Polysaccharide-based hydrogels offer a great overlook for environmental applications and help in the elimination of various noxious pollutants from the water system. Novel carrageenan and itaconic ...acid-based superadsorbent hydrogel having appreciable swelling properties and adsorption capacity towards Methylene blue (MB), Crystal violet (CV), and Methyl Red (MR) was synthesized by suspension polymerization technique. The swelling study showed the dependency upon the temperature in which the swelling rate increased with increasing temperature with a maximum swelling rate of 417% at 318 K. For ascertaining the maximum adsorption capacity, various influential parameters such as contact time, adsorbent dose, dye concentration, and temperature were systematically studied. Maximum adsorption capacity as calculated from the Langmuir isotherm was 2439.02, 1111.11, and 666.68 mg/g for MB, CV, and MR, respectively. Thermodynamic studies revealed the spontaneous nature of the undertaken dye adsorption experiment. Overall, the present study reveals that the synthesized superadsorbent hydrogel can be used as an efficient adsorbent for the removal of dyes from an aqueous solution.
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•Superadsorbent hydrogel designed for the adsorptive removal of cationic dyes.•Maximum adsorption capacity obtained for MB followed by CV and MR.•Results have been analyzed by isotherm and kinetic studies.•Superadsorbent hydrogel successfully recycled for consecutive 5 cycles.
Many novel materials and device designs have been proposed as photonic analogs to electrical diodes over the last four decades. This paper seeks to revisit these materials and designs as advanced ...technologies may enable experimental realization that was not possible upon conception of several of these designs. The background behind integration challenges, including waveguide birefringence, fabrication tolerances, garnet/semiconductor mismatch, and optimized interfaces will hopefully spark new ideas that will finally enable the realization of integrated optical isolators and circulators.
The remarkable multimodal functionalities of magnetic nanoparticles, conferred by their size and morphology, are very important in resolving challenges slowing the progression of nanobiotechnology. ...The rapid and revolutionary expansion of magnetic nanoparticles in nanobiotechnology, especially in nanomedicine and therapeutics, demands an overview of the current state of the art for synthesizing and characterizing magnetic nanoparticles. In this review, we explain the synthesis routes for tailoring the size, morphology, composition, and magnetic properties of the magnetic nanoparticles. The pros and cons of the most popularly used characterization techniques for determining the aforementioned parameters, with particular focus on nanomedicine and biosensing applications, are discussed. Moreover, we provide numerous biomedical applications and highlight their challenges and requirements that must be met using the magnetic nanoparticles to achieve the most effective outcomes. Finally, we conclude this review by providing an insight towards resolving the persisting challenges and the future directions. This review should be an excellent source of information for beginners in this field who are looking for a groundbreaking start but they have been overwhelmed by the volume of literature.
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•A novel quaternary BiOCl/g-C3N4/Cu2O/Fe3O4(BGC-F) photocatalyst was prepared.•Formation of p-n-p junction-intrinsic electric field.•Higher spectrum response and charge carriers ...separation.•Efficient degradation of sulphamethoxazole under simulated and real sunlight.•Toxicity and cytotoxicity analysis of degraded products.
Novel magnetic quaternary BiOCl/g-C3N4/Cu2O/Fe3O4 (BGC-F) nano-heterojunction with excellent photocatalytic activity was prepared by facile co-precipitation method. The visible photodegradation activity of the junction was analyzed for sulfamethoxazole (SME) as target pollutant. BGC-F with a dosage of 0.2 g L−1 exhibits high photocatalytic activity with 99.5% of SME (100 µM) degraded in 60 min under visible (Xe) lamp and 92.1% in 120 min under natural sunlight. The activity of quaternary junction was found to be 7.2, 6.8 and 4.2-fold higher as compared to C3N4/BiOCl/Fe3O4, Cu2O/BiOCl/Fe3O4 and Cu2O/BiOCl/C3N4 junctions respectively. Formation of an effective p-n-p junction (BiOCl-C3N4-Cu2O) leads to shifting of energy bands and rising of an in-built electric field and charge separation. The effect of parameters as pH, catalysts loading amount, NO3− and HCO3− have been studied. The O2− and OH was found to be major reactive species identified by scavenging experiments and the band gap structure analysis The results for mineralization were analyzed in terms of Liquid chromatography-mass spectroscopy (LC-MS), total organic carbon (TOC) removal and chemical oxygen demand (COD). 41.6% of TOC was removed in 3 h experiment under Xe lamp exposure. The drug degradation was also confirmed by testing activity on E. coli and cyto-toxicity on human peripheral blood lymphocytes (PBL). Only 2.1 mm zone of inhibition was observed for E. coli in case of exposure to SME degraded products while for pure SME it was 18.1 mm hinting complete mineralization. In addition 99% cell viability was observed for PBL cells treated with degraded products of SME. Furthermore, BGC-F exhibited good reusability after magnetic separation and regeneration, rendering it a promising multi-functional catalyst with active use of advanced oxidation processes for treating pharmaceutical waste water.
