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•Pd NPs supported ordered mesoporous were synthesized.•Pd NPs were characterized by XPS, XRD, TEM, SEM, FT-IR and NMR spectroscopy.•Catalyst loading, temperature, NaOH and NaBH4 ...concentration effects were examined.•Pd NPs catalyze the hydrolytic production of H2 from NaBH4 with TOF of 176 moleH2.molcat−1.min−1.•Pd NPs catalyst retains 71.6% of its initial catalytic activity after five cycles.
The ordered mesoporous silica supported Pd NPs, denoted as Pd NPs@KIT-6 2 and Pd NPs@KIT-6-PEG-imid 6, were synthesized by a deposition precipitation method using the KIT-6 1 or KIT-6-PEG-imid 5, respectively, and Na2PdCl4 followed by in situ reduction by NaBH4. The obtained supported Pd NPs 2 and 6 were fully characterized by XPS, XRD, TEM, SEM, FT-IR and solid-state 29Si and 13C NMR spectroscopy. The effect of several parameters such as catalyst loading, temperature, NaOH and NaBH4 concentration were examined to obtain the optimum reaction conditions. The supported Pd NPs 2 and 6 catalyze the hydrolytic production of H2 from NaBH4 with notable efficiencies and the catalyst stabilized by PEG and imidazolium ionic liquid based-KIT-6 6 is more active than its KIT-6 counterpart 2. A TOF of 176 moleH2.molcat−1.min−1 for 6 was achieved when the reaction was performed with a low catalyst loading of 0.1 mol%. Reaction kinetics studies showed that the hydrolysis is first order in catalyst and NaBH4 with apparent Ea of 35.0 and 35.7 kJ mol−1 for 2 and 6, respectively. The efficiency of catalyst 6 for the hydrolysis of NaBH4 was investigated in H2O and D2O and indicated that the reaction is considerably faster in H2O than in D2O with primary KIE kH/kD = 2.36. In addition, the PdNPs based KIT-6 mesoporous silica 6 retains 71.6% of its initial efficiency after five cycles.
Heavy metals like arsenic, copper, cadmium, chromium, nickel, zinc, lead, and mercury are major pollutants of fresh water reservoirs because of their toxic, non‐biodegradable, and persistent nature. ...The industrial growth is the major source of heavy metals introducing such pollutants into different segments of the environment including air, water, soil, and biosphere. Heavy metals are easily absorbed by fishes and vegetables due to their high solubility in the aquatic environments. Hence, they may accumulate in the human body by means of the food chain. Various methods have been developed and used for water and wastewater treatment to decrease heavy metal concentrations. These technologies include membrane filtration, ion‐exchange, adsorption, chemical precipitation, nanotechnology treatments, electrochemical and advanced oxidation processes. In this review, the methods as well as their mechanisms and efficiency are discussed.
To combat the shortage of fresh drinking water, the reuse of wastewater is becoming increasingly important. However, these wastewaters often contain toxic pollutants mostly coming from industrial sources. This review discusses efficient treatment strategies to remove heavy metals from wastewater with regard to their mechanisms and efficiencies.
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•The FeOCl/PMS/Vis system could efficiently remove and mineralize aquatic organic pollutants.•It was significantly enhancing the activation and utilization efficiency of ...PMS.•Operation across a broad range of environmental conditions.•The synergistic mechanism between photocatalysis and PMS activation in FeOCl/PMS/Vis system was revealed.
Inspired by the photosensitivity and self-heal properties of iron oxychloride (FeOCl), we used photocatalysis coupling peroxymonosulfate (PMS) activation for effective aquatic decontamination in a cost-efficient and environmentally friendly method. Synthesized FeOCl was appointed to activate PMS to degrade bisphenol A (BPA, 2,2-bis(4-hydroxydiphenyl) propane) persistently under visible light. The best performance of FeOCl/PMS/Vis system was ∼100% BPA degradation efficiency which achieved in 20 min. The BPA removal efficiency had a positive correlation with the dosages of FeOCl and PMS, but negatively related to BPA concentration. The FeOCl/PMS/Vis system also presented impressive degradation performance at a wide pH range (pH = 3–11) and showed well excellent stability and reusability. The addition of either bicarbonate or chloride had impressive promotion effect on BPA removal. The reaction mechanism of FeOCl/PMS/Vis system was studied deeply. PMS was activated to generate active radicals (SO4− and HO) by Fe(II) of FeOCl for BPA degradation. Then the as-formed Fe(III) was reduced to Fe(II) via trapping photoexcited electrons in conduction band (CB) of FeOCl, which effectively inhibited the recombination of photo-generate charges and the pollutants oxidation would recur via facilitating the Fe(II)/Fe(III) redox recycle. Thus, the activation and utilization efficiency of PMS was effectively improved. This work indicated the FeOCl/PMS/Vis system was a promising application in wastewater treatment.
