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Cyclic voltammetric and differential pulse voltammetric technique were used to investigate the oxidation behavior of nimesulide in these studies. An effort was made to use TiO 2 nanoparticles to modify the electrode surface to accentuate an effective technique for the determination of nimesulide. XRD and SEM investigation were carried out to understand the morphology of TiO 2 nanoparticles. Electro-oxidation studies for bare glassy carbon electrode and TiO 2 modified glassy carbon electrode shows an enhanced sensitivity for nanostructure-modified electrode. The electrode prepared was used to develop a sensible method for the trace determination of nimesulide. A wide linear range between 40 μM–100 μM with LOD and LOQ 3.37 nM and 11.2 nM were observed respectively. Further, it was observed that, two protons and two electrons were involved in the reaction mechanism with an irreversible and diffusion controlled electrode process at pH 2. In addition, charge transfer coefficient, heterogeneous rate constant, were calculated. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation of thiosalicylic acid in the presence of cationic surfactant, cetyl trimethylammonium bromide (CTAB), at a glassy carbon electrode was investigated. The electrochemical response of a modified sensor towards thiosalicylic acid determination was studied by the means of cyclic voltammetry, linear sweep voltammetry and differential pulse voltammetry (DPV). The liquid phase oxidation of thiosalicylic acid in the presence of CTAB leads to a notable enhancement in the peak current and a lowering of the peak potential. The electrochemical process was observed to be adsorption-controlled, irreversible and involves oxidation of one electron. Effects of anodic peak potential ( E ), anodic peak current ( I ) and heterogeneous rate constant ( k ) were calculated. The linear response was obtained in the range of 1.0 µM-1.0 mM with a detection limit of 113 nM. [ABSTRACT FROM AUTHOR]

A simple and highly sensitive method for the determination of erythrosine using glucose modified carbon paste sensor was presented. The electrochemical measurements were studied using cyclic voltammetry, differential pulse voltammetry and square wave voltammetry. The modified sensor exhibited excellent catalytic activity towards electrochemical oxidation of erythrosine in highly basic phosphate buffer, i.e. pH 11.2. The modified sensor facilitated the determination of erythrosine in the linearity range 1.0 × 10 −4 M to 1.0 × 10 −7 M with a detection limit of 21.6 nM. Good recovery from biological sample such as spiked urine indicates the applicability of the proposed method for clinical trials. The proposed method was successfully employed to detect erythrosine in pharmaceutical as well as food samples. The method exhibits tremendous reproducibility and has proved to be highly reliable for the analysis of erythrosine in biological samples. [ABSTRACT FROM AUTHOR]

The voltammetric oxidation of an anticancer drug, 5-fluorouracil, was investigated at a multiwalled carbon nanotubes-paraffin oil paste electrode using cyclic and differential-pulse voltammetry. The oxidation process was irreversible over the pH range studied and exhibited a diffusion-controlled behavior. In the range of 0.1 × 10−6to 5.0 × 10−6M, the current measured by differential-pulse voltammetry presents a good linear property as a function of the concentration of 5-flurouracil with a detection limit of 3.94 × 10−8M with good selectivity and sensitivity. The proposed method was successfully applied to 5-flurouracil determination in pharmaceutical and urine samples. [ABSTRACT FROM PUBLISHER]

