In-situ synthesis of magnetic iron-chitosan-derived biochar as an efficient persulfate activator for phenol degradation.

Persulfate activation is a forceful method for eliminating organic pollutants from coal chemical wastewater. In this study, an in-situ synthesis method was used to fabricate an iron-chitosan-derived biochar (Fe-CS@BC) nanocomposite catalyst using chitosan as a template. Fe was successfully imprinted into the newly synthesized catalyst. The Fe-CS@BC can activate persulfate to effectively degrade phenol. This point was confirmed by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The impact of various parameters on the removal rate was investigated in a single factor experiment. In Fe-CS@BC/PDS system, 95.96% of phenol (significantly higher than the original biochar of 34.33%) was removed within 45 min and 54.39% TOC within 2 h. The system showed superior efficiency over a broad pH value band from 3 to 9 and has a high degradation rate at ambient temperature. Free radical quenching experiment, EPR experiment and LSV experiment confirmed that multiple free radicals (including 1O2, SO4•-, O2•- and •OH) and electron transfer pathway combined to enhance phenol decomposition. Finally, the activation mechanism of persulfate by Fe-CS@BC was proposed to provide logical guidance on the treatment of organic pollutants in coal chemical wastewater.

Insulator Abnormal Condition Detection from Small Data Samples.

Insulators are an important part of transmission lines in active distribution networks, and their performance has an impact on the power system's normal operation, security, and dependability. Traditional insulator detection methods, on the other hand, necessitate a significant amount of labor and material resources, necessitating the development of a new detection method to substitute manpower. This paper investigates the abnormal condition detection of insulators based on UAV vision sensors using artificial intelligence algorithms from small samples. Firstly, artificial intelligence for the image data volume requirements was large, i.e., the insulator image samples taken by the UAV vision sensor inspection were not enough, or there was a missing image problem, so the data enhancement method was used to expand the small sample data. Then, the YOLOV5 algorithm was used to compare detection results before and after the extended dataset's optimization to demonstrate the expanded dataset's dependability and universality, and the results revealed that the expanded dataset improved detection accuracy and precision. The insulator abnormal condition detection method based on small sample image data acquired by the visual sensors studied in this paper has certain theoretical guiding significance and engineering application prospects for the safe operation of active distribution networks.

A Novel Functionalized MoS2-Based Coating for Efficient Solar Desalination.

Molybdenum disulfide (MoS2) has emerged as a promising photothermal material for solar desalination. However, its limitation in integrating with organic substances constrains its application because of the lack of functional groups on its surface. Here, this work presents a functionalization approach to introduce three different functional groups (-COOH -OH -NH2) on the surface of MoS2 by combining them with S vacancies. Subsequently, the functionalized MoS2 was coated on the polyvinyl alcohol-modified polyurethane sponge to fabricate a MoS2-based double-layer evaporator through an organic bonding reaction. Photothermal desalination experiments show that the functionalized material has higher photothermal efficiency. The evaporation rate of the hydroxyl functionalized the MoS2 evaporator evaporation rate is 1.35 kg m-2 h-1, and the evaporation efficiency is 83% at one sun. This work provides a new strategy for efficient, green, and large-scale utilization of solar energy by MoS2-based evaporators.

Chitin-derived biochar with nitrogen doping to activate persulfate for phenol degradation: Application potential and electron transfer pathway in system.

The fast and efficient removal of organic pollutants (e.g., phenolics) remains one of the focus problems in environment pollution. Thus, a chitin-derived biochar with nitrogen doping (N-BC) was successfully prepared at a lower calcination temperature of 600 °C, which is environmentally friendly and energy saving. The N-BC was analyzed by SEM, FTIR, BET, XRD, XPS and Raman spectroscopy to confirm that the doping of nitrogen element provided sufficient defect sites to promote the activation of persulfate (PDS). Quenching experiments and EPR results revealed the presence of •OH and •O2- contributed to phenol degradation in N-BC 600/PDS system. In addition, the linear sweep voltammogram experiments also demonstrated the existence of electron transfer pathway. The electrons were donated from phenol and shifted to PDS through N-BC. The graphitic N and carbon defects in N-BC served as the active sites of the reaction and involved absorption and transfer of electrons as the key character. Moreover, the removal rates of phenol and TOC reached 98.8% and 58.2% within 2 h, indicating that N-BC effectively activated the persulfate to degrade phenol. This study provides the theoretical support and potential applications for the activation of persulfate by nitrogen-doped biochar to degrade other phenolic compounds.

Preparation and characterization of lauric acid-stearic acid/expanded perlite as a composite phase change material.

