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The depleting fossil fuels and anthropogenic climate change require involvement of renewable energy resources, including animal wastes. One of the effective, although less studied, ways of the cattle manure transformation to a convenient energy source is its microwave pyrolysis (MWP) into a combustible gas. The MWP of cattle manure was experimentally studied, using differential thermal analysis, scanning electron microscopy, BET surface measurement, and high-speed video recording. Spark discharges between inorganic centers with metallic or semiconductor properties in the MWP-treated manure were found responsible for the MW-radiation impact. It was experimentally shown that on course of thermal destruction, the absorption of microwave radiation by manure increases almost two times probably due to a change in the composition of carbon-containing compounds and the release of gases, tar vapors, and pyrogenic water. The MWP treatment provides fast and uniform heating of manure with its more complete volatilization, leaving only 34.5% wt. of carbonaceous residue compared to 42.7% in thermal pyrolysis. The MWP gas is of relatively high calorific value (21.08 MJ m−3) at low content of ballast gases, thus providing environmentally friendly manure transformation with a lesser greenhouse effect. [ABSTRACT FROM AUTHOR]

Eucalyptus species are extensively cultivated trees commonly used for timber production, firewood, paper manufacturing, and essential nutrient extraction, while lacking consumption of the leaves increases soil acidity. The objective of this study was to recover bio-oil through microwave pyrolysis of eucalyptus camaldulensis leaves. The effects of microwave power (450, 550, 650, 750, and 850 W), pyrolysis temperature (500, 550, 600, 650, and 700 °C), and silicon carbide amount (10, 25, 40, 55, and 70 g) on the products yields and bio-oil constituents were investigated. The yields of bio-oil, gas, and residue varied within the ranges of 19.8–39.25, 33.75–46.7, and 26.0–33.5 wt %, respectively. The optimal bio-oil yield of 39.25 wt % was achieved at 650 W, 600 °C, and 40 g. The oxygenated derivatives, aromatic compounds, aliphatic hydrocarbons, and phenols constituted 40.24–74.25, 3.25–23.19, 0.3–9.77, and 1.58–7.75 area % of the bio-oils, respectively. Acetic acid (8.17–38.18 area %) was identified as a major bio-oil constituent, and hydrocarbons with carbon numbers C1 and C2 were found to be abundant. The experimental results demonstrate the potential of microwave pyrolysis as an eco-friendly and efficient way for converting eucalyptus waste into valuable bio-oil, contributing to the sustainable utilization of biomass resources. [ABSTRACT FROM AUTHOR]

To improve the homogeneity of heating, the magnetic absorbing material Fe3O4 is considered to use in microwave pyrolysis of oily sludge. Therefore, the effect of Fe3O4 on the microwave pyrolysis of oily sludge is investigated based on gas volatile products. Thermogravimetric mass spectrometry result certifies that Fe3O4 will increase the weight-loss ratio from 13.0% to 14.1%. Also, the characteristic peak intensity of CO in gas products decreases from 5.41 × 10−10 A/g to 1.95 × 10−10 A/g, while H2O increases from 3.57 × 10−10 A/g to 7.32 × 10−10 A/g and CO2 increases from 6.87 × 10−10 A/g to 8.92 × 10−10 A/g. This is caused by the esterification of alcohols and esters and the reduction of Fe3O4 by CO. Based on the decrease in activation energy and enthalpy values of Stage II and IV, it infers that Fe3O4 catalyzes the pyrolysis process of oily sludge to some extent. Similarly, gas chromatography-mass spectrometry results show that Fe3O4 can make the types of gas products increase. Especially, the number of molecular species increases from 5 to 46 under 200–300 °C. Finally, a simple molecular dynamics simulation model is conducted, and the results are in agreement with the experimental results. This study shows that Fe3O4 improves the pyrolysis homogeneity and the pyrolysis efficiency also improves. [ABSTRACT FROM AUTHOR]

Plastics have light weight and excellent performance, which are widely used in all kinds of automobiles. Polypropylene (PP) and its reinforcing materials are used in automotive components, where the surfaces of bumpers and fenders are coated with paint. Traditional recycling can frequently generate various pollutants, such as paint sludge. Microwave pyrolysis is a more environmentally friendly pyrolysis method with a higher heating coefficient than traditional electric pyrolysis. This study first explores the elemental composition of two types of automotive PP plastics and uses thermogravimetric analysis and the Kissinger-Akahira-Sunose method to preliminarily calculate the activation energy of automotive PP. The calculation results show that the activation energy of PP containing paint ranges from 189.145 kJ/mol-199.513 kJ/mol, with an average value of 193.903 kJ/mol. The activation energy of PP without paint is between 215.506 kJ/mol-265.794 kJ/mol, with an average value of 242.425kJ/mol. Then, pyrolysis experiments on PP for vehicles without paint are conducted using a microwave atmosphere tube furnace at different temperatures and microwave powers. The experimental results showed that, when the pyrolysis temperature increased from 500oC to 620 oC, the total proportion of gas products rose from 0.75 wt.% to 4.81 wt.%, and the content of alkanes in the liquid products improved from 26.21 wt.% to 34.37 wt.%; when the microwave power increased from 900 W to 1100 W, the gas product rose to 20.77 wt.%, and the content of aromatic compounds in the liquid product improved to 17.78 wt.%. In addition, the pyrolysis experiment of automotive PP containing paint showed that paint had a relatively minor effect on the pyrolysis products of automotive PP. This study shows that using microwave pyrolysis to treat automotive PP and PP with paint is feasible, which provides a reference for the clean treatment of automotive polymers. [ABSTRACT FROM AUTHOR]

This study proposes an integrated and sustainable approach for the effective conversion of kitchen waste into valuable products through a two-step process. The primary step involves the implementation of greenhouse solar drying to reduce the moisture content of kitchen waste. The secondary step implies microwave pyrolysis for effective degradation of kitchen waste to biooil, biogas and biochar. Biooil and biogas can be used as renewable fuel source. Biochar can be used as soil amendment. Selection of atmospheric conditions for biochar preparation is discussed, highlighting its crucial role in biochar characteristics. This article highlights, technology readiness level of biochar production from kitchen waste to assess the economic viability for the scalability of the process. In this entirety, the conversion of kitchen waste to valuable products through microwave pyrolysis has significant potential to address the challenges posed by high moisture content and heterogenous nature. With continued research and innovation, it is possible to develop a wide array of value-added products from kitchen waste, ultimately leading to a more eco-friendly and economic approach to waste management. [ABSTRACT FROM AUTHOR]

