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The impediment of sludge resource utilization stems from the presence of heavy metals within the sludge matrix. To optimize heavy metal removal techniques from undried sludge, it is essential to study the distribution of heavy metals in the sludge flocs structure and the changes in morphology in the sludge cells after different treatments. In this study, the sludge was subjected to chemical treatments using citric acid (CA), EDTA, and saponin, as well as electrokinetic treatment at 2 V/cm. The distribution and migration of Cu, Ni, and Zn in sludge flocs after various treatment methods were analyzed. The heavy metals were found to migrate from intracellular to extracellular polymeric substances (EPS) without causing extensive sludge cell lysis. They gradually diffused outward with the dispersion of the EPS layer. The migration efficiency of the three heavy metals in the sludge flocs was Zn, Ni, and Cu. This was mainly related to the initial distribution and morphology of the heavy metals. Under the influence of chemicals and an electric field, the acid-soluble and reducible heavy metals in the cells partially migrated to the EPS, while the stable heavy metals transformed into an unstable state. Furthermore, the order of chemical reagents in terms of their effect on the migration efficiency of heavy metals was CA > EDTA > Saponin, owing to the varying binding strengths of heavy metals and their impact on the degree of loosening of the EPS. Especially after CA treatment a greater proportion of Cu, Ni, and Zn were transferred from the cells to the EPS. The acidification effect near the anode during electrokinetic treatment intensifies the migration of heavy metals. This study provides basic research for subsequent engineering optimization aimed at removing heavy metals from sludge. [ABSTRACT FROM AUTHOR]

Constructing metal–organic frameworks (MOFs) with high volatile organic compounds (VOCs) adsorption capacity and excellent water resistance remain challenging. Herein, a monocarboxylic acid‐assisted mixed ligands strategy was designed to synthesize a novel fluorinated MOFs, MIL‐53 (Al). The monocarboxylic acid promoted crystallization and produced abundant crystal defects, which increased pore volume. Moreover, the competitive coordination between tetrafluoroterephthalic acid and 1,4‐dicarboxybenzene was moderated by monocarboxylic modulators, significantly improving the hydrophobicity. The toluene uptake of the optimal sample reached 254.85 mg g−1 under humid conditions, increased by 33.56 % of MIL‐53(Al), and the QWet/QDry (the ratio of adsorption quality under wet to adsorption quality under dry) was 0.92, remarkably surpassing that of origin MIL‐53 (0.72). The recycle experiment showed superior reusability with no performance degradation after 10 recycle under RH=50 % (relative humidity). The adsorptive kinetic and thermodynamic analysis proves that the adsorption process is controlled by surface mono‐layer adsorption and pore diffusion. The fluorine group affects the internal diffusion, which weakens the transfer rate. This strategy opens a new prospect of obtaining hierarchical functional MOFs for meeting the VOCs uptake under the practical application. [ABSTRACT FROM AUTHOR]

The design and synthesis of low-cost, excellent catalytic activity catalysts is the key to catalytic oxidation of VOCs. Nanomaterials have attracted great interest in recent years. Here, a simple impregnation method was used to synthesize the Cu-doped CeO2 nanostructure catalyst supported on a boron-rich carbon carrier and applied for the catalytic oxidation of acetone. After trace amounts of Cu were added to the single CeO2 supported on boron-rich carbon catalyst, Cu-doped CeO2 catalyst displayed better catalytic activity. Besides, it also has long-term stability and H2O resistance. The influence of copper doping on the performance of the catalyst was studied by many characterization technologies. The result indicated that the introduction of Cu can further limit the growth of CeO2 grains based on the limited growth of metal nanoparticles on the carrier, can make the amounts of Ce3+ and adsorb oxygen species increase, and can enhance the redox properties of CeO2. Therefore, Cu-doped CeO2 nanostructures in a boron-rich carbon catalyst have the potential for the removal of acetone. [ABSTRACT FROM AUTHOR]

