Effective oxidation and adsorption of As(III) in water by nanoconfined Ce-Mn binary oxides with excellent reusability.

Herein, a highly efficient As(III) purifier Ce-Mn@N201 with excellent reusability was developed by stepwise precipitating hydrated cerium(IV) oxides (HCO) and hydrated manganese(IV) oxides (HMO) inside N201, a widely-used gel-type anion exchange resin. Owing to confinement of unique nanopores in N201, the in-situ generated nanoparticles (NPs) inside Ce-Mn@N201 were highly dispersed with ultra-small sizes of around 2.6 nm. Results demonstrated that HMO NPs effectively oxidized As(III) to As(V) with the conversion of Mn(IV) to Mn(II), while the generated Mn2+ was mostly re-adsorbed onto the negatively-charged surface of HMO NPs. During the regeneration process by simple alkaline treatment, the re-adsorbed Mn2+ was firstly precipitated as (hydr)oxides of Mn(II) and then oxidized to HMO NPs by dissolved oxygen to fully refresh its oxidation capacity. Though HCO NPs mainly served as adsorbent for arsenic, they could partially oxidize As(III) to As(V) at the beginning, while the oxidation capacities continuously diminished with the irreversible conversion of Ce(IV) to Ce(III). In 10 consecutive adsorption-regeneration cycle, Ce-Mn@N201 efficiently decontaminated As(III) from 500 µg/L to below 5 µg/L with Mn2+ leaching less than 0.3% per batch. During 3 cyclic fixed-bed adsorptions, Ce-Mn@N201 steadily produced 8500-9150 bed volume (BV) and 3150-3350 BV drinkable water from the synthesized and real groundwater, respectively, with Mn leaching in effluent constantly < 100 µg/L.

Highly Efficient and Stable Binary Cross-Linkable/ Self-Assembled Organic Nonlinear Optical Molecular Glasses.

The development of electro-optical materials with high chromophore loading levels that possess ultrahigh electro-optic coefficients and high long term alignment stability is a challenging topic. Anthracene-maleimide Diels-Alder (DA) reaction and π-π interaction of Anthracene-pentafluorobenzene and benzene-pentafluorobenzene are developed for making highly efficient binary cross-linkable/self-assembled dendritic chromophores FZL1-FZL4. A covalently or non-covalently cross-linked network is formed by DA reaction or π-π interaction after electric field poling orientation, which greatly improves the long-term alignment stability of the materials. An electro-optic coefficient up to 266 pm V-1 and glass transition temperature as high as 178 °C are achieved in cross-linked film FZL1/FZL2, and 272-308 pm V-1 is achieved for self-assembled films FZL1/FZL4 and FZL3/FZL4 due to high chromophore density (3.09-4.02 × 1020 molecules cm-3 ). Long-term alignment stability tests show that after heating at 85 °C for over 500 h, 99.73% of the initial r33 value is maintained for poled crosslinked electro-optic films 1:1 FZL1/FZL2. The poled self-assembled electro-optic films 1:1 FZL1/FZL4 and 1:1 FZL3/FZL4 can still maintain more than 97.11% and 98.23%, respectively, of the original electro-optic coefficient after being placed at room temperature for 500 h. The excellent electro-optic coefficient and stability of the material indicate the practical application prospects of organic electro-optic materials.

Removal of Gaseous Volatile Organic Compounds by a Multiwalled Carbon Nanotubes/Peroxymonosulfate Wet Scrubber.

In this study, a wet scrubber coupled with a persulfate-based advanced oxidation process [carbocatalysts/peroxymonosulfate (PMS)] was demonstrated to efficiently remove gaseous volatile organic compounds (VOCs). The removal efficiency of a representative VOC, styrene, was stable at above 98%, and an average mineralization rate was achieved at 76% during 2 h. The removal efficiency of the carbocatalysts/PMS wet scrubber for styrene was much higher than that of pure water, carbocatalysts/water, or PMS/water systems. Quenching experiments, electron spin resonance spectroscopy, in-situ Raman spectroscopy and density functional theory (DFT) calculations indicated that singlet oxygen (1O2) and oxidative complexes are the main reactive oxygen species and that both contributed to styrene removal. In particular, carbonyl groups (C═O) in the carbocatalyst were found to be the active sites for activating PMS during styrene oxidation. The role of 1O2 was discovered to be benzene ring breaking and a possible non-radical oxidation pathway of styrene was proposed based on time-of-flight mass spectroscopy which was further verified by DFT calculations. In particular, the electron transfer process of multi world carbon nanotubes-PMS* in styrene oxidation was further studied in-depth by experiments and DFT calculations. The unstable vinyl on styrene was simultaneously degraded by the oxidative complexes and 1O2 into benzene, and finally oxidized by 1O2 into H2O and CO2. This study provides an effective method for VOC removal and clearly illustrates the complete degradation mechanism of styrene in a nonradical PMS-based process by a wet scrubber.