Conventional Pyrolysis Research Articles

Facile Preparation of Carbon Nitride-ZnO Hybrid Adsorbent for CO2 Capture: The Significant Role of Amine Source to Metal Oxide Ratio

The presence of CO2 in gaseous fuel and feedstock stream of chemical reaction was always considered undesirable. High CO2 content will decrease quality and heating value of gaseous fuel, such as biohydrogen, which needs a practical approach to remove it. Thus, this work aims to introduce the first C3N4-metal oxide hybrid for the CO2 cleaning application from a mixture of CO2-H2 gas. The samples were tested for their chemical and physical properties, using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), physical adsorption analysis (BET), fourier-transform infrared (FTIR), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). The CO2 capacity test was carried out by means of a breakthrough test at 1 atm and 25° C using air as a desorption system. Among the samples, amine/metal oxide mass ratio of 2:1 (CNHP500-2(2-1)) showed the best performance of 26.9 wt. % (6.11 mmol/g), with a stable capacity over 6 consecutive cycles. The hybrid sample also showed 3 times better performance than the raw C3N4. In addition, it was observed that the hydrothermal C3N4 synthesis method demonstrated improved chemical properties and adsorption performance than the conventional dry pyrolysis method. In summary, the performance of hybrid samples depends on the different interactive factors of surface area, pore size and distribution, basicity, concentration of amine precursors, ratio of amines precursors to metal oxide, and framework stability.

Bifunctional biomass-based catalyst for biodiesel production via hydrothermal carbonization (HTC) pretreatment – Synthesis, characterization and optimization

The hydrothermal carbonization (HTC) technique is known for its advantages in producing hydrochar from biomass samples with high water content compared to conventional pyrolysis techniques. This study utilized HTC to produce an activated carbon catalyst from renewable mesocarp fiber derived from palm oil processing. The introduction of K2CO3 and Cu(NO3)2 produced a bifunctional catalyst suitable for conversion of used cooking oil to biodiesel. The catalyst possessed a mesoporous structure with a BET surface area of 3909.33 m2/g. An optimum treatment ratio of 4:1 (K2CO3: Cu(NO3)2) provided elevated basic (5.52 mmol/g) and acidic (1.68 mmol/g) concentrations on the catalytic surface, which promoted esterification and transesterification reactions. Maximum yield (96.4%) of biodiesel was obtained at 70 °C for 2 h with 5 wt% catalyst and a 12:1 molar ratio of methanol to oil. The catalyst endured up to 5 reaction cycles while maintaining biodiesel yields of more than 80%. These findings indicated that HTC pretreatment yielded a high-quality bifunctional catalyst for conversion of low-quality used cooking oil for production of biodiesel.

Pyrolysis of waste oils for the production of biofuels: A critical review

The application of waste oils as pyrolysis feedstocks to produce high-grade biofuels is receiving extensive attention, which will diversify energy supplies and address environmental challenges caused by waste oils treatment and fossil fuel combustion. Waste oils are the optimal raw materials to produce biofuels due to their high hydrogen and volatile matter content. However, traditional disposal methods such as gasification, transesterification, hydrotreating, solvent extraction, and membrane technology are difficult to achieve satisfactory effects owing to shortcomings like enormous energy demand, long process time, high operational cost, and hazardous material pollution. The usage of clean and safe pyrolysis technology can break through the current predicament. The bio-oil produced by the conventional pyrolysis of waste oils has a high yield and HHV with great potential to replace fossil fuel, but contains a high acid value of about 120 mg KOH/g. Nevertheless, the application of CaO and NaOH can significantly decrease the acid value of bio-oil to close to zero. Additionally, the addition of coexisting bifunctional catalyst, SBA-15@MgO@Zn in particular, can simultaneously reduce the acid value and positively influence the yield and quality of bio-oil. Moreover, co-pyrolysis with plastic waste can effectively save energy and time, and improve bio-oil yield and quality. Consequently, this paper presents a critical and comprehensive review of the production of biofuels using conventional and advanced pyrolysis of waste oils.

