Multifunctional In-MOF and Its S-Scheme Heterojunction toward Pollutant Decontamination via Fluorescence Detection, Physical Adsorption, and Photocatalytic REDOX.

A novel doubly interpenetrated indium-organic framework of 1 has been assembled by In3+ ions and highly conjugated biquinoline carboxylate-based bitopic connectors (H2L). The isolated 1 exhibits an anionic framework possessing channel-type apertures repleted with exposed quinoline N atoms and carboxyl O atoms. Owing to the unique architecture, 1 displays a durable photoluminescence effect and fluorescence quenching sensing toward CrO42-, Cr2O72-, and Cu2+ ions with reliable selectivity and anti-interference properties, fairly high detection sensitivity, and rather low detection limits. Ligand-to-ligand charge transition (LLCT) was identified as the essential cause of luminescence by modeling the ground state and excited states of 1 using DFT and TD-DFT. In addition, the negatively charged framework has the ability to rapidly capture single cationic MB, BR14, or BY24 and their mixture, including the talent to trap MB from the (MB + MO) system with high selectivity. Moreover, intrinsic light absorption capacity and band structure feature endow 1 with effective photocatalytic decomposition ability toward reactive dyes RR2 and RB13 under ultraviolet light. Notably, after further polishing the band structure state of 1 by constructing the S-scheme heterojunction of In2S3/1, highly efficient photocatalytic detoxification of Cr(VI) and degradation of reactive dyes have been fully achieved under visible light. This finding may open a new avenue for designing novel multifunctional MOF-based platforms to address some intractable environmental issues, i.e., detection of heavy metal ions, physical capture of pony-sized dyes, and photochemical decontamination of ultrastubborn reactive dyes and highly toxic Cr(VI) ions from water.

RhB-Embedded Zirconium-Biquinoline-Based MOF Composite for Highly Sensitive Probing Cr(VI) and Photochemical Removal of CrO42-, Cr2O72-, and MO.

How to accurately detect and efficiently sweep Cr(VI) from contaminated water has come into focus. Zirconium-based metal-organic frameworks (MOFs) play vital roles in water environmental chemistry due to excellent hydrolysis-resistant stability. However, as photochemical probes and photocatalysts, poor performances in detection sensitivity, selectivity, and photosensitiveness limit sole Zr-MOFs' applications. So, it is urgent to quest valid strategies to break through the dilemmas. Embedding luminous dyes into MOFs has been considered one of the most feasible avenues. Herein, a dual-emissive RhB@Zr-MOF with orange-yellow fluorescence has been assembled by in situ-encapsulating rhodamine B (RhB) into a zirconium-biquinoline-based MOF. Actually, within RhB@Zr-MOF, the aggregation fluorescence quenching (ACQ) effect of RhB molecules was effectively avoided. Notably, RhB@Zr-MOF exhibits a rapid fluorescence quenching response toward Cr(VI) ions with high selectivity, sensitivity, and anti-interference abilities. More interestingly, unlike the most widely reported fluorescence resonance energy transfer (FRET) between MOFs and encapsulated guest modules, photoinduced electron transfer from RhB to Zr-MOF has been confirmed by modeling the ground state and excited states of RhB@Zr-MOF using density functional theory (DFT) and time-dependent DFT (TD-DFT). The effective electron transfer makes RhB@Zr-MOF more sensitive in probing Cr2O72- and CrO42- ions with ultralow detection limit (DL) values of 6.27 and 5.26 ppb, respectively. Prominently, the detection sensitivity based on DL values has been increased about 6 and 9 times, respectively, compared with pristine Zr-MOF. Moreover, rather negative CB and positive VB potentials make RhB@Zr-MOF have excellent photochemical scavenging ability toward Cr(VI) and MO.

Efficient degradation of bisphenol A via peroxydisulfate activation using in-situ N-doped carbon nanoparticles: Structure-function relationship and reaction mechanism.

