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High-purity H2O2 is widely used as an environmentally friendly wet electronic chemical for the production of printed circuit boards, semiconductors and integrated circuits. In this work, the authors prepared primary, secondary and tertiary amino-functionalized zirconia by the postgrafting method, and systematically studied the simultaneous adsorption process of metallic ions (M+, exist typically Al3+, Fe3+, Mg2+, Ca2+, K+, Na+), phosphate and total oxidizable carbon (TOC) fro [Detail] ...
Download coverThe applicability of the life cycle assessment (LCA) to the Fenton process should be considered not only at the laboratory-scale but also at the full-scale. In this study, the LCA process was applied to evaluate the homogeneous Fenton process for the treatment of high salinity pharmaceutical wastewater. The potential environmental impacts were calculated using Simapro software implementing the CML 2001 methodology with normalization factors of 1995 world. Foreground data obtained directly from the full-scale wastewater treatment plant and laboratory were used to conduct a life cycle inventory analysis, ensuring highly accurate results. By normalized results, the Fenton process reveals sensitive indicators, primarily toxicity indicators (human toxicity, freshwater aquatic toxicity, and marine aquatic toxicity), as well as acidification and eutrophication impacts, contributed by hydrogen peroxide and iron sludge incineration, respectively. Overall, hydrogen peroxide and iron sludge incineration contribute significantly, accounting for at least 78% of these indicators. In sludge treatment phase, treatment of iron mud and infrastructure of hazardous waste incineration plants were the key contributors of environmental impacts, adding up to more than 95%. This study suggests the need to develop efficient oxidation processes and effective iron sludge treatment methods to reduce resource utilization and improve environmental benefits.
Lignin, an abundant aromatic polymer in nature, has received significant attention for its potential in the production of bio-oils and chemicals owing to increased resource availability and environmental issues. The hydrodeoxygenation of guaiacol, a lignin-derived monomer, can produce cyclohexanol, a nylon precursor, in a carbon-negative and environmentally friendly manner. This study explored the porous properties and the effects of activation methods on the Ru-based catalyst supported by environmentally friendly and cost-effective hydrochar. Highly selective cleavage of Caryl–O bonds was achieved under mild conditions (160 °C, 0.2 MPa H2, and 4 h), and alkali activation further improved the catalytic activity. Various characterization methods revealed that hydrothermal treatment and alkali activation relatively contributed to the excellent performance of the catalysts and influenced their porous structure and Ru dispersion. X-ray photoelectron spectroscopy results revealed an increased formation of metallic ruthenium, indicating the effective regulation of interaction between active sites and supports. This synergistic approach used in this study, involving the valorization of cellulose-derived hydrochar and the selective production of nylon precursors from lignin-derived guaiacol, indicated the comprehensive and sustainable utilization of biomass resources.
Microbial lipid fermentation encompasses intricate complex cell growth processes and heavily relies on expert experience for optimal production. Digital modeling of the fermentation process assists researchers in making intelligent decisions, employing logical reasoning and strategic planning to optimize lipid fermentation. It this study, the effects of medium components and concentrations on lipid fermentation were investigated, first. And then, leveraging the collated data, a variety of machine learning algorithms were used to model and optimize the lipid fermentation process. The models, based on artificial neural networks and support vector machines, achieved R2 values all higher than 0.93, ensuring accurate predictions of the fermentation process. Multiple linear regression was used to evaluate the respective target parameter, which were affected by the medium components of lipid fermentation. Lastly, single and multi-objective optimization were conducted for lipid fermentation using the genetic algorithm. Experimental results demonstrated the maximum biomass of 50.3 g·L−1 and maximum lipid concentration of 14.1 g·L−1 with the error between the experimental and predicted values less than 5%. The results of the multi-objective optimization reveal the synergistic and competitive relationship between biomass, lipid concentration, and conversion rate, which lay a basis for in-depth optimization and amplification.