High-loading single-atom tungsten anchored on graphitic carbon nitride (melon) for efficient oxidation of emerging contaminants

Single-atom catalysts (SACs) have become an attractive concept in heterogeneous catalysis because of its high activity, selectivity and maximized utilization efficiency. However, constructing a high-loading SACs through conventional pyrolysis methods remains a challenge, because metal precursors usually have low thermal stability and the decrease of particle size will lead to an increase of surface energy. Herein, we used dicyandiamide to tailor the metatungstate and fix the W atoms during the thermal polymerization process, finally obtained a new kind of W-SAC (single W atoms anchored on graphitic carbon nitride, named as W-CN) with a high-loading of 11.16 wt% and a unique O, N coordination. The electrospray ionization high-definition mass spectrometry (ESI-HDMS) revealed that single W atoms were introduced into graphitic carbon nitride via the polycondense of W-containing dicyandiamide intermediate. The unique atomically dispersed N-W-O3 moieties, which promoted the separation efficiency of photogenerated electron-hole pairs, were identified by Aberration-corrected scanning transmission electron microscopy (AC-TEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure spectroscopy (XAFS) and Density functional theory (DFT) calculation. Moreover, compared to pure CN, the W-CN exhibited an enhanced catalytic performance for the oxidation of carbamazepine (CBZ) under solar light irradiation. The experiment results revealed that photogenerated holes (h+), superoxide radicals (•O2−), and singlet oxygen (1O2) were the predominant active species and played an important role in eliminating emerging contaminants. This work paves a facile and efficient path toward high-loading SAC, and opens new insight into tracking SAC structure evolution.

Rapid detoxification of dioxin and simultaneous stabilization of targeted heavy metals: New insight into a microwave-induced pyrolysis of fly ash

Presently, it is a great challenging issue to inhibit the regeneration for dioxin and simultaneously detoxify Municipal solid waste incinerators (MSWI) fly ash with conventional Hagenmaier pyrolysis process (250–400 °C). The addition of inorganic S- and/or N-containing dioxin inhibitors could effectively inhibit the catalytic roles of residual heavy metals (HMs; e.g. Cu, Pb) for formation pathway of dioxin. In this study, we conducted a newly-proposed single-mode Microwave (MW)-based Hagenmaier process to investigate the impact of N, S-containing inhibitors of Thiourea (TU) on inhibiting the catalytic roles of targeted HMs and simultaneously detoxifying fly ash as well as to elucidate the corresponding mechanism. Synchrotron radiation analysis verified the sulfidation of targeted HMs including Cu and Pb, indicating the inhibition routes for dioxin regeneration. Moreover, the pyrolysis products of TU could apparently increase the MW-absorption properties of fly ash layer, and shorten by ~81.5% of processing time compared with that in the absence of TU. Under the optimized conditions (pyrolysis temperature of 480 °C, a mass ratio of fly ash to SiC as 1:9 and the addition of 23.1 wt% TU), ~99.2% of dioxin and ~94.1% of the bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent values (Bio-TEQs) were eliminated. Furthermore, the fundamental mechanism of a single-mode MW-induced Hagenmaier process was also proposed in detail. Additionally, a series of Unintentionally-Produced Persistent Organic Pollutants (UP-POPs) including chlorobenzenes were also detoxified by a single-mode MW-based Hagenmaier pyrolysis process, simultaneously. To the best of our knowledge, this is the first report adopting TU to inhibit the regeneration of dioxin and simultaneously detoxify fly ash by a single-mode MW-based pyrolysis process.