In this study, a two-step method was applied to obtain an effective adsorbent for cadmium (Cd) (II) and lead (Pb)(II) adsorption. The first stage includes the production of activated carbon (AC) from almond shells, which is agricultural waste, by microwave heating and potassium hydroxide (KOH) chemical agent. The second stage includes nitrogen and oxygen doping by hydrothermal heating treatment of the obtained ACs with nitric acid. The obtained materials were characterized by thermogravimetric/differential thermal analyser (TG–DTA); Fourier transform infrared spectroscopy (FTIR); scanning electron microscope (SEM); energy-dispersive spectroscopy (EDS); C, H, N, S elemental analysis; and nitrogen adsorption analyses. The adsorption performance, mechanism, kinetics, and thermodynamics of nitrogen- and oxygen-doped activated carbons were evaluated. The obtained isotherm and kinetic results showed that the adsorption of Cd (II) and Pb (II) on nitrogen- and oxygen-doped ACs followed Langmuir isotherm and pseudo-second-order kinetics. The adsorption capacity values ​​(Qm) obtained for Cd (II) and Pb (II) adsorption were 106.38 mg/g and 76.33 mg/g, respectively. [ABSTRACT FROM AUTHOR]

Food waste pyrolysis has been reported widely these years. However, rare research discusses its industrial possibilities due to its high moisture content. This research focuses on the microwave co-pyrolysis of food waste and chinar leaves to tune the moisture and seek for solution. To find the optimal path for microwave co-pyrolysis of raw food waste (69 wt.% moisture) and chinar leaves, thermal characteristics, catalysts (Na2CO3 and MgO), and kinetics (KAS, OFW, Friedman) were conducted to reveal the pyrolysis behaviors and apparent activation energy in all conditions. Lastly, techno-economic analysis was done to estimate the operating costs of large-scale microwave co-pyrolysis. Results showed that Na2CO3 and MgO both suppressed the secondary pyrolysis between 355 and 398 ℃, which is consistent with the modified Broido–Shafizadeh model, respectively. Importantly, CL75-FW25-Na2CO3 performed higher pyrolysis rates between 306.7 and 471.7 ℃, and the presence of 5% alkali metal salt significantly lowered the apparent activation energy (from 195.2 to 122.4 kJ/mol, KAS). Moreover, it was found that the biogas collected from 250 to 800 ℃ contained a total of 26.5% H2, 17% C2H6, and 20.9% C2H4. The large-scale production cost of microwave co-pyrolysis of raw mixed food waste and chinar leaves is estimated to be USD 536.72 /ton. This research demonstrates that alkali metal salt and synergistic effects between food waste and chinar leaves can optimize the co-pyrolysis process, and its catalytic microwave co-pyrolysis also presents potential economic feasibility for the efficient disposal of solid municipal waste and clean biogas production. [ABSTRACT FROM AUTHOR]

In this study, NiFe2O4, ZnFe2O4, and MgFe2O4 catalysts are utilized to decompose plastic into hydrogen gas, liquids, and carbon nanotubes. Ferrite nanoparticles worked as a catalyst and heat susceptors for microwaves. MgFe2O4 catalyst resulted in highly structured carbon residue with fewer impurities than other catalysts. The oil yield of 13.5, 14, and 9.5 wt. % was obtained with NiFe2O4, ZnFe2O4, and MgFe2O4, respectively. Similarly, gas evolution was about 14, 13, and 12.5 wt. %, respectively. MgFe2O4 displayed superior H2 production efficiency of 90 % compared to the other two catalysts. These findings suggest high activity of MgFe2O4 catalyst compared to NiFe2O4 and ZnFe2O4 catalysts. This catalyst also showed stronger magnetic characteristics and reactivity. [ABSTRACT FROM AUTHOR]

In the domain of waste management, pyrolysis is widely regarded as a promising technology for energy recovery, involving the conversion of waste or biomass into high-value energy products. Microwave-metal-assisted pyrolysis (MMAP) is a technique that exploits microwave-metal interaction to enhance the quality of pyrolysis products. Despite the misconception that metals cannot couple well with microwaves and are hazardous when heated in a microwave field, research studies have shown that the presence of metals can generate a large amount of heat, which aids the heating of pyrolysis feedstock. This technique promotes pyrolysis over many materials, such as plastics, biomass, and tire powders. This work discusses the effect of several MMAP parameters such as microwave power, metal species, metal shape and quantity on the product yield, and distribution based on reported studies. This paper also addresses the challenges of MMAP and proposes some suggestions on the future outlook of this process. To conclude, this review discusses the available information and data on MMAP to enrich the knowledge in this field. [ABSTRACT FROM AUTHOR]

The rapid expansion of the scale of wind power has led to a wave of efforts to decommission wind turbine blades. The pyrolysis of decommissioned wind turbine blades (DWTBs) is a promising technological solution. Microwave pyrolysis offers the benefits of fast heating rates and uniform heat transfer, making it a widely used method in various heating applications. However, there are few studies on the microwave pyrolysis of DWTBs, and pyrolysis characteristics under different boundary conditions remain unclear. In this paper, we investigate the pyrolysis characteristics of DWTBs by utilizing silicon carbide (SiC) particles as a microwave absorbent. The results demonstrated that, when the microwave heating power increased from 400 W to 600 W, the heating rate and pyrolysis final temperature of the material increased, resulting in a reduction in pyrolysis residual solid yield from 88.30% to 84.40%. At 600 W, pyrolysis gas components included C2H4, CH4, and CO, while the tar components included phenol and toluene. The highest degree of pyrolysis was achieved under the condition of an SiC particle size of 0.85 mm, with better heating performance, and the calorific value of the pyrolysis gas generated was 36.95 MJ/Nm3. The DWTBs did not undergo pyrolysis when SiC was not added. However, when the mass ratio of SiC to DWTBs was 4, the tar yield was 4.7% and the pyrolysis gas yield was 17.0%, resulting in a faster heating rate and the highest degree of pyrolysis. Based on this, an optimal process for the microwave pyrolysis of DWTBs was proposed, providing a reference for its industrial application. [ABSTRACT FROM AUTHOR]

