PENENTUAN ARSEN SEBAGAI LOGAM RUNUT PADA LOGAM TIMAH DENGAN METODA PERAK-DIETILDITIOKARBAMAT

• Main Author: Razak, Darmilah
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/2183
• Institution: Institut Teknologi Bandung

Monoethanolamine-chloroform system is suggested as a new solvent for silver diethyldithiocarbamate (SDDC) in arsenic determination as trace element of tin. The solvent has no pungent odour as pyridine and is relatively less ex-pensive. The sample of tin is dissolved in hydrochloric acid and hydrogen peroxide. As(V) is reduced to As(III) by addition of potassium iodide and stannous chloride. Stannous chloride and potassium iodide have been used to reduce arsenic(V) to arsenic(III) and to remove some other oxidants. As3+ is reduced furthermore by zinc in acid solution in an arsine generator. The arsine generator is immersed in an ice cooled water bath to slow down the evolution of arsine gas. The generated arsine is then passed through a scrubber containing glass wool or cotton moistened with lead acetate solution, to bind sulfide as lead sulfide. The arsine is then absorbed by silver diethyldithiocarbamate dissolved in monoethanolamine-chloroform, forming a soluble red complex which is measured spectrophotometrically at 510 nm against a reagent blank. From this research it is observed that: <br /> - The time required for reducing As(V) to As(III) was 30 minutes. <br /> - Silver diethyldithiocarbamate is well dissolved in monoethanolamine-chloroform 6% volume at 42-5500. There are two kinds of silver diethyldithiocarbamate, G.R. made by Merck, the first has a yeast form with a light brown color and the second is a greenish yellow to pale yellow powder. In fact the solution of the yeast form of silver diethyldithiocarbamate is more stable than the second form. The solution of the first form of SDDC in monoethanolamine-chloroform 6% volume solution is stable until the fifth day, while the second form should be made fresh.<br /> - The best solvent is monoethanolamine-chloroform 6% volume solution.<br /> - The red solution of As-SDDC can be measured spectrophotometrically at 510 nm wavelength.<br /> - The complex of As-SDDC in monoethanolamine-chloroform 6% volume is stable until the third day, provided that it is placed in a dark bottle and well covered.<br /> - The content of arsenic in the sample of tin is ± 0,025 % w/w.<br /> - The range of measurement is 10 up to 60 ug/10 ml complex solution.