Low-Temperature Large-Area Zinc Oxide Coating Prepared by Atmospheric Microplasma-Assisted Ultrasonic Spray Pyrolysis

Zinc oxide (ZnO) coatings have various unique properties and are often used in applications such as transparent conductive films in photovoltaic systems. This study developed an atmospheric-pressure microplasma-enhanced ultrasonic spray pyrolysis system, which can prepare large-area ZnO coatings at low temperatures under atmospheric-pressure conditions. The addition of an atmospheric-pressure microplasma-assisted process helped improve the preparation of ZnO coatings under atmospheric conditions, compared to using a conventional ultrasonic spray pyrolysis process, effectively reducing the preparation temperature to 350 °C. A program-controlled three-axis platform demonstrated its potential for the large-scale synthesis of ZnO coatings. The X-ray diffraction results showed that the ZnO coatings prepared by ultrasonic spray pyrolysis exhibited (002) preferred growth orientation and had a visible-light penetration rate of more than 80%. After vacuum treatment, the ZnO reached a 1.0 × 10−3 Ωcm resistivity and a transmittance of 82%. The tribology behavior of ZnO showed that the vacuum-annealed coating had a low degree of wear and a low coefficient of friction as the uniformly distributed and dense coating increased its load capacity.

Edge-nitrogen enriched carbon nanosheets for potassium-ion battery anodes with an ultrastable cycling stability

Edge-nitrogen (pyridinic/pyrrolic nitrogen) doped carbon materials have been considered as promising anodes for potassium ion batteries (KIBs), which can provide a high surface-induced capacitive capacity beyond the K+-intercalated mechanism. However, achieving a high-level edge-nitrogen doping is still a great challenge owning to inevitable introduction of graphitic nitrogen into carbon materials via conventional pyrolysis process. Herein, we design porous carbon nanosheets with bundant defects and edge sites to graft nitrogen atoms to achieve a high-level edge-nitrogen doping (88.36%). The optimized edge-nitrogen doped carbon nanosheets (ENCNs-600) exhibits a high reversible capacity of 443 mAh g−1 at 0.1 A g−1 after 200 cycles, excellent rate performance (175 mAh g−1 at 20 A g−1), and ultrastable cycling stability (246 mAh g−1 at 5 A g−1 over 10,000 cycles). Density functional theory calculations and kinetic studies confirm that both edge-nitrogen doping and explanded interlayer distance are greatly conducive for the adsorption and diffusion of K+, thereby ensuring enhanced potassium-storage performance with a synergistic adsorption-intercalation mechanism.

An energy-saving and environment-friendly technology for debromination of plastic waste: Novel models of heat transfer and movement behavior of bromine

The recovery and reuse of waste brominated resin, which is a typical plastic waste, is troublesome because it contains toxic brominated flame retardants. Conventional pyrolysis of brominated resin was suggested to be an effective approach for debromination. However, conventional pyrolysis caused high energy consumption and high yield of toxic volatiles. An energy-saving and environment-friendly technology called infrared heating was reported in this study. According to computation of the developed heat transfer models, the critical debromination temperature was 260 °C in infrared heating, which was 271 °C lower than conventional pyrolysis. Meanwhile, no volatile product appeared in the reported technology. In the pyrolysis residue after infrared heating, bromine concentrated orientationally in the fixed and limited area on the resin particles. Free radicals, such as •CH3, H•, and Br•, were combined with Br• generated in infrared heating to form the concentrated bromine. Compared to the chaotic distribution of bromine in conventional pyrolysis, the orientational concentration of bromine was a progress for removing and collecting bromine in infrared heating. Moreover, compared to conventional pyrolysis, infrared heating could decrease 76.2% energy consumption. This work contributed to provide the novel technology for recovery of plastic wastes

Improving the Bio-Oil Quality via Effective Pyrolysis/Deoxygenation of Palm Kernel Cake over a Metal (Cu, Ni, or Fe)-Doped Carbon Catalyst.

Waste palm kernel cake (WPKC) is being utilized as a biomass feedstock for the sustainable production of catalysts/supports and bio-oil fuels. Herein, metal (Cu, Ni, and/or Fe)-doped carbon catalysts were prepared using conventional impregnation and pyrolysis methods. The physicochemical properties of the as-prepared catalysts were analyzed. According to the obtained results, the catalyst acidity was highly increased with the increase in the metal loading amount on a carbon support, leading to a better performance for deoxygenation/aromatization. A maximum yield of bio-oil from WPKC pyrolysis was achieved up to ∼60% under optimum conditions determined via statistical designs. From the results of bio-oil compositions, 15%Ni loading on activated carbon exhibited the best performance of about 72% for the production of hydrocarbon compounds. Monoaromatic hydrocarbons such as benzene, toluene, and xylenes (BTXs) could be reduced via condensation and polymerization with the increase of the Ni-loading amount. Moreover, the catalytic performance of the selected 15%Ni-carbon catalyst was also compared with those of commercial catalysts zeolite and alumina, and the results showed that the 15% metal-doped carbon catalyst presented much better stability/reusability for five times with less reduction of the hydrocarbon yield in the upgraded bio-oil. This research provided an eco-friendly strategy for the low-cost production of bio-oil fuel with a high quality/yield from waste biomass pyrolysis.