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Abstract The regulation of the pyrolysis process is a key step in increasing the carbon sequestration capacity of biochar. The effect of K3PO4 addition on the yield, chemical composition, characteristic functional groups, macromolecular skeleton, graphite crystallites, and stability of biochar was studied in this paper using two-dimensional infrared correlation spectroscopy (2D-PCIS), X-ray photoelectron spectroscopy, Raman spectrum, and other characterization methods combined with thermal/chemical oxidation analysis. It is discovered that adding K3PO4 may effectively minimize the graphitization temperature range and increase biochar's yield, aromaticity, H/C ratio, and proportion of refractory/recalcitrant organic carbon. The 2D-PCIS and Raman analysis revealed that K3PO4 mostly promoted the dehydrogenation and polycondensation process of the aromatic rings in the char precursor, transforming the amorphous carbon structure of biochar into an ordered turbostratic microcrystalline structure. K3PO4 enhanced biochar stability mostly at medium-high temperatures (350 ~ 750℃) by stimulating the transformation of unstable structures of biochar to stable carbon-containing structures or by inhibiting the interaction of its active sites with oxidants through the mineralization process. A 20% phosphorus addition increased biochar's refractory index (R50) by roughly 11%, and it also boosted biochar's oxidation resistance (H2O2 or K2CrO4) efficiency, reducing carbon oxidation loss by up to 7.31%. However, at higher temperatures (> 750 ℃), the doping of phosphorus atoms into the carbon skeleton degraded the biochar structure's stability. The results of this study suggest that using exogenous phosphorus-containing additives is an efficient way to improve the stability of biochar. Graphical abstract

The polymer precursor derived ceramics route is one of the important ways for the preparation of ceramics, and pyrolysis is absolutely necessary in the process. The traditional thermal pyrolysis suffers from slow heating/cooling rate, long processing time, and high energy consumption. In recent years, new technologies, including laser pyrolysis, microwave treatment, and discharge plasma sintering, have attracted the attention in the researchers due to the advantages of fast heating/cooling rate and low energy consumption. This paper summarizes the research progress in rapid pyrolysis in PDCs. The advantages of the new technologies in the preparation of high-performance ceramics are also discussed. [ABSTRACT FROM AUTHOR]

The regulation of the pyrolysis process is a key step in increasing the carbon sequestration capacity of biochar. The effect of K3PO4 addition on the yield, chemical composition, characteristic functional groups, macromolecular skeleton, graphite crystallites, and stability of biochar was studied in this paper using two-dimensional infrared correlation spectroscopy (2D-PCIS), X-ray photoelectron spectroscopy, Raman spectrum, and other characterization methods combined with thermal/chemical oxidation analysis. It is discovered that adding K3PO4 may effectively minimize the graphitization temperature range and increase biochar's yield, aromaticity, H/C ratio, and proportion of refractory/recalcitrant organic carbon. The 2D-PCIS and Raman analysis revealed that K3PO4 mostly promoted the dehydrogenation and polycondensation process of the aromatic rings in the char precursor, transforming the amorphous carbon structure of biochar into an ordered turbostratic microcrystalline structure. K3PO4 enhanced biochar stability mostly at medium-high temperatures (350 ~ 750℃) by stimulating the transformation of unstable structures of biochar to stable carbon-containing structures or by inhibiting the interaction of its active sites with oxidants through the mineralization process. A 20% phosphorus addition increased biochar's refractory index (R50) by roughly 11%, and it also boosted biochar's oxidation resistance (H2O2 or K2CrO4) efficiency, reducing carbon oxidation loss by up to 7.31%. However, at higher temperatures (> 750 ℃), the doping of phosphorus atoms into the carbon skeleton degraded the biochar structure's stability. The results of this study suggest that using exogenous phosphorus-containing additives is an efficient way to improve the stability of biochar. Highlights: K3PO4 promoted biochar precursor's dehydrogenation/polycondensation process to form fused-ring aromatic structures. K3PO4 increased recalcitrant carbon proportion and shielded biochar's active sites through the mineralization process. By adding 20 wt% of K3PO4, the thermal and chemical stability of biochar were enhanced by 11% and 7%, respectively [ABSTRACT FROM AUTHOR]

This study aims to convert composite textile structures composed of nonwoven and woven fabrics produced from cotton–jute wastes into activated carbon textile structures and investigate the possibilities of using them for electromagnetic shielding applications. To this end, the novel contribution of this study is that it shows that directly carbonized nonwoven textile via self-purging microwave pyrolysis can provide Electromagnetic Interference (EMI) shielding without any processing, including cleaning. Textile carbonization is generally achieved with conventional heating methods, using inert gas and long processing times. In the present study, nonwoven fabric from cotton–jute waste was converted into an activated carbon textile structure in a shorter time via microwaves without inert gas. Due to its polar structure, FeCl3 has been used as a microwave absorbent, providing homogeneous heating in the microwave and acting as an activating agent to serve dual purposes in the carbonization process. The maximum surface area (789.9 m2/g) was obtained for 5% FeCl3. The carbonized composite textile structure has a maximum of 39.4 dB at 1 GHz of EMI shielding effectiveness for 10% FeCl3, which corresponds to an excellent grade for general use and a moderate grade for professional use, exceeding the acceptable range for industrial and commercial applications of 20 dB, according to FTTS-FA-003. [ABSTRACT FROM AUTHOR]

Sugarcane bagasse (SB) is a widely available agro-industrial waste residue in China that has the potential to be converted into a cost-effective and renewable adsorbent. In this study, activated carbon (AC) was prepared from SB by microwave vacuum pyrolysis using H3PO4 as the activator. To enhance the sorption selectivity and yield, the pyrolysis process of SB-activated carbon (SBAC) should be well-designed. Central composite design was employed as an optimized experiment design, and response surface methodology was used to optimize the process parameters for maximized SBAC yield and its iodine number. The results showed that the optimized parameters obtained for the SBAC are 2.47 for the impregnation ratio (IR), 479.07 W for microwave power (MP), 23.86 mm for biomass bed depth, and 12.96 min for irradiation time, with responses of 868.7 mg/g iodine number and 43.88% yield. The anticipated outcomes were substantiated, revealing a marginal 5.4% variance in yield and a mere 1.9% discrepancy in iodine number from the forecasted values. The synthesized adsorbents underwent comprehensive characterization through instrumental methodologies, including FT-IR, BET, and SEM. The SBAC produced by the pyrolysis method contained a regular and homogeneous porous structure with a specific surface area of up to 1697.37 m2/g and a total 1.20 cm 3/g volume, which has favorable adsorption of toxic and harmful substances in the environment. [ABSTRACT FROM AUTHOR]

