Novel CNT Supported Molybdenum Catalyst for Detection of L-Cysteine in Its Natural Environment

In this study, novel carbon nanotube-supported Mo (Mo/CNT) catalysts were prepared with the sodium borohydride reduction method for the detection of L-cysteine (L-Cys, L-C). Mo/CNT catalysts were characterized with scanning electron microscopy with elemental dispersion X-ray (EDX-SEM), X-ray diffraction (XRD), UV-vis diffuse reflectance spectrometry (UV-vis), temperature-programmed reduction (TPR), temperature programmed oxidation (TPO), and temperature-programmed desorption (TPD) techniques. The results of these advanced surface characterization techniques revealed that the catalysts were prepared successfully. Electrochemical measurements were employed to construct a voltammetric L-C sensor based on Mo/CNT catalyst by voltammetric techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Further measurements were carried out with electrochemical impedance spectroscopy (EIS). Mo/CNT/GCE exhibited excellent performance for L-C detection with a linear response in the range of 0–150 µM, with a current sensitivity of 200 mA/μM cm2 (0.0142 μA/μM), the lowest detection limit of 0.25 μM, and signal-to-noise ratio (S/N = 3). Interference studies showed that the Mo/CNT/GCE electrode was not affected by D-glucose, uric acid, L-tyrosine, and L-trytophane, commonly interfering organic structures. Natural sample analysis was also accomplished with acetyl L-C. Mo/CNT catalyst is a promising material as a sensor for L-C detection.

Cu(II)/sodium borohydride-based electrocatalytic system for reduction and dyeing of indigo

Purpose To improve the problems as the heavy burden of sewage treatment and environmental pollution caused by the traditional sodium hydrosulfite reduction dyeing of indigo, this study aims to carry out the direct electrochemical reduction dyeing for indigo with the eco-friendly Cu(II)/sodium borohydride reduction system under normal temperature and pressure conditions. Design/methodology/approach The electrochemical behavior of Cu(II)/sodium borohydride reduction system was investigated by cyclic voltammetry. And, the dyeing performance of the Cu(II)/sodium borohydride reduction system was developed by optimizing the concentration of copper sulfate in the anode electrolyte, applied voltage and reduction time via single-factor and orthogonal integrated analysis. Findings The dyeing performance of the Cu(II)/sodium borohydride reduction system is superior to that of the traditional reduction dyeing with sodium hydrosulfite. In the case of the optimized condition, the soaping fastness and dry/wet rubbing fastness of the dyed fabric in the two reduction dyeing processes were basically comparable, the K/S value of electrocatalytic reduction of indigo by Cu(II)/NaBH4 is 11.81, which is higher than that obtained by traditional sodium hydrosulfite reduction dyeing of indigo. Originality/value The innovative electrocatalytic reduction system applied herein uses sodium borohydride as the hydrogen source combined with Cu(II) complex as the catalyst, which can serve as a medium for electron transfer and active the dye molecule to make it easier to be reduced. The electrochemical dyeing strategy presented here provides a new idea to improve the reduction dyeing performance of indigo by sodium borohydride.

Degradation Kinetics of Methyl Orange Dye in Water Using Trimetallic Fe/Cu/Ag Nanoparticles

The release of azo dye contaminants from textile industries into the environment is an issue of major concern. Nanoscale zerovalent iron (nZVI) has been extensively studied in the degradation of azo dye pollutants such as methyl orange (MO). In this study, iron was coupled with copper and silver to make trimetallic Fe/Cu/Ag nanoparticles, in order to enhance the degradation of MO and increase reactivity of the catalyst by delaying the rate of oxidation of iron. The synthesis of the trimetallic nanoparticles (Fe/Cu/Ag) was carried out using the sodium borohydride reduction method. The characterization of the particles was performed using XRD, XPS, EDX, and TEM. The analyses confirmed the successful synthesis of the nanoparticles; the TEM images also showed the desired structures and geometry of the nanoscale zerovalent iron particles. The assessment of the nanoparticles in the degradation of methyl orange showed a notable degradation within few minutes into the reaction. The effect of parameters such as nanoparticle dosage, initial MO concentration, and the solution pH on the degradation of MO using the nanoparticles was investigated. Methyl orange degradation efficiency reached 100% within 1 min into the reaction at a low pH, with lower initial MO concentration and higher nanoparticle dosage. The degradation rate of MO using the nanoparticles followed pseudo first-order kinetics and was greatly influenced by the studied parameters. Additionally, LC-MS technique confirmed the degradation of MO within 1 min and that the degradation occurs through the splitting of the azo bond. The Fe/Cu/Ag trimetallic nanoparticles have proven to be an appropriate and efficient alternative for the treatment of dye wastewater.

Efficient nitrogen reduction to ammonia by fluorine vacancies with a multi-step promoting effect

A new fluoride vacancy of tradition metal material (FV-LaF3-x nanosheets) is rationally designed and synthesized by sodium borohydride reduction at room temperature, which improves the nitrogen reduction performance due to multi-step promotion.

