Quantitative analysis of CL-20 explosive by smartphone-based chemiluminescence method.

A new smartphone-based chemiluminescence method has been introduced for the quantitative analysis of CL-20 (Hexanitroazaisowuertzitan) explosive. The solvent mixture, oxidizer agent, and concentration of the reactants were optimized using statistical procedures. CL-20 explosive showed a quenching effect on the chemiluminescence intensity of the luminol-NaClO reaction in the solvent mixture of DMSO/H2O. A smartphone was used as a detector to record the light intensity of chemiluminescence reaction as a video file. The recorded video file was converted to an analytical signal as intensity luminescence-time curve by a written code in MATLAB software. Dynamic range and limit of detection of the proposed method were obtained 2.0-240.0 and 1.1 mg⋅L-1, respectively, in optimized concentrations 1.5 × 10-3 mol⋅L-1 luminol and 1.0 × 10-2 mol⋅L-1 NaClO. Precursors TADB, HBIW, and TADNIW in CL-20 explosive synthesis did not show interference in measurement the CL-20 purity. The analysis of CL-20 spiked samples of soil and water indicated the satisfactory ability of the method in the analysis of real samples. The interaction of CL-20 molecules and OCl- ions is due to quench of chemiluminescence reaction of the luminol-NaClO.

Coupling of the optimized electro-Fenton-like process with pulsed laser ablation method to produce bimetallic nanoparticles of Fe°/Cu° and Fe°/Zn° in treatment of thiophene aqueous samples.

In this study, an electro-Fenton-like method in the presence of iron particles was used for degradation of toxic thiophene pollutant from aqueous samples with performance >99%. In an electrolytic reactor, the effect of current density, H2O2 dosage, and pH of the sample on the treatment efficiency was investigated and optimized using the response surface method in the experimental design methodology. The conditions were optimized in current density of 20 mA/cm2, H2O2 dosage 500 ppm and pH = 3.0. In this process, a laser pulse ablation was used to produce iron nanoparticles in the electro-Fenton reactor to decrease the treatment time. Also, two bimetallic iron-copper and iron-zinc were used to investigate the synergistic effect of bimetallic catalyst on degradation efficiency of thiophene. The removal of thiophene nearly 100% can be provided in the presence Fe0.5/Cu0.5, Fe0.5/Zn0.5 and Fe alone in 10, 15 and 20 min, respectively. Also, the effect of hydroxyl scavenger and the consumption of catalysts were studied in the proposed procedure. Techniques of gas chromatography-flame ionization detector (GC-FID), gas chromatography-sulphur chemiluminescence detector (GC-SCD) and total sulphur analyser were used to follow thiophene degradation. A thiophene petrochemical wastewater was treated by the proposed method, and the results showed a significant reduction in amounts of chemical oxygen demand (COD) and biochemical oxygen demand (BOD).

Using of multi-walled carbon nanotubes electrode for adsorptive stripping voltammetric determination of ultratrace levels of RDX explosive in the environmental samples.

A study of the electrochemical behavior and determination of RDX, a high explosive, is described on a multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE) using adsorptive stripping voltammetry and electrochemical impedance spectroscopy (EIS) techniques. The results indicated that MWCNTs electrode remarkably enhances the sensitivity of the voltammetric method and provides measurements of this explosive down to the sub-mg/l level in a wide pH range. The operational parameters were optimized and a sensitive, simple and time-saving cyclic voltammetric procedure was developed for the analysis of RDX in ground and tap water samples. Under optimized conditions, the reduction peak have two linear dynamic ranges of 0.6-20.0 and 8.0-200.0 mM with a detection limit of 25.0 nM and a precision of <4% (RSD for 8 analysis).