This research focus endeavour to compare the remediation of tetracycline (TC) through activated carbon (AC), crafted utilizing two distinct chemical activators: zinc chloride (ACZ), and potassium hydroxide (ACK), using pine cone biowaste as an effective carbon precursor, followed by microwave-assisted activation. The impact of TC removal by ACZ and ACK adsorbents was thoroughly examined. The influence of pH, adsorbent mass, adsorption isotherms, kinetics, and inclusive thermodynamics were studied. Our results revealed that the interaction between TC and ACZ or ACK adsorbents aligned well with the model of pseudo-second-order kinetics, whilst the Langmuir model fitted the adsorption isotherm data of ACZ and ACK. The ACZ have a maximum adsorption capacity of 327.87 mg/g compared to that of the ACK (283.29 mg/g). Adsorption of TC was facilitated by the suitable pore volume, abundant microporous, and mesoporous structure of these adsorbents. The ACZ adsorbent is abundant in oxygen-containing functional groups, compared to ACK with minimized reactive sites, in bonding with the TC molecules through hydrogen bonding, for faster removal of TC. Our finding from this work further highlights that the synthesized ACZ from pine cones evidenced significant environmental potentials in the elimination of antibiotics from aqueous solution, to promote clean application perspectives.

Catalytic microwave-assisted pyrolysis of biomass is gaining popularity as an alternative to fossil fuels due to health, environmental, climate, and economic issues. This study conducted a catalytic pyrolysis process of the Albizia plant's branches using an Iraqi clay catalyst (bentonite) focusing on the variables including the biomass-particle size, experimental time, microwave power level, and the catalyst-to-biomass ratio. The physical and chemical properties of the resulting biofuel were analyzed presented by HHV, acidity, density, viscosity, GC-MS, FTIR for bio-oil and SEM, EDX, BET, HHV, FTIR for biochar. The study revealed that addition of bentonite as a catalyst led to enhanced production of biogas produced from 5% to 45% and decreased the power level used from 700 W to 450 W. Also, it raised the production of bio-oil generated with less power level and duration time. The addition of catalyst also affected the characteristics of bio-oil produced such as reducing the acidity by increasing its pH from 5 to 5.7, lowering the viscosity from 4.8 to 3.3 cSt, and the density from 1045 to 1039.2 kg/m3. Adding catalyst increased the percentage of aromatic and alcoholic substances in the bio-oil which led to improve the calorific value from 19.5 to 23 MJ/kg. Additionally, the biochar properties also improved, where the surface area and pore volume increased from 0.5512 to 40.384 m2/g and 0.00011 to 0.0361cm3/g respectively. The higher heating value was raised from 23.5 to 25 MJ/kg also. CH4 is also increased from 3.6 to 8.6% which is one of the essential fuel gasses.

The ferric sulfate was added to reservoir rock catalyst (RC) and activated carbon catalyst (AC) to obtain Fe/RC and Fe/AC. Microwave pyrolysis (MP) was carried out to process low-rank coal (LRC) using catalysts and receptors (Fe/RC and Fe/AC). A comparison was made between the product distribution and the process factors (temperature, time, and power). The results show that the product is affected by MP with Fe/CR and Fe/AC through temperature acceleration and final temperature. When compared to conventional pyrolysis (CP) with the same conditions (620 °C and 60 min), the bio-oil generated from MP + 1.0% RC + 24.6% Fe was 42.0%, 4.4% greater than CP. Meanwhile, using MP + 1.0% AC + 24.6% Fe, 47.1% bio-oil was produced, with an increase of 4.0%. Meanwhile, using 1.0% RC + 24.6% Fe, the highest bio-oil production was seen at 60 min, 620 °C, and 600 W, generating 42.0% bio-oil. Study results can form the basis for obtaining fuel, chemicals, and environmental improvements. [Display omitted] • Microwave pyrolysis on LRC was carried out with catalyst Fe/RC and Fe/AC. • Effect of coal/catalyst ratio, time, and power were investigated. • Highest bio-oil was obtained at ratio of 1:100, 60 min, and 600 W. • Bio-oil was found to contain carboxyl and aliphatic units. [ABSTRACT FROM AUTHOR]

In the current study, the carbon quantum dots (CDs) were synthesized through a facile, rapid, and one-step microwave method using citric acid monohydrate and urea. The as-prepared CDs were spherical with diameters of 3-4 nm and displayed bright blue fluorescent under an excitation wavelength of 360 nm. Also, the as-prepared CDs had various properties, including high quantum yield (≈18%), favorable solubility in water, different functional groups, significant stability in various environmental conditions, and excellent optical performance. The results indicated that the CDs could be applied as a fluorescent probe for reliable and accurate detection of Diclofenac sodium (DFS) based on the enhancement of their native fluorescent intensity (turn-on). The emission spectra of the as-prepared CDs were strengthened gradually when the DFS concentration increased from 5 to 300 µM. In addition, the linear relationship was fabricated over the concentrations range of 5–300 µM for DFS with the detection limit of 2.33 µM. Furthermore, the findings showed that Fe doped CDs (Fe-CDs) like CDs have a good ability to detect various concentrations of DFS in the wide range of 5–300 µM. [ABSTRACT FROM AUTHOR]

The influence of a CO2 reactive medium and of a volume in the range 200–600 mL on the yield of basic components (CO, CO2, H2, and CH4) of a producer gas in microwave heating of biomass has been investigated. The dependences of the moderate and maximum concentrations of the gases on the volume of carbon dioxide fed to the chamber of a microwave reactor have been determined. Trends of variation in the concentrations of the enumerated gases with time have been obtained. Times of the onset of release of the concentrations of the gas components and their duration with variation of the CO2 volume fed to the chamber have been established. The influence of the feed of reactive gases on the mass of the char has been investigated. It has been shown that the injection of CO2 into the reactor chamber exerts a positive influence on the intensification of microwave pyrolysis of the biomass, with the result that the yield of volatiles of the formed gas mixture rises. [ABSTRACT FROM AUTHOR]

