2 min. Transport tests evidenced a good mobility of LAC when applied by gravity-driven percolation, without active injection. In 18 cm long columns, approximately 30% of LAC was retained, with a fairy homogeneous distribution along the bed length. Experimental and modelling results validate the concept of the LAC-enhanced MW heating and the fundamental role of the liquid enhancer for in situ remediation interventions.

Assessment of the synthesis method of Fe3O4 nanocatalysts and its effectiveness in viscosity reduction and heavy oil upgrading

In this research, Fe3O4 nanocatalysts were synthesized systematically microwave-assisted. The effectiveness of the synthesized nanocatalysts in reducing viscosity and upgrading heavy oil was evaluated. The nanocatalysts were investigated for their magnetic and electromagnetic properties. The impact of microwave radiation's time and power on the size and purity of nanocatalysts was investigated. The purities in the crystal network of Fe3O4 nanocatalysts expanded as a result of reducing microwave radiation time and power due to less heat production. Increased temperature leads to dope NH4Cl into the Fe3O4 nanocatalysts crystal network. At: 1 min and power of 400 watts the most satisfactory results in the size and purity of nanocatalysts. The electromagnetic properties, size, and effectiveness of the synthesized Fe3O4 nanocatalysts have been examined to determine the effect of the synthesis method. The performance of Fe3O4 nanocatalysts synthesized by co-precipitation and microwave-assisted viscosity reduction and heavy oil upgrading was evaluated and compared. The crystallite size of the Fe3O4 nanocatalysts synthesized by microwave-assisted was smaller than that synthesized using co-precipitation. Fe3O4 nanocatalysts synthesized by microwave-assisted and the co-precipitation method decreased viscosity by 28% and 23%, respectively. Moreover, Fe3O4 nanocatalysts synthesized by microwave-assisted reduced the sulfoxide index and aromatic index considerably more than the co-precipitation synthesized Fe3O4 (90% against. 48% and 13% vs. 7%, respectively).