Monitoramento automÃtico de pH, nÃquel e cloreto em banhos de nÃquel tipo watts utilizando um sistema SIA

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

The need to rapidly perform multiparametric analysis makes the development of automatic on-line monitoring systems highly desirable for many industrial processes. Electroplating is a process used to protect metallic pieces from corrosion. For this process to be successful, electrolytic baths must be constantly monitored. Consequently, the development of a sequential injection analysis (SIA) system was undertaken to determine the pH, chloride and nickel concentrations in Watts type nickel baths. For pH and chloride measurements, potentiometry with tubular selective was used, and nickel was determined by spectrophotometry at 660 nm. To reduce interference effects in chloride measurements, on-line dialysis of the samples with a cellulose acetate membrane was made. Applying the factorial planning technique, where the chemical composition of the carrier solution and the hydrodynamic parameters were evaluated, optimised the system. The best operation conditions were obtained with sample of 500 μL, a phosphate buffer concentration of 0.025 mol L-1, pH 6.3 and a flow rate of 2.22 and 9.10 mL L-1 for dialysis and propulsion fluids, respectively. For these conditions, a linear response ranges from 1 to 5 units of pH, 0.1 to 1.6 mol L-1 and 0.1 to 1.0 mol L-1 nickel and chloride, were obtained. This SIA system demonstrated a analytical throughput of 45 samples h-1, together with relative errors lower than 5 %, when applied to the Watts type nickel baths

ASSUNTO(S)

injeÃÃo sequencial sequential injection quimica planejamentos fatoriais galvanoplastia factorial planning galvanoplasty

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