Mo Removal Research Articles

TiO2 NTs/MoS2-CdS hybrid photocathode for visible light-driven photoelectrochemical performance: Waste water remediation, photoelectric conversion and hydrogen generation

Environmental pollution and resource shortage are big challenges for the development and life of human society, and the photocatalyst has been a prospective material to solve these problems by solar energy utilization and conversion. However, the issues including single function, low efficiency and weak photoelectrochemial stability still hinder the practical application of photocatalysts. In this work, ternary hereojunction photocatalysts with multiple photoelectrochemical applications were prepared by the hydrothermal deposition of MoS2 and CdS sensitizers on TiO2 nanotube arrays (TiO2 NTs), and the dramatically high photocatalytic performance and stability in pollutant treatment and photoelectric/H2 generation were obtained. The characterization data indicated that the high photocatalytic efficiencies of 51.57 %/3 h, 99.83 %/3 h, 99.51 %/2 h and 59.71 %/3 h were achieved toward the removal of MO, RhB, MB and Cr(VI), the photocurrent and photovoltage were 451.70 μA/cm2 and −0.31 V, and the photocatalytic H2 generation rate of 200.81 μmol·cm−2·h−1 was obtained under visible light irradiation. The straightway charge carrier transportation path of TiO2 NTs/MoS2-CdS photocatalysts is the effective guarantee for the low electron/hole recombination chance and high photocatalytic performance.

Study on inhibition effect of 3-amino-1, 2, 4-triazole on chemical mechanical polishing of GLSI low-techology node molybdenum barrier layer

Considerable attention has been paid to utilizing molybdenum (Mo) as a new generation of barrier layer material in the integrated circuit industry. However, there have a small amount of papers for Mo chemical mechanical polishing (CMP). In this study, the inhibition effect of 3-amino-1, 2, 4-triazole (ATA) on corrosion and CMP of Mo in the weakly alkaline slurry was investigated. Electrochemical experiment and chemical mechanical polishing experiment demonstrated that 100 ppm ATA has an excellent inhibition performance of Mo (removal rate of Mo decreased from 509 Å/min to 322 Å/min, static etching rate of Mo decreased from 839 Å/min to 208 Å/min and Mo surface roughness decreased from 9.48 nm to 1.01 nm). Langmuir adsorption isotherm analysis found that physical and chemical adsorption exists simultaneously between ATA and Mo. X-ray photoelectron spectroscopy analysis showed that the addition of ATA changed the contents of different kinds of Mo oxides. With the decreasing of MoO3, more MoO2 was generated and protected Mo from corrosion. This paper is devoted to studying the inhibition effect of a traditional corrosion inhibitor on a new barrier layer material and analyzing its mechanism. Additionally, this paper is also helpful to prevent galvanic corrosion between Mo and other interconnection materials during CMP.

Nanoscaled MnSnO2@CsPbBr3 quantum dots heterostructure photocatalyst as efficient organic pollutants degradation by peroxymonosulfate; DFT calculation