We present a new top-illumination scheme for tip-enhanced Raman spectroscopy (TERS) in a gap-mode configuration with illumination and detection in a straightforward fashion perpendicular to the ...sample surface. This illumination focuses the light tightly around the tip end, which effectively diminishes far-field background contributions during TERS measurements. The setup maintains the entire functionality range of both the scanning probe microscopy and the confocal optical microscopy of the setup. For the first time, we show large (64 × 64 up to 200 × 200 pixels), high-resolution TERS imaging with full spectral information at every pixel, which is necessary for the chemical identification of sample constituents. With a scanning tunneling microscope tip and feedback, these TERS maps can be recorded with a resolution better than 15 nm (most likely even less, as discussed with Figure 6). An excellent enhancement (∼10(7)×, sufficient for detection of few molecules) allows short acquisition times (<<1 s/pixel) and reasonably low laser power (in the microwatt regime) yielding spectroscopic images with high pixel numbers in reasonable time (128 × 128 pixels in <25 min). To the best of our knowledge, no Raman maps with similar pixel numbers and full spectral information have ever been published.
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•Visible active Biochar@Bi2O2CO3/g-C3N4/CoFe2O4 assembly.•Intimate charge transfer at the interface.•Degradation of herbicide paraquat under visible and solar light.•Higher conversion ...of 4-nitrophenol into 4-aminophenol.•Superior reduction of CO2 into CH4, CO & O2.
The development of novel visible powered nano-heterojunctions with multi-pronged capabilities for environmental and catalytic applications has been gaining importance for persistent pollutant degradation & clean energy production. A magnetically recoverable biochar supported ternary g-C3N4/Bi2O2CO3/CoFe2O4 heterojunction (BCBF) was fabricated which shows a high visible photoactivity. The heterojunction was used for degradation of pesticide paraquat under visible radiation (Xe lamp), natural sunlight, photo-ozonation, peroxymonosulphate, and coupled conditions. A high degradation of 99.3% was achieved under visible radiation in 90 min and 92.1% under solar light in 120 min. Biochar supported ternary junction performs manifold faster than Bi2O2CO3/CoFe2O4, g-C3N4/CoFe2O4, g-C3N4/CoFe2O4, Bi2O2CO3 (BOC), CoFe2O4 (CF) and g-C3N4 (CN). The effect of operational parameters as effect of pH, H2O2, anions, ozone and peroxymonosulphate (PMS) was also studied. In BCBF + PMS + O3 + Vis protocol a spectacular complete degradation was observed in less than 30 min. Ternary band structure efficiently reduces the charge recombination rate and promotes spectral activity which was confirmed by photoluminescence, photocurrent response and EIS analysis. By LC-MS, scavenging experiments and ESR studies a possible mechanism was also proposed. Cyto-toxicity studies of degraded products on human peripheral blood cells revealed almost 99% cell viability affirming the complete mineralization. The junction was also used for reduction of 4-nitrophenol into 4-aminophenol with complete conversion in less than 5 min with rate constant 13.05 × 10−3 s−1. In addition the ternary junction shows a high visible powered conversion of CO2 producing CH4 (∼119 µmol g−1), CO (∼131 µmol g−1) and O2 (∼242 µmol g−1) with a high rate constant of 13.05 × 10−3 s−1.