Development of methods for the detection of an analyte at low concentration with less time for analysis has become a prior point of interest to every analyst. In reflection of this fact, an effort has been made to synthesize 5% barium doped zinc oxide nanoparticles and was characterized by using XRD, EDX, SEM, and TEM. Further, 5% barium doped zinc oxide nanoparticle modified glassy carbon electrode was used for investigating the electro-chemical behavior of nimesulide. Voltammograms obtained in a range of 3.0–11.2 (I = 0.2 M) pH had a maximum peak current at pH 7.0. Various physio-chemical parameters such as, process on the surface of the electrode, which was found to be diffusion controlled, heterogeneous rate constant, number of electrons transferred and charge transfer coefficient were estimated. Further, a method for nimesulide determination in a linear range of 1.0 × 10 − 5 to 1.0 × 10 − 7 M with LOD 1.794 nM was proposed. This technique was later used for analytical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar has unique properties to effectively remove hazardous pollutants. • Engineering biochar preparation methods enhance its properties and efficacy. • Feedstock composition, carbonization technology and conditions govern biochar properties. • It is a low-cost and natural substitute of commercial activated carbons. The accelerated urbanization and industrialization worldwide has increased the pollution via toxic chemicals, thus generating environmental hazards to public health and ecosystems. As a consequence, the national authorities and scientists are paying more attention to the development and implementation of viable cost-effective detoxification solutions. Biochar has emerged as a biomass-derived material that can be produced through a variety of feedstocks and carbonization techniques. Distinct characteristics of biochar can be appropriate, cost-effective, and eco-friendly for removing a wide spectrum of inorganic and organic pollutants. This review aims to emphasize the crucial function of biochar-based materials in the abatement of toxic emerging pollutants. It covers the synthesis and applications of engineered biochars by discussing extensive research and knowledge in this area. The relationships of biochar properties with feedstock, synthesis conditions, technologies and modification methods have also been discussed. Biochars with different surface functionalities (e.g., COO−, Fe-O, etc.,) can be obtained by either varying the feedstock material (lignocellulosic or non-lignocellulosic) or by modifying it with different chemicals (e.g., metal ions, rare earth elements, surfactants) including the preparation of composites. The interaction mechanisms between biochar and various pollutants are reviewed and analyzed. The type of interactions (e.g., electrostatic, π-π stacking, hydrogen bonding) depends on the different surface functionalities of biochar. This review also illustrates that biochar and its related composites have shown remarkable properties and versatility for their effective application in adsorption, photocatalysis and oxidation processes in aqueous phase. Finally, prospective research directions and opportunity areas for biochar research are also discussed. The article provides a comprehensive review on the production, modification and environmental application of engineered biochar. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical oxidation of acyclovir at fullerene-C60-modified glassy carbon electrode has been investigated using cyclic and differential pulse voltammetry. In pH 7.4 phosphate buffer, acyclovir showed an irreversible oxidation peak at about 0.96V. The cyclic voltammetric results showed that fullerene-C60-modified glassy carbon electrode can remarkably enhance electrocatalytic activity towards the oxidation of acyclovir. The electrocatalytic behavior was further exploited as a sensitive detection scheme for the acyclovir determination by differential pulse voltammetry. Effects of anodic peak potential (Ep/V), anodic peak current (Ip/μA) and heterogeneous rate constant (k0) have been discussed. Under optimized conditions, the concentration range and detection limit were 9.0×10−8 to 6.0×10−6 M and 1.48×10−8 M, respectively. The proposed method was applied to acyclovir determination in pharmaceutical samples and human biological fluids such as urine and blood plasma as a real sample. This method can also be employed in quality control and routine determination of drugs in pharmaceutical formulations. [Copyright &y& Elsevier]

The kinetics of oxidation of a loop diuretic drug furosemide (Fur) by diperiodatoargentate(III) (DPA) has been investigated spectrophotometrically in alkaline medium at a constant ionic strength of 0.20 mol dm-3. The stoichiometry was 1 : 2 (Fur: DPA). The order of the reaction with respect to [DPA] was unity while the order with respect to [Fur] was less than unity over the concentration range studied. The rate increased with increase in [OH-] and decreased with increase in [IO4-]. The oxidation products were identified as 2-(4-carboxy-2-oxo-but-3-enylamino)-4-chloro-5-sulfamoyl-benzoic acid and Ag(I). The reaction constants involved in the different steps of the reaction mechanism were calculated. Kinetic experiments suggest that [Ag(H2IO6)(H2O)2] is the reactive silver(III) species. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation of 6-aminopenicillanic acid (6-APA) by diperiodatocuprate(III) (DPC) has been investigated both in the absence and presence of a ruthenium(III) catalyst in aqueous alkaline medium, at a constant ionic strength of 0.20moldm−3, spectrophotometrically. The stiochiometry was the same in both cases, i.e. [6-APA]/[DPC]=1:2. In both the catalyzed and uncatalyzed reactions, the order of the reaction with respect to [DPC] was unity, while the order with respect to [6-APA] was <1 over the concentration range studied. The rate increased with an increase in [OH−] and decreased with an increase in [] in both cases. The order with respect to [Ru(III)] was unity. The oxidation products were identified by spectral analysis and suitable mechanisms were proposed. The reaction constants involved in the different steps of the reaction mechanisms were calculated for both cases. The catalytic constant (KC ) was also calculated for the catalyzed reaction at different temperatures. The activation parameters with respect to the slow step of the mechanism and also the thermodynamic quantities were determined. Kinetic experiments suggest that [Cu(H2IO6)(H2O)2] is the reactive copper(III) species and [Ru(H2O)5OH]2+ is the reactive Ru(III) species. [Copyright &y& Elsevier]