In this work, we developed a promising photocatalyst in CsPbBr3 quantum dots (QDs) because of their exceptional optoelectronic characteristics. However, QDs applications in the field of photocatalysis were mainly hampered by their poor stability and insufficient charge transfer efficiency. Herein, a novel and efficient MnSnO2@CsPbBr3 (MSO@QDs) nanocomposite was first time effectively designed and synthesized by a wet impregnation method for peroxymonosulfate (PMS) activation under the light. The newly generated interface phase of QDs between MnSnO2 (MSO) showed great potential to improve light absorption, leading to effective separation and transfer of photoelectron-hole pairs. This novel nanocomposite MSO@QDs showed great Flurbiprofen (FL) removal efficiency under the PMS/Light system. It should be noted that this nanocomposite removed 85.74% of FL in just 70 min, which was almost 1.11 and 2.51 times greater than using pure QDs and pure MSO, respectively. Based on thorough measurements of structural analysis, Brunauer-Emmett-Teller (BET), UV-vis spectra, electrochemical impedance spectroscopy (EIS), transient photocurrent response, and a potential mechanism for organic pollutants degradation over MSO@QDs nanocomposite was envisioned. The principal reactive species of photoinduced holes (h+), i.e. O2˙−, SO4˙−, ˙OH, and non-radical (1O2) were characterized via scavengers’ technique and electron paramagnetic resonance (EPR) measurements. The highest photocatalytic performance for the removal of MO, MB, and IBU was demonstrated by MSO@QDs nanocomposite/PMS, revealing their excellent ability to remove organic pollutants through photo-oxidation. Furthermore, the developed nanocomposite exhibited good stability in an aqueous medium. According to computational investigation using the density functional theory (DFT) method, the site's higher Fukui index f0 value corresponds to a greater propensity to be attacked by reactive species. This work offers a fresh perspective on developing further high-efficiency, low-cost photocatalysts for wastewater treatment.

Effect of synergetic inhibition of nonionic surfactant and benzotriazone for molybdenum in chemical mechanical polishing

The continuous miniaturization of the feature size of integrated circuit makes it crucial to find proper barrier layer materials. With the properties of low resistivity (∼5.34 μΩ•cm) and good adhesion to Cu, Molybdenum (Mo) has become the most promising materials of the next generation of barrier layer. However, the studies on Mo chemical mechanical polishing (CMP) are limited. The problems of controlling Mo removal rate (RR) and improving its surface quality (Sq) are still unsolved. Here in, this paper focuses on minimizing Mo RR and Sq during CMP. Compared the inhibition effect of isooctanol polyoxyethylene ether (JFCE) and fatty alcohol polyoxyethylene ether (AEO-9) combine with benzotriazole (BTA) on Mo CMP, JFCE was selected as the most suitable surfactant. The addition of a small amount of JFCE can decrease Mo RR (from 308 Å/min to 176 Å/min) and static etching rate (SER) (from 201 Å/min to 50 Å/min) significantly. Furthermore, Mo Sq was also improved (from 6.34 nm to 0.255 nm) during CMP. The synergetic inhibition mechanism of JFCE and BTA was characterized by electrochemical test, contact angle test, adsorption isotherm, X-ray photoelectron spectroscopy, scanning electron microscopy and density functional theory. JFCE not only can change the proportion of Mo oxide, but also can complex with Mo chemically and physically, thus playing an inhibition effect on the convex and concave part of Mo surface. Furthermore, JFCE could keep the slurry stable at least for 7 days. This paper combined with experimental and theoretical methods to find a new Mo inhibitor, which has a promising effect to the study of barrier layer planarization of 14 nm sub-technology node.

Submerged macrophytes mediated remediation of molybdenum-contaminated sediments.

Molybdenum (Mo) sourced mainly from artificial activities is an emerging environmental concern whose remediation is seldom reported. This study screened the Mo-enriched macrophyte Vallisneria natans (Lour.) Hara due to its high enrichment factor (10.25). Phytoremediation (V. natans) and microorganism-assisted phytoremediation (V. natans-Serratia marcescens A2) efficiency were compared. S. marcescens A2 improved phytoremediation in the early stage, however, it reduced the total Mo removal rate by 8.42%. Further experiments were conducted to investigate the environmental factors (light intensity and overlying water flow rate) on the phytoremediation by V. natans. The optimal phytoremediation performance was achieved under a high overlying water flow rate (0.022cm·s-1) with intense light (60μmol·m-2·s-1) conditions. In addition, increasing the light intensity or flow rate increased the microbial communities' diversity in the sediment. Notably, the abundance of norank_f__Bacteroidetes_vadinHA17, related to Mo release in sediments, increased by 147.96% at optimal conditions. This study illustrated that the phytoremediation of Mo-contaminated sediments by V. natans is of practical potential.