Zeolites with uniform pore structures and surface properties are potential adsorbents for volatile organic compounds (VOCs) adsorption. Although various zeolites have been researched for VOCs adsorption, the adsorption capacity still needs to be improved. In this work, EMT zeolite was synthesized and modified by polyethylene glycol (PEG400) as a high-capacity adsorbent for acetone purification. The structures of sorbents were characterized by X-ray diffraction, scanning electron microscopy, N2 adsorption–desorption isotherm, Fourier transform infrared, thermogravimetric analysis, and X-ray fluorescence spectrometer. Experimental results indicated that 0.6PEG-modified EMT zeolite with high specific surface area, large mesoporous volume, and more hydroxyl groups significantly improved the acetone adsorption property, which was 20.6% higher than pure EMT zeolite. The addition of PEG400 also enhanced the cyclic stability. The adsorption mechanism was further analyzed via adsorption kinetics and thermodynamics, which demonstrated the adsorption of acetone in EMT zeolite belonged to physical adsorption. Overall, PEG400-modified EMT zeolite presented the potential to be a promising candidate for efficient acetone adsorption in commercial applications. [ABSTRACT FROM AUTHOR]

Coal gangue is a typical waste produced during coal mining and washing. Synthesis of zeolites via coal gangue can contribute to resource recycling and environmental protection. In this study, high-silica SSZ-13 was synthesized by one-step hydrothermal synthesis from coal gangue without the traditional pretreatment methods of high-temperature roasting and alkali melting, making it more convenient and energy efficient. The synthesis time, gel silicon–aluminum ratio and silicon source were systematically studied to optimize the synthesis of SSZ-13. Experimental results indicated that the nucleation time of SSZ-13 could be shortened to 7 h, which was half the synthesis time by using chemicals. Tetrahedral aluminum was the main factor for rapid synthesis, which also accelerated the transformation of octahedral aluminum and further accelerated the synthesis of SSZ-13. The DeNOx activity of the synthesized Cu-SSZ-13 was over 90% across a broad range from 180 to 400 °C, and it remained over 85% in this temperature range even after hydrothermal treatment for 12 h. It also demonstrated good water resistance (over 95% DeNOx in the range of 200 to 400 °C) and sulfur resistance (over 95% DeNOx in the presence of 100 ppm SO2). [ABSTRACT FROM AUTHOR]

Background: Acetone is a volatile organic compound (VOC) that is often associated with poor air quality. Acetone has chronic toxicity towards humans and has a significant impact on the overall atmospheric air quality. In this study, several layer double oxides (with M2+ = Mg, Ni, Co or Mn and M3+ = Al or Ce) were tested as catalysts for acetone oxidation. Results: MnAl‐LDO was found to be the most efficient catalyst. 50% acetone conversion was achieved at 170 °C (T50%) and 90% conversion at 200 °C (T90%).The incorporation of Ce on MnCeAl‐LDO did not improve its catalytic properties over MnAl‐LDO (the T50% for MnCeAl‐LDO was 12 °C higher than for MnAl‐LDO). The good performance on MnAl‐LDO was due to the presence of Mn3+ and the low reduction temperature. MnAl‐LDO was not affected when water was introduced into the catalytic reaction setup. Less than 5% fluctuation in the acetone conversion rate at 170 and 200 °C was detected in the presence of 5.5% water. The incorporation of Ce on CoCeAl‐LDO improved its catalytic performance over CoAl‐LDO (T50% of CoCeAl‐LDO was 15 °C lower than CoAl‐LDO). Our results showed that the good catalytic performance of CoCeAl‐LDO was ascribed to the increased Co2+/Co3+ ratio and the abundance of lattice oxygen (Olatt). Conclusion: MnAl‐LDO has good catalytic properties for acetone oxidation, even under humid conditions. The LDO catalysts tested here can be developed into efficient catalysts for acetone oxidation and serve as functional materials for the reduction in acetone or VOC emission. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Novel Mn−Eu−Fe catalysts were prepared via co‐precipitation method for NOx removal by selective catalytic reduction with NH3 (NH3−SCR). The Mn−Eu−Fe(1)‐500 catalyst possessed the highest level of low‐temperature activity, giving 98 % NO conversion at 100 °C. This catalyst also exhibited excellent H2O resistance capacity, even at a high gas hourly space velocity (GHSV) of 75,000 h−1. The NO conversion still maintained at approximately 90 % in the presence of 15 % H2O at 230 °C after 50 h, and the adverse effects of H2O could be quickly eliminated after the removal of H2O. Detailed characterization and analysis indicated that strong interactions among Mn, Eu and Fe resulted in the excellent low‐temperature SCR activity and H2O resistance of the Mn−Eu−Fe(1)‐500 catalyst. The strong interactions lead to larger specific surface area, higher concentrations of Mn4+, Fe3+ and Oα; improved redox properties, increased acid sites and acid strength, and more adsorption amounts of NO/NH3 in the presence of H2O. The Mn−Eu−Fe(1)‐500 catalyst is a potential future catalyst for low‐temperature NOx removal derived from high‐H2O‐content flue gases of natural gas combustion. [ABSTRACT FROM AUTHOR]