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•A novel nZVI@Fe2P core–shell was fabricated and employed for the degradation of SDZ.•100% SDZ removal was achieved in 15 mins and kept 60% even in the 9th cycles.•The material after ...ten cycles remains superior effective through re-phosphorization.•Both experimental and DFT revealed the dominant role of Fe2P shell layer.•Fe2P could promote electron transfer and donate electrons for continuous reaction.
Nano zero valent iron (nZVI) is widely used in traditional hydrogen peroxide (H2O2)-based Fenton reactions for the degradation of persistent organic pollutants in aqueous environments. How to restrain the blocked electron transfer aroused from thickening of the iron oxide passivation layer and reinforce the Fe(III)/Fe(II) dynamic cycling is essential for Fenton reactions. In this work, a novel core–shell structural nZVI@Fe2P was fabricated and employed for the degradation of sulfadiazine (SDZ). Compared to nZVI, the nZVI@Fe2P demonstrated a significant performance and stability in the degradation of SDZ. Completed SDZ removal is achieved in less than 15 min and the SDZ removal kept over 60% even in the ninth consecutive cycles. Although the SDZ removal decreased dramatically to only 27.4% in the tenth cycle, the value could be restored to 80.6% after a facile re-phosphorization process. Both experimental and density function theory (DFT) calculation revealed the dominant role of Fe2P in promoting H2O2 activation and strengthening the Fe(III)/Fe(II) dynamic cycling. In the nZVI@Fe2P/H2O2 system, the low impedance and high proton conductivity of the Fe2P shell layer played a dual function, i.e., accelerating electron transfer and donating electrons for the continuous Fenton reaction. This implication of these findings provides a novel strategy by integrating the state-of-the-art material science, advanced oxidation process, and mechanism elucidation for practical environmental wastewater remediation.
The effects of global warming on the environment and society are substantial, making it a major global concern. Finding strategies to reduce CO2 output from energy systems that rely on chemical ...processes is one of the biggest problems in this area. In order to address this challenge, researchers are looking into creative solutions, such as carbon capture and storage and developing alternative energy systems with low carbon footprints. For this, the present work introduces a creative integration of molten carbonate and solid oxide fuel cells to maximize efficiency while reducing energy costs. This system also has a recovery unit to reuse the generated CO2 as the gasification agent for reduced environmental impact. Besides, the surplus heat is exploited through the vanadium chloride cycle for clean hydrogen production. A techno-economic, sustainability, and exergo-environmental assessment is carried out to evaluate the system's feasibility from all facets. According to the parametric results, there is a conflictive trend among performance indicators by changing the fuel utilization factor and compressor pressure ratio. Therefore, a comparative analysis of various multi-objective optimization scenarios is performed to find the best condition from various perspectives. According to the findings, compared to the system without a recovery unit, the proposed model produces optimal hydrogen of 1.3 kg/s with a very low environmental effect and power costs of 5.3 kg/GWh and 19.4 $/MWh. The results further reveal that when power is considered an additional optimization goal, it increases up to 494.95 MWh, resulting in the lowest environmental effect and the cost of 4.4 kg/GWh and 16.3 $/MWh, respectively. The scatter distribution of the key variables ultimately reveals that, while the current density should be maintained at its highest level, the optimal points of utilization factor are distributed throughout the entire domain.
•A new hybrid SOFC and MCFC system is proposed.•The system feasibility is studied from techno-economic-environmental aspects.•Various optimization scenarios based on machine learning techniques are applied.•A considerable emission is reduced through carbon recovery.•The minimum emission and the LCOP of 4.43 kg/GWh and 16.29 $/MWh are achieved.
