SOUTHERN JOURNAL OF SCIENCES

Remains of human activity, such as sewage sludge, caused by population growth, ate a challenge to the environment and need urgent solutions. Cadmium from contaminated biosolid (sewage sludge) in Red Nitosoil, in PVC tubes (10 cm diameter and 80 cm height) located in the greenhouse, has been analyzed. Natural biosolid in one treatment (control), cadmium-and-lead contaminated biosolid in other two treatments (2,500 and 5,000 μg.g^-1); cadmium-and-lead contaminated biosolid in other two treatments (2,500 Cd⁺ 2,500 Pb and 5,000 Pb μg.g^-1, respectively) were added to the 0- 20 cm soil surface layer. Maize was the test plant in the triple replication experiment. The aerial part of maize plants, samples of surface soil (0 - 20 cm), and that within the tubes, divided into internal and external samples of each tube, were harvested seventy-five days after sowing. After the preparation and nitro perchloric digestion of samples, Cd concentrations were measured by atomic absorption spectrometry. Cd concentrations in maize were within phytotoxic tolerance. There was no significant difference among treatments in the production of plant dry matter. The highest Cd concentration was found in the 0-20 cm soil layer and differed significantly from the rest.

The inhibition effect of N-cyclohexyl benzothiazole sulphen amide (NCBSA) was studied on the corrosion of carbon steel in diluted ammoniacal solution at temperatures of 25°C and 30°C. The effects of the inhibitor on the corrosion were investigated and determined by using electrochemical measurements (curves of intensity - voltage). The efficiency of NCBSA increased with an increase in concentration but decreased with an increase in temperature. The free energy of activation was determined from the Arrhenius type equation. Experimental data fitted on adsorption isotherm of Langmuir type, while the results Were correlated to the chemical structure of the inhibitor.