Removal of Molybdenum from Contaminated Groundwater Using Carbide-Derived Carbon

In the present work, the removal of Mo from aqueous solutions and real groundwater by using the novel high-surface-area adsorbent carbide-derived carbon (CDC) was performed. The adsorbent was characterized using X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), Brunauer, Emmett, and Teller (BET) surface area analysis, and Fourier-transform infrared spectroscopy (FTIR). The effect of the operational parameters (contact time, CDC loading, Mo concentration, and pH) on the adsorptive performance of the sorbent in the batch adsorption mode was studied. The experimental work revealed that the adsorption of Mo onto CDC is a very fast process and provides 99% Mo removal in less than 30 min. The adsorption process was pH-dependent, achieving the maximum adsorptive removal at a pH range of 3–5. The highest adsorption capacity corresponded to 16.24 mg/g at a Mo concentration of 10 ppm, adsorbent loading of 0.6 g/L, and pH 3. Four models were used to analyze the adsorption isotherms of Mo onto CDC, which were Freundlich, Langmuir, Temkin, and Sips. The obtained adsorption results were also processed using four adsorption kinetic models: intra-particle diffusion, Elovich, second-order, and pseudo-first-order. The adsorption of Mo onto CDC was found to fit the Freundlich isotherm model, as confirmed by the highest R2 values (0.9118) and lowest SSE (0.4777), indicating the heterogeneous multilayer adsorption of Mo onto CDC. Likewise, the experimental adsorption data were found to be more consistent with the pseudo-second-order model. The main adsorption mechanisms contributing to Mo adsorption were found to be electrostatic interactions and ligand–ligand exchange, in addition to surface complexation or ion exchange between Mo ions and oxygen-containing groups on the CDC’s surface. Moreover, the removal efficiency under acidic conditions (pH: 3) was found to be stable and high (>99%), regardless of the Mo concentration (0.5–10 ppm) due to the characteristic PZC corresponding to CDC (pH 9.9). A performance test of the CDC using both real groundwater and GW spiked with 570 µg/L Mo showed an almost complete removal of Mo from GW. The regeneration tests confirmed that adsorbed Mo can be recovered from CDC by pH adjustment and the regenerated CDC can be reused.

Nonconservative behavior of dissolved molybdenum and its potential role in nitrogen cycling in the Bohai and Yellow Seas

Molybdenum plays an important role in marine biological activity, especially in nitrogen cycling as a cofactor for N2 fixation and nitrate reductase. However, the dissolved Mo (dMo) behavior and its interaction with N cycling in the coastal waters is still unclear. In this study, the dMo concentrations and parameters related to Mo distribution and N cycling in surface and bottom seawaters of the Bohai (BS) and Yellow Seas (YS) were examined. The results showed that dMo concentrations ranged from 36.4 nmol L-1 to 125.0 nmol L-1, most of which deviated significantly from the conservative line, indicating nonconservative behavior of Mo relative to salinity. The highest dMo concentrations occurring in 36°N section of north of the South YS (SYS), were close to conservative value (105 nmol L-1). Significant depletion up to 40-50 nmol L-1 of dMo mainly appeared in the BS, NYS and south of the SYS, suggesting the possible removal of dMo by biological utilization and particle adsorption. Particularly, the increasing dMo concentrations away the Yellow River estuary indicated that freshwater dilution was one of reasons for dMo distributions in the BS. The similar spatial distribution of dMo and dissolved Mn concentrations suggested the possible scavenging by MnOx phases for Mo removal. The negative correlation between dMo and chlorophyll-a (Chl-a) concentrations in surface seawaters suggested that biological uptake was involved in dMo removal. The depleted dMo in most of sites corresponded with the higher nitrite concentrations, implying the possible involvement of nitrate reduction process. Although the highest N2 fixation rates and relative abundances of cyanobacteria appeared in 36°N section, corresponding with the conservative dMo, suggesting that Mo may play a minor role in N2 fixation process there. The ten-folds of relative abundance of bacteria with nitrate reduction function than that with N2 fixation function suggested that dMo seems to play more important role in nitration reduction than nitrogen fixation in the BS and YS.