Anchoring Carboxyl Functionalized Gold-Aryl Nanoparticles to Graphene Oxide Platforms for Environmental Nanoremediation

Graphene oxide (GO) was decorated with gold-aryl (Au-C) nanoparticles AuNPs-COOH by sodium borohydride reduction of aryldiazonium tetrachloroaurate(III) salt at room temperature in aqueous solutions. BET (Brunauer-Emmett-Teller) measurements supported the anchoring of GO by AuNPs modified with carboxyl functional groups; surface area dropped significantly. Morphology of AuNPs-COOH/GO nanocomposite (NC) was probed using AFM and TEM and images showed surface roughness and wrinkling. Molecular dynamics (MD) calculations endowed support of favorable wrinkling at the edges and carboxyl intercalation to GO surface of types p-p, hydrogen bonding, and hydrophobic interactions. Solvent accessible surface area calculations (SASA) of GO showed a decrease in total surface area, in agreement with BET results. Environmental nanoremediation of the catalytic reduction of nitrophenol and the electrocatalytic reduction of CO₂(model pollutants) were investigated. The apparent rate constants K_app of the four catalytic reduction cycles of nitrophenol were measured. The highest value is 1.17 × 10^-1 min^-1for the first cycle which decreased to 4.49 × 10^-2 min^-1 for the fourth cycle. Electrocatalytic studies revealed that the NC enhanced the CO₂ reduction. The NC exhibited higher current densities in the CO₂ solution saturated (48 mA/cm²) compared to N₂ (37 mA/cm²), indicating its superior catalytic activity in CO₂ reduction.

Anchoring Carboxyl Functionalized Gold-Aryl Nanoparticles to Graphene Oxide Platforms for Environmental Nanoremediation

Graphene oxide (GO) was decorated with gold-aryl (Au-C) nanoparticles AuNPs-COOH by sodium borohydride reduction of aryldiazonium tetrachloroaurate(III) salt at room temperature in aqueous solutions. BET (Brunauer-Emmett-Teller) measurements supported the anchoring of GO by AuNPs modified with carboxyl functional groups; surface area dropped significantly. Morphology of AuNPs-COOH/GO nanocomposite (NC) was probed using AFM and TEM and images showed surface roughness and wrinkling. Molecular dynamics (MD) calculations endowed support of favorable wrinkling at the edges and carboxyl intercalation to GO surface of types p-p, hydrogen bonding, and hydrophobic interactions. Solvent accessible surface area calculations (SASA) of GO showed a decrease in total surface area, in agreement with BET results. Environmental nanoremediation of the catalytic reduction of nitrophenol and the electrocatalytic reduction of CO₂(model pollutants) were investigated. The apparent rate constants K_app of the four catalytic reduction cycles of nitrophenol were measured. The highest value is 1.17 × 10^-1 min^-1for the first cycle which decreased to 4.49 × 10^-2 min^-1 for the fourth cycle. Electrocatalytic studies revealed that the NC enhanced the CO₂ reduction. The NC exhibited higher current densities in the CO₂ solution saturated (48 mA/cm²) compared to N₂ (37 mA/cm²), indicating its superior catalytic activity in CO₂ reduction.

Mechanical stretching changes crosslinking and glycation levels in the collagen of mouse tail tendon

Collagen I is a major tendon protein whose polypeptide chains are linked by covalent crosslinks. It is unknown how the crosslinking contributes to the mechanical properties of tendon or whether crosslinking changes in response to stretching or relaxation. Since their discovery, imine bonds within collagen have been recognized as being important in both crosslink formation and collagen structure. They are often described as acidic or thermally labile, but no evidence is available from direct measurements of crosslink levels whether these bonds contribute to the mechanical properties of collagen. Here, we used MS to analyze these imine bonds after reduction with sodium borohydride while under tension and found that their levels are altered in stretched tendon. We studied the changes in crosslink bonding in tail tendon from 11-week-old C57Bl/6 mice at 4% physical strain, at 10% strain, and at breaking point. The crosslinks hydroxy-lysino-norleucine (HLNL), dihydroxy-lysino-norleucine (DHLNL), and lysino-norleucine (LNL) in-creased or decreased depending on the specific crosslink and amount of mechanical strain. We also noted a decrease in glycated lysine residues in collagen, indicating that the imine formed between circulating glucose and lysine is also stress labile. We also carried out mechanical testing, including cyclic testing at 4% strain, stress relaxation tests, and stress-strain profiles taken at breaking point, both with and without sodium borohydride reduction. The results from both the MS studies and mechanical testing provide insights into the chemical changes during tendon stretching and directly link these chemical changes to functional collagen properties.

Formation of a Sterically Crowded 1,6,6αλ4-Triselenapentalene and 4H-Selenopyran-4-selones Fused with Two Bornane Skeletons Through the Reaction of d-Camphor p-Toluenesulfonylhydrazone With a Base and Elemental Selenium

Reaction of d-camphor p-toluenesulfonylhydrazone with t-butoxide and elemental selenium in dimethylformamide at an elevated temperature afforded a stable compound having a unique 1,6,6αλ4-triselenapentalene ring and 4 H-selenopyran-4-selones along with dialkenyl diselenide, dibornylenes, and 1,2,5-triselenepin, and the structural confirmation of these products were carried out by X-ray crystallographic analysis. The sterically crowded 1,6,6aλ4-triselenapentalene ring fused with two bornane sleketons was stable enough under aerobic exposure and was inactive toward sodium borohydride reduction but was converted into 1,2-diselenole derivative through m-chloroperbenzoic acid oxidation.