Microwave assisted carbonization and activation of biochar for energy-environment nexus: A review

Conventional thermochemical conversion techniques for biofuel production from lignocellulosic biomass is often non-selective and energy inefficient. Microwave assisted pyrolysis (MAP) is cost and energy-efficient technology aimed for value-added bioproducts recovery from biomass with less environmental impacts. The present review emphasizes the performance of MAP in terms of product yield, characteristics and energy consumption and further it compares it with conventional pyrolysis. The significant role of biochar as catalyst in microwave pyrolysis for enhancing the product selectivity and quality, and the influence of microwave activation on product composition identified through sophisticated techniques has been highlighted. Besides, the application of MAP based biochar as soil conditioner and heavy metal immobilization has been illustrated. MAP accomplished at low temperature creates uniform thermal gradient than conventional mode, thereby producing engineered char with hotspots that could be used as catalysts for gasification, energy storage, etc. The stability, nutrient content, surface properties and adsorption capacity of biochar was enhanced by microwave activation, thus facilitating its use as soil conditioner. Many reviews until now on MAP mostly dealt with operational conditions and product yield with limited focus on comparative energy consumption with conventional mode, analytical techniques for product characterization and end application especially concerning agriculture. Thus, the present review adds on to the current state of art on microwave assisted pyrolysis covering all-round aspects of production followed by characterization and applications as soil amendment for increasing crop productivity in addition to the production of value-added chemicals, thus promoting process sustainability in energy and environment nexus.

Confined Chemical Transitions for Direct Extraction of Conductive Cellulose Nanofibers with Graphitized Carbon Shell at Low Temperature and Pressure.

Cellulose is the most abundant renewable natural polymer on earth, but it does not conduct electricity, which limits its application expansion. The existing methods of making cellulose conductive are combined with another conductive material or high-temperature/high-pressure carbonization of the cellulose itself, while in the traditional method of sulfuric acid hydrolysis to extract nanocellulose, it is usually believed that a too high temperature will destroy cellulose and lead to experimental failure. Now, based on a new research perspective, by controlling the continuous reaction process and isolating oxygen, we directly extracted intrinsically conductive cellulose nanofiber (CNF) from biomass, where the confined range molecular chains of CNF were converted to highly graphitized carbon at only 90 °C and atmospheric pressure, while large-scale twisted graphene films can be synthesized bottom-up from CNFene suspensions, called CNFene (cellulose nanofiber-graphene). The conductivity of the best CNFene can be as high as 1.099 S/cm, and the generality of this synthetic route has been verified from multiple biomass cellulose sources. By comparing the conventional high-pressure hydrothermal and high-temperature pyrolysis methods, this study avoided the dangerous high-pressure environment and saved 86.16% in energy. These findings break through the conventional notion that nanocellulose cannot conduct electricity by itself and are expected to extend the application potential of pure nanocellulose to energy storage, catalysis, and sensing.

