Aqueous Oxytetracycline and Norfloxacin Sonocatalytic Degradation in the Presence of Peroxydisulfate with Multilayer Sheet-Like Zinc Oxide.

Multilayer ZnO sheet-like flakes were synthesized by a simple method of precipitation and characterized by the techniques of X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The findings are proven that the SEM images show the overall morphology of a single sheet-like ZnO nanostructure made from uniformly thick nano-sheets. In an aqueous environment, the acoustic ability of the prepared material was assessed using ultrasound (US) radiation to degrade oxytetracycline (OTC) and norfloxacin (NF). To increase the degradation efficiency, a US/ZnO/peroxodisulfate system was developed by introducing ammonium persulfate ((NH4)2S2O8) and sodium persulfate (Na2S2O8), exhibiting excellent synergistic effects. Result show the decomposition efficiency for NF removal with Na2S2O8 (64%) appeared to be slightly better than with (NH4)2S2O8 (56%). By contrast, the ultrasonic catalytic efficiency of Na2S2O8 (98%) was slightly better than that of (NH4)2S2O8 (94%) for OTC removal. The addition of scavengers to the US/ZnO/peroxodisulfate system through the NF and OTC results in the largest effect of holes. The degradation is considered to be often caused by holes. In this system, the Na2S2O8 can have two roles to increase the rate of degradation: (1) The SO4- formed by Na2S2O8 under ultrasonic irradiation directly degraded to norfloxacin on ZnO surface; and (2) S2O82- behaved as an electron acceptor, inhibiting recombination of electron hole pairs, enabling the development of more ·OH. Therefore, the synergistic effect significantly increases US/ZnO/peroxodisulfate sonocatalytic activity (Hu, S.B., et al., 2017. Aqueous norfloxacin sonocatalytic degradation with multilayer flower-like ZnO in the presence of peroxydisulfate. Ultrasonics Sonochemistry, 38(1), pp.446-454).

Effective disinfection of airborne microbial contamination in hospital wards using a zero-valent nano-silver/TiO2 -chitosan composite.

A novel antimicrobial composite of zero-valent silver nanoparticles (AgNPs), titania (TiO2 ), and chitosan (CS) was prepared via photochemical deposition of AgNPs on a CS-TiO2 matrix (AgNPs@CS-TiO2 ). Electron microscopy showed that the AgNPs were well dispersed on the CS-TiO2 , with diameters of 6.69-8.84 nm. X-ray photoelectron spectra indicated that most of the AgNPs were reduced to metallic Ag. Fourier-transform infrared spectroscopy indicated that some AgNPs formed a chelate with CS through coordination of Ag+ with the CS amide II groups. The zones of inhibition of AgNPs@CS-TiO2 for bacteria (Escherichia coli and Staphylococcus epidermidis) and fungi (Aspergillus niger and Penicillium spinulosum) were 6.72-11.08 and 5.45-5.77 mm, respectively, and the minimum (critical) concentrations of AgNPs required to inhibit the growth of bacteria and fungi were 7.57 and 16.51 µg-Ag/mm2 , respectively. The removal efficiency of a AgNPs@TiO2 -CS bed filter for bioaerosols (η) increased with the packing depth, and the optimal filter quality (qF) occurred for packing depths of 2-4 cm (qF = 0.0285-0.103 Pa-1 ; η = 57.6%-98.2%). When AgNPs@TiO2 -CS bed filters were installed in the ventilation systems of hospital wards, up to 88% of bacteria and 97% of fungi were removed within 30 minutes. Consequently, AgNPs@TiO2 -CS has promising potentials in bioaerosol purification.

Preparation of Zn-Doped Amino Functionalized Biochar from Hazardous Waste for Arsenic Removal.

The utilization of sludge from Far Eastern Memorial hospital (New Taipei city, Taiwan) wastewater treatment plants as biochar adsorbent was investigated. The sludge was carbonized using microwave carbonization and then chemically activated at high temperatures by using ZnCl2 to enhance porosity and surface area. A newly designed Zndoped amino-functionalized sludge biochar (Zn-SBC-DETA) presents effective As adsorption in water. The adsorbent was characterized by nitrogen adsorption-desorption, scanning electron microscopy (SEM) and thermogravimetric analysis. Results show that the surface area and average pore volume of Zn-SBC-DETA are 525 m² g-1 and 0.35 cm³ g-1, respectively. SEM results reveal that Zn-SBC-DETA has uniform pore size. The highest adsorption efficiency of As(III) is 79% at pH 3 with an adsorption capacity of 0.84 mg g-1. In addition, the adsorption efficiency of As(V) is 98% at pH 3 with an adsorption capacity of 1.43 mg g-1. The adsorption data can be described well by the Langmuir model rather than by the Freundlich model The data show good compliance with the pseudo second-order equation, and the correlation coefficient for the linear plots is higher than 0.97. Combined with the As species after reacting with Zn-SBC-DETA, the As transformation and adsorption mechanism are also discussed.

Effects of Different Sacrificial Agents and Hydrogen Production from Wastewater by Pt-Graphene/TiO2.

The Pt and graphene (GN) were used to modify TiO2 nanoparticles. GN/TiO2, Pt-TiO2, Pt-GN/TiO2 were successfully synthesized by modified Hummers' method, alcohol thermal and photodeposition method, respectively. The characterizations of the synthesized catalysts by different characterization techniques, including N2 adsorption-desorption isotherm, fourier transform infrared spectroscopy (FTIR), inductively coupled plasma (ICP) technique and element analyzer (EA), respectively. In addition, different sacrificial agents (methanol, ethanol, n-propanol, i-propanol, n-butanol, ethylene glycol, 1,2-propanediol, 1,3-propanediol and glycerol) have been investigated. There is clearly a linear relationship between hydrogen production rate and the polarity of monohydric alcohols. According to the Langmuir-Hinshelwood results, the surface pseudo-first order rate constant k = 15.06 mmol h-1 g-1 and the adsorption coefficient k = 0.50 mol L-1 were obtained. The feasibility of hydrogen production from wastewater obtained from terephthalic acid industry was studied. After reusing the catalyst under the same experimental conditions, the hydrogen production rate has only slightly decreased for 3 more cycles, which indicated the stability of the synthesized catalysts.

Preparation of Zn-Doped Biochar from Sewage Sludge for Chromium Ion Removal.

Recycling and reuse waste can result in significant savings in materials and energy. In this study, the adsorption of Cr(VI) was analyzed using activated carbon (AC) and biochar (BSC) made from sewage sludge. BSC materials were synthesized using zinc chloride as an activator coupled with carbonized sewage sludge. Specific surface area, pore size distribution, and pore volume were determined by measuring nitrogen adsorption-desorption (BET). BSC morphology was measured using field-emission scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). Results showed that the surface area and average pore volume of the BSC were 490 m2 g-1 and 0.8 cm3 g-1, respectively. SEM results revealed that BSC had uniform pore size. Effects of varying the initial Cr(VI) concentrations, pH values, and dosages of BSC on adsorption performance were also determined. Results showed that the maximum removal efficiency of Cr(VI) was above 99%, and adsorption capacity of 50% ZnCl2-BSC was 677 mg g-1.