We proposed a facile synthesis of single-Ni-atom catalysts on low-cost porous carbon using a calcination method at the temperatures of 850–1000 °C, which were used for CO2 electrochemical reduction to CO. The porous carbon was prepared by carbonizing cheap and abundant humic acid. The structural characterizations of the as-synthesized catalysts and their electrocatalytic performances were analyzed. The results showed that the single-Ni-atom catalyst activated at 950 °C showed an optimum catalytic performance, and it reached a CO Faradaic efficiency of 91.9% with a CO partial current density of 6.9 mA·cm−2 at −0.9 V vs. reversible hydrogen electrode (RHE). Additionally, the CO Faradaic efficiency and current density of the optimum catalyst changed slightly after 8 h of continuous operation, suggesting that it possessed an excellent stability. The structure-activity relations indicate that the variation in the CO2 electrochemical reduction performance for the as-synthesized catalysts is ascribed to the combined effects of the increase in the content of pyrrolic N, the evaporation of Ni and N, the decrease in pore volume, and the change in graphitization degree.
With regard to green chemistry and sustainable development, the fixation of CO2 into epoxides to form cyclic carbonates is an attractive and promising pathway for CO2 utilization. Metal oxides, renowned as promising eco-friendly catalysts for industrial production, are often undervalued in terms of their impact on the CO2 addition reaction. In this work, we successfully developed ZnO nanoplates with (002) surfaces and ZnO nanorods with (100) surfaces via morphology-oriented regulation to explore the effect of crystal faces on CO2 cycloaddition. The quantitative data obtained from electron paramagnetic resonance spectroscopy indicated that the concentration of oxygen vacancies on the ZnO nanoplate surfaces was more than twice that on the ZnO nanorod surfaces. Density functional theory calculations suggested that the (002) surfaces have lower adsorption energies for CO2 and epichlorohydrin than the (100) surfaces. As a result, the yield of cyclochloropropene carbonate on the ZnO nanoplates (64.7%) was much greater than that on the ZnO nanorods (42.3%). Further evaluation of the reused catalysts revealed that the decrease in the oxygen vacancy concentration was the primary factor contributing to the decrease in catalytic performance. Based on these findings, a possible catalytic mechanism for CO2 cycloaddition with epichlorohydrin was proposed. This work provides a new idea for the controllable preparation of high-performance ZnO catalysts for the synthesis of cyclic carbonates from CO2 and epoxides.
Removal of boric acid from seawater and wastewater using reverse osmosis membrane technologies is imperative and yet remains inadequately addressed by current commercial membranes. Existing research efforts performed post-modification of reverse osmosis membranes to enhance boron rejection, which is usually accompanied by substantial sacrifice in water permeability. This study delves into the surface engineering of low-pressure reverse osmosis membranes, aiming to elevate boron removal efficiency while maintaining optimal salt rejection and water permeability. Membranes were modified by the self-polymerization and co-deposition of dopamine and polystyrene sulfonate at varying ratios and concentrations. The surfaces became smoother and more hydrophilic after modification. The optimum membrane exhibited a water permeability of 9.2 ± 0.1 L·m−2·h−1·bar−1, NaCl rejection of 95.8% ± 0.3%, and boron rejection of 49.7% ± 0.1% and 99.6% ± 0.3% at neutral and alkaline pH, respectively. The water permeability is reduced by less than 15%, while the boron rejection is 3.7 times higher compared to the blank membrane. This research provides a promising avenue for enhancing boron removal in reverse osmosis membranes and addressing water quality concerns in the desalination process.
This study utilized a thermogravimetric analyzer to assess the thermal decomposition behaviors and kinetics properties of vacuum residue (VR) and low-density polyethylene (LDPE) polymers. The kinetic parameters were calculated using the Friedman technique. To demonstrate the interactive effects between LDPE and VR during the co-pyrolysis process, the disparity in mass loss and mass loss rate between the experimental and calculated values was computed. The co-pyrolysis curves obtained through estimation and experimentation exhibited significant deviations, which were influenced by temperature and mixing ratio. A negative synergistic interaction was observed between LDPE and VR, although this inhibitory effect could be mitigated or eliminated by reducing the LDPE ratio in the mixture and increasing the co-pyrolysis temperature. The co-pyrolysis process resulted in a reduction in carbon residue, which could be attributed to the interaction between LDPE and the heavy fractions, particularly resin and asphaltene, present in VR. These findings align with the pyrolysis behaviors exhibited by the four VR fractions. Furthermore, it was observed that the co-pyrolysis process exhibited lower activation energy as the VR ratio increased, indicating a continuous enhancement in the reactivity of the mixed samples during co-pyrolysis.