Rapid energy consumption stimulates the development of energy-saving materials. In this work, the L-S eutectic mixture used as a PCM was compounded with EP via vacuum adsorption to synthesize LS/EP CPCM. The maximum mass adsorption rate of EP on L-S is determined to be 70% via leakage experiments. The microscopic morphology, chemical, and crystal structure were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD), respectively. The phase change properties were measured by differential scanning calorimetry (DSC). The melting temperature of LS/EP is 37.79 °C, with a latent heat of 126.05 J g-1, and it has a crystallinity of over 90%. The thermal decomposition was evaluated by TGA. The initial decomposition temperature is 132.20 °C for LS/EP. In addition, the results of accelerated phase change cycling experiments showed that LS/EP CPCM has good reliability.

Thermal Properties and Reliabilities of Lauric Acid-Based Binary Eutectic Fatty Acid as a Phase Change Material for Building Energy Conservation.

Thermal properties, stability, and reliability of lauric acid-based binary eutectic mixtures for building energy efficiency were studied. The eutectic points and phase change performance of these binary PCMs were obtained as follows: (1) For lauric acid-myristic acid, the mass eutectic point is 70 wt % LA/30 wt % MA. (2) For lauric acid-palmitic acid, the eutectic point is 79 wt % LA/21 wt % PA. (3) For lauric acid-stearic acid, the eutectic point is 82 wt % LA/18 wt % SA. The eutectic PCMs have a melting enthalpy of 166.18, 183.07, and 189.50 J·g-1 and a melting temperature of 35.10, 37.15, and 39.29 °C for lauric-myristic acid, lauric-palmitic acid, and lauric-stearic acid binary eutectic PCMs, respectively. The experimental results are very close to the theoretical results. Moreover, from FT-IR and XRD investigations, we realized that during the preparation of the lauric acid-based binary eutectic fatty acids, no new functional groups were produced. Besides, the TG illustrated that the LA-MA eutectic PCMs, LA-PA eutectic PCMs, and LA-SA eutectic PCMs exhibit excellent thermal stability below 126.51, 135.7, and 110.08 °C, respectively. Finally, lauric acid-based binary eutectic PCMs still show excellent thermal properties and chemical structure after 500 hot and cold cycles. All in all, as a novel material for building energy conservation, lauric acid-based binary eutectic PCMs have broad prospects and good practicability.

Thermal properties and reliabilities of myristic acid-paraffin wax binary eutectic mixture as a phase change material for solar energy storage.

In this work, a myristic acid (MA)-paraffin wax (PW) binary eutectic phase change material (PCM) was prepared by a melt-solution blending method. The eutectic point of the MA-PW binary system was determined to be 62 wt% MA-38 wt% PW using a cooling curve. In addition, the phase transition properties and thermal stability of MA-PW binary eutectic PCM were investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG) analysis. The melting temperature and latent heat as well as starting temperature of decomposition for MA-PW binary eutectic PCM were 41.99 °C, 171.43 J g-1 and 137.86 °C, respectively. Besides, analysis of the chemical and crystal structures of MA, PW and MA-PW revealed no chemical reaction between MA and PW to produce a new molecular structure and no change in the crystal structure. Finally, MA-PW binary eutectic PCM still has good thermal properties and chemical stability after 500 cold-hot cycles.

The elucidation of surrounding alginate gels on the pollutants degradation by entrapped nanoscale zero-valent iron.

The adsorption capacity of calcium alginate (Ca-alginate) beads was evaluated by measuring the removal of three organic compounds with different charges (malachite green, p-chlophenol and methyl orange). The diffusion was investigated in Ca-alginate hydrogel as a function of solute charge. It was found that an increased electrostatic attraction between the hydrogel and solute would improve the mobility of solute and hence enhance its adsorption efficiency. The degradation kinetics of charged pollutants by Ca-alginate with NZVI entrapped (NZVI-alginate) beads was compared to that of bare NZVI and the data followed a pseudo-first-order kinetic model. Negatively charged Ca-alginate hydrogel strongly adsorbed positively charged pollutant, which led to an enhancement in degradation rate. However, the degradation efficiency of neutral and negatively charged pollutants by NZVI-alginate was comparable with that by bare NZVI. Thus, the degradation ability of NZVI-alginate was related with the diffusion and adsorption behavior of solutes in Ca-alginate hydrogel. The experimental results showed that the free calcium ions containing in Ca-alginate had a significant impact on the adsorption and degradation behaviors of positively charged pollutant, but those of neutral and negatively charged pollutants were only moderately affected. With the dispersity of NZVI particles in beads (1:1-1:4, w/w) increasing, the degradation efficiency of malachite green was improved, whereas further increase of NZVI dispersity (1:6, w/w) brought about a depressed degradation.