Ag3PO4-based photocatalysts and their application in organic-polluted wastewater treatment

Computational investigation on physical properties of lead based perovskite RPbBr3 (R = Cs, Hg, and Ga) materials for photovoltaic applications

In the modern era, the major problem is solving energy production and consumption. For this purpose, perovskite materials meet these issues and fulfill energy production at a low cost. Density functional theory and the Cambridge Serial Total Energy Package (CASTEP) are used to examine the characteristics of the cubic inorganic perovskites RPbBr3 (R = Cs, Hg, and Ga). In the context of the generalized gradient approximation (GGA), the ultrasoft pseudo-potential plane wave technique and the Perdew-Burke-Ernzerhof exchange-correlation functional are used for investigations. Structural, mechanical, electronics, and optical properties are investigated using CASTEP code. According to structural properties, compounds have a cubic nature with space 221 (Pm3m). Compounds formation energy (- 3.46, - 2.21, and - 3.14 eV)of (CsPbBr3, HgPbBr3, and GaPbBr3) and phonon calculations are studied and find that compounds are stable. The results of our investigation show that the compounds have narrow bandgaps of direct kind, with 1.85 eV for CsPbBr3, 1.56 eV for HgPbBr3, and 1.71 eV for GaPbBr3, respectively, indicating that they may be used to improve conductivity. Additionally, anisotropy (2.135, 3.651, 10.602), Pugh's ratio (1.87, 2.25, 2.14), and Poison's ratio (0.27, 0.31, 0.29) are traits that the compounds (CsPbBr3, HgPbBr3, GaPbBr3) display a ductile nature. The CsPbBr3 compound showed significant optical conductivity and absorption in terms of their optical properties, especially in the visible region, which makes them suitable for use in solar cell applications as well as for LED applications.

Ochratoxin A in coffee and coffee-based products: a global systematic review, meta-analysis, and probabilistic risk assessment

Contamination of food with mycotoxins can pose harmful effects on the health of consumers in the long term. Coffee contamination with mycotoxins has become a global concern. This study attempted to meta-analyze the concentration and prevalence of ochratoxin A (OTA) in coffee products and estimate consumers' health risks. The search was conducted among international databases, including Scopus, PubMed, Embase, and Web of Science, for 1 January 2010 to 1 May 2022. The concentration and prevalence of OTA in coffee products were meta-analyzed according to country subgroups. Health risk assessment was conducted based on Margin of Exposures (MOEs) using the Monte Carlo simulation (MCS) technique. The three countries that had the highest Pooled concentration of OTA in coffee were observed in Chile (100.00%), Kuwait (100.00%), and France (100.00%). The overall prevalence of OTA in coffee products was 58.01%, 95% CI (48.37-67.39). The three countries that had the highest concentration of OTA were Philippines (39.55 μg/kg) > Turkey (39.32 μg/kg) > and Panama (21.33 μg/kg). The mean of MOEs in the adult consumers in Panama (9,526) and the Philippines (8,873) was lower than 10,000, while the mean of MOEs in other countries was higher than 10,000. Therefore, monitoring and control plans should be carried out in different countries.

Enhanced visible light photocatalytic activity of octopod Ag3PO4 microcrystals with high index crystal faces

Novel octopod shaped Ag3PO4 microcrystals were successfully fabricated by a simple ion exchange method under the conditions of a hot water bath using [Ag(NH3)2]+ solution and Na2HPO4 solution as the precursors. Meanwhile, sphere and cube shaped Ag3PO4 microcrystals were also prepared followed by changing reaction materials as well as temperature. The surface morphology, microstructure and photocatalytic performance were investigated on the three different shaped crystals respectively. Compared to sphere and cube counterparts, the obtained octopod shaped Ag3PO4 crystals possess 8 symmetric feet with sharp tips and exhibit higher photocatalytic activity and better cycle stability. After further exploring its formation process, UV-vis diffusion reflectance properties as well as photocurrent transient response, it was found that the Ag3PO4 octopod had exposed high index crystal faces, and possessed a narrow band gap as well as high photoexcited transient charge separation efficiency. The results show that the improved photocatalytic activity of octopod shaped Ag3PO4 is mainly due to the synergistic action of the strong light absorption capacity and high carrier separation efficiency. These results highlight the tremendous practical application of octopod Ag3PO4 microcrystals in visible light photocatalysis.

