Thermochemical processes such as pyrolysis and gasification are excellent platforms for recycling and valorisation of agriculture, municipal and mining waste. The advancement of these processes ...involves successfully navigating and resolving intricate challenges, and saving significant effort and time. Considerable efforts have been made to formulate methodologies for computer-assisted modelling of thermochemical conversion processes. These efforts aim to pinpoint optimal operational parameters that enhance performance, reduce costs, and promote environmental sustainability. This study provides a comprehensive review of the contemporary advancements in modelling the thermochemical conversion of waste materials. Special attention is directed towards the recent progressions in chemical process modelling, Computational Fluid Dynamics (CFD), and Machine Learning (ML) models. The merits of each modelling technique are individually underscored, while certain limitations and bottlenecks within existing models are pinpointed as areas warranting further investigation. Through the integration of advanced modelling approaches, the future outlook of waste recycling targets achieving high efficiency and sustainability, addressing the escalating challenges posed by burgeoning global waste streams.
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•Comprehensive review of advancements in thermochemical process modelling.•Examination of pyrolysis and gasification for waste recycling.•Description of applications of Aspen Plus, CFD, and ML in process modelling.•Identification of current limitations and areas for further research.•Discussion of high efficiency and sustainability in waste conversion.
•Enhanced accessibility to recycling facilities would encourage the behavior.•Correlation between the tendency to recycle and facility accessibility is non-linear.•The psychological structure ...antecedent to recycling behavior is stable.•The gap between behavioral intention and behavior is confirmed.
In China, less than 2% of waste processed in the municipal disposal system is recycled. Past research has dedicated great efforts in identifying reasons for the country's low recycling rate. However, these studies are constrained for their over-dependence on survey methodology and ignoring the potential gap between reported intention to behave and behavior. In a controlled lab experiment, this study examines waste recycling behaviors, as well as the associated psychological behavioral antecedents, with varied levels of accessibility of recycling facilities. We confirm the hypothesis that lack of effective recycling facilities constitutes one of the obstacles that keep Chinese people from sorting and reusing most recyclable wastes. The results indicate that enhanced accessibility of recycling facilities would lower behavioral costs and encourage people to take that action. While this strategy directly changes behaviors, it has little impact on those behavioral antecedents. The study also confirms the gap between behavioral intention and behavior. While all participants in all scenarios showed equally strong willingness to recycle, the percentage of people who recycled is over 25% higher in the scenario with easily accessible recycling facilities, compared to those with hardly accessible facilities. All the above findings are relevant for making recycling promotion policies and cut through the vicious mixed waste disposal and collection cycle.
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•Novel biochar composite impregnates goethite nanorods in hierarchical porous structure.•Synergistic effects are achieved between α-FeOOH nanorods and porous biochar.•An adsorption ...capacity of 144.7 mg g−1 is achieved and maintained after several cycles.
A novel biochar composite impregnated with α-FeOOH nanorods in hierarchical porous structures (α-FeOOH@PC) was synthesized by molten salt assisted carbonization of corn straws and hydrothermal treatment for crystallization of adsorbed ferric ions within carboxyl functionalized porous carbon. The structures and surface properties of biochar composites were characterized by scanning electron microscopy images (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, and Brunauer-Emmett-Teller (BET) analysis. The active α-FeOOH nanocrystals were encapsulated in the gradient porous biochar framework (macropores-mesopores-micropores) via C-O-Fe bonding. The α-FeOOH@PC composites presented excellent performance of both goethite containing a large amount of reactive surface hydroxyl sites and porous carbon consisting of large surface area and huge porous volume. The α-FeOOH@PC composites outperformed other sorbents for copper removal (adsorption capacity of 144.7 mg g−1). The synergistic effects of α-FeOOH and porous carbon in the biochar composite profoundly improved the removal efficiency (71.9%) compared to those of individual porous carbon foam (42.3%) and α-FeOOH nanorods (6.7%). A high adsorption capacity of 124.4 mg g−1 was maintained after three adsorption-desorption cycles. This study suggests that biochar composite is a potentially promising candidate for environmental remediation.
