Single-step synthesis of magnesium-iron borates composite; an efficient electrocatalyst for dopamine detection

© 2020 We have synthesized composite of magnesium-iron borates Mg2(X).Fe3(Y) (here; B2O5 = X and BO6 = Y), using a facile and single-step hydrothermal approach. Where, the synthesis of the composites can help not only to effectively utilize the properties of both i.e. magnesium borates (Mg2B2O5) and iron borates (Fe3BO6) in a single material but also making it thermodynamically more stable at higher temperatures as compared to the individual metallic borates. The as prepared heterostructured-composite was analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR), and thermal gravity analysis (TGA) to confirm the morphology, crystallinity, composition, and thermal stability. Further, the composite was explored as a catalyst in the construction of a biosensor where it showed an excellent electrocatalytic activity toward dopamine (DA) oxidation. This study offers a clue to design a borates-based composite to be explored as an efficient electrocatalyst in the application of biosensing field

Ammonium chloride and urea based deep eutectic solvent: toxicological and antioxidant profile

In the present study, the toxicity potential of ammonium chloride and urea-based deep eutectic solvent (DES) was studied. A homogeneous DES solution was obtained by heating at 60°C for 20 minutes. Fourier Transform Infrared Spectroscopy (FTIR) analysis was used to verify the synthesis. The toxicity profiling of ammonium-based DES was performed using in vitro cell lines (fibroblast growth factor) and microbes (fungi, Gram positive and gram negative bacteria) and in vivo model organism (fish). DES was found to the had maximum zone of inhibition against tested bacterial (Staphylococcus aureus) and fungal strains (Candida albicans). Ammonium chloride-urea DES had higher LC50 against Cyprinus carpio. DES was found to have a higher percentage of cell viability at higher concentration along with DPPH scavenging activity of 92%. In conclusion, ammonium chloride-urea based DES had been successfully formed and found less harmful at higher concentrations, thus can be used as promising solvents in the future

Ionic liquid tuned titanium dioxide nanostructures as an efficient colorimetric sensing platform for dopamine detection

Dopamine is a neurotransmitter distributed in the central and peripheral nervous system, its lower or higher production results in various pathological disorders. Various nanoparticles systems have been used in the sensing of dopamine while in the present work ionic liquid tuned titanium dioxide nanoparticles (TiO2 NPs) was first time evaluated in colorimetric detection of dopamine. TiO2 NPs have been synthesized by hydrothermal process and analyzed by different characterization techniques such as FTIR, XRD, and SEM that confirmed the desired synthesis. 1-H-3-methylimidazolium acetate (ionic liquid-a known conducting species) was prepared by the neutralization method. Colorimetric change in color from pinkish grey to reddish-brown with an increase in dopamine concentration was analyzed using a UV–Vis spectrophotometer. To optimize the protocol various parameters like nanoparticles loading, conc. of dopamine etc were optimized. The quantification and limit of detection for the proposed sensor were calculated as 2.55 × 10−7 M and 7.67 × 10−8 M respectively, and 1 × 10−8–3.6 × 10−6 M linear range with an R2 value of 0.9998. At an optimum temperature of 25 °C and at pH 12 the proposed sensor response time was just 4 min for dopamine detection. The proposed sensor has been also used for the dopamine detection in physiological solution. The proposed sensor showed good sensitivity and selectivity for dopamine sensing

Simultaneous enrichment & on-line detection of low-concentration Copper, Cobalt, & Nickel Ions in Water by Near-Infrared diffuse reflectance spectroscopy combined with chemometrics

Sensitive detection of heavy metal ions in water is of great importance considering the effects that heavy metals have on public health. A developed fluidized bed enrichment technique was used to concentrate and detect low concentrations of Cu2+, Co2+, and Ni2+ in water samples by near-IR diffuse reflectance (NIDR) spectroscopy (NIDRS) directly without using any chemicals or reagents. The NIDR spectra of adsorbent were measured on-line, and quantitative detection was achieved by applying a built partial least-squares chemometric model. Sensitivity and accuracy was improved significantly because large-volume mixture solutions were used in the enrichment process. Root mean square error of cross-validation values for Cu2+, Co2+, and Ni2+ were 0.29, 0.41, and 0.35 μg/mL, respectively, with mean relative error values in the acceptable range of 6.56-10.27%. This study confirms the potential application of fluidized bed enrichment combined with NIDRS and chemometrics for the simultaneous detection of trace heavy metal ions in water, with low relative error