PH-Driven Selective Adsorption of Multi-Dyes Solutions by Loofah Sponge and Polyaniline-Modified Loofah Sponge.

In the last decades, sorbent materials characterized by low selectivity have been developed for the removal of pollutants (in particular dyes) from wastewater. However, following the circular economy perspective, the possibility to selectively adsorb and desorb dyes molecules today represents an unavoidable challenge deserving to be faced. Herein, we propose a sequential treatment based on the use of PANI-modified loofah (P-LS) and loofah sponge (LS) to selectively adsorb cationic (rhodamine, RHB, and methylene blue, MB) and anionic (methyl orange, MO) dyes mixed in aqueous solution by tuning the adsorption pH (100% MO removal by P-LS and 100% and 70% abatement of MB and RHB, respectively, by LS). The system maintained high sorption activity for five consecutive cycles. A simple and effective regeneration procedure for the spent adsorbents permits the recovery of the initial sorption capability of the materials (81% for MO, ca. 85% for both RHB and MB, respectively) and, at the same time, the selective release of most of the adsorbed cationic dyes (50% of the adsorbed MB and 50% of the adsorbed RHB), although the procedure failed regarding the release of the anionic component. This approach paved the way to overcome the traditional procedure based on an indiscriminate removal/degradation of pollutants, making the industrial wastewater a potential source of useful chemicals.

Progressive expansion of seafloor anoxia in the Middle to Late Ordovician Yangtze Sea: Implications for concurrent decline of invertebrate diversity

The Great Ordovician Biodiversification Event (GOBE) achieved its peak during the Middle Ordovician, likely in association with climatic cooling and a rise of atmospheric O2. However, unstable redox states developed widely in contemporaneous epeiric seas, challenging previous assumptions about sustained oceanic oxygenation driven by deep-ocean ventilation in the aftermath of Ordovician cooling. Here, we investigate two Middle-Upper Ordovician shale-dominated successions from intra-shelf basin and slope settings of the Yangtze Sea, South China. Negative shifts in bulk δ15N and productivity proxies reveal temporal changes in the pattern of nutrient cycling under moderate-to-high productivity conditions, which were likely sustained by increased upwelling of cold and nutrient-rich deep waters in sync with contemporaneous climatic cooling. As a result, marine anoxia likely expanded in deep waters of the Yangtze Sea, as reflected in enrichments of highly reactive iron and redox-sensitive metals (Mo, U). Although moderate Mo abundances (25-50 ppm) and δ98/95Mo values (+0.4 to +0.8‰) within the euxinic interval suggest that bottom waters had low sulfide concentrations, the δ98/95Mo values are comparable with those of coeval euxinic facies (∼+0.6‰). Furthermore, our modeling results show that low δ98/95Mo can be produced when sulfidic sinks dominate Mo removal, suggesting that Middle-Late Ordovician oceans may have been less oxygenated than previously assumed, at least for the continental seas of South China, Baltica and Laurentia. These environmental changes may provide a new explanation for the ∼50% decline of invertebrate species following the peak of GOBE. Our findings thus link the progressive expansion of marine anoxia and climatic cooling to a profound biotic change during the Mid-Late Ordovician Period.