The oxidation of amino acid, L-tryptophan (L-trp) by diperiodatoargentate (III) (DPA) in alkaline medium at a constant ionic strength of 0.02 mol dm-3 was studied spectrophotometrically. The reaction between L-trp and DPA in alkaline medium exhibits 1:2 stoichiometry (L-trp:DPA). Intervention of free radicals was observed in the reaction. Based on the observed orders and experimental evidences, a mechanism involving the monoperiodatoargentate (III) (MPA) as the reactive oxidant species has been proposed. The products were identified by spot test and characterized by spectral studies. The reaction constants involved in the different steps of mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed. The thermodynamic quantities were also determined for different equilibrium steps. Isokinetic temperature was also calculated and found to be 192.2 K. [ABSTRACT FROM AUTHOR]

Abstract: The kinetics of oxidation of atenolol (ATN) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.10moldm−3 was studied spectrophotometrically. The reaction between DPC and ATN in alkaline medium exhibits 1:2 stoichiometry (ATN:DPC). The reaction is of first order in [DPC] and has less than unit order in both [ATN] and [alkali]. However, the order in [ATN] and [alkali] changes from first order to zero order as their concentration increase. Intervention of free radicals was observed in the reaction. Increase in periodate concentration decreases the rate. The oxidation reaction in alkaline medium has been shown to proceed via a monoperiodatocuprate(III)–ATN complex, which decomposes slowly in a rate-determining step followed by other fast steps to give the products. The main oxidative products were identified by spot test, IR, NMR and LC–ESI-MS studies. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed, and thermodynamic quantities are also determined. [Copyright &y& Elsevier]

Abstract: Oxidation of penicillin derivative, ampicillin (AMP) by diperiodatocuprate(III) (DPC) in alkaline medium at a constant ionic strength of 0.01-moldm−3 was studied spectrophotometrically. The reaction between DPC and ampicillin in alkaline medium exhibits 1:4 stoichiometry (ampicillin:DPC). Intervention of free radicals was observed in the reaction. Based on the observed orders and experimental evidences, a mechanism involving the protonated form of DPC as the reactive oxidant species has been proposed. The oxidation reaction in alkaline medium has been shown to proceed via a DPC–AMP complex, which decomposes slowly in a rate determining step to yield phenyl glycine (PG) and free radical species of 6-aminopenicillanic acid (6-APA), followed by other fast steps to give the products. The two major products were characterized by IR, NMR, LC–MS and Spot test. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed and thermodynamic quantities were also determined. [Copyright &y& Elsevier]