Development of new organic-inorganic, hybrid bionanocomposite from cellulose and clay for enhanced removal of Drimarine Yellow HF-3GL dye

© 2020 Elsevier B.V. Cellulose/clay composites were prepared and applied for the adsorption of Drimarine Yellow HF-3GL direct dye. The prepared composites were characterized by FTIR, TGA, EDX, SEM and XRD techniques. Bagasse was used as a cellulose source, while clay was obtained from local source, which was modified chemically before composite preparation. Adsorption efficiencies were compared of composite I and II as a function of contact time, temperature, pH, initial dye concentration and composite dose. Non-linear kinetic and equilibrium isotherm employed and dye adsorption data fitted well to pseudo-second order kinetics model. Among isotherms, the Redlich-Peterson isotherm well defined the sorption process of dye on to composites. Thermodynamic factors (ΔS°, ΔH° and ΔG°) revealed that the sorption process was spontaneous, exothermic and feasible. Cellulose/clay composite I and II removed 88.64% and 89.95% dye with 60 min at pH 2 and 30 °C, respectively. For reusability, desorption was performed using different eluting agents and NaOH showed higher desorption efficiency. For the treatment of wastewater, the developed composites were applied to textile effluents and color removal of (90–96.07%) and (97–98.23%) was achieved using cellulose/clay composite I and II, respectively. The results showed that cellulose/clay composite are efficient for the removal dyes and could possibly be used for the treatment of textile effluents

Effect of gold and iron nanoparticles on photocatalytic behaviour of titanium dioxide towards 1-butyl-3-methylimidazolium chloride ionic liquid

© 2019 Elsevier B.V. The high water solubility, chemical stability and low volatility of ionic liquids (ILs) have made them potentially persistent than conventional pollutants and toxic to the aquatic organisms. Therefore, extensive research efforts are being directed with an aim to develop cheap and efficient protocols to reduce the uncontrolled release of ILs in the environment. In the same line of action, titanium dioxide (TiO2) loaded with gold and iron nanoparticles were trialled for the photocatalytic degradation of highly concentrated 1-butyl-3-methylimidazolium chloride [BmimCl] ionic liquid. Furthermore, results pertaining to the degradation of the [BmimCl] using TiO2 loaded with gold nanoparticles (AuNPs) were compared with results obtained by using TiO2 loaded with Fe (NO3)3.9H2O and pristine TiO2 under same set of conditions. It was found that TiO2 decorated AuNPs demonstrated 7 times higher photocatalytic degradation for highly concentrated [BmimCl] in 60 min of reaction time in comparison to the pristine TiO2. Congruently, investigations also revealed that TiO2 loaded AuNPs expressed 3.3 times higher photocatalytic degradation of [BmimCl] in comparison to conventional photocatalyst TiO2@Fe under same reaction conditions. The higher photocatalytic performance associated with TiO2 loaded AuNPs was due to the enhanced Schottky barrier, which could have minimized the photocharge carrier resistance separation and migration. The mechanism for photocatalytic degradation of [BmimCl] using TiO2 loaded AuNPs has been also been described

Aging study of the powdered magnetite nanoparticles

© 2016 Elsevier B.V. Magnetite nanoparticles were produced via co-precipitation method and then stored at room temperature for 6 years in aerobic atmosphere. Variations in the inherent solid phase and solid interfacial properties of the prepared magnetite nanoparticles were investigated. For this purpose the fresh and aged samples were characterized using transmission electron microscopy, vibrating sample magnetometer, X-ray diffractometer and energy dispersive X-ray spectrometer. The solid phase transformations of magnetite nanoparticles to maghemite nanoparticles as well as formation of other iron oxides were happened. After aging of 6 years, no change was occurred in the magnetic features; however increase in particle size from 9.6 to 18.5 measured by transmission electron microscopy was confirmed. The crystallite size and vibrating sample magnetometer values were measured before and after aging and found to increase from 8.98 nm and 47.23 emu/g to 16.18 nm and 58.36 emu/g respectively. The formation of other iron oxides, recrystallization and agglomeration during aging process, caused a significant decrease in the specific surface area from 124.43 to 45.00 m2/g of the stored sample