Enhanced degradation of tetracycline under natural sunlight through the synergistic effect of Ag3PO4/MIL-101(Fe) photocatalysis and Fenton catalysis: Mechanism, pathway, and toxicity assessment

Here, we show that the adverse environmental and health effects of tetracycline (TC) can be efficiently reduced by encapsulating Ag₃PO₄ into MIL-101(Fe) to construct a Ag₃PO₄/MIL-101(Fe) heterojunction composite through advanced oxidation processes, such as Fenton catalysis, photocatalysis, and photo-Fenton catalysis. Notably, the reaction can be driven by natural sunlight and does not require any artificial energy source. Remarkably, the optimal degradation of TC can be achieved under different compositions of the composite system through photocatalysis and photo-Fenton catalysis. For photo-Fenton catalysis, the maximum degradation rate of TC (2.5730 min^-1) is achieved when the mass ratio of MIL-101(Fe) to Ag₃PO₄ in the composite is 5:1, which is 31.65- and 3.12-fold of that in the Ag₃PO₄ + PDS + Sunlight and MIL-101(Fe) + PDS+ Sunlight catalyst systems, respectively. Moreover, the internal conversion of matrix during photocatalysis and Fenton catalysis processes inhibits the photocorrosion of Ag₃PO₄ and improves the reusability of the composite. Furthermore, it is found that both radical and non-radical species participate in the TC degradation. Besides, the degradation products and catalytic mechanism of Ag₃PO₄ and Ag₃PO₄/MIL-101(Fe) systems are explored. The toxicity evaluation results suggest that the intermediates produced during Ag₃PO₄/MIL-101(Fe) catalysis have a lower biotoxicity than those produced during Ag₃PO₄ catalysis. Overall, this work provides an effective strategy to inhibit the inherent photocorrosion of Ag₃PO₄ and establishes an efficient catalytic system for the treatment of organic-contaminated wastewater under natural sunlight conditions.

Investigating the Effect of Bi2MoO6/g-C3N4 Ratio on Photocatalytic Degradation of Sulfadiazine under Visible Light

In this study, a series of Bi2MoO6/g-C3N4 composites were prepared through a wet-impregnation method, and their photocatalytic properties were investigated for the degradation of sulfadiazine (SDZ) under visible light irradiation. Physical and chemical characterizations were carried out using X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence spectroscopy (PL), UV-vis diffuse reflectance spectra (UV-vis), and electrochemical impedance spectra (EIS). Compared to pure g-C3N4, the introduction of Bi2MoO6 significantly enhanced the visible light responsive photocatalytic activity, with the 1:32 Bi2MoO6/g-C3N4 composite exhibiting the highest photodegradation efficiency towards SDZ under visible light irradiation with a photocatalytic efficiency of 93.88% after 120 min of visible light irradiation. The improved photocatalytic activity can be attributed to the formation of a heterojunction between Bi2MoO6 and g-C3N4, which promotes the transfer of photogenerated electron-hole pairs, thereby elevating its photocatalytic activity. The results suggest that Bi2MoO6/g-C3N4 composites have potential application for the degradation of sulfonamides in aquatic environments.

Fabrication of a Novel CNT-COO-/Ag3PO4@AgIO4Composite with Enhanced Photocatalytic Activity under Natural Sunlight

In this study, a carboxylated carbon nanotube-grafted Ag₃PO₄@AgIO₄ (CNT-COO^-/Ag₃PO₄@AgIO₄) composite was synthesized through an in situ electrostatic deposition method. The synthesized composite was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and energy-dispersive X-ray spectroscopy (EDS). The electron transfer ability of the synthesized composite was studied using electrochemical impedance spectroscopy (EIS). The CNT-COO^-/Ag₃PO₄@AgIO₄ composite exhibited higher activity than CNT/Ag₃PO₄@AgIO₄, Ag₃PO₄@AgIO₄, and bare Ag₃PO₄. The material characterization and the detailed study of the various parameters thataffect the photocatalytic reaction revealed that the enhanced catalytic activity is related to the good interfacial interaction between CNT-COO and Ag₃PO₄. The energy band structure analysis is further considered as a reason for multi-electron reaction enhancement. The results and discussion in this study provide important information for the use of the functionalized CNT-COOH in the field of photocatalysis. Moreover, providinga new way to functionalize CNT viadifferent functional groups may lead to further development in the field of photocatalysis. This work could provide a new way to use natural sunlight to facilitate the practical application of photocatalysts toenvironmental issues.