The oxidation of 4-hydroxycoumarin (HDC) by diperiodatonickelate( IV) (DPN) in aqueous alkaline medium at a constant ionic strength of 1.0 mol dm-3 was studied spectrophotometrically at 298 K. The reaction between DPN and 4-hydroxycoumarin in alkaline medium exhibits 1:3 stoichiometry (HDC: DPN). The reaction is of first order in [DPN] and has less than unit order in [HDC] and fractional order in [alkali]. The oxidation reaction in alkaline medium has been shown to proceed via a DPN- 4-hydroxycoumarin complex, which decomposes slowly in a rate-determining step followed by other fast steps to give the products. The main products were identified by spot test, IR, 1HNMR studies. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed and thermodynamic quantities were also determined. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation of an anticancer drug 5-fluorouracil (5-FU) by diperiodatoargentate(III) (DPA) was carried out both in the absence and presence of osmium(VIII) catalyst in alkaline medium at 27°C and a constant ionic strength of 0.20moldm−3 spectrophotometrically attached with HI-TECH SFA-12 stopped flow accessory. The oxidation products in both the cases were identified as fluoroketene and Ag(I). The stoichiometry is same in both cases, i.e., [5-FU]:[DPA]=1:1. The reaction was of first order in both catalysed and uncatalysed cases, with respect to [DPA] and was less than unit order in [5-FU] and negative fraction in [alkali]. The order in Os(VIII) was unity. In both cases [Ag(H3IO6)2]− itself is the active species of DPA. The uncatalysed reaction in alkaline medium has been shown to proceed via a DPA-5-fluorouracil complex, which decomposes in a rate determining step to give the products. In catalysed reaction, it has been shown to proceed via a Os(VIII)-5-fluorouracil complex, which further reacts with one molecule of DPA in a rate determining step to give the products. The reaction constants involved in the different steps of the mechanisms were calculated for both the reactions. The catalytic constant (k Cat.const.) was also calculated for catalysed reaction at different temperatures. The activation parameters with respect to slow step of the mechanisms were computed and discussed for both the cases. The thermodynamic quantities were also determined for both reactions. [Copyright &y& Elsevier]

The kinetics of oxidation of antibiotic drug, ampicillin (AMP) by diperiodatoargentate (III) (DPA) in alkaline medium at a constant ionic strength of 0.25-mol dm-3 was studied spectrophotometrically. The reaction between DPA and AMP in alkaline medium exhibits 1:2 stoichiometry (AMP:DPA). The reaction is of first order in [DPA] and has less than unit order in both [AMP] and [alkali]. Added periodate retarded the rate of reaction and intervention of free radicals was observed in the reaction. The oxidation reaction in alkaline medium has been shown to proceed via a DPA–AMP complex, which decomposes slowly in a rate-determining step followed by other fast steps to give the products. The main products were identified by spot test, IR and NMR studies. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed and thermodynamic quantities were also determined. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

[Display omitted] • Elaboration of advancements in electrochemical method for the treatment of PFAS. • Complete mineralization of PFAS is possible via electrochemical treatment. • The latest trends in the electrode material were comprehensively reviewed. • Ceramic microporous Magneli phase Ti 4 O 7 anodes exhibit least energy-requirement. • Combining other techniques with electro-oxidation boosts overall system efficiency. The ubiquitous presence of poly- and perfluoroalkyls (PFAS) is a severe concern in view of their bioaccumulation and persistence in the environment because of strong C − F bonds (485 kJ/mol) that are recalcitrant towards thermal, chemical, and biological decomposition. The predominance of PFAS having toxicological effects can be quite hazardous to environment, wildlife, and human beings, especially the children. Efforts are continuously pursued to investigate complete mineralization of PFAS to detect and destroy these chemicals from the environment. Of all the many methods used, electrochemical approach is promising. This review explores the latest advances and limitations of the electrochemical treatment methods of PFAS. Recent findings emphasize the use of boron-doped diamond (BDD) anodes and titanium sub-oxide ceramic anodes, specifically Magnéli phase Ti 4 O 7 electrode as these can achieve almost ∼ 99% of PFAS removal with the least energy requirement compared to other existing anodes. The influence of design parameters and electrode materials are considered and the mechanisms of electro-oxidation of PFAS onto anodic surface degradation, besides the various side-products formed after the process are analyzed. The viability of macroscale application of electrochemical treatment faces some obstructions because of the concentration effects and mass transfer limitations. Reactive electrochemical membrane operation could facilitate inter-phase mass transfer through the filtration of contaminated samples over the porous materials that can act as a membrane plus anode all at once. Adopting different techniques such as nanofiltration, ion exchange resin, and reverse osmosis with electro-oxidation may boost the system effectiveness to reduce the overall expenses as well as alleviate the concentration of unfavorable and harmful side products after the degradation of PFAS. Nonetheless, an assessment of different electrode materials, consideration of realistic conditions, and implementation of feasible and workable approaches are essential for the scalability of laboratory research to large-scale applications. [ABSTRACT FROM AUTHOR]