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•Atrazine removal using chitin based nanohydrogel- adsorption & desorption.•Chitin-cl-poly(acrylamide-co-itaconic acid) - microwave synthesis.•Results shows the maximum adsorption ...capacity of 204.08 mg/g.•Chitin-cl-poly(acrylamide-co-itaconic acid) nanohydrogel - pH responsive nature.
Removal of commonly used pesticide, atrazine was examined by employing chitin based nanohydrogel. Chitin-cl-poly (acrylamide-co-itaconic acid) nanohydrogel was synthesized by microwave method. Dissolution of chitin was done by freezing thawing method in NaOH/urea solution. The morphology and functional characteristics were confirmed by FTIR, XRD, SEM, TGA, TEM, and EDX techniques. Maximum swelling capacity, isotherm study, kinetics, adsorption and desorption of atrazine pesticide were evaluated in this study. Maximum adsorption capacity of designed nanohydrogel was found to be 204.08 mg/g. Langmuir and pseudo- second order models were determined to be applicable for explaining the undertaken adsorption process. Neutral pH was found to be favorable for maximum adsorption. In addition, results have specified the pH responsive nature of nanohydrogel for controlled release of atrazine.
Adsorption of coomassie brilliant blue R-250 on starch/poly(alginic acid-cl-acrylamide).
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•Starch/Poly(alginic acid-cl-acrylamide) have been synthesized by co-polymerization ...method.•The efficacy of the prepared nanohydrogel has been studied for the removal of coomassie brilliant blue R-250 from the aqueous solution.•The optimum pH for the adsorption of the CB dye was found 5.•The adsorption of CB was endothermic and spontaneous in nature.
In this study, we have synthesized a starch/poly(alginic acid-cl-acrylamide) nanohydrogel (ST/PL(AA-cl-AAm) NHG) by co-polymerization method which was used as an effective adsorbent for the removal of coomassie brilliant (CB) blue R-250 dye from the aqueous solution. The synthesized nanohydrogel was characterized by FTIR, SEM and TEM techniques. The effect of initial dye concentration, temperature, and agitation time on the adsorption ability of the nanohydrogel was studied comprehensively. The experimental outcomes exhibited that the prepared nanohydrogel had high adsorption tendency to remove the CB from the aqueous solution. The regression coefficient values for Langmuir (0.99), Frendluich (0.93) and Tempkin (0.98) recommended that adsorption process fit to langmuir isotherm. The pseudo-second-order equation showed the better adsorption kinetics of the adsorption process. The feasibility of CB adsorption onto ST/PL(AA-cl-AAm) NHG was also studied thermodynamically and the results indicated that the adsorption was spontaneous and chemical in nature.
Human activities such as industrialisation, urbanisation and agriculture have adversely impacted terrestrial and aquatic ecosystems. Water pollutants such as heavy metals and nanoparticles can ...undergo bioaccumulation and bioaugmentation. Heavy metals cannot be degraded and are hence added permanently. Nanoparticles are a potential threat because of their small size and unique properties. This article reviews the impact of various pollutants on aquatic biota and presents remediation methods. Benthic macroinvertebrates can be used as bioindicators to study the impact of pollutants on aquatic ecosystems. Fishes occupy the highest trophic level in the aquatic food chain and can therefore accumulate large amounts of metal from water, ultimately leading to biomagnification. Some organic compounds such as pesticides and fungicides are carcinogenic and sometimes resistant to degradation.
Optical isolators are unidirectional devices that employ the magneto-optical (MO) property of iron garnets to block the reflected light in almost all optical systems. Sputter deposition of either ...doped yttrium iron garnets (YIG) with seed-layers or seed-layer free terbium iron garnets (TIG) will help realize integrated planar isolators. Faraday rotation waveguides are designed as a viable solution to enable these monolithically integrated garnets to overcome the limitations inherent to hybrid integration of interferometric devices. In fact, small footprint Faraday rotation devices have been achieved using doped TIG for both TE/TM modes with sufficiently low loss and large isolation ratios.
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