Nanosheet-MoO3/Ti Porous Membrane Electrode for Dye Wastewater Treatment

Membrane coupling with electrochemical processes has proven to be an effective way for wastewater treatment. However, it still suffering from high energy consumption and low operational stability. Three different forms nanosheet-MoO3 were prepared by hydrothermal synthesis method via adjusting various additives to ammonium heptamolibdate. MoO3 loaded porous Ti membranes was employed as anode to constitute fixed-bed electrocatalytic reactor (FBER) for synthetic dye wastewater treatment to overcome the drawback of three different forms. The electrochemical properties of MoO3/Ti membranes were investigated, results showed that the MoO3/Ti membranes with hexadecyltrimethylammonium bromide (CTAB) additive exhibited the best electrochemical performance. Meanwhile, three MoO3/Ti membranes were used to constitute FBER for 100 mg l−1 MO wastewater treatment, the MO and COD removal rate of MoO3/Ti without additive, MoO3/Ti with CrCl3 additive and MoO3/Ti with CTAB additive were 78.6% and 65.3%, 83.2% and 72.9%, 90.3% and 81.6%, respectively. Furthermore, the energy consumption of MoO3/Ti with CTAB additive was only 0.76 kWh·kg−1·COD. After 3 repeated stabilities experiment of 12 h MO wastewater treatment, the removal rate of MO and COD remained above 97.2% and 88.6%. In sum, the FBER exhibits a great potential in the dye wastewater treatment with high efficiency and excellent stability.

Pollution Removal Performance of Chemically Functionalized Textile Waste Biochar Anchored Poly(vinylidene fluoride) Adsorbent

Preparation of adsorbent materials in powder and polymeric composite form was achieved by controlled carbonization of ZnCl2 pretreated textile waste at low temperatures. Structural and surface properties of carbonized textile waste samples (CTW) and polymeric composites were prepared by the addition of CTW to PVDF-DMF solution at 0, 5, 10, 15, 20, and 30 mass% ratios analyzed by FT-IR, XRD, SEM, and BET analysis. Adsorption performances of powder and composite adsorbents were investigated for MO dye removal from an aqueous solution. Zn-CTW obtained with carbonization of ZnCl2 treated textile waste at 350 °C presented 117.5 mg/g MO removal. Those were higher than CTW-350 and CTW-400. The presence of 1545 cm-1 band at the IR spectrum of Zn-CTW proved the formation of functional groups that increase dye adsorption performance with honeycomb-like pores on the surface. Zn-CTW reflected its properties onto the PVDF matrix. Improved porosity percentage, BET surface, and dye adsorption of Pz20 were recorded as 105.3, 15.22 m2/g, and 41 mg/g, respectively, compared with bare PVDF. Disposal of textile waste and preparation of functional activated carbon were achieved in a low-cost and easy way. Zn-CTW loaded PVDF composites are promising materials to use as a dye removal adsorbent from water or filtration membranes.

Adsorption of Methyl Orange on a Novel Palygorskite/UiO-66 Nanocomposite

Herein, a novel composite material containing UiO-66 and palygorskite (Pal) clay mineral was prepared using a facile one-pot synthesis process. The material was studied using a variety of techniques and applied as did not affect the structure of the metal-organic framework (MOF) part, but induced a small increase in specific surface area. The developed Pal/UiO-66 composite presented excellent adsorption efficiency against MO removal, as evidenced by detailed kinetic and isotherm experiments. An impressive maximum adsorption capacity at equilibrium was evidenced; 340 mg g−1 at pH = 5 and T = 25 °C. This corresponds to a 34.5 % increase compared with pure UiO-66, considering only the MOF content. Furthermore, the Pal/UiO-66 composite was proven stable and highly recyclable, losing less than 9% of the removal capacity after five consecutive cycles. The study highlights the synergistic effect of the coupling of MOF structures with low-cost and abundant clay minerals for the development of advanced absorbents.

