Enhancement of Cadmium and Zinc Flame Spectrometric Signals by Using APDTC-nButylamine-MIBK Extractants

Ammonium pyrrolidine-dithiocarbamate (APDTC) and methyl-isobutyl-ketone (MIBK) extractant were jound to be considerably improved by the addition of nbutylamine especially for the chemical analysis of Cd(II) and Zn(II) ions. Solvent extraction oj the bivalent metal ions is a function of pH and the concentration of APDTC and nbutylamine. Cd(II) and Zn(II) ions exhibit considerable flame spectrometric signal enhancement for pH ranges from 7 to 12 and 2 to 12 respectively when APDTC-nbutylamine-MIBK was used as the extractant in place oj APDTC-MIBK. The signal enhancement observed may be interpreted in terms of the formation of synergistic amine adduct and/or mixed solvent effect

Solvent Extraction of Cd(II) using n-Butylamine-ClO:-MIBK and n-Butylamine-Oxine-MIBK

n-Butylamine-perchlorate-1WJBK and n-butylamine-oxine-MIBK extractants were found to be effective for the extraction of Cd(II) ions under strongly alkaline conditions (pH>10). This extraction is a function of the concentration of oxine, perchlorate, n-butylamine and pH. The flame AAS signal for Cd(II) was considerably enhanced by using the above extractants. The signal enhancement and the increase in % extraction of Cd(II) can be attributed to the formation of synergistic amine adducts

Cyclic square wave polargraphic studies of tin (IV) in the presence of picolinic acid

The irreversible reaction of stannic-tin, Sn(IV), in noncomplexing supporting electrolyte was found to be reversible in the presence of picolinic acid (PA). Experimental evidences obtained from Tast polarography, electrocapillarity studies and cyclic square wave polarography indicated that Sn(II)-PA complex was adsorbable at the electrode surface but not Sn(IV)-PA complex. The adsorption effect has caused some degree of current enhancement. The enhancement and reversibility of the electrode reaction was dependence on pH, electrolyte, sweep rate, initial potential and presence of interference such as triton X-100

Electrochemical reduction of potassium ferricyanide mediated by magnesium diboride modified carbon electrode.

Use of a glassy carbon (GC) modified by adhered microparticles of MgB2 mediates the reduction process of Fe(III)(CN)63- during cyclic voltammetry. Peak potential was observed to shift slightly to less negative value by about 50 mV and current is significantly enhanced by about two folds. The sensitivity under conditions of cyclic voltammetry is significantly dependent on pH, electrolyte and scan rate. The result of scanning electron micrograph of MgB2 obtained before and after electrolysis show the size increased slightly to the size ranging from 2 - 5.5 µm attributing to the hydration effect and/or incorporation of some ionic species into the crystal lattices of MgB2. Interestingly, redox reaction of Fe(III) solution using modified GC electrode remain constant even after 15cycling. It is therefore evident that the MgB2 modified GC electrode posseses some degree of stability. Potential use of MgB2 as a useful electrode material is therefore clearly evident

Removal of lead, cadmium and zinc by waste tea leaves

The solid waste of commercially available tea leaves of local produce were found to be good sorbents of metal ions, especially Pb(II), Cd(II) and Zn(II) ions. The extent of adsorption depends on pH, ionic strength, metal concentration, substrate concentration, and the presence of interfering ions and surfactants. Among the various types of surfactants studied, cetyl trimethylammonium bromide severely hindered the metal uptake while Triton XlOO interfered mildly. Initial enhancement of Pb(II) and Zn(II) uptake was observed in the presence of small amount of sodium dodecyl sulphate. The enhancement effect decreased as the anionic surfactant concentration increased. Metal concentration dependence curves can be described by a Langmuir isotherm. Adsorption capacities of tea leaves were found to be 0.38, 0.28 and 0.18 mmole/g for Pb, Cd and Zn respectively.Column experiments revealed near 100% efficiency for metal removal of as much as 100 ppm Pb(ll) ion at pH 6, using 1.8 g waste tea leaves and flow rate of 25 ml/min. The relative affinities of metal ions towards waste tea leaves is in the order of Pb > Cd > Zn

Adsorption enhancement of Pb(II) Ion in the presence of Nicotinic Acid during Cyclic Voltammetry.

