•Guar gum stabilised Pt nanoparticles (GG-s-PtNPs) was developed.•Guar gum were used as stabilizer and reducer.•The spherical, nanometre-sized particles formed.•Green approach to the fabrication of ...highly active nanocatalysts.•GG-s-PtNPs exhibits superior catalytic activity for the reduction of p-nitrophenol.
We report a facile and green method to synthesise highly stable dispersions of platinum nanoparticles (PtNPs) with an average particle size of ∼6nm. Natural, nontoxic, eco-friendly biopolymer guar gum was utilised as both the reducing and capping agent precursor in aqueous medium. The PtNPs that had been stabilised by guar gum (GG-s-PtNPs) were characterised by UV–vis spectroscopy, XRD, TEM and XPS. GG-s-PtNPs performed better in terms of catalytic activity for the liquid phase reduction of p-nitrophenol (p-NP) compared to p-aminophenol (p-AP). The efficiency of the catalytic reduction of p-NP over GG-s-PtNPs was found to be 97% in a total time of 320s at room temperature. The mechanisms of the synthesis and catalytic reduction of p-NP are also discussed. The synthesis approach presented here does not require stringent conditions or toxic agents and thus is a straightforward, rapid, efficient, and green approach to the fabrication of highly active catalysts.
Polymers derived from plant and animal sources are of great interest in wastewater remediation due to their cost-effectiveness and renewable adsorption capabilities, one such polymer is nanocellulose ...(NC). NC has gained a lot of attention in various research fields due to its abundance in nature, nano-dimension, high surface area, stability and bio-compatibility. As a result, NC has emerged as a great potential adsorbent for the removal of contaminants such as heavy metals, organic dyes, oils, pharmaceutical and etc. in the environmental remediation. This review focuses on the description of the building blocks, structure, properties, isolation and also discusses the potential of nanocellulose based composites materials with reinforcements such as activated carbon, carbon nanotube, graphene oxides, metals, non-metals and ceramics that were effectively used as an adsorbents for diverse organic and inorganic contaminants in water.
•Nanocomposite of Gg-cl-P(AA-co-AAm) and Fe3O4 MNPs were successfully synthesized.•The maximum adsorption capacity was found to be 654.87mg/L.•The adsorption isotherm data fitted well with Langmuir ...isotherm model.•Adsorption kinetics followed the pseudo second order rate model.•Desorption studies confirmed the reusability of the adsorbent.
This article reports the development of a new nanocomposite using gum ghatti crosslinked with poly(acrylic acid-co-acrylamide) reinforced with iron oxide magnetic nanoparticles. The nanocomposite was characterized through BET, FT-IR, XRD, SEM-EDX, TGA and TEM and applied for the removal of RhB. Different optimized adsorption parameters were adsorbent dose (0.8g/L) and pH (7.0). The adsorption isotherm data was used to study Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich isotherm models. The value of correlation coefficient confirmed the applicability of Langmuir isotherm model with maximum adsorption efficiency of 654.87mg/g. The adsorption kinetics data showed pseudo second order reaction. Thermodynamic studies showed that the adsorption process was endothermic and spontaneous. Moreover, the adsorbent was successfully utilized for successive three cycles for the adsorption–desorption of RhB.
The chitosan/clay hybrid was prepared by solvent casting method. Possible interaction mechanism of Cr(VI) with chitosan and organoclay was discussed. Display omitted
► Chitosan-clay nanocomposite ...prepared by solvent casting method. ► Chitosan -clay nanocomposite act as an efficient chromium(VI) removal. ► Possible interaction mechanism of Cr(VI) with chitosan and organoclay. ► Nanocomposite useful for the fabrication and design of wastewater treatment plant. ► Nanocomposite has higher adsorption capability, reusability, and stability.
Organic–inorganic hybrid of chitosan and nanoclay (Cloisite 10A) was chosen to develop a nanomaterial with combine properties of hydrophilicity of an organic polycation and adsorption capacity of inorganic polyanion. The chitosan/clay nanocomposite (CCN) was prepared by solvent casting method. The material synthesis was found most efficient in adsorbent behavior was studied in detail taking Cr(VI) as representative ion. The chemical, structural and textural characteristics of the material were determined by FTIR, XRD, TEM, SEM and EDAX analysis. XRD and TEM results indicated that an exfoliated structure was formed with addition of small amounts of MMT–Na+(montmorillonite–Na+) to the chitosan matrix. These composite material were used for the removal of chromium(VI) from aqueous solution. The conditions for the adsorption by the composite have been optimized and kinetics and thermodynamic studies were performed. Though the adsorption takes place in wide pH range, pH 3 was found most suitable and at this pH the adsorption data were modeled using the Langmuir and Freundlich isotherms at 15°C and 35°C, where the data fitted satisfactorily to Langmuir isotherms, the R2 values being 0.998 and 0.999 respectively indicating unilayer adsorption. Based on Langmuir model, Qo was calculated to be 357.14mg/g. The adsorption showed pseudo second order kinetics with a rate constant of 8.0763×10−4gmg−1min−1 at 100ppm Cr(VI) concentration.