Efficient Solar Light Photocatalyst Made of Ag3PO4 Coated TiO2-SiO2 Microspheres

Solar light active photocatalyst was prepared as silver phosphate (Ag₃PO₄) coating on titania-silica (TiO₂-SiO₂) microspheres. Titania-silica microsphere was obtained by spray drying TiO₂-SiO₂ colloidal solutions, whereas Ag₃PO₄ was applied by wet impregnation. XRD on the granules and SEM analysis show that the silver phosphate particles cover the surface of the titania-silica microspheres, and UV-visible diffuse reflectance analysis highlights that Ag₃PO₄/TiO₂-SiO₂ composites can absorb the entire visible light spectrum. BET measurements show higher specific surface area of the composite samples compared to bare Ag₃PO₄. Photocatalytic activity was evaluated by dye degradation tests under solar light irradiation. The prepared catalysts follow a pseudo-first-order rate law for dye degradation tests under solar light irradiation. The composite catalysts with an Ag₃PO₄/TiO₂-SiO₂ ratio of 1:1.6 wt% show better catalytic activity towards both rhodamine B and methylene blue degradation and compared with the results with uncoated TiO₂-SiO₂ microspheres and the benchmark commercial TiO₂ (Evonik-P25) as a reference. The composite photocatalyst showed exceptional efficiency compared to its pristine counterparts and reference material. This is explained as having a higher surface area with optimum light absorption capacity.

The Strengthened Photocatalytic NOx Removal of Composites Bi4O5Br2/BiPO4: The Efficient Regulation of Interface Carriers by Integrating a Wide-Bandgap Ornament

A series of binary composites Bi₄O₅Br₂/BiPO₄ (PBX) was fabricated through a simple mechanical ball milling protocol. Relevant microstructural, morphological, and optical properties were thoroughly analyzed via various techniques. The integration of both components was confirmed to produce heterojunction domains at the phase boundaries. Upon exposure to visible light irradiation, the as-achieved PBX series possessed the reinforced photocatalytic NO_x removal efficiencies and the weakened generation of toxic intermediate NO₂ in comparison to both bare components, chiefly attributed to the efficient transport and separation of carriers and boosted production of superoxide radicals (·O₂^-) through the combination of a wide-bandgap ornament BiPO₄ as an electron acceptor. In particular, the composite PB5 with the optimal phase composition exhibited the highest NO_x removal of 40% with the lowest NO₂ formation of 40 ppb among all tested candidates. According to the band structures' estimation and reactive species' detection, a reasonable mechanism was ultimately proposed to describe the migration of charge carriers and the enhancement of photocatalytic performance.

Metal-Terpyridine Assembled Functional Materials for Electrochromic, Catalytic and Environmental Applications

Molecular assembly induced by metal-terpyridine-based coordinative interactions has become an emergent research topic due to its ease of synthesis and diverse applications. This article highlights recent significant developments in the metal-terpyridine-based supramolecular architectures. At first, the design aspect of the molecular building blocks has been described, followed by elaboration on how the ligand backbone plays an important role for achieving different dimensionalities of the resulting assemblies which exhibit a wide range of potential applications. After that, we discussed different synthetic approaches for constructing these assemblies, and finally, we focused on their significant developments in three specific areas, viz., electrochromic materials, catalysis and a new application in wastewater treatment. In the field of electrochromic materials, these assemblies made important advancements in various aspects like sub-second switching time (<1 s), low switching voltage (<1 V), increased switching stability (>10000 cycles), tuning of multiple colors by using multimetallic systems, fabrication of charge storing electrochromic devices, utilizing and storing solar energy etc. Similarly, the catalysis field witnessed application of the metal-terpyridine assemblies in C-H monohalogenation, heterogeneous Suzuki-Miyaura coupling, photocatalysis, reduction of carbon dioxide, etc. Finally, the environmental application of these coordination assemblies includes capturing Cr(VI) from waste water efficiently with high capture capacity, good recyclability, wide pH independency etc.

