Three thermal modeling methods for phase change materials (PCMs): enthalpy-based method, effective heat capacity method and apparent heat capacity method, are presented in details. Their characteristics and application limitations are compared and discussed. We found that enthalpy-based method and effective heat capacity method are both approximation treatments, and can be well used in steady state problems, while apparent heat capacity method tracks the moving phase change boundary in PCMs, and it is the most accurate and applicable method of the three for dealing with transient processes. This work might provide useful information for the study of using PCMs in temperature control field, especially in aircraft environmental temperature control and thermal management.
In this study, cost-effective alkali-activated materials made from industrial side streams (blast furnace slag and Na-jarosite) were developed for catalytic applications. The catalytic activity of the prepared materials was examined in catalytic wet peroxide oxidation reactions of a bisphenol A in an aqueous solution. All materials prepared revealed porous structure and characterisation expressed the incorporation of iron to the material via ion exchange in the preparation step. Furthermore, the materials prepared exhibited high specific surface areas (over 200 m
This study employed lignin-sulfonated (LS) to develop biobased carbon materials (LS-Cs) through a sulfur-doping approach to enhance their physicochemical properties, adsorption capabilities, and energy storage potentials. Various characterization techniques, including BET surface area analysis, SEM imaging, XPS, Raman spectroscopy, and elemental composition (CHNS), were employed to assess the quality of the LS-Cs adsorbent and electrode samples. Response Surface Methodology (RSM) was utilized for optimizing the two main properties (specific surface area, A
This work is focused on crystal phase transition of solid wastes and functional application of crystal analcime in waste water purification, which provide a new environment-friendly route. In this paper, analcime was synthesized from steel slag and Circulating fluidized bed combustion (CFBC) fly ash (CFA) by hydrothermal method enhanced via geopolymerization (non-crystallized process). Then the analcimes were used for the removal of heavy metal ions (Pb2+, Cu2+) in aqueous solutions. Both the raw materials and products were characterized by XRF, XRD, FT-IR, SEM-EDS, and TEM. The results showed that non-crystallized process reduced the time of hydrothermal reaction and promoted the purity of analcime. The adsorption kinetics of analcime were all well fitted the pseudo-second-order model, and adsorption isotherms were well described by the Langmuir model. The maximum adsorption capacity of analcime for Pb2+ and Cu2+ were around 75.76, and 21.83 mg/g, respectively. The preference order observed for adsorption is Pb2+ > Cu2+.
Abstract Naturally occurring layered double hydroxide mineral, brucite (BRU), was compared with hydromagnesite (HYD) and a commercial Mg-rich mineral adsorbent (trade name AQM PalPower M10) to remove antimony (Sb) from synthetic and real wastewaters. The BRU and HYD samples were calcined prior to the experiments. The adsorbents were characterized using X-ray diffraction, X-ray fluorescence, and Fourier transform infrared spectroscopy. Batch adsorption experiments were performed to evaluate the effect of initial pH, Sb concentration, adsorbent dosage, and contact time on Sb removal from synthetic wastewater, mine effluent, and textile industry wastewater. Several isotherm models were applied to describe the experimental results. The Sips model provided the best correlation for the BRU and M10. As for the HYD, three models (Langmuir, Sips, and Redlich–Peterson) fit well to the experimental results. The results showed that the adsorption process in all cases followed the pseudo-second-order kinetics. Overall, the most efficient adsorbent was the BRU, which demonstrated slightly higher experimental maximum adsorption capacity (27.6 mg g -1 ) than the HYD (27.0 mg g -1 ) or M10 (21.3 mg g -1 ) in the batch experiments. Furthermore, the BRU demonstrated also an efficient performance in the continuous removal of Sb from mine effluent in the column mode. Regeneration of adsorbents was found to be more effective under acidic conditions than under alkaline conditions.
Activated carbons obtained from organosolv lignin by chemical activation with KOH and oxidized with diluted HNO3 were studied as catalysts for aerobic oxidative dehydrogenation (ODH) reactions. The structure/activity relationship was investigated through multiple techniques revealing the crucial role of oxygen functionality distribution in promoting two mechanistically archetypical ODH probe reactions: (i) the tetrahydroquinoline (THQ) aromatization, which represents ODH triggered by hydride transfer, and (ii) the 2-phenyl indole homocoupling reaction, a model for single-electron transfer-promoted reactions. In particular, the catalytic activity, correlating with oxygen functionality distribution on the basis of X-ray photoelectron spectroscopy and temperature-programmed desorption analysis, was associated with the C═O surface functionalities, as confirmed by blocking experiments with 2,2,2-trifluoroethyl hydrazine. Kinetic profiling tools were employed to assess THQ ODH product inhibition effects on the overall yield of the process as well as the extent of stoichiometric activity of the carbocatalyst. The breadth of the developed catalysts' applicability was explored through selected relevant ODH reactions.
Anaerobic co-digestion of sewage sludge and corn silage with zero-valent iron powder (Fe 0 ), cellulase, and papain as reinforcement means was conducted.COD-based feeding ratio of sewage sludge to corn silage was set to 2:1, the solids retention time (SRT) 20 day, digestion temperature 35 °C, and mixing speed 60 rpm.Removal rates of total COD during the control group, and Fe 0 , papain, cellulase, and papain, Fe 0 , and the two kinds of enzyme-added tests were 38.04, 41.02, 34.62, 34.55, 35.42, and 48.21%, respectively.The corresponding biogas production was 2.12, 2.62, 2.22, 2.41, 2.25, and 2.81 dm 3 /day, respectively.The results indicated the addition of cellulase, and papain could maximize the decomposition and hydrolysis of organic matter in sewage sludge and corn silage to volatile fatty acids.Fe 0 could reduce the redox potentials of the anaerobic co-digestion, optimize the circumstances of the methanogenesis stage, accelerate biogas production, and improve biogas components.Fe 0 and enzymes played a synergistic role in the anaerobic co-digestion system.Life cycle assessment indicated that the anaerobic co-digestion of sludge and corn silage co-substrates could benefit the economy, environment, and social development under the synergistic action of Fe 0 and enzymes.
Phosphorus as phosphate and nitrogen as ammonium or nitrate are the main nutrients in wastewaters and agricultural sludges. They runoff easily to waterways and cause eutrophication in water bodies. However, ammonium and phosphate could be precipitated simultaneously and used as recycled nutrients. In this research, dolomite calcined at 650 °C, 750 °C, or 950 °C and commercial MgO were used as precipitants in simultaneous phosphate and ammonium removal from synthetic (NH4)2HPO4 solution and agricultural sludge. Calcination at 750 °C was the preferred option as dolomite was decomposed to MgO and CaCO3 for optimal struvite precipitation. Molar ratios of 1.1–1.6:1–2:2 (Mg:P:N) were employed in the experiments. Very robust ammonium removal was obtained with MgO (57%), dolomite 650 °C and dolomite 750 °C (75%). MgO removed almost all phosphate, while dolomite 650 °C removed 65%, and dolomite 750 °C removed 60% (70% from agricultural sludge). Some part of the phosphate was adsorbed, most likely by CaCO3, during dolomite precipitation. Struvite was the only identified reaction product in all samples after 24 h of precipitation. Calcined dolomite had great potential in ammonium and phosphate precipitation from both synthetic waters and agricultural sludges and the precipitates could be used as recycled fertilizers.
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