Three-dimensional hierarchical porous sludge-derived carbon supported on silicon carbide foams as effective and stable Fenton-like catalyst for odorous methyl mercaptan elimination

The poor reusability of catalysts and secondary pollution are critical issues for sulfur-containing volatile organic compounds (S-VOCs) removal. In this paper, a three-dimensional (3D) hierarchical porous sludge-derived carbon supported on silicon carbide foams (SiC) has been fabricated for deep decomposition of S-VOCs under ambient conditions. The sludge-derived Fenton-like catalyst has been confirmed to be hierarchical 3D porous structure based on detailed characterization by scanning electron microscopy (SEM), X-ray diffraction (XRD), Nitrogen adsorption-desorption measurements and Raman spectroscopy. Significantly, the catalyst after KOH activation (SC_FeK-SiC) shows excellent catalytic decomposition of methyl mercaptan (CH₃SH) with almost complete CH₃SH oxidation into sulfate using hydrogen peroxide as an oxidant under ambient conditions. This catalyst also possesses relative low iron dissolution and excellent cycling performance. The efficient catalytic ability of SC_FeK-SiC can be attributed to SiC foam functioned as a stable 3D macroporous skeleton, in which the porous sludge-derived carbon immobilizes the active iron species and promotes the efficient capture of gaseous CH₃SH, thus facilitating the decomposition of CH₃SH by generating reactive species, specifically ·OH. The reaction mechanism was systematically investigated. Herein, the design of the porous sludge-derived carbonaceous Fenton-like catalyst paves an avenue for efficient VOCs treatment and rational sludge disposal.

Tuning role and mechanism of paint sludge for characteristics of sewage sludge carbon: Paint sludge as a new macro-pores forming agent

For the first time, paint sludge waste (PS) was used as a pore forming agent in the preparation of sewage sludge derived carbon (SC). The tuning role and mechanism of PS for characteristics of SC were explored. It was found that a sludge carbon (SC_PS-Zn) with rich macro-, meso- and micro- porous could be produced by one-step pyrolytic process of sludge in the presence of PS and ZnCl_2. Its surface area could reach as high as 680.5m²g^-1 as 88.4 times and 4.8 times of sludge carbon without addition of PS and ZnCl₂ (SC) and only addition of ZnCl₂ (SC_Zn)_, respectively. The macro- pores fabricated by PS provided much inner-space for ZnCl₂ to generate meso- and micro- porous, leading to a hierarchical porous structure. SC_PS-Zn showed a high adsorption capacity of 685.4mgg^-1 for Chrysophenine, which is 1.3 and 1.7 times that of SC_PS and SC_Zn respectively. The adsorption difference could be simply attributed to the fact that the great molecules were difficult to enter micro- pores of SC_Zn. It was also found that the difference was also dependent on orientation of Chrysophenine, which was related to pH value of solution.

Jujube leaf green tea extracts inhibits hepatocellular carcinoma cells by activating AMPK

Here we evaluated the anti-hepatocellular carcinoma activity by the Jujube leaf green tea extracts (JLGTE). We showed that JLGTE exerted anti-proliferative, cytotoxic and pro-apoptotic activities against HepG2 and primary human hepatocellular carcinoma cells. It was however non-cytotoxic to the normal hepatocytes. JLGTE activated AMP-activated protein kinase (AMPK) signaling, which was required for its cytotoxicity against hepatocellular carcinoma cells. Silence of AMPKα1, via targeted short hairpin RNAs or CRISPR-Cas9 genome editing, inhibited JLGTE-induced AMPK activation and HepG2 cell apoptosis. Further, in-activation of AMPK by a dominant negative AMPKα1 (T172A) also alleviated JLGTE's cytotoxicity against HepG2 cells. On the other hand, forced-activation of AMPK by introduction of a constitutively-active AMPKα1 (T172D) mimicked JLGTE's actions and led to HepG2 cell apoptosis. These results suggest that JLGTE inhibits human hepatocellular carcinoma cells possibly via activating AMPK.

Activation of peroxymonosulfate by nitrogen-functionalized sludge carbon for efficient degradation of organic pollutants in water

Nitrogen-functionalized sludge carbon (NSC) was prepared by urea-mediated pyrolysis of sewage sludge (SS) and was introduced, for the first time, as a potential metal-free catalyst to activate peroxymonosulfate (PMS) for oxidative removal of organic pollutants in water. The nitrogen functionalization of NSC catalysts significantly affected the chemical micro-environments as well as microstructures (morphology and porosity), improving the PMS activation activity towards removing various pollutants, e.g., acid orange 7, phenol and rhodamine B. On the basis of quenching studies and electron paramagnetic resonance, the formed dominant reactive oxidative species (ROS) in the NSC/PMS system was clarified to be nonradical singlet oxygen, in addition to the typical radical ROSs, sulfate and hydroxyl radicals. The incorporated pyridine N, graphite N and pristine CO in the NSC framework promoted the generation of ROS. This study provided new insights into environmentally friendly resourcing SS and exploiting novel cost-effective metal-free catalyst for PMS activation.

Dayside response of the magnetosphere to a small shock compression: Van Allen Probes, Magnetospheric MultiScale, and GOES-13

Observations from Magnetospheric MultiScale (~8 Re) and Van Allen Probes (~5 and 4 Re) show that the initial dayside response to a small interplanetary shock is a double-peaked dawnward electric field, which is distinctly different from the usual bipolar (dawnward and then duskward) signature reported for large shocks. The associated E × B flow is radially inward. The shock compressed the magnetopause to inside 8 Re, as observed by Magnetospheric MultiScale (MMS), with a speed that is comparable to the E × B flow. The magnetopause speed and the E × B speeds were significantly less than the propagation speed of the pulse from MMS to the Van Allen Probes and GOES-13, which is consistent with the MHD fast mode. There were increased fluxes of energetic electrons up to several MeV. Signatures of drift echoes and response to ULF waves also were seen. These observations demonstrate that even very weak shocks can have significant impact on the radiation belts.

Performance and Mechanism of Piezo-Catalytic Degradation of 4-Chlorophenol: Finding of Effective Piezo-Dechlorination

Piezo-catalysis was first used to degrade a nondye pollutant, 4-chlorophenol (4-CP). In this process, hydrothermally synthesized tetragonal BaTiO₃ nano/micrometer-sized particles were used as the piezo-catalyst, and the ultrasonic irradiation with low frequency was selected as the vibration energy to cause the deformation of tetragonal BaTiO₃. It was found that the piezoelectric potential from the deformation could not only successfully degrade 4-chlorophenol but also effectively dechlorinate it at the same time, and five kinds of dechlorinated intermediates, hydroquinone, benzoquinone, phenol, cyclohexanone, and cyclohexanol, were determined. This is the first sample of piezo-dechlorination. Although various active species, including h⁺, e^-, •H, •OH, •O₂^-, ¹O₂, and H₂O₂, were generated in the piezoelectric process, it was confirmed by ESR, scavenger studies, and LC-MS that the degradation and dechlorination were mainly attributed to •OH radicals. These •OH radicals were chiefly derived from the electron reduction of O₂, partly from the hole oxidation of H₂O. These results indicated that the piezo-catalysis was an emerging and effective advanced oxidation technology for degradation and dechlorination of organic pollutants.