Carbon Resources Conversion最新文献

In recent years, hydrothermal treatment has been considered as among the most promising option for sludge solubilisation and carbon recovery in terms of sludge management. In this study, the effect of different individual hydrothermal operating conditions like temperature (110–250 °C), sludge pH (6–13) and reaction time (0.5–3 h) were varied to understand their influence on sludge solubilisation. The most effective hydrothermal conditions (severity factor of 9.7) were found to be at 200 °C, sludge pH of 12 and reaction time of 1 h which solubilised about 1743 mg/g and 131 mg/g of COD and carbohydrates respectively into the aqueous phase. Also, gas chromatography- mass spectrometry (GC–MS) analysis was done that identified the organic compounds in the treated liquid phase to be mainly carboxylic acids, phenols, esters, and their derivatives. Although further studies are required to efficiently separate and recover the different organic compounds present, this work provides more insights for future valorisation of the organic rich hydrothermally treated liquid phase.

The sorption-enhanced method can change the thermodynamic equilibrium by absorbing CO₂. However, it also brings about the problems of high regeneration temperature of adsorbent and large regeneration energy consumption. In order to study the impact of enhanced adsorption methods on the overall energy cost of the system in the hydrogen production process, this paper analyzes and compares steam methane reforming and reactive adsorption-enhanced steam methane reforming with the energy consumption of hydrogen production products as the evaluation index. The results showed that the energy consumption per unit hydrogen production decreased from 276.21 MJ/kmol to 131.51 MJ/kmol, and the decomposition rate of H₂O increased by more than 20% after the addition of adsorption enhancement method. It is proved that the advantage of sorption enhanced method on pre-separation of CO₂ in the product makes up for the disadvantage of energy consumption of adsorbent regeneration. In addition, the ability of the process to obtain H element is improved by the high decomposition rate of H₂O, which realizes a more rational distribution of the element.

Biomass-derived 2,5-bis(hydroxymethyl)furan (BHMF) has received great attention and interest due to its broad application prospects in polyesters and medicine. Over the past decades, the catalytic systems including thermocatalytic, biocatalytic, electrocatalytic, and photocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) into BHMF have been developed to a great extent. To understand the present status and challenges of BHMF production, this review systematically evaluates recent findings and developments of HMF hydrogenation through various reaction systems, with an emphasis on catalyst screening, synthesis processes, and reaction mechanism. Furthermore, a few potential research trends are also proposed, in order to provide innovative ideas for further exploration of BHMF synthesis in a simpler, efficient, and economical way.

Rice husk-based activated carbon was prepared with the help of zinc chloride using microwave and electrical dual-mode heating. The pore characteristics and chemical properties of rice husk-based activated carbon (RH-AC) were characterized by BET, XRD, Raman spectra, FTIR and pH_IEP (pH of isoelectric point). The specific surface area of RH-AC is 1719.32 m²/g with a total pore volume of 1.05 cm³/g. The performance of RH-AC for removing Cr(VI) from aqueous solution was examined considering the variation of the contact time (0–120 min), pH value (2.0–9.0), adsorbent dose (0.5–3.0 g/L), initial concentration (28–145 mg/L) and solvent temperature (15–45 °C). The ideal pH for Cr(VI) removal is between 2.0 and 3.0 with the equilibrium time of 90 min, achieving the maximum adsorption capacity of 56.82 mg/g with the pH of 3.0. Comparable study on the established kinetic models and isotherms to simulate the removal of Cr(VI) by RH-AC was carried out to sort out the inherent mechanism of the absorption. Reasonable agreements could be obtained by the pseudo-second-order kinetic model and Langmuir, Freundlich and Tempkin isothermal models. Results from Body model simulation suggest that external mass transfer was the essential cause for rate-controlling in the adsorption process of Cr(VI).

As a new type of green solvent with non-volatility, high thermal stability, high conductivity and various adjustable properties, ionic liquid (IL) has been widely used in the capture and electrochemical reduction of carbon dioxide (CO₂). To date, many studies have been made to investigate CO₂ capture by using different types of ILs and CO₂ electrochemical reduction (CO₂ER) with ILs as either electrolyte or other catalytic active components. Some structure–activity relationships between the structure and adsorption or catalytic properties of ILs have been found. Herein, the absorption performances and mechanisms of conventional ILs, amino-functionalized ILs, non-amino functionalized ILs and supported ILs for CO₂ capture, as well as the performances and action mechanisms of ILs as the electrolyte, electrolyte additive, and/or electrode modifier in the process of CO₂ER are summarized. Many researches indicate that the unique interaction between the anion or cation of IL and CO₂ has a significant contribution to promote the absorption and conversion of CO₂. However, the ILs used for CO₂ capture and electrochemical reduction should be further explored. Especially, a more in-depth investigation of the adsorption and catalytic mechanisms with the help of quantum chemical calculation, molecular simulation, and in situ characterization techniques is necessary. It is expected to design and develop more efficient ILs used for CO₂ capture and conversion on a large scale.