Conventional and Microwave Pyrolysis for Preparation of Sewage Sludge- Activated Carbons for Pharmaceuticals Removal: A Mini-Review

Abstract: Sewage sludge shows excellent potential as pyrolysis feedstock in generating valuable products such as Activated Carbons (ACs). In this mini-review the preparation of sewage sludge- ACs by two kinds of pyrolysis conventional and microwave heating is presented and discussed. The main difference between conventional pyrolysis and the microwave-assisted method is the way the heat is generated, and both can provide ACs with different textural and chemical properties. Based on what was demonstrated in this work, it is possible to say that both kinds of pyrolysis (microwave and conventional methods) can produce high specific surface area and efficiently activated carbons from sewage sludge. It was also demonstrated that sludge-ACs produced by both pyrolysis methods could reach very high uptakes of pharmaceuticals from aqueous solutions. The van der Waals interactions, hydrogen bonding and π-π interactions of the aromatic ring of the adsorbent with the aromatic rings of the pharmaceuticals have been mentioned to be some of the main mechanisms governing the pharmaceuticals adsorption by ACs.

Current Developments in the Chemical Upcycling of Waste Plastics Using Alternative Energy Sources.

The management of plastics waste is one of the most urgent and significant global problems now. Historically, waste plastics have been predominantly discarded, mechanically recycled, or incinerated for energy production. However, these approaches typically relied on thermal processes like conventional pyrolysis, which are energy-intensive and unsustainable. In this Minireview, some of the latest advances and future trends in the chemical upcycling of waste plastics by photocatalytic, electrolytic, and microwave-assisted pyrolysis processes are discussed as more environmentally friendly alternatives to conventional thermal reactions. We highlight how the transformation of different types of plastics waste by exploiting alternative energy sources can generate value-added products such as fuels (H2 and other carbon-containing small molecules), chemical feedstocks, and newly functionalized polymers, which can contribute to a more sustainable and circular economy.

Methane Cracking for Hydrogen Production: A Review of Catalytic and Molten Media Pyrolysis

Currently, hydrogen is mainly generated by steam methane reforming, with significant CO2 emissions, thus exacerbating the greenhouse effect. This environmental concern promotes methane cracking, which represents one of the most promising alternatives for hydrogen production with theoretical zero CO/CO2 emissions. Methane cracking has been intensively investigated using metallic and carbonaceous catalysts. Recently, research has focused on methane pyrolysis in molten metals/salts to prevent both reactor coking and rapid catalyst deactivation frequently encountered in conventional pyrolysis. Another expected advantage is the heat transfer improvement due to the high heat capacity of molten media. Apart from the reaction itself that produces hydrogen and solid carbon, the energy source used in this endothermic process can also contribute to reducing environmental impacts. While most researchers used nonrenewable sources based on fossil fuel combustion or electrical heating, concentrated solar energy has not been thoroughly investigated, to date, for pyrolysis in molten media. However, it could be a promising innovative pathway to further improve hydrogen production sustainability from methane cracking. After recalling the basics of conventional catalytic methane cracking and the developed solar cracking reactors, this review delves into the most significant results of the state-of-the-art methane pyrolysis in melts (molten metals and salts) to show the advantages and the perspectives of this new path, as well as the carbon products’ characteristics and the main factors governing methane conversion.

Process modeling and techno-economic analysis of a solar thermal aided low-rank coal drying-pyrolysis process

This study investigated the feasibility of integration of concentrated solar power (CSP) to low-rank coal pyrolysis process from the economic and technical perspective. Victorian brown coal is generally used in local power plants with low efficiency and great greenhouse gas emissions. Therefore, the development of low-emission technologies for an efficient use of such vast resources is paramount. The principal objective of this process is to upgrade Victorian brown coal to alternative fuels through a solar-assisted pyrolysis process. Upon a robust design of four different scenarios for the process integration, the effects of a variety of key variables have been examined, including different types of solar collectors, heat transfer fluids (HTF) and pyrolysis temperature. The plant operation analysis showed that integrating solar tower (ST) to provide heat for both coal drying and pyrolysis within the plant can save an average of 12.8% of the annual thermal energy demand. For the optimum solar tower design, it requires a solar multiple of 2, using carbonate salts as HTF, a design point DNI of 750 W/m2 and a heat storage capacity of 8 h to maximize its total solar energy output over a year. However, from an economical perspective, the use of solar tower for both drying and pyrolysis is economically infeasible. Instead, the parabolic trough solar collectors (PTC) designed to cover the heat required for coal drying only is most economically viable. It even shows a slightly better economic performance than the conventional pyrolysis process. The parabolic trough solar assisted pyrolysis process has the potential to reach a high net present value (NPV) of $81.1 million and a short payback period of 4.9 years, relative to an NPV of $52.8 million and a payback period of 5.1 years for the conventional pyrolysis process.

