This paper presents an experimental work regarding the optimal conditions of pH for removing mercury from a contaminated soil sample using 0,1M solution of KI. A test stand with a column packed with contaminated soil has been done. A KI solution with neutral pH passes through the column, then a KI solution with acidic pH passes through another similar column and a KI solution with basic pH through the third column. It was collected periodically 10 mL fraction volume. The extracted mercury concentration from the solution is determined by atomic absorption spetrophotometry The results shows that the optimal conditions for cleaning the soil are using an acidic KI solution with a pH = 1, 5 � 2 and 150 mL of KI solution meaning 15 fractions of 10 mL each.
-Phosphate removal from waste waters has become an environmental necessity, since these phosphates stimulate the growth of aquatic plants and planktons and contribute to the eutrophication process in general. The physicochemical methods of phosphate ion removal are the most effective and reliable. This paper presents studies on the process of phosphate ion removal from waste waters resulting from the fertiliser industry's use of the method of co-precipitation with iron salts and with calcium hydroxide as the neutralizing agent. The optimal process conditions were established as those that allow achievement of a maximum degree of separation of the phosphate ions. The precipitate resulting from the co-precipitation process was analysed for chemical composition and establishment of thermal and structural stability, and the aim was also to establish in which form the phosphate ions in the formed precipitate can be found. Based on these considerations, the experimental data obtained in the process of phosphate ion removal from waste waters were analysed mathematically and the equations for the dependence of the degree of phosphate separation and residual concentration versus the main parameters of the process were formulated. In this paper an automated scheme for the phosphate ion removal from waste waters by co-precipitation is presented.
The paper presents studies about the process of obtaining the fertilizers based on ammonium phosphates (NH 4 ) 2 HPO 4 and NH 4 H 2 PO 4 with boron added as micronutrient. As boron source was used boric acid, which has been introduced into the neutralization mass at various NH 3 :H 3 PO 4 molar ratio, in order to obtain thermal stable compounds, with a minimum loss of nutritional elements (N, P). The variation of pH, considered the process control parameter, as a function of NH 3 :H 3 PO 4 molar ratio was recorded during the neutralization.Specific analyses has been used in order to determine phosphorus, ammonia nitrogen and boron content in the obtained fertilizers. The thermal behaviour of the fertilizers was studied using TG and DTG. The lowest total mass loss was observed at a 1.5 NH 3 :H 3 PO 4 molar ratio.
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