Synergistic enhanced activation of peroxymonosulfate by heterojunction Co3O4-CuO@CN for removal of oxytetracycline: Performance, mechanism, and stability.

Metal-organic frameworks (MOFs) as precursors for catalysts has drawn growing attentions. In this study, heterojunction Co3O4-CuO doped carbon materials (noted as Co3O4-CuO@CN) were prepared by direct carbonization of CuCo-MOF in air. It was found that the Co3O4-CuO@CN-2 exhibited excellent catalytic activity with the highest Oxytetracycline (OTC) degradation rate of 0.0902 min-1 at 50 mg/L of Co3O4-CuO@CN-2 dosage, 2.0 mM of PMS and 20 mg/L of OTC, which was 4.25 and 4.96 times that of CuO@CN and Co3O4@CN, respectively. Furthermore, Co3O4-CuO@CN-2 was efficient over a wide pH range (pH 1.9-8.4), and possessed good stability and reusability without OTC degradation decrease after five consecutive uses at pH 7.0. In a comprehensive analysis, the rapid regeneration of Cu(II) and Co(II) is responsible for their excellent catalytic performance, and the p-p heterojunction structure formed between Co3O4 and CuO acts as an intermediary of electron transfer to accelerate PMS decomposition. Moreover, it was interesting to find that Cu rather than Co species played a vital role in the PMS activation. The quenching experiments and electron paramagnetic resonance demonstrated that .OH, SO4•-, and 1O2 were the reactive species responsible for oxidation of OTC and the non-radical pathway triggered by 1O2 was dominant.

A Shape Reconstruction and Measurement Method for Spherical Hedges Using Binocular Vision.

The center coordinate and radius of the spherical hedges are the basic phenotypic features for automatic pruning. A binocular vision-based shape reconstruction and measurement system for front-end vision information gaining are built in this paper. Parallel binocular cameras are used as the detectors. The 2D coordinate sequence of target spherical hedges is obtained by region segmentation and object extraction process. Then, a stereo correcting algorithm is conducted to keep two cameras to be parallel. Also, an improved semi-global block matching (SGBM) algorithm is studied to get a disparity map. According to the disparity map and parallel structure of the binocular vision system, the 3D point cloud of the target is obtained. Based on this, the center coordinate and radius of the spherical hedges can be measured. Laboratory and outdoor tests on shape reconstruction and measurement are conducted. In the detection range of 2,000-2,600 mm, laboratory test shows that the average error and average relative error of standard spherical hedges radius are 1.58 mm and 0.53%, respectively; the average location deviation of the center coordinate of spherical hedges is 15.92 mm. The outdoor test shows that the average error and average relative error of spherical hedges radius by the proposed system are 4.02 mm and 0.44%, respectively; the average location deviation of the center coordinate of spherical hedges is 18.29 mm. This study provides important technical support for phenotypic feature detection in the study of automatic trimming.

Synthesis of Bimetallic FeCu-MOF and Its Performance as Catalyst of Peroxymonosulfate for Degradation of Methylene Blue.

Bimetallic MOFs have recently emerged as promising materials for wastewater treatment based on advanced oxidation processes. Herein, a new bimetallic MOF (FeCu-MOF) was fabricated by hydrothermal process. The structural, morphological, compositional and physicochemical properties of the as-synthesized bimetallic FeCu-MOF were characterized by XRD, FT-IR, SEM, TEM, BET, and XPS. TEM and XPS confirmed the homogeneous distribution of CuO2 nanoparticles in the as-synthesized materials. The result of wastewater treatment indicated that 100% of MB was removed by 6.0 mM PMS activated with 0.6 g/L of FeCu-MOF in 30 min. The high catalytic performance of FeCu-MOF was probably due to the accelerated electron and mass transfer resulting from the existence of a homogeneous distribution of unsaturated metal sites and an abundant mesoporous structure. The obtained results from the competitive quenching tests demonstrated that sulfate radicals (SO4•-) were the major species responsible for MB oxidation. In addition, hydroxyl (·OH) and singlet oxygen (1O2) also had a nonnegligible role in the MB removal. Interestingly, the addition of acetate ion (CHCOO-) promoted the removal of MB while other anions (including NO2-, H2PO4-, SO42-, HPO42-, and HCO3-) inhibited the MB removal. Furthermore, a possible mechanism based on both heterogeneous and homogeneous activation of PMS was proposed, along with the MB degradation mechanism.