In this study, biochar was produced in a microwave pyrolysis reactor and three microwave reaction conditions were introduced. They were pyrolysis temperatures (500, 600, 700, 800, and 900°C), microwave powers (600, 650, 700, 750, and 800 W), and pyrolysis times (30, 40, 50, 60, and 70 min), respectively. The produced biochar was mixed with deionized water and then treated with water washing in a shaker. The yields and microstructure of biochar obtained from the microwave reactor were detailed and the pore structure of washed biochar was also studied. Results showed that the corn stover biochar yield ranged between 44.71 wt.% and 59.92 wt.% depending on the conditions used. The pores in biochar were dominated by macropores and mesopores. As the three reaction conditions were elevated, nanoscale pores appeared, pores were clogged, the pore structure became more obvious and the biochar structure got fragile. Water-washing treatment enlarged the pore sizes, cleaned the clogged pores, and removed watersoluble salts. At longer pyrolysis times, the action of water flow can cause biochar to collapse This study can provide guidance for future microstructure regulation of biochar. [ABSTRACT FROM AUTHOR]

The main objective of the present research work is to utilise the produced bio-oil from microwave pyrolysis of Karanja, a non-edible seed, as fuel for diesel engines by increasing some up-gradation in the quality of the fuel. The emulsification process is carried out to improve the stability of the diesel–bio-oil blend using SPAN 80 and TWEEN 80, which lasted for 28 days without any layer separation termed as EKB20. The addition of 5% DEE and 10% DEE into EKB20 is done to enhance the combustion characteristics of the diesel engine. The produced bio-oil fuels were tested in a Kirloskar make, four-stroke, single-cylinder, direct injection diesel engine of 5.2 kW rated power output. The addition of DEE reduces the peak pressure by 4 bar and increases the heat release rate due to the higher volatility of DEE. At full load conditions, the thermal brake efficiency improved by 9.31% and 14.11%, respectively, compared to EKB20. Adding 5% DEE and 10% DEE at the rated power output reduced the smoke density by 18.42% and 60.25%, respectively, compared to EKB20 and 5% and 4% compared to diesel. The addition of 5% DEE and 10% DEE shows a 39% and 51% increase in NOX concentration and a 90% reduction in CO emission at the maximum brake power output. Hence, it is concluded that the fuels EKB20 + 5% DEE and EKB20 + 10% DEE can be used as alternative fuels for diesel engines. [ABSTRACT FROM AUTHOR]

To valorize livestock manure, the present study investigated the production of biochar from cow dung (CD) by microwave pyrolysis. The pore properties and chemical characteristics of CD and CD-based biochar products were found to correlate with the process parameters like microwave power (300–1000 W) and residence time (5–20 min). The findings indicated that CD is an excellent biomass based on the richness of lignocellulosic constituents from the results of proximate analysis and thermogravimetric analysis (TGA). Higher calorific values were obtained at mild microwave conditions, giving the maximal enhancement factor 139% in comparison with the calorific value of CD (18.97 MJ/kg). Also, it can be concluded that the biochar product obtained at 800 W for a holding time of 5 min had the maximal BET surface area of 127 m2/g and total pore volume of 0.104 cm3/g, which were microporous and mesoporous in the nitrogen adsorption–desorption adsorption analysis. On the other hand, the CD-based biochar contained oxygen-containing functional groups and inorganic minerals based on the spectroscopic analyses by Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS), thus featuring to be prone to hydrophilicity in aqueous solutions. [ABSTRACT FROM AUTHOR]

Higher heating value, energy and exergy analysis of bio-oil and biochar from microwave pyrolysis have been assessed. The energy efficiency for the pyrolysis system has been analyzed by the comparisons of energy based on heating values. The exergy analysis was done using standard relationships by the fraction of energy actually available for practical uses as biofuel. The yield of bio-oil and its higher heating value (HHV) were increased by 2–13% and 25–130% respectively when the microwave power increased from 500 W to 700 W, then both are decreased at 900 W. Using activated carbon (AC) had a remarkable effect on increasing the yield and HHV of bio-oil by 18–31% and 3–7 times respectively more than other cases. By using the additives, the yield of biochar decreased remarkably, while its HHV increased by 12%-40% compared to without additive. The maximum energy and exergy rate (1.74 MJ/h) of the bio-oil were obtained at 700 W level of microwave power using AC additive, while for biochar were 1.95 MJ/h and 2 MJ/h when no additive used. The maximum values of energy and exergy of the bio-oil were computed to be 27% and 26% respectively at 700 W using AC as an additive. The maximum values of energy and exergy efficiency of biochar were calculated to be 33% and 32% respectively when pyrolyzed at 500 W using AC. The energy and exergy efficiencies of the pyrolysis system were computed to be maximum value of 53.3% and 52.8% respectively at 700 W using AC additive. [ABSTRACT FROM AUTHOR]

Increasing amounts of waste resulting from over-consumption carry substantial risks for human and environmental health, and disposing of this waste requires enormous amounts of energy. As a result, waste-to-wealth and circular economy approaches have gained attention in both academia and the commercial sector in recent years. Accordingly, this study aims to develop electromagnetic shielding materials by converting non-conductive waste textiles into conductive value-added product and porous fabrics by carbonizing the structure itself rather than by adding any conductive particles. To this end, the novel contribution of the present study is that waste textiles were converted into activated carbon in a shorter time and without compromising the integrity of the fibrous network via microwave pyrolysis without inert gas. Sulfuric acid was used as a dehydration and activation agent, suppressing the release of volatile organic substances and eliminating greenhouse gas emissions. This approach also increased product yield and reduced energy consumption and sample shrinkage. The structures of the activated carbon textile showed EMI shielding within 20–30 dB (99.9% attenuation) in the 1–6 GHz frequency range. The maximum SSE/t value of 950.71 dB·cm2·g−1 was obtained with the microwave post-treated activated carbon textile. Micropores were dominant characteristics of these materials, and pore diameters increased with increased acid concentration. The maximum surface area of 383.92 m2/g was obtained with 8% acid. Ultrasound treatment reduced water-energy consumption and cost. Only 5 min of microwave post-treatment increased textile conductivity and thermal stability and contributed positively to electromagnetic shielding. [ABSTRACT FROM AUTHOR]

