The experience of measuring aluminium ion in water

Summary

Practical use of the measuring techniques (specified in ПНД Ф 14.1:2:4.166-2000 and State Standard ГОСТ 18165-89) revealed a number of defaults in the process of determining low concentrations of aluminium in water. The technique of measurement is using the effect of aluminium-aluminon complex coloration with different chemical dosing methods. The experimental investigations showed that replacing successive addition of low concentrations of chemicals with reaction mixture improves the reproducibility of the results. However, the estimate accuracy of measurements (below 0.1 mg/l concentration) carried out with the certified aluminium determination techniques were not reached. Thus, the metrological performance of ПНД Ф 14.1:2:4.166-2000 and State Standard ГОСТ 18165-89 technique have to be revised the more especially that they have been widely used.

Key words

potable water , concentration , aluminium , aluminon solution , sample , absorbency

Precipitation of dyes from spent solutions using magnesium-containing agents

Summary

Spent solutions generated in the process of skin dyeing make a significant negative contribution to the pollution of the total amount of wastewater of the enterprise; hence, the need arises for their local treatment to reduce the concentration of organic dyes before discharging into the total wastewater flow. The aim of the work was to study the possible use of magnesium-containing agents for the precipitation of dyes from local wastes. The experiments were conducted with simulated solutions of acid dyes that differed in molecular structure and the number of auxochrome groups to ensure the solubility of the dye and its adsorption by the dyeing material. Dyes were precipitated using magnesium-containing agents, i. e. suspension of magnesium hydroxide and magnesium oxide (MagPro), and for comparison, aluminium sulfate. The efficiency of the precipitation of dyes from solutions was evaluated by the amount of separated precipitate and the optical density of the supernatant. The effect of the precipitation agent consumption on the efficiency of removing dyes from the solution is shown. The results of the experiment provided for establishing the optimal consumption of precipitation agents for each of the dyes used. It was found that aluminum sulfate and MagPro were equally effective with respect to the direct brown solution. The acid black dye is predominantly precipitated with aluminum sulfate, while Luganyl brown NG is precipitated only with magnesium-containing agents. To precipitate dyes from local effluents with an equal precipitate yield, the consumption of MagPro agent is 10 times less than while using aluminum sulfate. MagPro is more effective in sedimentation and discoloration of local effluents after skin dyeing at pH above 12.

Key words

settling , aluminium sulphate , absorbency , local wastes , dyes , magnesium-containing agents , magnesium hydroxide , discoloration of solutions