Electronic waste has become a global concern, as it has been steadily increasing over the years. The lack of regulation and appropriate processing facilities has rendered these wastes an ...environmental hazard. However, they represent excellent alternative sources of precious metals, which are highly in demand in various industries. Adsorption has been a popular method for metal removal/recovery because of several advantages, such as ease of use and low cost. In this regard, it is crucial to develop an inexpensive and functionalized adsorbent to selectively adsorb precious metals. Thus, silica, which is derived from rice husk and is abundantly present in Indonesia, was functionalized using an ionic liquid (SiRH_Im) and used for Au(III) adsorption from a simulated mobile phone leach liquor. SiRH_Im exhibited a high adsorption capacity (232.5 mg g-1). The Au(III) adsorption kinetic suitably fitted with the pseudo-second-order kinetic model. The Au(III) adsorption followed a chemisorption route that suited the monolayer model. Thomas' and Yoon-Nelson's models were well suited for the continuous Au(III) behavior. Selective recovery of Au(III) from SiRH_Im was achieved via sequential desorption. SiRH_Im also showed excellent reusability, as indicated by a negligible decrease in adsorptive performance over three cycles. The functionalization of silica derived from rice husk using an ionic liquid led to the successful creation of a solid adsorbent with a high adsorption capacity toward precious metals present in a simulated leach solution. Our results highlight the benefit of the functionalization of biomass through the immobilization of an ionic liquid toward the enhancement of its adsorption capability.
•Different current methods of FOG management were compared.•The challenges in biodiesel production from FOG were discussed.•Pros and cons of FOG pretreatment for biodiesel production were ...outlined.•FOG-biodiesel possesses future potential to replace petroleum diesel.•Integrated approaches for biofuel production from FOG are of great importance.•More research focus is needed for enhancement of brown grease conversion.
Wastewater discharges from restaurants, kitchens, food processing plants and slaughterhouses contain high proportion of fat, oil, and grease (FOG). Critical overview on the attractive features, current state, and needed advancements are timely essential for FOG-derived biodiesel production. Although FOG conversion into biodiesel does not compete with human food, the high contents of moisture and free fatty acids (FFAs) are the main challenges for FOG efficient utilization. The present review discussed the various methods of high FFAs-lipidic feedstocks pretreatment including acid esterification, steam stripping, nanocatalytic technology, biological conversion, glycerolysis, supercritical esterification, and simultaneous in situ conversion. Comparing to other feedstocks, FOG-derived biodiesel showed better characteristics concerning oxidative stability, flash point, cetane number, and total emissions. In addition, most of the FOG-derived biodiesel fuel met the recommendations of the international standards as well as conventional diesel. Due to its lower price, the economic analysis showed that FOG is a strong competitor to other biodiesel feedstocks. The decrease in feedstocks availability, continuous rise in the crude oil prices, life threatening environmental deterioration, and food-versus-fuel debate support FOG to be a potential biodiesel feedstock in the near future. However, the cost of FOG-biodiesel production is still far away from the acceptable ranges to compete fossil diesel. Lastly, this paper suggested a number of future perspectives in order to enhance the economy and feasibility of FOG-derived biodiesel including developing new methods for efficient conversion of brown grease, integrated approaches for sequential production of biofuels from FOG, and co-esterification of FOG with other lipidic feedstocks.
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Wastes of steel nails WSN and wastes of lead fishing weights WLFW were successfully recycled in concrete to enhance its ability to attenuate neutrons and gamma rays. A series of studies on the effect ...of partially replacing coarse aggregates of concrete with different percentages (5, 10, and 20%) of WSN or WLFW on the density, slump, compressive strength, and attenuation of neutrons and gamma rays were implemented. The compressive strength of WSN-reinforced concrete ranged between 36.2 and 45.2 MPa, while that of WLFW-reinforced concrete ranged between 28.6 and 45.1 MPa. The ability of WSN- or WLFW-reinforced concrete to attenuate neutrons and gamma rays was tested by using two types of neutron energies; slow and total slow neutrons; and three gamma rays energies 661.64, 1173.23, and 1332.51 keV. Slow and total slow neutrons macroscopic cross-section, linear and mass attenuation coefficients of gamma rays, and half value layer for both types of nuclear radiation were obtained. The results showed that there is a significant improvement in the slow and total slow neutron attenuation efficiency of the considered concrete when reinforced by WSN or WLFW. On the other hand, due to the increase in the atomic number and density of both Fe present in WSN and Pb in WLFW, the attenuation ability of the studied gamma ray energies increased. The WLFW-reinforced concrete showed better value in the gamma rays and neutrons attenuation parameters compared to the WSN-reinforced concrete. Hence, the considered concretes reinforced by WSN or WLFW are a distinguished choice as radiation shields in nuclear power reactors, in addition to their adaptability to high concentrations of waste.
•A green one-step route was developed to convert waste coffee grounds into porous C/Fe hybrids.•The highest yield of C/Fe hybrids reached to 55.45 wt%.•The strongest reflection loss of C/Fe hybrids ...was -52.86 dB.•The effective absorption bandwidth of C/Fe hybrids was 6.40 GHz.