The 12 chapters comprehensively cover the development and advances on emerging carbon-based nanocomposites for wastewater applications and discuss the following topics: The emerging carbon-based ...nanocomposites for remediation of heavy metals and organic pollutants from wastewater; Functional green carbon nanocomposites for heavy-metal treatment in water; Green nanocomposites and their applications in environmentally-friendly carbon nanomaterials; Carbon-based nanocomposites as heterogeneous catalysts for organic reactions in environment-friendly solvents; Carbonaceous nanomaterials for arsenic and chromium removal from waste water; Biochar-based adsorbents for the removal of organic pollutants from aqueous systems; Describes carbon nanomaterials based green nanocomposites; The removal of trihalomethanes from water using nanofiltration membranes and The transformation of wide bandgap semiconductors for visible-light photocatalytic degradation of organic dyes; Nanocomposite materials as electrode materials in microbial fuel cells for the removal of water pollutants; Plasmonic smart nanosensors for the determination of environmental pollutants.
Organic/inorganic hybrid materials prepared by the sol–gel approach have rapidly become a fascinating new field of research in materials science. The explosion of activity in this area in the past ...decade has made tremendous progress in both the fundamental understanding of the sol–gel process and the development and applications of new organic/inorganic hybrid materials. Polymer-inorganic nanocomposite present an interesting approach to improve the separation properties of polymer material because they possess properties of both organic and inorganic such as good permeability, selectivity, mechanical strength, and thermal and chemical stability. Composite material derived by combining the sol–gel approach and organic polymers synthesis of hybrid material were the focus area of review It has also been demonstrated in this review that a more complete understanding of their structure–property behavior can be gained by employing many of the standard tools that are utilized for developing similar structure–property relationships of organic polymers. This review article is introductory in nature and gives introduction to composite materials/nanocomposite, their applications and the methods commonly employed for their synthesis and characterization. A brief literature survey on the polysaccharide templated and polysaccharide/protein dual templated synthesis of silica composite materials is also presented in this review article.
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► High efficient adsorbents, PPy-gly were synthesized as an effective adsorbent for Cr(VI). ► Doping of glycine in the polypyrrole matrix was confirmed by ATR-FTIR and XRD studies. ► ...The maximum adsorption capacity was found to be 217mg/g at 25°C. ► The adsorption kinetics is rapid and fitted well with pseudo-second order model. ► The adsorption is an endothermic in nature.
Glycine doped polypyrrole (PPy-gly) adsorbent was prepared via in situ polymerization of pyrrole (Py) monomer in the presence of glycine (gly) for the removal of Cr(VI). Formation of PPy homopolymer and inclusion of gly in the PPy matrix were confirmed by ATR-FTIR and XRD, respectively. Field emission scanning electron microscopic imaging of PPy-gly revealed the formation of nearly spherical agglomerated particles. The adsorption of Cr(VI) onto the PPy-gly adsorbent was highly pH dependent and removal efficiency by PPy-gly was much higher compared to PPy homopolymer. The kinetic process followed pseudo-second-order rate model with equilibrium reached within 30–150min. Intra-particle diffusion model was also applied for better understanding of kinetic mechanism. Isotherm data fitted well with the Langmuir isotherm model with maximum adsorption capacity of 217.39–232.55mg/g at 25–45°C. Desorption experiment showed PPy-gly can be regenerated and reused for three consecutive cycles without loss of its removal efficiency. The adsorption process for the removal of Cr(VI) was governed by the ionic interaction between protonated amine groups of gly and HCrO4- ions.
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•Magnetic recoverable Fe3O4/TiO2 heterostructure photocatalysts synthesised hydrothermal approach.•Up to 91% photocatalytic degradation of RhB was achieved in 120 min.•The ...photocatalytic activity was affected by the ratio of Fe3O4 to TiO2.•In five consecutive runs, the photocatalyst shows reasonable stability.•Hydroxyl radicals played a prominent role in the degradation of RhB.
