A rapid, simple, sensitive and selective spectrophotometric determination of trace nitrite is described.The method is based on a diazotization-coupling reaction between dapsone and N-( 1-naphthy1)ethylenediamine dihydrochloride (NEDA) in a hydrochloric acid medium. The molar absorptivity and Sandell's sensitivity were found to be 7 . 2~1 0~ 1 mol-' cm-'and 0.00063 pg ml-', respectively. The calibration graph is linear for 0.002-0.6 pg in-' of nitrite. The interference effects of various cations and anions were also studied and reported. This method has been found to be applicable to the determination of nitrite in various water samples.

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Aluminium sulfide (Al2S3) nanoparticles were successfully synthesized by electrochemical method. Further, the synthesized nanoparticles were used as a photocatalyst for degradation of trichloroacetic acid, chloroacetic acid, acetic acid and degradation kinetics was studied by volumetric method using NaOH under various experimental conditions. The Al2S3 nanoparticles were characterized by UV-visible spectroscopy, X-ray diffraction and SEM-EDAX. The study of UV-visible spectroscopy indicates that Al2S3 nanoparticles shows maximum intensity peak at 222 nm in the UV region and there is no absorption peak in the visible region, therefore the synthesized nanoparticles is active under UV light and band gap energy was found to be 3.07 eV, which was calculated using Tauc plot. The structure of Al2S3 was found to be tetragonal structure and average crystal size was found to be 25.76 nm, which was calculated using Debye-Scherrer′s formula. The SEM results showed that Al2S3 appears as nanoflakes with agglomerated. The presence of aluminium and sulfur was confirmed using EDAX spectra. The photocatalytic activity of the synthesized Al2S3 nanoparticles was examined by taking three carboxylic acids by volumetric method. Taft LFER was tested, the isokinetic temperature β was calculated for oxidation of carboxylic acids. The antibacterial activity was investigated for synthesized nanoparticles by using Bacillus subtilis MTCC 2763 and Escherichia coli MTCC 40 of different bacteria.

Cadmium oxide (CdO) nanomaterial has been synthesized by electrochemical method which is simple and inexpensive method. The synthesized cadmium oxide nanomaterial was used as a catalyst for the photocatalytic degradation of acetic acid, formic acid and oxalic acids under varies experimental conditions by volumetric method. The synthesized nanomaterials were characterized by various techniques such as UV-Visible spectroscopy, SEM-EDAX, FT-IR spectrum and X-ray diffraction studies. The UV-VIS spectroscopy study revealed that the band gap energy of cadmium oxide nanomaterials to be 2. 85 eV Tauc plot. The structure of cadmium oxide was found to be cubic structure and crystal size was found to be 32 nm which was confirmed from XRD data. SEM reports showed that the cadmium oxide nanomaterials have regular spherical shape and uniform size. The presence of cadmium and oxygen in the nanomaterial is confirmed from the EDAX spectrum. FT-IR spectra reveal the presence of characteristic band corresponds to Cd-O mode. The photocatalytic activity of the synthesized cadmium oxide nanomaterial was examined by the kinetics of photodegradation of carboxylic acids by volumetric method by using NaOH solution. Taft LFER was tested the isokinetic temperature β was calculated for oxidation of carboxylic acids. The antibacterial activity of cadmium oxide nanomaterial was investigated.