Surface decoration and characterization of solar driven biochar for the removal of toxic aromatic pollutant

AbstractBACKGROUNDIn the current work, the conventional pyrolysis technique was replaced by new concentrated solar power (CSP) driven technique to fabricate and modify biochar (BC) for more sustainable, energy independent, cost‐effective, and ecofriendly pyrolysis processes. Double‐glazed vacuum tube was used as a reactor for pyrolysis along with solar tracking system on CSP plant, meanwhile nitrogen flow was maintained during pyrolysis to create an inert environment. Further, a novel approach was used to modifying BC by loading bimetal oxide (Mn‐Ferrite) on pristine biochar (P‐BC) using pre‐ and post‐treatment to enhance its sorption capacity for anionic aromatic pollutant i.e., Eriochromie Black T (EBT) dye from aqueous solution.RESULTSFerric chloride hexahydrate (FeCl3·6H2O) and Ferrous sulfate heptahydrate (FeSo4·7H2O) were used to develop magnetic nanoparticles (MNPs) γ‐Fe2O3 by co‐precipitation technique. Both Biomass and P‐BC were treated with MnCl2·4H2O and MNPs to fabricate an innovative bi‐metal oxide (MnFe2O4) biochar. The characterization of modified biochars via Elemental analyzer, SEM (scanning‐electron‐microscopy), BET (Brunauer–Emmet–Teller), XPS (X‐ray‐photoelectron‐spectroscopy), FTIR (Fourier‐transform‐infrared‐spectra), and VSM (Vibrating‐sample‐magnetometer), ensured the loading of magnetic bimetal oxide over P‐BC. Various kinetic and isotherm models were employed from which pseudo‐second‐order have proven to be the best fit kinetic model on all types of BCs with highest correlation coefficient value (R2 = 0.999). While among isotherm models, Langmuir demonstrated best regression coefficient (R2 = 0.98) and Qmax for EBT was up to 121.95 mg·g−1.CONCLUSIONSAltogether, the results indicated that innovative Mn‐ferrite loaded BC has better sorption ability to EBT than simple metal oxide of Mn and Fe. © 2021 Society of Chemical Industry (SCI).

“Thermal-dissolution based carbon enrichment” treatment of biomass wastes: Mechanism study of biomass pyrolysis in a highly-dispersed medium

A novel treatment denoted as the “Thermal-dissolution based carbon enrichment (TDCE)” was proposed in our previous work to effectively deoxygenate and de-ash biomass under mild conditions. The main reactions during this process occurred in a highly-dispersed and inert medium, thus its mechanism was unclear. In this study, cellulose was chosen as the model compound to investigate the underlying reaction mechanisms of TDCE process. It was confirmed that three distinct stages were involved in this process, which were physical dissolution stage, intramolecular deoxygenation and rearrangement stage, and stabilization stage. The deoxygenation attributed to the intramolecular dehydration at around 300 °C and the formations of CO2 and CO through subsequent aromatization in liquid phase at around 350 °C. Around 67% and 19% of oxygen were removed by these two pathways, respectively. About 80% of carbon remained in the solid products in all conditions. A two-step process was verified for the aromatic substance formation: furan structure formation at the beginning and the subsequent conversion to benzene ring. Especially, unlike large molecular bio-char formation in conventional pyrolysis, small molecular aromatics were formed in TDCE process. Undoubtedly, the highly-dispersed and inert medium contributed to these intramolecular reactions and suppressed the intermolecular reactions, although it wasn’t involved in the chemical reactions. Hence, the unique reaction mechanism of biomass in a highly-dispersed medium was specified, providing theoretical guidance to the practical application of TDCE method.