Magnetic photocatalysts are crucial for creating a feasible photocatalytic technique for the degradation of organic contaminants due to the ease of photocatalyst separation and recycling. In this study, magnetic Fe3O4/TiO2 nanocomposites as an effective and recyclable photocatalyst with different Fe3O4 loading percentages were successfully synthesized by a hydrothermal method. The physicochemical properties of the synthesized materials were characterized using XRD, FTIR, BET, TGA, TEM, EDS, XPS, PL, and UV − vis DRS. The nanocomposite poses a higher BET surface area (164.76 m2/g,) than TiO2 (177.67 m2/g) due to the synergistic effect and interface between the two different oxides. The optical properties results showed that the incorporation of magnetite Fe3O4 to TiO2 nanoparticles shifted the light absorption of TiO2 from ultraviolet (UV) to the visible region and postponed the electron-hole recombination. The synthesized photocatalysts were used for photocatalytic degradation of rhodamine B as the model pollutant under simulated solar light irradiation. The maximum degradation efficiency of 91% was achieved after 120 min using 20% FT nanocomposite. The enhanced photocatalytic activity of 20% FT nanocomposite was attributed to the high surface area, increased light absorption, and formation of heterojunction structure which promotes the separation efficiency of photogenerated electron-hole pairs. The photocatalyst maintained good stability with a 3% loss in efficiency after 5 cycles of re-use. Scavenger trapping assays showed that the main active species for the degradation of RhB are hydroxyl radicals. Moreover, the effect of Fe3O4 loading, solution pH, photocatalyst dosage, rhodamine B concentration, and reusability of the photocatalyst on the degradation efficiency of dye pollutants were studied. The results attained in this study suggest that stable magnetic recoverable photocatalysts could be used to remediate organic water pollutants and can be extended to environmental samples application.
A polypyrrole-coated halloysite nanotube nanocomposite (PPy-HNTs NC) was prepared via in situ polymerization of pyrrole (Py) in the dispersion of HNTs and assessed for the removal of toxic Cr(VI) ...from aqueous solutions. ATR-FTIR and XRD results confirmed the formation of the nanocomposite. The FE-SEM and TEM images revealed the coating of PPy in the halloysite matrix and the surface morphology of the PPy-HNTs NC. Batch adsorption study showed that the adsorption process was very fast and kinetic data well fitted with pseudo-second-order kinetic model. Adsorption isotherms followed the Langmuir isotherm model and the maximum adsorption capacity was found to be 149.25mg/g at pH2.0 at 25°C. The adsorption process was spontaneous and endothermic in nature. XPS study confirmed the adsorption of Cr(VI) onto the NC where some part of Cr(VI) reduced to Cr(III) by electron-rich PPy moiety. The desorption study suggested that the nanocomposite (NC) can be reused three times without loss of its original removal efficiency. Tests on contaminated groundwater and chrome mine water indicated the potential applicability of the adsorbents for the removal of Cr(VI) for actual field application.
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•Polypyrrole (PPy) coated halloysite nanotube was prepared for removal of Cr(VI).•Microscopic images revealed the coating of PPy in halloysite nanotubes (HNTs) matrix.•The maximum adsorption capacity was found to be 149.25mg/g at pH2.0 at 25°C.•PPy-HNTs can be reused for three times without loss of its original efficiency.•The potential applicability was found with ground and chrome mine water tests.
A nanoadsorbent was synthesized from kraft lignin derived from paper and pulp black liquor, chitosan, and titania (TiO2) and used to remove Brilliant Black dye (BB) from aqueous solution. ...Transmission electron microscopy measurements confirmed the material was nanoscale and BET studies showed a pore width of 11.36 nm with a BET surface area (SBET) of 10.75 m2/g. The presence of NH, O and TiO functional groups was confirmed by ATR-FTIR, and thermogravimetric analysis indicated the nanoadsorbent was thermally stable up to 300 °C. Scanning electron microscopy showed that lignin had larger particles with well-defined edges, while the surface morphology of chitosan showed non-uniform, short fibrous microstructures. The diffraction patterns of the nanocomposite showed a polycrystalline anatase phase and selected area electron diffraction analysis showed the nanocomposite has small spots making up a ring, indicating the nanoparticles has a crystalline structure. The effects of contact time, solution pH, adsorbent dosage, and initial dye concentration on the adsorption of BB were investigated. The batch adsorption data obeyed the Freundlich isotherm (r2 = 0.91), and the monolayer adsorption capacities calculated using the linear Langmuir isotherm was 15.8 mg/g at 25 °C. The adsorption kinetic data were described by the pseudo-second order kinetic model (r2 = 0.93).
•Lignin derived from paper and pulp black liquor•Nanoadsorbent for the removal of Brilliant Black dye•Effects of experimental conditions were investigated.•Minimize environmental and public health risks in aqueous system