For a gasification process, the char-CO₂ gasification is the controlling step worthwhile to be deeply investigated. The article chosen corn stalk (CS), poplar sawdust (PS) and bagasse residue (BR) as the typical waste species derived from agricultural, forestal and industrial sources. The char-CO₂ gasification behavior, reaction kinetics and carbon structure were studied to reveal the intrinsic factors determining the reaction kinetics. Generally, the carbon conversion and maximum conversion rate were influenced by the feedstocks species and char preparation temperatures, as influenced by ash proportion, potassium content in ash and carbon structure of char. The char-CO₂ reaction for CS was subject more to the catalytic effect of alkali compositions, while pore structure affected more the gasification reaction for PS char. The isoconversional kinetic analysis indicated that the gasification reaction became stable at carbon conversion of 0.5. Subsequently, sectionalized kinetic parameters were calculated for the initial gasification temperature to the temperature reaching 50% conversion. The result showed that high initial gasification temperature increased the char-CO₂ gasification barrier to hardly start the reaction but accelerate the reaction rate. The carbon structure analyses further clarified that the reaction activation energy was highly related to the microcrystalline structure of carbon, while the reaction rate was more determined by carbon pore structure.

Soybean can serve as an efficient carbon and nitrogen source for in-situ fabrication of efficient composite electrocatalysts with conductive nitrogen-doped carbon (N-C) material. In this study, the iron-doped cobalt nitride/phosphide (Fe-Co₃N/CoP) nanosheet was composited with a conductive N-C material by using soybean as C and N source, as well as NH₃ as additional nitrogen source. During the nitridation process of Fe-Co₃N, N-C bond was formed as a newly generated Co(Fe)-N-C active sites. Therefore, it fabricates a good microscopic contact interface between the catalyst and carbon material for charge transfer. Besides, the introduction of Fe-CoP by partially phosphating Fe-Co₃N further improved the OER activity due to the high catalytic activity of Co sites with high valence state. As a result, the obtained electrocatalyst exhibited overpotentials as low as 285 and 390 mV for supporting 10 and 100 mA/cm⁻² current densities. This work indicates that the design of materials with good interfaces could be an effective approach for the preparation of electrocatalysts for water electrolysis.

The suitability of the abundant agro-industrial residues wheat straw (WS; control), barley and oats straw (BOS) and rice husk (RH), supplemented with various sources of oils (sunflower, corn oil), nitrogen (peptone, yeast extract) and calcium salts (CaSO₄·2H₂O, CaCl₂), as novel substrates in solid-state fermentation of selected Pleurotus ostreatus and P. eryngii mushrooms was investigated. The possible effect of different additives on mycelial growth rate, biomass production and endoglucanase, laccase and lipase biosynthesis were evaluated. Moreover, their impact on essential cultivation aspects (earliness, total mushroom yield, biological efficiency) and carposome quality parameters (weight, morphological characteristics) was assessed. Both fungi showed their highest growth rates on BOS substrates and the most positive implementation was CaSO₄·2H₂O 6 % w/w (Kr = 9.58 mm/ day; P. ostreatus, Kr = 9.42 mm/ day; P. eryngii), while different additives led to enhancement of biomass production. Pleurotus species demonstrated minimal levels of endoglucanase activity, with values ranging from 0.01 to 0.42 U/g of dry weight, regardless of the substrate and the stage of colonization. On the contrary, the maximum values of laccase activity were observed at 50 % of colonization on BOS and RH, while supplementation with nitrogen and calcium sources positively affected its biosynthesis. P. ostreatus and P. eryngii cultivated on BOS supplemented with peptone at 2 and 5 % w/w, synthesized significant laccase amounts, i.e., 12,165.78 and 8,624.55 U/g d.w., respectively. Satisfactory amounts of lipase were produced, especially in substrates supplemented with sunflower 2 % w/w, in quantities up to 1.42 U/g d.w., whereas the highest lipase activity was achieved by P. eryngii on WS supplemented with corn oil at 2 % w/w, with a value of 4.25 U/g d.w. being recorded. Regarding fermentation of Pleurotus species in polypropylene bags, WS and BOS supported faster colonization and shorter earliness period than RH substrates, whereas supplementation did not seem to affect these culture parameters. Furthermore, oils supplementation had a positive effect on BE of both species, with values up to 100 % for P. ostreatus and 80 % for P. eryngii on WS and BOS, whereas on RH the lowest BE values were detected. Morphological characteristics were not significantly affected by the additives. Results indicate the positive impact that certain additives have on mushroom productivity and production of enzymes with great financial and environmental importance.

Waste pulp (WP) is a typical byproduct of paper industry, and Chemical-looping gasification (CLG) as a recently developed technology is highly suited to dispose high-volatile wastes like WP. In order to make a high-efficiency oxygen carrier (OC) for CLG of WP, the Ni-containing electroplating sludge (NES) was used as the matrix and NiO modification was performed to enhance the hydrogen production in CLG. These resulted in a potentially high-efficiency OC denoted as NNES. Testing CLG of WP was in a fixed-bed reactor at 850 °C by adopting NNES as the OC, injecting 2.4 mL/g(WP) water, and keeping a mass ratio of 1.0 between OC to WP. It produced 1.73 Nm³/kg syngas that has an LHV of 11.9 MJ/Nm³ and a H₂/CO ratio of 3.63. In 10 redox cycles, the syngas yield did not have obvious decrease, but a certain reduction in the activity of NNES was observed. Characterization of the spent NNES revealed that it is the Ni agglomeration and inert silicate generation which reduced the activity of NNES.