COSMO-RS predictions, hydrogen bond basicity values and experimental evaluation of amino acid-based ionic liquids for lignocellulosic biomass dissolution

© 2018 Elsevier B.V. In this study, the bamboo dissolution capability of six amino acid-based ionic liquids (AAILs) with two different cations, i.e. 1-ethyl-3-methylimidazolium (Emim) and Tetrabutylphosphonium (P4444) and three anions derived from amino acids were investigated by Conductor-like screening model for real solvents (COSMO-RS) prediction and hydrogen bond basicity (β) of Kamlet–Taft parameters. COSMO-RS was used for calculating sigma profile, activity coefficients (γi) and aqueous base dissociation constant of corresponding acids of the anions (pKa) of AAILs. The trends in sigma profile, γi and pKa for AAILs were compared with β values and the effect of structure moiety of ionic liquids was also discussed. The trend of COSMO-RS prediction for anions was noted similar to the β values of AAILs with the exception of serinate anion. Similarly, the trend predicted by COSMO-RS and β values was also found same while changing the cations of AAILs. To investigate, the correlation of the above-mentioned properties with experimental dissolution ability, tetrabutylphosphonium aminoethanic acid ([P4444]Gly) and 1-ethyl-3-methylimidazolium aminoethanic acid ([Emim]Gly) ionic liquids were synthesized and evaluated. The trend predicted by COSMO-RS and the β values were not correlating with efficiency of AAILs for bamboo dissolution. Both AAILs were able to dissolve the bamboo. However, material of [P4444]Gly treated sample was evaluated through XRD analysis where change in crystallinity of cellulose was identified after dissolution and regeneration of bamboo. Scanning Electron microscopy also showed homogenous structure for regenerated materials

Potential of siltstone and its composites with biochar and magnetite nanoparticles for the removal of cadmium from contaminated aqueous solutions: Batch and column scale studies

© 2020 Elsevier Ltd The present study is the first attempt to evaluate the pilot and batch scale adsorption potential of siltstone (SS) and its nanocomposites with biochar (EDB/SS), magnetite nanoparticles (MNPs/SS) and MNPs/EDB/SS for Cd removal from contaminated water. The SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were characterized with FTIR, XRD, BET, SEM, TEM, TGA and point of zero charge (PZC). The effects of adsorbent dosage, contact time, initial Cd concentration, pH and presence of competing ions were evaluated on the Cd removal and its adsorption. The order for Cd removal was: MNPs/EDB/SS \u3e MNPs/SS \u3e EDB/SS \u3e SS (95.86–99.72% \u3e 93.10–98.5% \u3e 89.66.98–98.40% \u3e 74.90–90%). Column scale experiments yielded maximum retention (95%) of Cd even after 2 h of injection at 100 mg Cd/L. The exhausted SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were reused without losing significant adsorption potential. Similarly, maximum Cd adsorption (117.38 mg/g) was obtained with MNPs/EDB/SS at dose 1.0 g/L. The results revealed that coexisting cations reduced the Cd removal due to competition with Cd ions. The experimental results were better explained with Freundlich isotherm model and pseudo 2nd order kinetic models. The results revealed that SS and its composites can be used efficiently for the removal of Cd from contaminated water

Cellulose‐based Materials for the Removal of Heavy Metals from Wastewater – An Overview

Water pollution due to increase in population and high rates of wastewater generation have become serious concerns since the last few decades. Heavy metals are amongst the main wastewater pollutants due to their ability to persist in the environment. Materials and techniques are being investigated for the treatment of heavy metals in wastewater. Cellulose is one of the materials gaining attention due to its excellent physical, chemical, and mechanical properties. Cellulose-based materials are being widely studied for the adsorption of heavy metals. This overview highlights research efforts to enhance the role of cellulose in wastewater treatment through cellulose-based materials. It also discusses the effects of cellulose modifications such as cellulose gels, cellulose composites, cellulose derivatives, functionalized cellulose, and nanocrystalline cellulose on the capacity of heavy metals adsorption