The consumption of fossil fuels has caused many challenges, including environmental and climate damage, global warming, and rising energy costs, which has prompted seeking to substitute other alternative sources. The current study explored the microwave pyrolysis of Albizia branches to assess its potential to produce all forms of fuel (solid, liquid, gas), time savings, and effective thermal heat transfer. The impact of the critical parameters on the quantity and quality of the biofuel generation, including time, power levels, biomass weight, and particle size, were investigated. The results revealed that the best bio-oil production was 76% at a power level of 450 W and 20 g of biomass. Additionally, low power levels led to enhanced biochar production, where a percentage of 70% appeared when employing a power level of 300 W. Higher power levels were used to increase the creation of gaseous fuels in all circumstances, such as in 700 W, the gas yield was 31%. The density, viscosity, acidity, HHV, GC-MS, and FTIR instruments were used to analyze the physical and chemical characteristics of the bio-oil. The GC-MS analysis showed that the bio-oil consists of aromatic compounds, ketones, aldehydes, acids, esters, alkane, alkenes and heterocyclic compounds. The most prevalent component was aromatic compounds with 12.79% and ketones with 12.15%, while the pH of the oil obtained was 5, and the HHV was 19.5 MJ/kg. The pyrolysis productions could be promising raw materials for different applications after further processing.

Relevance. The need of the Tomsk region for valuable energy resources obtained from local low-grade resources to develop iron ore deposits available in the region and cover energy needs. Aim. To study gaseous and solid products obtained from low-grade brown coal of the Talovsky deposit (Tomsk region) under microwave pyrolysis conditions in relation to the energy and metallurgical industries. Objects. Brown coal of the Talovsky deposit (Tomsk region). Methods. Certified SS methods to determine thermal characteristics and elemental composition of coal organic and mineral parts, the "transmission-reflection" method for measuring imaginary (ε'') and real (ε') components of the complex dielectric permittivity, physical experiment, gas analysis, Brunauer–Emmett–Teller method for measuring texture characteristics. Results. Brown coal of the Talovsky deposit has high values of moisture and ash contents for operating conditions, which leads to a low calorific value. Such characteristics make it possible to classify coal as a low-grade fuel, which indicates the inexpediency of its use as a raw material for the energy and metallurgical industries. Thermal processing by means of microwave pyrolysis makes it possible to obtain a high-calorie (heat of combustion over 21 MJ/m3) and environmentally friendly (hydrogen content over 29%) gaseous fuel from the low-grade brown coal of the Talovsky deposit. The resulting solid carbonaceous residue has an ash content of over 48%, which required its chemical treatment in a solution of HF and HCl. As a result of the solid carbonaceous residue treatment, its ash content decreased by more than 38%, the sulfur content – by more than 1.5 times. According to its characteristics, the resulting product corresponds to the currently available carbonaceous products – semi-coke, coke and carbon reducing agent for ferroalloy production.

Date palm trees play a crucial role in the provision of essential nutrition by producing date fruits and are widely cultivated in Qatar. The processing of date fruits generates substantial quantities of carbon-rich date stone possessing remarkable energy potential. This inherent energy can be harnessed by applying pyrolysis techniques, which facilitate the production of many products with commercial value. Despite being a novice process, microwave (MW) pyrolysis has emerged as a promising avenue for converting biomass waste into eco-friendly biofuels. Nonetheless, the adoption of this new approach necessitates a comprehensive exploration of its ecological implications, warranting a meticulous life-cycle analysis (LCA) to ascertain its environmental footprint. As a result, using GaBi software, this study compares the life-cycle environmental impact of conventional and microwave-aided pyrolysis processes of date stone waste. The study also assesses the techno-economic analysis of the two processes. The physical and thermal analyses of the date stone waste indicated that the biomass is a high-energy source (Net calorific value-15.6 MJ/kg). While the life-cycle assessment indicated that MW pyrolysis has a greater implication on climate change (14.94 % more), ozone depletion (14.29 % more), ionizing radiation (14.36 % more), and photochemical ozone production (14.44 % more) than conventional pyrolysis. This demonstrates that conventional pyrolysis is less harmful to the environment than MW pyrolysis. The techno-economic analysis infers that conventional pyrolysis mode is superior to MW pyrolysis for the valorisation of date stone waste in terms of profitability, financial stability, and overall success.

The consumption of fossil fuels has caused many challenges, including environmental and climate damage, global warming, and rising energy costs, which has prompted seeking to substitute other alternative sources. The current study explored the microwave pyrolysis of Albizia branches to assess its potential to produce all forms of fuel (solid, liquid, gas), time savings, and effective thermal heat transfer. The impact of the critical parameters on the quantity and quality of the biofuel generation, including time, power levels, biomass weight, and particle size, were investigated. The results revealed that the best bio-oil production was 76% at a power level of 450 W and 20 g of biomass. Additionally, low power levels led to enhanced biochar production, where a percentage of 70% appeared when employing a power level of 300 W. Higher power levels were used to increase the creation of gaseous fuels in all circumstances, such as in 700 W, the gas yield was 31%. The density, viscosity, acidity, HHV, GCMS, and FTIR instruments were used to analyze the physical and chemical characteristics of the bio-oil. The GC-MS analysis showed that the bio-oil consists of aromatic compounds, ketones, aldehydes, acids, esters, alkane, alkenes and heterocyclic compounds. The most prevalent component was aromatic compounds with 12.79% and ketones with 12.15%, while the pH of the oil obtained was 5, and the HHV was 19.5 MJ/kg. The pyrolysis productions could be promising raw materials for different applications after further processing. [ABSTRACT FROM AUTHOR]