The solution phase voltammetry employed in the study of metal ion interaction with a selected ligand. Voltammetry behaviours of lead (II) ion in the presence of ligand with N-heterocycle compounds, such as nicotinic acid (pyridine-3-carboxylic acid) were being studied using cyclic voltammetry (CV) on a hanging dropping mercury electrode (HDME). Assessment of the chemical and physical conditions that may favour optimum current enhancement was done by studying the effect of varying pH, concentration of metal ion and scan rate. It was found that in presence nicotinic acid (NA) result in a shift in peak potential (Ep) and peak current (Ip) in the determination of Pb(II). The addition of 1 x 10-2 M nicotinic acid in 0.1 M potassium chloride at pH 4.0 and scan rate of 100 mV/s in CV was required for optimum current enhancement to be observed by about 4.9 fold and 1.6 fold in oxidation and reduction current of Pb(II) respectively. Based on chronocoulometry and chronoamperometry technique the diffusion for Pb(II) were estimated by 9.18 x 10-6 cm2/s and 5.0 μc/cm2 respectively. The procedure was successfully applied to the simultaneous determination of Pb(II) ion in some real samples

Electrochemical studies of Mn(II) mediated by Li+ doped Indium Titanium Oxide (ITO) electrode.

An electrochemical investigation of Manganese species has been carried out by using cyclic voltammetry (CV) at Lithium doped Indium Tin Oxide (ITO) electrode. The doping of the Li+ ion onto the Indium Tin Oxide (ITO) electrode was carried out to 10 potential cycling in the presence of 0.1M LiOH. The modified Li+/ITO electrode used as working electrode and was applied for the detection of Mn(II) in 0.1M KCl aqueous solution using cyclic voltammetry (CV). Electrode responses were obtained for the reduction of 50μM of Mn(II) at lithium doped modified ITO electrode, and bare ITO electrode. A well defined peak appeared at -136mV vs Ag/AgCl with a current enhancement and peak potential shift toward higher potential due to the presence of Lithium doped. Besides that, the presence of Lithium doped caused an increase of the reduction peak of Mn (II) ion (current enhancement) by about 2.9 times compared to use of bare ITO electrode. The optimum physical and chemical conditions such as pH, concentration of Mn(II) ion solution, and scan rate for current enhancement would be obtained. A linear relationship (y= 1777.3x + 42.145, R2=0.995) was observed for the plot of current (μA) versus concentration range of 10μM to 1.0mM of Manganese in 0.1M KCl using Lithium doped modified ITO electrode. Based on the background noise of 50 data points, adjacent to the reduction peak of Mn (II), and 3σ/slope, a detection limit of 1.0nM was determined

Development of electrochemical sensor for detection of mercury by exploiting His-Phe-His-Ala-His-Phe-Ala-Phe modified electrode.

A sensitive voltammetric method for detection of mercury ions is described which is made by modifying a gold electrode with 3-mercaptopropionic acid followed by covalent attachment of the octapeptide His-Phe-His-Ala-His-Phe-Ala-Phe to the self-assembled monolayer using carbodiimide coupling. A linear working range for concentration of mercury between 0.25 to 0.81 with LOD 9.5×10 -9 M was obtained which is below the WHO guidelines for drinking water. The reproducibility of the analytical signal is 4.5% in indicating a reproducible and reliable detection system. The developed method was applied for the detection of Hg(II) in spiked wastewater and validated against ICPMS. Good agreement was obtained between the developed method and ICPMS. Insignificant interference was observed by As 3+, Cr 3+, Cu 2+, Ni 2+, Pb 2+and Zn 2+ in detection of Hg(II) thus making the developed system highly potential for electrochemical sensor in Hg(II) detection