•Boron significantly promoted Fe3O4/PAA process for SMT removal.•·OH, (R-O·), and Fe(IV) contributed important role in SMT removal.•Possible SMT degradation pathway and the toxicity of transformation ...products were analyzed.•B/Fe3O4/PAA was an efficient approach for removing antibiotic in natural fresh water.
Nowadays, antibiotic pollution is increasingly serious and posing a huge threat to ecology and human health. Therefore, it is vital to find effective approaches to remove antibiotics.
In this study, boron (B) was adopted to accelerate the surface and solution Fe2+ recycle in Fe3O4/peracetic acid (PAA) system, which showed excellent performance for antibiotics removal.
According the XPS analysis and experiments detection, both recycle of surface and solution Fe2+ could be enhanced in the presence of boron in Fe3O4/PAA system. 74.0% sulfamethazine (SMT) could be removed within 60 min in Fe3O4/PAA system while 93.4% could be removed within only 20 min in B/Fe3O4/PAA system and the value of k in B/Fe3O4/PAA system (0.136 min−1) was also much higher than that in Fe3O4/PAA system (0.028 min−1). The effect of boron, Fe3O4, PAA dosage and initial pH on removing SMT in Fe3O4/PAA system were also conducted. Quenching experiments and EPR experiments demonstrated that ·OH, organic radicals (R-O·) and Fe(IV) exhibited 63.1%, 17.3%, and 16.2% role in removing SMT, respectively. Possible SMT degradation pathway and the toxicity of transformation products were analyzed. B/Fe3O4/PAA exhibited superior resistance to inorganic ions and nature organic matters, good recycle ability, excellent adaptability to various pollutants, and efficient performance for antibiotics removal in natural fresh water.
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•(NH4)2SO4-H2SO4 synergistic system was introduced to vanadium extraction process.•NH4+ contained waste water was recycled in the following leaching process.•93.45% vanadium and 0.24% ...chromium was leached.•V2O5 with a purity of 95.71% was prepared.
A cleaner and novelty leaching medium, (NH4)2SO4-H2SO4 synergistic system was introduced into the leaching process for extracting vanadium efficiently after calcification roasting with high chromium vanadium slag (HCVS), and then V2O5 was prepared after precipitation and roasting. The effects of leaching and precipitation conditions were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). 93.45% vanadium and 0.24% chromium were leached when the calcification roasted sample was leached in the (NH4)2SO4-H2SO4 synergistic system at 20 °C for 60 min with a liquid–solid ratio (L/S) of 10, achieving the efficient separation of vanadium and chromium in HCVS. The optimal (NH4)2SO4-H2SO4 synergistic system was composed with 250 g/L (NH4)2SO4 and 3.75 mol/L H2SO4, the amount of H2SO4 was 1 mL in every 30 mL leaching system. The introduction of (NH4)2SO4 provided much NH4+, which could promote the acid leaching reaction. 99.75% vanadium was precipitated further from vanadium-containing leaching liquid when heating the liquid at 60 °C for 60 min after adjusting the system pH at 8.0, and the deposit was ammonium polyvanadate (NH4)2V6O16. Then, V2O5 with a purity of 95.71% was prepared after roasting, and recovery rate of vanadium from HCVS was higher than 93%. After precipitation, the supernatant containing a large amount of NH4+ could be recycled as the new leaching medium with some (NH4)2SO4 adding according to NH4+ loss after vanadium precipitation. This process achieved the efficient extraction of vanadium from HCVS and provided a new thinking for the leaching process based on the (NH4)2SO4-H2SO4 synergistic system.
Deep learning has made substantial breakthroughs in many fields due to its powerful automatic representation capabilities. It has been proven that neural architecture design is crucial to the feature ...representation of data and the final performance. However, the design of the neural architecture heavily relies on the researchers’ prior knowledge and experience. And due to the limitations of humans’ inherent knowledge, it is difficult for people to jump out of their original thinking paradigm and design an optimal model. Therefore, an intuitive idea would be to reduce human intervention as much as possible and let the algorithm automatically design the neural architecture.