Assessment in carbon-based layered double hydroxides for water and wastewater: Application of artificial intelligence and recent progress

Layered double hydroxides (LDHs) are a class of clays with brucite like layers and intercalated anions. Hybrids of carbon nanomaterials and layered double hydroxides (C-LDHs) are promising nanomaterials due to their versatile properties and the large number of composition/preparation variables available for fine-tuning. Several techniques are available for the synthesis of these novel C-LDHs nanocomposites. This article assess developments in the synthesis and applications of C-LDHs in water and wastewater treatment via using artificial intelligence approaches. In addition, current challenges and possible strategies are discussed from the viewpoint of synthesis and application. It is concluded that the use of C-LDH is expected to produce interesting results. The anisotropic properties and good dispersion ability make them suitable to be used as particulates in the dispersion phase of electro-responsive and electro-rheological fluids. Although these materials have been tested for the removal of contaminants from single component solutions in water. In addition, application of artificial intelligence in this regard is discussed. At the end, the necessity of evaluating their performance in the removal of contaminants from multi-components solutions is proposed. Finally the challenges in obtaining material with precisely controlled particle sizes and morphology must be addressed.

Using the aluminum decorated graphitic-C3N4 quantum dote (QD) as a sensor, sorbent, and photocatalyst for artificial photosynthesis; a DFT study

In this project, we have investigated the possibility of mimicking the natural photosynthesis, as well as sensing and adsorption application of aluminum decorated graphitic C₃N₄ (Al-g-C₃N₄) QDs (toward some air pollutants containing CO, CO₂, and SO₂). The results of the potential energy surface (PES) studies show that in all three adsorption processes, the energy changes are negative (-10.70 kcal mol^-1, -16.81 kcal mol^-1, and -79.97 kcal mol^-1 for CO, CO₂, and SO₂ gasses, respectively). Thus, all of the adsorption processes (mainly SO₂) are spontaneous. Moreover, the frontier molecular orbital (FMO) investigations indicate that the Al-g-C₃N₄ QD could be used as a suitable semiconductor sensor for detection of CO, and CO₂ (as carbon oxides) in one hand, and SO₂ gaseous species on the other hand. Finally, the results reveal that those QDs could be applied for artificial photosynthesis (in presence of CO₂; Δμ^h-e = 1.43 V), and for water splitting process for the H₂ generation (Δμ^h-e = 1.23 V) as a clean fuel for near future.

Improved neural network with least square support vector machine for wastewater treatment process

This research offers a unique interval by using the predicting approach for discharge indicators of water quality data such as biochemical oxygen demand (BOD) and ammonia nitrogen (NH3-N). This is considered one of the significant quality metrics in wastewater treatment plants for water quality management as well as surveillance. To begin, the effluent information for BOD/NH3-N and their supplementary parameters are gathered. Hence BOD and NH3 are considered major feature sources for estimating water pollutants. BOD is high then oxygen level is very low in the water due to pollutants or algae. Ammonia nitrogen is an organic waste component in water from sewage. The significant characteristics with good correlation levels of BOD and NH3-N are examined and identified using a grey correlation analysis method after certain basic data pre-processing procedures. The BOD/NH3-N effluent information of a water treatment plant is predicted using an upgraded feed-forward neural network with the least square support vector machine (FFNN-LSSVM) method. An optimization approach for an enhanced feed-forward neural network (IFFNN) is built by Machine Learning Algorithms. The IFFNN used regular influent water quality, influent rate of flow, and Wastewater performance monitoring and operational conditions as input parameters. For future prediction, input variables were previous different wastewater quality measurements. Lastly, the analysis shows that, when compared to other current algorithms, the proposed methodology can forecast wastewater quality of water with high accuracy in predicting BOD and NH3 levels, limited computation duration, mean error less than 10% and R² is 90% proves better than existing techniques.

