Chromium contamination and effect on environmental health and its remediation: A sustainable approaches.

Recent advances in applications of low-cost adsorbents for the removal of heavy metals from water: A critical review

Photoelectrocatalysis (PEC) is an advanced oxidation water treatment technology which combines the strengths of both heterogeneous photocatalysis and anodic oxidation for the effective degradation of organic pollutants in water. At the heart of this technology is the search for photocatalytic materials that exhibit excellent photo(electro)catalytic properties. In this article, we reviewed studies on WO3, one of the most promising photocatalysts for solar water treatment technology. Specific attention was paid to its properties, synthesis/preparation methods and strategies for improving its performance. Discussions were presented on some reports wherein the semiconductor and/or its composites were used to catalyse the degradation of organic pollutants in water.

WO3-based catalysts for photocatalytic and photoelectrocatalytic removal of organic pollutants from water – A review

This chapter discusses topics related to tungsten trioxide (WO3) and its application in water treatment. It examines the influence of morphology, the effect of the starting precursor on the synthesis and crystalline structure, on the photocatalytic properties of WO3. It also addresses the synthesis of nanostructures, composites, and/or heterostructures of WO3 to increase their photocatalytic performance. It is concluded that WO3 heterostructures are efficient for separating charges from semiconductors and improving their photocatalytic performance. In addition, heterostructures of WO3 with a Z-scheme configuration allow efficient separation of photogenerated charge carriers, a decrease in their recombination, and an enhanced photocatalytic performance compared to conventional heterostructures.

Nanostructured-based WO3 photocatalysts: Recent development, activity enhancement, perspectives and applications for wastewater treatment

Global environmental pollution is thought to be the principal source of emission of industrial untreated effluent. Photocatalysis is the versatile process to eliminate these pollutants which is utilizing semiconductor metal oxides. A nanocomposite WO3/TiO2 working under visible-light (λ ≥ 420 nm) has been prepared employing cis-butenedioic acid to associate component semiconductors of WO3 and TiO2 nanoparticle. The composite was optimized to 5 mol% WO3/TiO2 in terms of photocatalytic activity to decompose phenol and methylene blue dye in aqueous under visible-light. Afterwards, Au nanoparticle was deposited on to the surface of optimized WO3/TiO2. Au loaded WO3/TiO2 were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscope (EDX) mapping and UV–vis absorption spectra. Photocatalytic efficiency of Au-WO3/TiO2 has been measured to degrade above organic pollutants in aqueous phase under visible-light. Au-WO3/TiO2 demonstrated extraordinarily high photocatalytic efficiency in decomposing the pollutants compare to 5 mol% WO3/TiO2 nanocomposite. After 120 min of visible irradiation, 63 % decomposition of phenol and 52 % degradation of methylene blue dye was observed under the identical condition. The outstanding improvement of photocatalytic efficiency of Au-WO3/TiO2 nanocomposite ascribed due to the perfect matching of energy band positions of WO3 and TiO2 which inhibit photo-excited (e‾)–hole (h+) recombination as well as favor inter particle transfer between WO3 and TiO2. Au nanoparticles enhances transfer of electron (e‾) from CB of WO3. Thus, possible recombination of photo-excited electron (e‾)–hole (h+) pair was retarded and photocatalytic efficiency was greatly improved.

Visible-light responsive novel WO3/TiO2 and Au loaded WO3/TiO2 nanocomposite and wastewater remediation: Mechanistic inside and photocatalysis pathway