Neural Architecture Search
(
NAS
) is just such a revolutionary algorithm, and the related research work is complicated and rich. Therefore, a comprehensive and systematic survey on the NAS is essential. Previously related surveys have begun to classify existing work mainly based on the key components of NAS: search space, search strategy, and evaluation strategy. While this classification method is more intuitive, it is difficult for readers to grasp the challenges and the landmark work involved. Therefore, in this survey, we provide a new perspective: beginning with an overview of the characteristics of the earliest NAS algorithms, summarizing the problems in these early NAS algorithms, and then providing solutions for subsequent related research work. In addition, we conduct a detailed and comprehensive analysis, comparison, and summary of these works. Finally, we provide some possible future research directions.
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•A functionalized carboxymethyl chitosan aerogel is explored for Cu(Ⅱ) adsorption.•The maximum capacity of PCCSA-1.0 for absorbing Cu(Ⅱ) is 175.56 mg/g.•Continuous filtration of ...industrial wastewater with fixed bed columns is achieved.•PCCSA-1.0 is conducive to inhibit the enrichment of Cu(Ⅱ) ions in rice.•The generated waste after adsorption is converted into a material for secondary use.
Copper ions (Cu(II)) in water pose a huge threat to human health and ecosystem security. Therefore, developing eco-friendly and sustainable strategies to eliminate the toxicity risk of Cu(II) in the aqueous environment remains a great challenge. In this work, an elastic polyethyleneimine-modified carboxymethyl chitosan aerogel was developed via a freeze-drying process for the adsorption of Cu(II). The adsorption kinetic and isotherm experiments demonstrated that the adsorption process was monolayer chemisorption and the maximum adsorption capacity calculated from Langmuir model was 175.56 mg g−1. The obtained aerogels exhibited preferential selectivity for Cu(II) even when the competing cations and organics existed. Besides, about 0.93 g of aerogel realized continuous fixed-bed column filtration of industrial wastewater with an effective purification volume of 4.14 L. Mechanistic analysis via FTIR and XPS revealed that the excellent adsorption performance for Cu(II) might be attributed to the strong electrostatic force, Vander Waals' force and coordination of N/O -containing functional groups. It is worth mentioning that the adsorbed Cu(II) ions in the aerogel were converted into a reusable photocatalyst, avoiding the secondary leakage of heavy metals. This work opened a door to synthesize carboxymethyl chitosan aerogel, promising for heavy metal wastewater treatment and realizing the concept of waste utilization.
•Modified BG-11 and Zarrouk media successfully grew Spirulina with similar dry biomass.•Aerated air exhibit the optimal biomass productivity for Spirulina cultivation.•After 3 cultivation cycles, ...biomass productivity decreased from 0.2246 to 0.0802 g/L/d.•Pretreatment methods on recycled medium and rainwater improve biomass productivity.•Economical cost of various pretreatment methods were assessed in this study.
The cultivation of microalgae represents a water-intensive process, prompting the need to reduce its water footprint and explore alternative water sources. Therefore, this research work aims to investigate the growth of Spirulina by recycling the culture medium obtained from the post-cultivation process and substituting rainwater resources for the preparation of the culture medium.
The effect of pre-treatment methods, specifically microfiltration and UV-light was investigated. These methods were applied to treat the recycled medium and rainwater resources used for Spirulina cultivation. Biomass concentration, biomass productivity and phycocyanin accumulation of Spirulina were examined to assess the Spirulina growth under different pre-treatment conditions.
After three cultivation cycles in the recycled medium, biomass productivity decreased from 0.2246 to 0.0802 g/L/d which might be due to high salinity and biological pollutants that inhibit Spirulina growth. However, different pre-treatment methods using microfiltration and UV-light on the recycling medium were found to be effective in increasing biomass productivity from 0.1395 to 0.1861 g/L/d. Additionally, the use of rainwater for Spirulina cultivation was explored. Applying pre-treatment methods to the rainwater, biomass productivity was further improved from 0.3211 to 0.3837 g/L/d. These findings suggest that the use of pre-treatment methods and alternative rainwater resources can improve the biomass productivity of Spirulina and potentially reduce the environmental impact throughout the microalgae cultivation process.
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