Design and development of a rotating heater pyrolysis reactor

AbstractBiochar is a valuable product of pyrolysis. A new rotating heater pyrolysis reactor (RHP) was developed to process a variety of biomass feedstocks of up to 30 L and produce biochar batches of several kilograms. The RHP design was simple, allowing for easy construction, low‐cost operation, and low energy consumption. Biochar produced from softwood woodchip biomass in the RHP for 2–3 h was determined to have physical and chemical properties comparable to biochar produced from a conventional batch pyrolysis reactor at temperatures between 375–425°C.

Sustainable and recoverable waste-based magnetic nanocomposites used for the removal of pharmaceuticals from wastewater

This work aimed at producing easily recoverable magnetic iron-oxide functionalized activated carbons (AC) through environmentally and energetically sustainable methods, evaluating their efficacy towards the removal of the pharmaceuticals diclofenac (DCF) and venlafaxine (VEN) from different aqueous matrices (ultrapure water and wastewater treatment plant effluents). Two AC were prepared by chemical activation of a biomassic industrial waste followed by either conventional (CP) or microwave (MW) pyrolysis. Then, magnetic iron oxide nanoparticles were loaded onto the produced AC. Differences related to the production procedure were not especially remarkable, since both the resulting magnetic composites (MAC-CP and MAC-MW) presented well-developed micropore structures with specific surface areas of 644 and 548 m2 g−1 and saturation magnetization of 32.9 and 22.5 emu g−1, respectively, which conferred them a high adsorptive performance and efficient magnetic recovery from solution. The kinetic data were well described by both pseudo-first and pseudo-second order models. As for the equilibrium data, Langmuir isotherm provided a good fitting, with maximum adsorption capacities ranging between 97 ± 2 and 215 ± 4 µmol g−1 for MAC-CP and between 80 ± 2 and 172 ± 3 µmol g−1 for MAC-MW. Additionally, in binary (DCF and VEN) solutions and wastewater, adsorption onto both MAC was somewhat inhibited due to competitive effects. MW-assisted regeneration of exhausted MAC was effective, as their adsorptive properties and chemical surface features (according to X-Ray photoelectron spectroscopy) remained unchanged. Overall, the produced waste-based magnetic carbon composites simultaneously combine high adsorptive efficiency, easy retrievability and successful regeneration/reutilization.

Valorization of municipal wastes using co-pyrolysis for green energy production, energy security, and environmental sustainability: A review

• Emerging pyrolysis techniques for valorisation of municipal waste is reviewed. • Focus on key parameters, comparison to conventional technique, concerns, disputes. • Emphasis is then on progress and application of co-pyrolysis as recent technique. • Synergistic reaction mechanism in co-pyrolysis valorisation is discussed. • Co-pyrolysis is a promising method to obtain green energy and energy security. Pyrolysis is a potential technology used for the transformation of municipal wastes into energy products such as biofuel. Existing reviews on pyrolysis mainly focus on agroforestry biomass and conventional pyrolysis heating techniques. There is limited literature on the application of recent pyrolysis techniques, types of reactors, key operating parameters, and properties of pyrolysis products from conventional versus recent/novel pyrolysis techniques, and particularly the application of the oil products in fuel engines. Here we focus on the performance of various pyrolysis techniques for valorizing municipal wastes, with an explicit emphasis on the progress and application of co-pyrolysis as a recent technique for value-added products recovery from municipal wastes. We review the main operating parameters of co-pyrolysis, concerns and disputes arisen from the technique, and the resultant liquid fuel properties. In particular, co-pyrolysis using microwave heating shows proficiency to resolve several drawbacks of conventional pyrolysis techniques such as reduced oxygen content and viscosity and increased calorific value of liquid oil, hence promising as a method to generate environmental friendly and sustainable third-generation fuels. Sorting of municipal wastes is recommended as an approach to improve the feasibility of co-pyrolysis by having desired quantity and type of municipal wastes as the feedstock, and more research and development on co-pyrolysis utilizing municipal wastes is necessary to maximize the yield and quality of target pyrolytic products. Thus, we conclude that co-pyrolysis is a feasible and sustainable method for recovering biofuel from municipal wastes to obtain green energy and energy security.