In recent years, semiconductor nanostructures have gained enormous attention of researchers because of their excellent electrocatalytic activity and applications in various fields. Zinc oxide (ZnO) nanoparticles, which possess excellent electrocatalytic properties and stability, are versatile materials for a variety of sensing applications. The present research presents the fabrication of the ZnO-nanoparticle-modified glassy carbon electrode and itsapplication to quantify an antihistamine drug, methdilazine (MDH). Transmission electron microscopy, and X-ray diffraction studies were carried out to investigate the surface characteristics of ZnO nanoparticles. Furthermore, to investigate the effects of pH, accumulation time, scan rate, excipients, and concentration on the oxidation behavior of MDH, cyclic voltammetry, linear sweep voltammetry, and square wave voltammetry were carried outat a pH of 10.4. The electrode displayed excellent analytical performance for the quantification of MDH with a low limit of detection compared to earlier reports. The constructed sensor showed outstanding characteristics and could be readily applied to analyze MDH in urine and pharmaceutical samples. • The glassy carbon electrode was modified with non-toxic ZnO nanoparticles. • ZnO-electrodes were studied for their surface properties. • Modified electrode showed high oxidation potential. • Modified electrode showed excellent electrochemical oxidation towards methdilazine. [ABSTRACT FROM AUTHOR]

Abstract: The electrochemical oxidation of gabapentin has been investigated for the first time by cyclic, linear sweep and differential-pulse voltammetry at different pH at gold electrode. Cyclic voltammetric studies were performed in a wide range of sweep rates and various concentrations of gabapentin. The effect of surfactants was studied. The anodic peak was characterized and process was adsorption-controlled. The oxidation peak corresponds to the amine and probable mechanism was proposed. According to the linear relation between the peak current and the gabapentin concentration, differential-pulse voltammetric method for the quantitative determination in pharmaceuticals was developed. The linear response was obtained in the range of 0.3–15μM with a detection limit of 0.13μM with good selectivity and sensitivity. The proposed method was successfully applied to gabapentin determination in pharmaceutical samples and for the detection of gabapentin in urine as a real sample. [Copyright &y& Elsevier]

[Display omitted] • Clay-based nanostructured materials were fabricated via ultrasonication process. • Nanoclay modified electrodes were used for highly effective electrochemical sensor. • Developed electrochemical sensor has excellent sensitivity, selectivity, and stability. • Spiked samples of urine showed recovery in the range of 91.83–98.37% • It detects famotidine in biological samples with lower LOD values of 3.7 × 10–8 M. Famotidine (FAM) is used in the treatment of stomach ulcers and intestines by decreasing the concentration of acid (e.g., Zollinger-Ellison syndrome) produced in the stomach. FAM can prompt impaired mental conditions and cause kidney disease in older adults. This drug is listed as a persistent contaminant in the environmental samples. In this regard, FAM determination was carried out in urine and pharmaceutical samples utilizing a sensitive sensor. Novel clay nanosheets were fabricated through an ultrasonication-assisted process, and utilized nanoclay to surface modify the carbon paste electrode (NC/CPE), and employed for investigating electrooxidation of famotidine (FAM) in 0.2 M phosphate buffer solution (PBS) of pH 5.0. The sensing vicinity of the electrode is increased by nanoclay sheets; hence improvement in the interaction of FAM was achieved, which results in enhanced oxidation peak current than bare CPE. Based on the estimated interaction parameters, the involvement of a number of electrons during oxidation was calculated as one, and a heterogeneous constant (k0) was found to be 3.66 × 103 s−1. The values of the detection limit and the quantification limit were determined to be 3.7 × 10–8 M and 12.5 × 10–8 M, respectively. The designed electrode was showed an intensification of peak current with better sensibility, stability, reproducibility, repeatability, along with the existence of substances that interfere with the biological systems. Comfortable values of recovery were achieved via the analysis of FAM in urine (97.6–98.3%) and medicinal samples (91.83–98.37%). The study suggests that the use of nanoclay as a modifier was significantly influenced the electrochemical properties. [ABSTRACT FROM AUTHOR]