Primary, secondary and tertiary amino-functionalized zirconia (ZrO2−NH2, ZrO2−NH and ZrO2−N) was synthesized by the postgrafting method for the adsorption removal of typical metallic ions, phosphate and total oxidizable carbon from a real H2O2 solution. ZrO2−NH2, ZrO2−NH and ZrO2−N exhibited similar pore sizes and sequentially increased zeta potentials. The adsorption results of single and binary simulated solutions showed that the removal efficiency increased in the order of Fe3+ > Al3+ > Ca2+ > Na+. There is competitive adsorption between metallic ions, and Fe3+ has an advantage over the other metals, with a removal efficiency of 90.7%. The coexisting phosphate could promote the adsorption of metallic ions, while total oxidizable carbon had no effect on adsorption. The adsorption results of the real H2O2 solution showed that ZrO2−NH2 exhibited the best adsorption affinity for metallic ions, as did phosphate and total oxidizable carbon, with a total adsorption capacity of 120.9 mg·g–1. Density functional theory calculations revealed that the adsorption process of metallic ions involves electron transfer from N atoms to metals and the formation of N-metal bonds.
A novel, cheap and highly efficient Ni-Co/Mo2C/Co6Mo6C2@C nanocomposite has been successfully constructed through simple one-step carbonization method in a nitrogen atmosphere. Polyethyleneimine in the precursor can effectively anchor molybdenum-based Keggin-type polyoxometallate and NiCo-layered double hydroxide through electrostatic and coordination interactions, which avoids the aggregation of catalyst particles during the pyrolysis process. After optimization, the obtained Ni-Co/Mo2C/Co6Mo6C2@C possesses small size (3–8 nm), large specific surface area and hierarchical pore structure. More importantly, Ni-Co/Mo2C/Co6Mo6C2@C presents remarkable hydrogen evolution reaction activity with low overpotentials in 0.5 mol·L–1 H2SO4 (102.3 mV) and 1 mol·L–1 KOH (95 mV) to afford the current density of 10 mA·cm–2, as well as small Tafel slopes of 82.49 and 99.92 mV·dec–1, respectively. Simultaneously, this catalyst also shows outstanding stability for 12 h without a significant change in current density. The excellent catalytic performance of Ni-Co/Mo2C/Co6Mo6C2@C can put down to the synergistic effect between multiple components and the small size of the catalyst. This work provides unique insights into the preparation of efficient transition metal-based catalysts for HER.
We report results from computational modeling of the relative stability of germanosilicate SCM-15 structure due to different distribution of germanium heteroatoms in the double four-member rings (D4Rs) of the framework and the orientation of the structure directing agent (SDA) molecules in the as-synthesized zeolite. The calculated relative energies of the bare zeolite framework suggest that structures with germanium ions clustered in the same D4Rs, e.g., with large number of Ge–O–Ge contacts, are the most stable. The simulations of various orientations of the SDA in the pores of the germanosilicate zeolite show different stability order—the most stable models are the structures with germanium spread among all D4Rs. Thus, for SCM-15 the stabilization due to the presence of the SDA and their orientation, is thermodynamic factor directing both the formation of specific framework type and Ge distribution in the framework during the synthesis. The relative stability of bare structures with different germanium distribution is of minor importance. This differs from SCM-14 germanosilicate, reported earlier, for which the stability order is preserved in presence of SDA. Thus, even for zeolites with the same chemical composition and SDA, the characteristics of their framework lead to different energetic preference for germanium distribution.