A highly efficient and visible light (λ ≥ 420 nm) responsive composite photocatalyst, Co3O4/FeWO4 was prepared by simple impregnation method. The heterojunction semiconductors Co3O4/FeWO4 demonstrated notably high photocatalytic activity over a wide range of composition than the individual component Co3O4 or FeWO4 for the complete degradation of 1,4-dichlorobenzene (DCB) in aqueous phase under visible light irradiation. The photocatalytic activity of composite was optimized at 1/99 Co3O4/FeWO4 composition. After 2 h of visible light irradiation 51% decomposition of 1,4-dichlorobenzene (DCB) was observed utilizing 1/99 Co3O4/FeWO4 photocatalyst while the end members demonstrated a negligible degradation under the same experimental condition. The valence band (VB) and conduction band (CB) of Co3O4 is located above the VB and CB of FeWO4, respectively. Both the semiconductors Co3O4 and FeWO4 exhibit strong absorption over the wide range of visible light. The obviously enhanced photocatalytic performance of Co3O4/FeWO4 composite has been discussed on the hole (h+) as well as electron (e−) transfer mechanism between the VB and CB of individual semiconductors.

Novel Visible-Light-Driven Photocatalyst Co 3 O 4 /FeWO 4 for Efficient Decomposition of Organic Pollutants

A novel magnetic bioadsorbent based on jute stick powder (MB-JSP) was synthesized with Fe2+ and Fe3+ solutions by in situ co-precipitation technique and applied for the elimination of Cr (VI) from aqueous solution. The adsorption capability of fresh jute stick powder (JSP) was also studied to compare with the magnetic bioadsorbent (MB-JSP). The characteristics of these bio-adsorbents were measured individually. The magnetic saturation of MB-JSP touched 14.25 emu/g which was sufficient for the separation of MB-JSP from aqueous solution. This magnetic bioadsorbent worked perfectly within a substantial pH range of 1–2. The Cr (VI) removal by MB-JSP was seamlessly supported by the Langmuir isotherm model (R2 = 0.997–0.999) and pseudo-second-order kinetic model (R2 = 0.994–0.995). The maximum capacity of Cr(VI) adsorption by MB-JSP and JSP were 47.125 and 30.422 mg/g, respectively at 303.15 K by Langmuir isotherm model. The regeneration experiment specified its merit of regeneration and firmness with the recovery efficiency of 90.17% and 80.23% for MB-JSP and JSP, respectively. It was observed by considering the results that the removal Cr(VI) ions was accomplished via the attraction between the opposite charges of different functional groups present on the adsorbents surface and ion exchange. Moreover, the process of removal was very effective and a rapid separation from aqueous solution was achieved.

Removal of Chromium (VI) from Effluent by a Magnetic Bioadsorbent Based on Jute Stick Powder and its Adsorption Isotherm, Kinetics and Regeneration Study

Acoustic and aggregation properties of sodium dodecyl sulfate in aqueous amino acid systems have been studied through ultrasonic velocity techniques at different temperature as a function of concentration and at different temperature (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15 K) and atmospheric pressure using density and sound velocity analyzer (DSA 5000, Anton paar, Austria). Densities and ultrasonic velocity of sodium dodecyl sulfate in aqueous amino acid have been measured and from the experimental data, adiabatic compressibility (βS), apparent molar adiabatic compressibility (φk), critical micelle concentration (CMC), acoustic impedance (Z), relative association (RA) and molar sound velocity (Rm) have been calculated. The results show significant information about acoustic properties of sodium dodecyl sulfate (solute-solute interactions, aggregation behaviour, relative association and structure formation) in aqueous and aqueous amino acid solution.

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Md. Masudur Rhaman

Papers

Visible-light responsive novel WO3/TiO2 and Au loaded WO3/TiO2 nanocomposite and wastewater remediation: Mechanistic inside and photocatalysis pathway

Novel Visible-Light-Driven Photocatalyst Co 3 O 4 /FeWO 4 for Efficient Decomposition of Organic Pollutants

Removal of Chromium (VI) from Effluent by a Magnetic Bioadsorbent Based on Jute Stick Powder and its Adsorption Isotherm, Kinetics and Regeneration Study

Studies on Acoustic and Aggregation Properties of Sodium Dodecyl Sulfate in Amino Acid Solutions through Ultrasonic Velocity Technique