Recent Progress in Photocatalytic Removal of Environmental Pollution Hazards in Water Using Nanostructured Materials

Water pollution has become a critical issue because of the Industrial Revolution, growing populations, extended droughts, and climate change. Therefore, advanced technologies for wastewater remediation are urgently needed. Water contaminants are generally classified as microorganisms and inorganic/organic pollutants. Inorganic pollutants are toxic and some of them are carcinogenic materials, such as cadmium, arsenic, chromium, cadmium, lead, and mercury. Organic pollutants are contained in various materials, including organic dyes, pesticides, personal care products, detergents, and industrial organic wastes. Nanostructured materials could be potential candidates for photocatalytic reduction and for photodegradation of organic pollutants in wastewater since they have unique physical, chemical, and optical properties. Enhanced photocatalytic performance of nanostructured semiconductors can be achieved using numerous techniques; nanostructured semiconductors can be doped with different species, transition metals, noble metals or nonmetals, or a luminescence agent. Furthermore, another technique to enhance the photocatalytic performance of nanostructured semiconductors is doping with materials that have a narrow band gap. Nanostructure modification, surface engineering, and heterojunction/homojunction production all take significant time and effort. In this review, I report on the synthesis and characterization of nanostructured materials, and we discuss the photocatalytic performance of these nanostructured materials in reducing environmental pollutants.

Synthesis and application of AuNi@AC nano adsorbents for the removal of Maxilon Blue 5G azo dye from aquatic mediums

In this research, gold-nicel supported on activated carbon (AC) nanoadsorbent (AuNi@AC) synthesized by following a series of physicochemical procedures was prepared for the removal of Maxilon Blue 5G (MB) which is a cationic textile dye. Experimental studies based on parameters specifically pH, contact time, nano catalytic adsorbent particle, initial MB dye concentration and temperature effect were conducted in aqueous solutions in a batch system. AuNi@AC nanoadsorbents (NAs) reached the equilibrium in 30 min under optimum conditions in adsorption of the dye. The pseudo-first, second-order, and intra-particle diffusion models were tested to evaluate a the experimental results. Adsorption kinetics were found to be represented by the pseudo-second-order model, and the maximum adsorption capacity (q_max.) was calculated to be 542.90 mg/g (or 2.041 mmol/g). The synthesized magnetic AuNi@AC nanoadsorbent showed a high-efficiency reusability effect of about 64% after five reuse runs. Also, thermodynamic function parameters such as activation energy (Ea), Gibbs free energy (ΔG *), and entropy (ΔS *) were investigated in the sorption study. After all evaluation of data, it was concluded that the novel AuNi@AC nanoadsorbent could be considered as an effective support material for the removal of various organic pollutants in aquation solution especially for the removal of MB.

Improvement of Monitoring Technology for Corrosive Pollution of Marine Environment under Cloud Computing Platform

In view of the increasingly serious problem of marine ecological environmental pollution, the traditional marine environmental corrosive pollution monitoring technology has poor monitoring accuracy and poor monitoring timeliness, and the improvement of the marine environmental corrosive pollution monitoring technology under the cloud computing platform is proposed. The research significance and corrosion influence factors of steel corrosion in the marine environment are described, and the research progress of corrosion mechanism in five different zones of the marine environment is reviewed. Cloud computing parallelizes the processing of corrosive pollution data in the marine environment through virtualization and distributed technology, which greatly improves the efficiency of the algorithm. This paper studies the existing cloud computing platform and ocean monitoring system architecture, uses the distributed architecture to design a cloud computing-oriented ocean monitoring system and meets the design requirements in data collection and data processing. The experimental results show that the precision of marine environmental corrosion pollution monitoring technology proposed in this paper is 96% on average, and the completion rate of monitoring images is 82% on average, which can effectively realize marine environmental corrosion pollution monitoring.

Zirconium-based cubic-perovskite materials for photocatalytic solar cell applications: a DFT study

The structural, electronic, optical, and mechanical characteristics of cubic inorganic perovskites XZrO3 (X = Rb and K) were studied using the Cambridge serial total energy package-based DFT.