The role of Fe dissolution in olivine-hydroxylamine-induced Fenton reaction for enhanced oxidative degradation of organic pollutant

In this study, a dye pollutant (methyl orange, MO) was effectively oxidized in a hydroxylamine (HA)-assisted Fenton system using various Al/Si/Fe- and Fe-containing minerals. The fastest degradation kinetics of MO were observed in the olivine-HA Fenton system, whereas other Al/Si/Fe and Fe-rich minerals (magnetite and lepidocrocite) demonstrated much slower degradation kinetics. The degradation rate constants were proportional to dissolved Fe(II) quantities in mineral suspensions (R2 = 0.98), indicating the crucial role of dissolved Fe(II) quantity in HA-assisted Fenton reactions. Radical scavenging and electron spin resonance results revealed that MO was dominantly oxidized by ·HO produced in the olivine-HA Fenton system. The continuous production of aqueous Fe(II) via direct Fe(II) dissolution at a pH of 3 and further Fe dissolution from the reductive dissolution of surface Fe(III) by HA was the main driving force for efficient MO degradation. Furthermore, lowering the pH by the addition of hydroxylamine hydrochloride resulted in the effective removal of MO under various pH conditions (3–9), indicating the additional advantage of HA use in Fenton reactions. Liquid chromatography-mass spectroscopy analysis revealed that the cleavage of C–N and C–C bonds, demethylation, hydroxylation, and dehydroxylation were the main processes for MO oxidation in the olivine-HA Fenton system.

Mechanisms of Selected Anionic Dye Removal by Clinoptilolite

The extensive use of color dyes in modern society has resulted in serious concerns of water contamination. Many organic dyes bear charges; thus, materials of opposite charges have been tested for sorptive removal. However, the results from several studies also showed that anionic dyes methyl orange (MO) and alizarin red S (ARS) could be removed from water using minerals of negative charges, but the mechanisms were not addressed. In this study, negatively charged clinoptilolite was tested for its removal of anionic dyes MO and ARS from water under different physico-chemical conditions and to investigate the mechanism of Mo and ARS removal. The sorption capacities were 166 and 92 mmol/kg for MO and ARS, respectively, confirming the uptake of anionic dyes on negatively charged framework silicates. The influence of solution pH and ionic strength on MO removal was minimal, indicating the strong affinity of anionic dyes for clinoptilolite in comparison to other inorganic species. It was speculated that the N in the dimethyl group may bear a partial positive charge, which may have a net electrostatic attraction to the negatively charged mineral surfaces for MO sorption. For ARS, sorption may involve hydrogen bonding formation between the dye and the clinoptilolite. Moreover, under the experimental conditions, the MO molecules form dimers in solution via dimeric π-π interactions. Thus, the sorption of the dimers or aggregation of the MO monomers and dimers on clinoptilolite surface was attributed to additional MO removal, as suggested by molecular dynamic simulations. The speculation was supported by FTIR analyses and molecular dynamic simulations. As such, negatively charged Earth materials may be used as sorbents for the removal of certain anionic dyes via sorption, a new perspective for the innovative use of Earth materials.

Covariation between molybdenum and uranium isotopes in reducing marine sediments

The isotopic compositions of redox-sensitive elements such as uranium (U) and molybdenum (Mo) have been extensively used to track the evolution of redox conditions on Earth's surface. However, additional investigation of the behaviors of U and Mo in modern marine sediments—particularly in reducing sediments underlying oxic seawater—can bolster understanding and improve application of these systems as biogeochemical tracers. Here we present elemental and isotopic Mo and U data from reducing sediments from various sites in the Bering Sea where the extent of bioturbation is well characterized. Total Mo concentrations and total organic carbon contents (TOC) are positively correlated, as are authigenic Mo isotopic compositions and TOC, indicating the presence of authigenic Mo enrichments in these sediments. Similar to what has previously been observed in euxinic settings, we observe a positive correlation between authigenic U and Mo concentrations, and a negative correlation between the isotopic compositions of authigenic U and Mo (δ238Uauth and δ98Moauth). These patterns likely reflect close associations of U and Mo reduction to organic carbon degradation. Observed variation in δ98Moauth values could reflect variations in Mo removal efficiency or Mo isotopic fractionation between particles and seawater related to porewater H2S levels. Conversely, we interpret variation in δ238Uauth values in these Bering Sea samples to be related to varying extents of U reduction and removal, coupled with anaerobic carbon degradation. There is no significant correlation between the extent of bioturbation and Mo or U isotope values, suggesting that bioturbation would likely not have a significant influence on sedimentary Mo and U records. Further, the array of U and Mo isotopic data from these sediments is distinct from those observed in anoxic sediments below euxinic seawater—suggesting that a combination of U and Mo isotopic compositions could help to more accurately resolve the redox state of depositional environments from past intervals of Earth's history.

