CTAB-assisted synthesis of Bi2MoO6 hierarchical microsphere and its application as a novel efficient and recyclable adsorbent in removing organic pollutants

Efficient Removal of Methylene Blue Dye from Aqueous Media Using Facilely Synthesized Magnesium Borate/Magnesium Oxide Nanostructures

Methylene blue dye in water sources can pose health risks to humans, potentially causing methemoglobinemia, a condition that impairs the blood's ability to carry oxygen. Hence, the current study investigates the synthesis of novel magnesium borate/magnesium oxide (Mg3B2O6/MgO) nanostructures and their efficiency in removing methylene blue dye from aqueous media. The nanostructures were synthesized using the Pechini sol-gel method, which involves a reaction between magnesium nitrate hexahydrate and boric acid, with citric acid acting as a chelating agent and ethylene glycol as a crosslinker. This method helps in achieving a homogeneous mixture, which, upon calcination at 600 and 800 °C, yields Mg3B2O6/MgO novel nanostructures referred to as MB600 and MB800, respectively. The characterization of these nanostructures involved techniques like X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, N2 gas analyzer, and field-emission scanning electron microscope (FE-SEM). These analyses confirmed the formation of orthorhombic Mg3B2O6 and cubic MgO phases with distinct features, influenced by the calcination temperature. The mean crystal size of the MB600 and MB800 samples was 64.57 and 79.20 nm, respectively. In addition, the BET surface area of the MB600 and MB800 samples was 74.63 and 64.82 m2/g, respectively. The results indicated that the MB600 sample, with its higher surface area, generally demonstrated better methylene blue dye removal performance (505.05 mg/g) than the MB800 sample (483.09 mg/g). The adsorption process followed the pseudo-second-order model, indicating dependency on available adsorption sites. Also, the adsorption process matched well with the Langmuir isotherm, confirming a homogeneous adsorbent surface. The thermodynamic parameters revealed that the adsorption process was physical, exothermic, and spontaneous. The MB600 and MB800 nanostructures could be effectively regenerated using 6 M HCl and reused across multiple cycles. These findings underscore the potential of these nanostructures as cost-effective and sustainable adsorbents for methylene blue dye removal.

Experimental and theoretical revealing of piezo-photocatalyst Bi2O2CO3 for degradation of ciprofloxacin in water

In this report, we have attempted to experimentally and theoretically reveal a new piezo-photocatalyst Bi2O2CO3 for efficient removal of ciprofloxacin (CIP) from water. Bi2O2CO3 nanoplates were synthesized to evaluate their photocatalytic (irradiation source: simulated-sunlight), piezocatalytic (irradiation source: ultrasonic) and piezo-photocatalytic (irradiation source: simulated-sunlight and ultrasonic) performances for CIP elimination. Under the condition CCIP = 10 mg/L and Ccatalyst = 1 g/L, the piezo-photodegradation rate constant is obtained as kapp = 0.07811 min-1, which surpasses that of photocatalysis (kapp = 0.04686 min-1) and piezocatalysis (kapp = 0.01233 min-1); this phenomenon manifests an obvious piezo-enhanced photocatalytic behavior in terms of the "1 + 1 > 2" principle. The ultrasonic-induced piezoelectric behavior in Bi2O2CO3 nanoplates and involved piezo-photocatalytic mechanism were theoretically elucidated by density functional theory (DFT) and finite-element method (FEM) studies. Additionally, the effects of various factors on the CIP degradation, decomposition mechanism of CIP and toxicity of the decomposition intermediates were also analyzed.

Nano spinel NiAl2O4: structure, optical and photocatalytic performance evaluation and optimization

Four kinds of spinel NiAl2O4were synthesized by the polyacrylamide gel method using Al2(SO4)3·18H2O and Al(NO3)3·9H2O as aluminum salts and anhydrous NiSO4and NiSO4·6H2O as nickel salts. The effects of different aluminum salts and nickel salts on the structure, optical and photocatalytic activity of spinel NiAl2O4were confirmed by various characterizations. There is no NiO impurity in the spinel NiAl2O4synthesized with Al2(SO4)3·18H2O as aluminum salt, while NiAl2O4, NiO and C-O functional group coexist in the target product with Al(NO3)3·9H2O as aluminum salt, and C-O functional group and NiO inhibits the photocatalytic activity of the system. Based on photocatalytic experiment, response surface methodology and free radical verification experiment, the influence of experimental parameters including synthesis pathway, initial drug concentration, initialpHand catalyst content on the photocatalytic activity of spinel NiAl2O4and the main active species involved in the reaction were investigated. The degradation percentage of spinel NiAl2O4synthesized with Al2(SO4)3·18H2O as aluminum salt and NiSO4·6H2O as nickel salt was 86.3% at the initial concentration of 50 mg l-1,pH= 5.33 and catalyst content of 1 g l-1. The mechanism investigation confirmed that the C-O functional group plays the dual role of impurity level and electron transfer in the degradation of tetracycline hydrochloride by spinel NiAl2O4.