A novel in-situ N-doped carbon nanoparticles (NCNs) was prepared through direct pyrolysis of N-rich polyaniline (PANI) without using external N-containing precursor and the as-prepared materials were employed as metal-free peroxydisulfate (PDS) activator for bisphenol A (BPA) degradation. The catalyst derived from PANI carbonization at 900 °C (NCNs-9) displayed the excellent catalytic activity to activate PDS, resulting in 96.0% BPA degradation efficiency within 20 min. The catalytic activity of NCNs was closely related to their structure-composition, and higher graphitic N content and larger BET surface area were beneficial to the generation of reactive oxygen species (ROS). The quenching tests and electron paramagnetic resonance (EPR) demonstrated that BPA degradation in PDS/NCNs system was accomplished via non-radical (1O2) and radical ( ·OH, SO4·-, and O2·-) pathways, in which O2·- was the main ROS. The origin of O2·- was the conversion of dissolved oxygen and the activation of PDS. The possible degradation pathways of BPA were also proposed. This study might provide inspirations to design in-situ N-doped carbon nanoparticles as the PDS activator for efficient degradation of persistent organic compound via advanced oxidation processes (AOPs).

Enhanced anaerobic co-digestion of waste activated sludge and food waste by sulfidated microscale zerovalent iron: Insights in direct interspecies electron transfer mechanism.

The enhancement of zerovalent iron (ZVI) on anaerobic digestion (AD) has been proved, but there are still some problems that constrain the large-scale application of ZVI, such as the destruction of cell membrane and the inhibition of methanogenesis led by rapid H2 accumulation. Aiming at these problems, sulfidated microscale zerovalent iron (S-mZVI) was employed to evaluate its effect on anaerobic co-digestion (AcoD) of waste activated sludge (WAS) and food waste (FW). Experimental results showed that S-mZVI promoted the direct interspecies electron transfer (DIET) between specific bacteria and methanogens, resulting in higher methane yield. At S-mZVI 10 g/L, the cumulative methane yield and ETS activity reached 264.78 mL/g-VS and 24.62 mg INTF/(g-TS h), which was 1.33 and 1.83 times that of blank. Microbiological analysis demonstrated that the abundance of DIET-related microorganisms such as Syntrophomonas, Methanosarcina and Methanobacterium increased with the increasing dosage of S-mZVI.

Synergistic adsorption and electrocatalytic reduction of bromate by Pd/N-doped loofah sponge-derived biochar electrode.

In this work, a novel Pd/N-doped loofah sponge-derived biochar (Pd/NLSBC) material with three-dimensional (3D) network structure was prepared through the carbonization-impregnation method and applied as cathode for electrocatalytic bromate removal. The N-doped biochar not only increased the adsorption capacity of electrode, but also facilitated electron transfer, subsequently resulting in the high electrocatalytic activity for bromate removal. The results indicated higher bromate adsorption capacity of Pd/NLSBC electrode was favorable to the electrocatalytic bromate removal. The influences of significant operating factors including calcination temperature, initial solution pH, applied current intensity, and initial bromate concentration on electrocatalytic bromate removal were also optimized. Under the current intensity of 10 mA, Pd/NLSBC-800 exhibited the highest bromate removal efficiency (96.7 %) and the bromide conversion rate reached almost 100 % at the initial bromate concentration of 0.781 µmol L-1. This process could be effectively performed over a wide range of pH (2.0-9.0) and be well fitted to the pseudo-first-order kinetic model under different conditions. The reaction mechanism study indicated that both direct electron transfer and indirect reduction by the active hydrogen atom (H*) contributed to the elctrocatalytic bromate removal. Meanwhile, Pd/NLSBC-800 electrode could maintain its high electrocatalytic activity for bromate removal after five cycles.

Evaluating the effect of biochar on mesophilic anaerobic digestion of waste activated sludge and microbial diversity.

This study compared the effects of sewage sludge-derived pyrochar (PC300, PC500, and PC700) and hydrochar (HC180, HC240, and HC300) on mesophilic anaerobic digestion of waste activated sludge (WAS). It was demonstrated that hydrochar can better promote the methane production compared with pyrochar. The highest accumulative methane yield of 132.04 ±â€¯4.41 mL/g VSadded was obtained with HC180 addition. In contrast, the PC500 and PC700 showed a slightly negative effect on methane production. Sludge-derived HC not only accelerated the solubilization and hydrolysis of sludge floc, but also improved the production of acetic acid and propionate, further resulting in improved methane production. Simultaneously, the syntrophic microbes facilitating direct interspecies electron transfer (DIET) such as Syntrophomonas, Peptococcaceae, Methanosaeta and Methanobacterium bred rapidly with the addition of HCs. These results indicated that the hydrochar is more ideal as the accelerant to promote the methane production from mesophilic anaerobic digestion of WAS than the pyrochar.