This study focused on the highly efficient pyrolysis of rice husk (RH) for producing high-porosity biochar at above 450 °C under various microwave output powers (300–1000 W) and residence times (5–15 min). The findings showed that the maximal calorific value (i.e., 19.89 MJ/kg) can be obtained at the mildest microwave conditions of 300 W when holding for 5 min, giving a moderate enhancement factor (117.4%, or the ratio of 19.89 MJ/kg to 16.94 MJ/kg). However, the physical properties (i.e., surface area, pore volume, and pore size distribution) of the RH-based biochar products significantly increased as the microwave output power increased from 300 to 1000 W, but they declined at longer residence times of 5 min to 15 min when applying a microwave output power of 1000 W. In this work, it was concluded that the optimal microwave pyrolysis conditions for producing high-porosity biochar should be operated at 1000 W, holding for 5 min. The maximal pore properties (i.e., BET surface area of 172.04 m2/g and total pore volume of 0.1229 cm3/g) can be achieved in the resulting biochar products with both the microporous and the mesoporous features. On the other hand, the chemical characteristics of the RH-based biochar products were analyzed by using Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS), displaying some functional complexes containing carbon–oxygen (C–O), carbon–hydrogen (C–H), and silicon–oxygen (Si–O) bonds on the surface of the RH-based biochar. [ABSTRACT FROM AUTHOR]

Lignocellulosic and waste materials, such as sewage sludge, can be broken down into its useful constituents and converted into fuel for engines. This paper investigates microwave pyrolysis to decompose biomass into H2 and CO (syngas), which may be catalysed in the Fischer–Tropsch (F-T) process to liquid biofuels. Using microwave radiation as the heat source for pyrolysis proves to yield large quantities of gas with higher concentrations of H2 and CO compared to conventional heating methods. This is largely due to the energy transfer mechanism of microwaves. Pyrolysis parameters such as temperature (which increases with input power), feedstock type, microwave absorber, and biomass moisture content influence syngas yield. Several papers reviewed for this study showed differing optimal conditions for microwave pyrolysis, all being heavily dependent on the biomass used and its composition. However, all researchers agreed on the thermal efficiency of microwave heating and how its material-selective nature can increase syngas yield. Compared to diesel fuels (while processing a similar efficiency and a higher cetane number), FT fuels and specifically pyrolysis may yield the benefit of reduced nitric oxides (NOx), particulate matter (PM), unburnt hydrocarbons (HC) and carbon monoxide (CO) emissions. [ABSTRACT FROM AUTHOR]

The significant quantities of food waste that require disposal have a high environmental impact, and the depletion of non-renewable fuel sources has heightened the need to investigate sustainable and efficient methods of biomass conversion into energy. This research focuses on utilising pumpkin peel as a feedstock for energy recovery through microwave pyrolysis under different operating conditions. The study demonstrated that a higher biochar yield (11 wt%) was achieved at 0.9 kW. However, results revealed that superior quality biochar was obtained at 1.2 kW, characterized by high carbon content (70.33%), low oxygen content (23%), and significant pore formation in the carbon surface area. Optimal operating conditions, such as 1.2 kW, resulted in superior quality biochar and higher bio-oil generation. The pumpkin peel demonstrated the potential for CO2 (carbon dioxide) sequestration, with a rate of 14.29 g CO2 eq/kg. The research findings contribute to the exploration of sustainable solutions for biomass conversion and emphasize the importance of utilizing food waste for energy production while mitigating environmental impacts. [ABSTRACT FROM AUTHOR]

Bromine in waste printed circuit boards has caused serious harm to the environment. How to deal with it safely is a problem. In this paper, the debromination of waste printed circuit boards by microwave gasification pyrolysis was studied, and the properties of pyrolysis products and the migration of bromine were analyzed. The optimum pyrolysis conditions of microwave steam atmosphere were 600 °C, 1000 W, 50 min, 2 mL/min. Compared with conventional pyrolysis and conventional steam pyrolysis, less solid products (60.39 wt %) were obtained, and more metal copper was enriched. The content increased from 27.46 % and 28.35 % to 30.63 %, respectively, and the diffraction peak intensity of copper was also enhanced. There is no obvious change in the type of functional groups of the solid product, and its microscopic morphology is smoother. Compared with conventional pyrolysis, the phenolic compounds in pyrolysis oil decreased, and increased compared with conventional steam pyrolysis. The content of H2 in the pyrolysis gas increased significantly, and the content of CO decreased significantly. Compared with conventional pyrolysis, the bromine content in pyrolysis gas and pyrolysis oil decreased from 94.5 % and 5.5 % to 1 %, respectively, and more bromine (98 %) in the raw material entered the aqueous solution. [ABSTRACT FROM AUTHOR]

The spatial complexity of oil shale systems is manifested by microstructure, pore space randomness and extensive heterogeneity. A microwave pyrolysis device developed for this study was used to pyrolyze oil shale, and the microstructure before and after pyrolysis was visually examined and quantified. The internal structure of the rock and the extent of pore and fracture expansion are more accurately determined in this way. The microstructure of oil shale at different temperatures before and after microwave pyrolysis is identified by X-ray microcomputed tomography (μCT) with automatic ultra-high-resolution scanning electron microscopy (SEM), to observe the heterogeneous state of oil shale on 2D and 3D scales and define the distribution of internal pores and fractures by post-processing μCT visualization. The study found that fractures sized from microns to millimeters along with pore fractures were observed at increasing microwave temperatures. The fractures gradually expanded with increasing temperature in the direction of horizontal or vertical laminae and generated a more connected pore network. The kerogen gradually decreased with a rise in temperature. The porosity increased from 0.26% to 13.69% at the initial temperature. This research is essential for the qualitative as well as quantitative analysis of the internal structure of oil shales under microwave radiation.

This study aims to convert composite textile structures composed of nonwoven and woven fabrics produced from cotton–jute wastes into activated carbon textile structures and investigate the possibilities of using them for electromagnetic shielding applications. To this end, the novel contribution of this study is that it shows that directly carbonized nonwoven textile via self-purging microwave pyrolysis can provide Electromagnetic Interference (EMI) shielding without any processing, including cleaning. Textile carbonization is generally achieved with conventional heating methods, using inert gas and long processing times. In the present study, nonwoven fabric from cotton–jute waste was converted into an activated carbon textile structure in a shorter time via microwaves without inert gas. Due to its polar structure, FeCl3 has been used as a microwave absorbent, providing homogeneous heating in the microwave and acting as an activating agent to serve dual purposes in the carbonization process. The maximum surface area (789.9 m2/g) was obtained for 5% FeCl3. The carbonized composite textile structure has a maximum of 39.4 dB at 1 GHz of EMI shielding effectiveness for 10% FeCl3, which corresponds to an excellent grade for general use and a moderate grade for professional use, exceeding the acceptable range for industrial and commercial applications of 20 dB, according to FTTS-FA-003.

