A method for the extraction and determination of uranyl ion in natural waters using octadecyl bonded silica membrane disks modified with piroxicam and spectrophotometry with arsenazo(III) is proposed. The perconcentration step was studied with regard to experimental parameters such as amount of extractant, type and amount of eluent, pH, flow rates and tolerance limit of diverse ions on the recovery of uranyl ion. The limit of detection of the proposed method is 0.4 micro g L(-1) of uranyl. The method was applied to the recovery of uranyl from different water samples.

Piroxicam was found to be a highly selective carrier for uphill transport of Cu2+ ions through a chloroform liquid membrane. The transport occurs via a counterflow of protons from the receiving phase to the source phase. The effects of several parameters on the transport of Cu2+ ions, such as the carrier concentration, pH of the source phase, composition of the receiving phase, and duration are described. A high transport efficiency (98+/-2%) was provided by the carrier for Cu2+ ions in a receiving phase of 0.01 mol l(-1) sulfuric acid after 4 h. Different metal ion transport experiments showed that Cu2+ ions were selectively transported over other ions, such as Co2+, Ni2+, Cd2+, Pb2+, Zn2+, UO2(2+) and ZrO2(2+) . In the presence of fluoride ions (used as a suitable masking agent in the source phase), the interfering effects of UO2(2+) and ZrO2(2+) ions were eliminated. The applicability of the method was tested on a real sample, and the results obtained show that it is potentially useful for solvent extraction of copper.