Critical Reviews on Engineered Nanoparticles in Environmental Remediation

Environmental contamination is one of the important issues that the world is facing today, it is always expanding and leading to the grave and harmful effect on the Earth. Nanoparticles have a diameter less than 100 nm exhibit new size-dependent properties compared with the bulk material. Engineered nanoparticles (ENPs) have unique characteristics in addition to the high surface area-to-volume ratio, which may increase their toxicity relative to bulk materials. Due to the high volume production of ENPs products such as carbon nanotubes, titanium dioxide, silver, zinc oxide environmental exposure to these compounds is very common. ENPs have their unique properties and applications in the areas of medicine, food& drink, construction, automotive, textiles, energy, electronics, environment etc. The present critical review is focused on the recent development of the applications of ENPs in the environmental remediation and their toxic effects.

Paper ionophoretic technique in the study of biologically important beryllium(II) / cobalt(II)-homoserine binary complexes in solution

Quantitative indication of the process of forming a complex comes from the evaluation of the stability constants, which characterize the equilibria corresponding to the successive addition of ligands. A method, involving the use of paper electrophoretic technique is described for the study of binary complex system in solution. Present method is based upon the migration of a spot of metal ions on a paper strip at different pH’s of background electrolyte. A graph of pH against mobility gives information about the binary complexes and permits calculation of their stability constants. The first and second stability constants of [Be(II)-homoserine] and [Co(II)-homoserine] complexes were found to be (7.13 ± 0.02; 6.11 ± 0.09) and (4.27 ± 0.07; 3.47 ± 0.11) (logarithm stability constant values) for Be(II) and Co(II) complexes, respectively, at ionic strength of 0.1 mol/L and a temperature of 35 °C.

Studies on biologically important copper(II) / manganese(II) / uranyl(II) – norvaline binary complexes

In coordination compounds studies, a knowledge of the magnitude of the stability constants of complexes is necessary for preliminary quantitative treatment. Described herein is a method that involves the use of advanced ionophoretic technique for the study of the equilibria in binary complex systems in solution. This method is based upon the migration of a spot of the metal ion on a paper strip at different pH values of background electrolyte containing 0.1 M perchloric acid and 0.01 M norvaline. A graph of pH against mobility provides information about the nature of the complexation and helps in calculating stability constants. Using this method, the stability constants of binary complexes metal(II) – norvaline have been determined to be (8.11 ± 0.02, 7.03 ± 0.09); (3.77 ± 0.11, 2.39 ± 0.07) and (7.59 ± 0.05, 6.17 ± 0.04) (log K values) for Cu(II), Mn(II) and UO2(II) complexes, respectively, at 35 ºC.

Paper electrophoretic determination of the stability constants of binary and ternary complexes of copper(II) and cobalt(II) with nitrilotriacetate and cysteine

A paper ionophoretic method is described for the study of equilibria in mixed ligand (nitrilotriacetate-cysteine) complex system in solution. The proportion of ionic species of nitrilotriacetate (NTA) and cysteine were varied by changing the pH of background electrolyte. The stability constants of Cu(II)-NTA-cysteine and Co(II)-NTA-cysteine complexes were found to be 6.35+/-0.05 and 5.45+/-0.02 (logarithm stability constant values), respectively, at ionic strength 0.1 M and a temperature of 35 degrees C.

Removal of p-aminophenol and p-nitrophenol from aqueous solution through adsorption on antimony, cadmium, and zirconium ferrocyanides

Adsorptive interaction of p-aminophenol and p-nitrophenol in the concentration range 10(-4)-10(-5) M and at room temperature (30+/-1 degrees C) was studied with antimony, cadmium, and zirconium ferrocyanides. The interaction followed the Langmuir type of adsorption in general. The p-nitrophenol was found to have greater affinity for the antimony, cadmium, and zirconium ferrocyanides then the p-aminophenol.

Electrophoretic studies on the chelating tendency of bioactive sulphur-containing amino acids. The metal-methylcysteine-cysteine system

Stability constants of binary Fe(III)-methylcysteine, Cr(III)-methylcysteine and mixed Fe(III)-methylcysteine-cysteine, Cr(III)-methylcysteine-cysteine complexes have been determined by paper electrophoresis at 0.1 M ionic strength and a temperature of 35 degrees C. The stability constants of Fe(III)-methylcysteine-cysteine and Cr(III)-methylcysteine-cysteine mixed complexes were found to be 6.00 +/- 0.07 and 5.05 +/- 0.15 (logarithm of stability constant values), respectively.

Ionophoretic studies on mixed metal--nitrilotriacetate--penicillamine complexes

Paper ionophoresis is described for the study of equilibria in a mixed ligand complex system in solution. This method is based on the movement of a spot of metal ion in an electric field with the complexants added in the background electrolyte at pH 8.5. The concentration of the primary ligand (nitrilotriacetate) was kept constant, while that of the secondary ligand (penicillamine) was varied. The stability constants of the metal-nitrilotriacetate-penicillamine complexes have been found to be 6.26 +/- 0.09 and 6.68 +/- 0.13 (log K values) for Al3+ and Th4+ complexes, respectively, at 35 degrees C and ionic strength 0.1 M.

Interaction of o-Aminophenol and o-Nitrophenol with Copper, Zinc, Molybdenum, and Chromium Ferrocyanides

Removal of o-aminophenol and o-nitrophenol from aqueous solution through adsorption on copper zinc, molybdenum, and chromium ferrocyanides were studied in pH range 2-10 at 27°C. At pH 7.0 o-nitrophenol adsorbed more than o-aminophenol on all the metal ferrocyanides studied. The Langmuir type of adsorption is followed in the concentration range of 10(-3) to 10(-4) M of o-aminophenol and o-nitrophenol solutions. Copyright 1997 Academic Press. Copyright 1997Academic Press

Paper electrophoresis in the study of mixed ligand complexes in solution. The system Fe(III)- and Cr(III)-methyl cysteine-penicillamine

A method involving use of paper electrophoresis is described for the study of equilibria in mixed ligand [methyl cysteine-penicillamine] complex systems in solution. The concentration of the primary ligand methyl cysteine was kept constant, while that of secondary ligand penicillamine was varied. The plots of -log [penicillamine] against mobility were used to obtain information on the formation of mixed complex and to calculate its stability constants. The binary equilibria M(III)-methyl cysteine have also been studied since this is a pre-requisite for the investigation of mixed complexes. The stability constants of [Fe(III)- methyl cysteine-penicillamine] and [Cr(III)-methyl cysteine-penicillamine] complexes were found to be 7.40 +/- 0.13 and 4.80 +/- 0.07 (log K values) for Fe(III) and Cr(III) complexes, respectively, at mu = 0.1 mol/L and at a temperature of 35 degrees C.