Enhanced sequestration of molybdenum(VI) using composite constructed wetlands and responses of microbial communities.

The molybdenum (Mo) non-point source pollution in the mining area has an irreversible impact on the surrounding water and soil ecosystems. Herein, three integrated vertical subsurface flow constructed wetlands (CWs) were constructed to assess the effects of combination substrates and plant on the removal of Mo(VI). Results showed that CW1 with combination substrates and cattail exhibited a favorable removal performance for Mo(VI) at 80.90%. Moreover, most Mo(VI) retained in the CWs was retained in the substrate (58.13-88.04%), and the largest fraction of Mo(VI) retained was the water-soluble fraction on the surface of the combination substrates. Mo(VI) removal was also influenced by the microbial community composition in substrate, especially their co-occurrence networks. The species that showed significant positive correlation with Mo(VI) removal were Planctomycetes, Latescibacteria, Armatimonadetes, and Gemmatimonadetes. Moreover, CWs added plants showed that more co-occurrences interaction between taxa occurs, which means that the wetlands efficiently select recruitment of potential microbial consortia and change the co-occurrences to remove pollution in the substrate. These results could be useful in providing an ecology-based solution for the treatment of Mo(VI) in wastewater, especially in adjusting the microbial communities for Mo(VI) removal at the genetic level.

Synergistic photocatalytic dye mitigation and bacterial disinfection using carbon quantum dots decorated dual Z-scheme Manganese Indium Sulfide/Cuprous Oxide/Silver oxide heterojunction

A novel CQDs decorated MnIn2S4/Cu2O/Ag2O dual Z-scheme tandem hybrid is fabricated via hydrothermal method for MO removal and E. coli disinfection under visible light illumination. CQDs shuttle electrons in CQDs-MnIn2S4/Cu2O/Ag2O interface via dual Z-scheme electron transferal route which lead to upgrade in charge separation and visible light absorption. The Z-scheme hybrid displayed best catalytic inactivation performance of E. coli and degradation of MO which totally disinfect bacteria within 3 h and displayed 98.6% of MO degradation in 70 min in visible light radiation. The unique dual Z-scheme junction supports enhanced redox capabilities, prolong lifespan of photo-excitons, stability, spatial separation and enhanced visible light absorption.

Engineering Commercial TiO2 Powder into Tailored Beads for Efficient Water Purification.

In this study, efficient commercial photocatalyst (Degussa P25) nanoparticles were effectively dispersed and stabilized in alginate, a metal binding biopolymer. Taking advantage of alginate’s superior metal chelating properties, copper nanoparticle-decorated photocatalysts were developed after a pyrolytic or calcination-sintering procedure, yielding ceramic beads with enhanced photocatalytic and mechanical properties, excellent resistance to attrition, and optimized handling compared to powdered photocatalysts. The morphological and structural characteristics were studied using LN2 porosimetry, SEM, and XRD. The abatement of an organic pollutant (Methyl Orange, MO) was explored in the dark and under UV irradiation via batch experiments. The final properties of the photocatalytic beads were defined by both the synthesis procedure and the heat treatment conditions, allowing for their further optimization. It was found that the pyrolytic carbon residuals enabled the adhesion of the TiO2 nanoparticles, acting as binder, and increased the MO adsorption capacity, leading to increased local concentration in the photocatalyst vicinity. Well dispersed Cu nanoparticles were also found to enhance photocatalytic activity. The prepared photocatalysts exhibited increased MO adsorption capacity (up to 3.0 mg/g) and also high photocatalytic efficiency of about 50% MO removal from water solutions, reaching an overall MO rejection of about 80%, at short contact times (3 h). Finally, the prepared photocatalysts kept their efficiency for at least four successive photocatalytic cycles.