Recently great efforts have been focused on designing high-performance microwave absorbers using sustainable biomass resources, but there remains a lack of green and efficient fabrication methods. Herein, inspired by natural porous character of biomass waste, we demonstrated a green one-step route to convert waste coffee grounds into porous C/Fe hybrids, and further explored their potential applications for broadband and high-efficiency microwave absorption. In this design, the WCG-20-750 (incorporated 20 wt% Fe(C₅H₇O₂)₃ catalyst and carbonized at 750 °C) exhibited porous microstructure with the highest char yield of 55.45 wt%. Furthermore, the as-prepared C/Fe hybrids from WCG-20-750 displayed excellent microwave absorption performances. Typically, the minimum reflection loss (RLmin) reached to -52.86 dB and the widest effective absorption bandwidth (EAB) was 6.40 GHz at the thickness of 3.0 mm. This work provides an economically viable and environmentally friendly strategy to convert biomass wastes into value-added microwave absorbers, ultimately making contributions to the upcycling of renewable biomass resources and the fostering of sustainable environment.
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There is a notable discrepancy between intention on household waste sorting and the actions taken to support this environmental initiative among residents in China. This study aims to explore the ...influences of personal attitudes, facilities accessibility, and government stimulus on this discrepancy. Built on an integrated framework of Theory of Planned Behaviour (TPB) and Norm Activation Model (NAM), this study examines the relationship between intention and household waste sorting behaviour considering the psychological behavioural antecedents and circumstantial constraints among Chinese residents. Results from a questionnaire survey administered in China confirm the discrepancy, and show that the link between intention and behaviour on waste sorting is weakened after adding the influencing paths from the factors of facilities accessibility and government stimulus to waste sorting behaviour: however, the presence of these two factors directly promote waste sorting behaviour, but do not moderate the intention-behaviour relationship as their interaction items with behavioural intention are not significantly related to waste sorting behaviour. Furthermore, the personal norm is found to be the major factor influencing intentions of Chinese residents towards waste sorting while both subjective norms and perceived behavioural control were unexpectedly found to have no significant influence thereon. These findings are useful for promotion and planning of waste sorting by policy-makers to ease the waste disposal problem.
•We examine the discrepancy between intention and behaviour on waste sorting in China.•Facilities accessibility and government motivation directly promote waste sorting behaviour.•However, the above two factors do not moderate the intention-behaviour relationship.•Personal norm is found as the major factor for behavioural intention of waste sorting.
This work aims to evaluate the use of bottom biomass ash as an alternative raw material in porcelain stoneware bodies. For this purpose, ash coming from a biomass thermoelectric power plant in ...Emilia-Romagna (Italy) was selected and its chemical, mineralogical and thermal properties determined. Data indicated its technological role as a flux, so it was introduced in a porcelain stoneware batch in partial replacement of feldspars and experimented at laboratory scale. A bottleneck, relative to the rheological behavior of the slips, was overcome by a slight deflocculant increase. The powder compacts were fired from 1000° to 1220 °C in order to follow the evolution of the technological properties, phase composition (XRPD-Rietveld) and microstructure (SEM). The introduction of ash allowed to lower the firing temperature by 20 °C, while keeping the technological properties comparable with those of the benchmark. Moreover, the mineralogical and microstructural data revealed different sintering kinetics.
•Currently 75% of tyres, 55% of plastics, 75% of glass, 47% of fly ash and 60% of C&D wastes are disposed in landfills.•Crumb rubber in concrete can degrade physical and mechanical properties but ...improve thermal and dynamic properties.•Recycling is the best practice of managing waste plastics followed by landfill and incineration.•Waste glass could be a good alternative to replace natural sands in concrete.•Recycling 10,000 tons of waste can create 9.2 jobs while this number is only 2.8 if disposed in landfill.
The world is moving towards a circular economy that focuses on reducing wastes and keeping materials in use for the longest time possible. This paper critically reviewed three of the largest volume of landfill waste materials (tyres, plastics and glass) that are becoming a major concern for many countries. At present, crumb rubbers (from tyres) and glass sands (from crushed waste glass) are being used in concrete and road constructions while plastics are often used in manufacturing civil structures. However, only 10% tyres, 19.5% plastics and 21% glass are currently recycled globally. The massive volume of remaining unused wastes goes to landfill creating environmental problems. Therefore, finding new strategies of utilising these landfill wastes is vital. The global and country specific production, recycling and landfilling rates of these waste are summarised to understand the present situation of global waste crisis. Future strategies for improved waste management, potential investment and research directions are highlighted. New options for recycling wastes tyres, plastics and glass in construction are also presented to provide practical and economical solutions to extract maximum value and ensure their continued use in a closed loop system.