Hierarchically porous graphene-like biochar for efficient removal of aromatic pollutants and their structure-performance relationship: A combined experimental, MD and DFT study

Development of high-efficiency adsorbents and exploration of the structure-performance relationship holds exciting implications for removal of aromatic pollutants (APs) from water. Herein, hierarchically porous graphene-like biochars (HGBs) were successfully prepared by K₂CO₃ simultaneous graphitization and activation of Physalis pubescens husk. The HGBs possess high specific surface area (1406-2369.7 m²/g), hierarchically meso-/microporous structure and high graphitization degree. The optimized HGB-2-9 sample exhibits rapid adsorption equilibrium time (t_e) and high adsorption capacities (Q_e) for seven widely-used persistent APs with different molecular structures (e.g., phenol: t_e = 7 min, Q_e = 191.06 mg/g; methylparaben: t_e = 12 min Q_e = 482.15 mg/g). HGB-2-9 also shows a wide pH (3-10) suitability and good ionic strength (0.01-0.5 M NaCl) resistance properties. The effects of the physicochemical properties of HGBs and APs on the adsorption performance were deeply investigated by the adsorption experiments, molecular dynamics (MD) and density functional theory (DFT) simulation. The results demonstrate that the large specific surface area, high graphitization degree and hierarchically porous structure of HGB-2-9 can supply more active sites on accessible surface and facilitate the transport of APs. And the aromaticity and hydrophobicity of APs play the more crucial roles during the adsorption process. Besides, the HGB-2-9 presents good recyclability and high removal efficiency for APs in various real water, which further confirms its potential for practical applications.

Construction of Z-Scheme Ag2MoO4/ZnWO4 Heterojunctions for Photocatalytically Removing Pollutants

Facilitation of the photocarrier separation is a crucial strategy for developing highly efficient photocatalysts in eliminating environmental pollutants. Herein we have developed a new kind of Ag2MoO4/ZnWO4 (AMO/ZWO) composite photocatalysts with a Z-scheme mechanism by anchoring AMO nanoparticles onto ZWO nanorods. Multiple characterization methodologies and density functional theory (DFT) calculations were employed to study the performances of the AMO/ZWO heterojunctions as well as the underlying photocatalytic mechanism. Simulated-sunlight-driven photodegradation experiments for removing methylene blue (MB) demonstrates that the 8%AMO/ZWO heterojunction can photocatalytically remove 99.8% of MB within 60 min, and the reaction rate constant is obtained as 0.10199 min-1, which is enhanced by 6.8 (or 4.9) times when compared with that of pure ZWO (or AMO). On the base of the experimental results and DFT calculations, the enhanced photocatalytic mechanism of the AMO/ZWO heterojunctions was revealed to be the efficient separation of photocarriers via a Z-scheme transfer process. In addition, photodegradion of various organic pollutants over 8%AMO/ZWO was further compared and aimed at incorporating it into industrial application in pollutant removal.

Construction of a Z-scheme Ag2MoO4/BiOBr heterojunction for photocatalytically removing organic pollutants

How to facilitate photogenerated-carrier separation is an important step in developing excellent semiconductor photocatalysts for environmental pollutant removal. Herein, Ag₂MoO₄ (AMO) nanoparticles were assembled onto the surface of BiOBr (BOB) nanosheets to construct a highly efficient Z-scheme AMO/BOB heterojunction photocatalyst. Several analytical techniques were used to elucidate the characteristics and photocatalytic mechanism of the AMO/BOB heterojunction. Photodegradation experiments for removing methylene blue under simulated-sunlight irradiation reveal that a 20%AMO/BOB heterojunction exhibits excellent photodegradation activity with η(30 min) = 93.8% and k_app = 0.08638 min^-1, which were greater by 4.5 and 5.6 times in comparison with that of pure BOB and AMO, respectively. Based on the experimental and density functional theory (DFT) calculation results, it is proposed that the Z-scheme carrier transfer/separation mechanism dominates the enhanced photodegradation performance of the composite photocatalysts. Additionally, the potential application of AMO/BOB photocatalysts in degrading various organic pollutants (including organic dyes, antibiotics and other serious organic pollutants) was also investigated.