Ultrasonic treatment is a good method of facilitating sewage sludge dewatering characteristics. It can also promote the potential of sludge electro-osmosis dewatering (EDW), which is an accepted method of deep dewatering, but the treatment method and optimizing conditions should be determined by performing experiments. In this study, we consider two treating methods: ultrasonic pre-treatment, which uses ultrasonic treatment as sludge pre-treatment before electro-osmosis dehydration, and ultrasonic coupling, which uses ultrasonic and electric fields simultaneously. Using sludge from the Tianjin Jizhuangzi sewage treatment plant, we analyze the influence of ultrasonic intensity and treatment time on sludge dewatering by performing two different methods. The results show that they effectively facilitated sludge EDW. Under the same conditions, i.e. 2 cm cake initial thickness, voltage of 60 V for 5 min, and 0.1 MPa mechanical pressure for 5.5 min, the optimum processing conditions for ultrasonic pre-treatment were found to be 0.510 W/cm2 and 3.5 min, the dehydration rate reached 34.71%, and the optimum conditions for ultrasonic coupling were 0.255 W/cm2 and 3.5 min, while the dehydration rate reached 40.78%. The dehydration rates for both approaches were clearly better than 17.40%, which was obtained under pure electro-osmosis dehydration. To compare the effects of ultrasonic pre-treatment and ultrasonic coupling on the electro-osmosis dehydration process, in this paper, we present the curves of dehydration rate, electric current, electro-osmosis flow, and scanning electron microscopy for dewatered sludge. Compared with the ultrasonic pre-treatment method, the effect of ultrasonic coupling on electro-osmosis dehydration was more obvious. [ABSTRACT FROM AUTHOR]

Based on the theories of acoustic agglomeration and dust wet removal, an experimental apparatus was constructed to study the combined effects of acoustic agglomeration and atomization humidification in the pretreatment process to analyze the filtration performance of filter material. According to the concentration of coal-fired fly ash chosen in the experiments, the proper amount of atomization humidification and the proper sound pressure level (SPL) were determined. Under the relative humidity (RH) of 69% and with SPL in the range of 100 dB to 135 dB, the removal efficiency of fly-ash, the compressibility of the fly-ash particle layer on the filter media, and the performance of pulse filter cleaning were studied. The results indicate that the combined effects of sound fields and atomization humidification can effectively remove PM10and PM2.5, and change the interaction and movement of particles, which can improve the pore structure of the fly-ash particle layer and increase the porosity of the dust layer. The results also indicate that with the proper amount of atomization humidification and appropriate SPL, the joint acoustic-atomization pretreatment can delay the filter material blocking, which reduces the pulse filter cleaning frequency and extends the filter cleaning cycle. It can also reduce the residual resistance after filter cleaning and prolong the operating lifetime of the filter media. © 2017 American Association for Aerosol Research [ABSTRACT FROM PUBLISHER]

Electro-osmotic dewatering (EDW) is one of the effective deeply dewatering technologies that is suitable for treating sludge with 55–80% of moisture content. Regarding EDW as the pre-treatment process of drying or incinerating, this article investigated the drying characteristics of electro-osmosis-dewatered sludge, including shear stress test, drying curves analysis, model analysis, and energy balance calculation. After EDW pre-treatment, sludge adhesion was reduced. The sludge drying rate was higher compared to the non-pre-treated sludge, especially under high temperatures (80–120°C). In addition, it is better to place the sludge cake with cathode surface facing upward for improving the drying rate. An adjusted model based on the Logarithmic model could better describe the EDW sludge drying process. Using the energy balance calculation, EDW can save the energy consumed in the process of sludge incineration and electricity generation and enable the system to run without extra energy input. [ABSTRACT FROM PUBLISHER]

Cover Feature: Synthesis of Hierarchical-Porous Fluorinated Metal-Organic Frameworks with Superior Toluene Adsorption Properties (ChemSusChem 16/2022) Competitive coordination, hydrophobicity, mixed ligand, monocarboxylic acid, toluene adsorption Keywords: competitive coordination; hydrophobicity; mixed ligand; monocarboxylic acid; toluene adsorption EN competitive coordination hydrophobicity mixed ligand monocarboxylic acid toluene adsorption 1 1 1 08/23/22 20220819 NES 220819 B The Cover Feature b shows a rod like metal-organic framework adsorbent. [Extracted from the article]