In this work, the effect of volumetric drying and surface drying pretreatment on microwave pyrolytic characteristics of tobacco stems was investigated. The microwave oven was used for volumetric drying with different power outputs, while the electric oven was used for surface drying at 105℃. The biomass dried using microwave drying was compared with the dried using oven drying, and the yields and properties of solids, liquids, and gases were determined. Besides, the decomposition mechanism of nicotine was preliminarily expounded. The results showed that the drying rate of microwave could reach up to 1.093 g m−2 s−1, which was approximately 5 times the maximum drying rate of oven. There was little change in the yield of biochar, and the yield of bio-oil increased, while the yield of non-condensable gas decreased by microwave compared to oven. When microwave drying was used, the concentration of CO2 in the pyrolysis gas was higher, but the yields of H2, CO and CH4 were lower. The preliminary analysis of pyrolytic bio-oil revealed that the relative content of alcohols, acids, aldehydes, and ketones increased to 6.46%, 3.39%, 18.59%, and 18.18%, and the relative content of phenols decreased to 8.74% by microwave. After oven drying, the residence time of volatiles in the reaction zone increased during the pyrolytic process, and nicotine was thermally decomposed at high temperatures and combined with other free radicals; the relative contents of nicotine in the bio-oil have decreased from 11.78 to 6.55%. Microwave drying decreased the water content of bio-oil. At the same time, the stability of bio-oil improved. Therefore, microwave drying is an economical pretreatment method for biomass fast pyrolysis. [ABSTRACT FROM AUTHOR]

A facility for conducting experiments on the microwave (MW) pyrolysis of peat at a source operating frequency of 2.45 GHz has been developed. The MW pyrolysis of peat for the production of low-molecular-weight organic components has been experimentally studied. The products of peat MW radiation-induced decomposition were determined, and reaction schemes for the degradation of peat components were proposed. A carbonaceous residue with relative carbon, hydrogen, nitrogen, and sulfur contents of 83–85, 4–5, 2–3, and <0.3 wt %, respectively, was obtained. [ABSTRACT FROM AUTHOR]

In order to seek efficient resource utilization, the carbonization of agricultural and forestry wastes through microwave pyrolysis technology is an important research hotspot to develop value-added products. The main objective is to produce value-added biochar through microwave pyrolysis of peanut shell in this study. The product yields, functional groups, and biochar HHVs caused by pyrolysis temperature (400, 450, 500, 550, and 600 °C), microwave power (350, 450, 550, 650, and 750 W), and residence time (10, 20, 30, 40, and 50 min) were investigated, and the energy recovery efficiencies were evaluated. It was obtained that the biochar yield declined monotonously within the range of 45.3–86.0 wt% with the enhancement of pyrolysis temperature, microwave power, or residence time. The pyrolysis temperature of 400 °C, microwave power of 350 W, and residence time of 10 min generated the maximum biochar yield (86.0 wt%). The value-added biochar was obtained with high HHV (20.15–31.02 MJ/kg) and abundant oxygen-contained functional groups (C–O bonds and C=O bonds). The maximum energy recovery efficiency during the whole process reached 97.96%. The results indicated that the peanut shell could reach high biochar yield through microwave pyrolysis, and potentially be transformed into value-added products with high energy recovery efficiency. [ABSTRACT FROM AUTHOR]

Chicken cartilage was used for the first time as a raw material for the microwave-assisted synthesis of biochar and activated carbon. Various microwave absorbers, i.e., commercial active carbon, scrap tyres, silicon carbide, and chicken bone-derived biochar, as well as various microwave powers, were tested for their effect on the rate of pyrolysis and the type of products formed. Biochars synthesised under 400 W in the presence of scrap tyres and chicken bone-derived biochar were activated with KOH and K2CO3 with detergent to produce activated carbon with a highly developed porous structure that would be able to effectively adsorb xylene vapours. All carbons were thoroughly characterised (infrared spectroscopy, X-ray fluorescence spectrometry, nitrogen adsorption/desorption, Raman spectroscopy, proximate and ultimate analysis) and tested as xylene sorbents in dynamic systems. It was found that the activation causes an increase of up to 1042 m2·g−1 in the specific surface area, which ensures the sorption capacity of xylene about 300 mg·g−1. Studies of the composition of biogas emitted during pyrolysis revealed that particularly valuable gaseous products are formed when pyrolysis is carried out in the presence of silicon carbide as a microwave absorber. [ABSTRACT FROM AUTHOR]

The design of a technological complex for microwave processing of organic materials is proposed. The electrodynamic system of an oversized microwave reactor for low-temperature pyrolysis has been developed. The constructive elements of the complex that allow its continuous failure-free operation in conditions of high radiation intensity are described. Based on the prototype of the elaborated reactor, model experiments on microwave pyrolysis of peat were carried out. The elemental composition of the solid fraction was analyzed during the conducted experiments. The possibility of the efficiency enhancement of the proposed processing method and potential applications of the novel technology are discussed. [ABSTRACT FROM AUTHOR]

Biomass is a promising resource for the production of renewable energy, liquid fuels, and chemicals. Microwave pyrolysis is one of the directions of multifunctional conversion of raw materials. In the present work, the effect of microwave power on the characteristics of sawdust pyrolysis is studied. With an increase in power, the maximum yield of combustible gases increased, and a large proportion of the total pyrolysis time included the useful time for the release of gases. An increase in power affected the yield of individual gases non-linearly and on a different scale. The average yield of CO and CO2 remained practically unchanged when the microwave power was increased from 840 to 1760 W. However, with a further increase in power to 2200 W, there was a significant increase in the average yield of CO and CO2 (2.5 and 1.4 times, respectively). An increase in power by 2.6 times contributed to an increase in the average yield of CH4 by 5 times and H2 by 3.8 times. The increased power of microwaves contributed to the degassing of wood and intensification of secondary pyrolysis reactions, which resulted in a decrease in the mass of the solid residue by 5.3 times and a decrease in the liquid product yield by 2.7 times. A comprehensive analysis using MCDA showed that an increase in energy costs with an increase in microwave power is integrally compensated by an improvement in pyrolysis performance. So, when the power was varied from 840 W to 2200 W, the pyrolysis efficiency indicator increased by 1.3–2.2 times, considering the growth in energy consumption. [ABSTRACT FROM AUTHOR]