Enhanced adsorption of molybdenum(VI) from aquatic solutions by chitosan-coated zirconium–iron sulfide composite

• CS@Zr-FeS showed higher Mo(VI) removal efficiency compared to FeS. • The removal of Mo(VI) follows the pseudo-second-order adsorption kinetics. • Hydrogen bonding and surface complexation were the main Mo(VI) removal mechanisms. • CS@Zr-FeS showed good applicability to pH and aerobic environment. • CS@Zr-FeS maintained high Mo(VI) removal efficiency after 60 days’ aging. Nano-sized iron sulfide (FeS) plays a vital role in heavy metal removal; However, FeS nanoparticles are easily agglomerated, oxidized, and deactivated due to their poor stability. In order to solve these problems, this work synthesized chitosan-coated zirconium–iron sulfide composite (CS@Zr-FeS) by the coprecipitation method using FeS, zirconia sol (ZrO 2 ), and chitosan (CS) as the raw materials and tested it for enhancing the performance of molybdenum(VI) removal. The obtained CS@Zr-FeS exhibited a higher specific surface area (85.43 m 2 /g) than FeS (47.92 m 2 /g), with the maximum molybdenum(VI) adsorption capacity of 120.80 mg/g. The adsorption of molybdenum(VI) onto CS@Zr-FeS followed the pseudo-second-order kinetics and Langmuir isotherm. The adsorption process was partially inhibited by the competing anions (e.g., PO 4 3− and HCO 3 − ) and humic acids but was not influenced by dissolved oxygen. Moreover, the obtained CS@Zr-FeS had high stability. Spectroscopy analysis and density functional theory (DFT) calculations demonstrated that hydrogen bonding and surface complexation were the primary mechanisms for molybdenum(VI) removal. These results imply that the CS@Zr-FeS composite exhibits a higher potential for molybdenum(VI) removal from the aquatic solutions than the pristine FeS nanoparticles.

The effects of pH, neutralizing reagent and co-ions on Mo(VI) removal and speciation in Fe(III)–Mo(VI) coprecipitation process

Coprecipitation of molybdate (Mo(VI)) with ferric iron (Fe(III)) is usually employed for the treatment of Mo-bearing acid mine drainage (AMD) and mineral-processing effluents. However, the speciation of Mo(VI) in the Fe(III)–Mo(VI) coprecipitates and the roles of process parameters in Mo(VI) removal remain unclear. In this work, the effects of pH, neutralization reagents (CaO vs NaOH) and co-ions (Zn2+, Cu2+ and Ni2+) on the removal and speciation of Mo(VI) were investigated. It was found that Mo(VI) removal was significantly enhanced at circum-neutral pH by using CaO as base instead of NaOH or in the presence of Ni2+ ions. X-ray diffraction, Fourier transform infrared, Raman and linear combination fitting of Mo K-edge X-ray absorption near edge structure (XANES) spectra results indicated that amorphous ferric molybdate was the major Mo(VI) phase in the coprecipitates formed at acidic pH regardless of the base used. While at circum-neutral pH, Mo(VI) mainly existed as surface adsorbed form on ferrihydrite in NaOH neutralized coprecipitates, and as calcium molybdate in CaO neutralized coprecipitates. The pre-edge features of Mo K-edge and L3-edge XANES features indicated the formation of polymeric molybdate in the acidic coprecipitates. This work may have implications to Mo(VI) immobilization via coprecipitation with Fe(III) and the fate of Mo(VI) in tailings.