Studies on the purification of wastewaters with high nickel ions content

The paper presents studies on the removal of nickel from wastewaters with high nickel ions content resulting from galvanizing process. In the first step of the purification process, nickel ions were precipitated using a 10 M NaOH solution as precipitation agent. By increasing the pH of the Ni2+ solutions up to 11, the residual concentration of nickel ions reached the values required for the discharge in sewerage and in water resources. Taking into account that this pH value does not allow the discharge, the solution resulting from the precipitation process at pH 9 was submitted in the second step to an advanced treatment using as adsorbent material an Amberlite XAD-4 resin impregnated with di-2(ethyl-hexyl) phosphoric acid. To establish the conditions for the adsorption process was studied the influence of contact time and of adsorbent dosage on the efficiency of nickel ions removal from the solution. The maximum efficiency of ~ 94% was reached after 90 min for an adsorbent dosage of 0.3 g:25 mL. The residual concentration of nickel ions was ~0.5 mg/L, value that allows the discharge in the sewerage and even in water resources

Studies Regarding Tailings Pond Seepage Water from Mining Activities over Avena sativa L. Germination Influence

Cultivation of oat in the limiting areas of tailings pond might be regarded as one of the possibilities that could lead to the general amelioration of these places. In order to characterize the waste products, to determine and evaluate the components that may be leached from waste products and that can affect the limiting areas of tailings pond, leaching tests were performed. In this paper, we have observed the influence of eluate, obtained from leaching tests, on seed germination, radicle and coleoptyle development as well as on the amount of accumulated dry matter for Avena sativa L., genotypes. According to our researches, we may conclude that the studied genotypes of Avena sativa L. showed tolerance to eluate while values registered for seed germination, radicle and coleoptyle development as well as dry matter content were comparatively higher than those registered for the control variant

Studies regarding the turning to account of the waste resulting from coal exploitation

In this paper was studied the possibility of turning to account of the waste resulting from coal mining. One way was to use the waste in order to stabilize ash dumps. The chemical analysis of the coal waste and ash showed that both have high zinc and nickel content. As remediation method was chosen for this study the cultivation of barley as bio-indicator plant on substrates obtained by mixing the coal waste and ash in various proportions. After bio-remediation, the zinc content of the substrates fell under the maximum permitted value for all coal-ash mixtures. The nickel content decreased very much, but remained somewhat higher than the maximum permitted value. Another way was to use waste material as adsorbent in view of removal of organic dyes from wastewaters resulting from inkjet cartridge remanufacturing. The coal waste was used in various dosages (S:L = 0.1 g:25 mL; 0.2:25; 0.3:25; 0.4:25 and 0.5:25) and the suspensions were shaken for various contact times (15, 30, 45, 60 and 120 min). The highest removal efficiency ( -60%) was reached for a S:L ratio of 0.5:25 after a 60 min contact time

Use of impregnated resins as adsorbents in view of heavy metals removal from aqueous solutions

The presence of heavy metal ions in environment is a major concern because of their toxicity to many life forms. Heavy metal ions can be removal from water by adsorption on solid support. In the present work, we tested the adsorption of metal ions on solvent impregnated resin (SIR). Di-(2-ethylhexyl)-phosphoric acid (D2EHPA) has been chosen as an extractant for the purpose of this study. The interaction between XAD4 resin and D2EHPA was evaluated by physico-chemical methods of analysis (EDX and SEM). The experimental studies on adsorption of metal ions were carried out on Pb2+, Cu2+, Cd2+, Cr3+, Ni , Fe3+, Zn2+ and Ca2+. A separation method was developed for metals ions and was investigated the influence of contact time on the residual concentration of metal ions, on their removal efficiency and on the adsorption capacity of resin towards metal ions

Magnesium silicate functionalized with sodium-β-glycerophosphate used for Sr(II), Cs(I), Tl(I) adsorption

In this research Sr(II), Cs(I), Tl(I) were removed through adsorption using a functionalized solid support, magnesium silicate with sodium-β-glycerophosphate. The influence of the initial concentration of metal in the solution and of the contact time were investigated. The adsorption process runs quickly obtaining the highest adsorption capacity for Sr(I) 7 mg/g

Mining activity: Environmental impact in the West area of Romania

Pollution is a major problem updated in every corner of the world. The sources of pollution are diverse, from the natural pollution to the anthropogenic pollution. Anthropogenic pollution has a significant impact. Industrial activity, with all its fields, represents one of the most important sources of anthropic pollution. Also, the mining activities can be a source of pollution worth considering. Even if the mining activity has been completed, the possibility of pollution exists. Mining activity is the major source of industrial waste. At present, the mining units can fall into three categories: active mining, where the activity continues; in conservation mining, where the closing and greening program has not yet been applied; closed mining, which are in the Closing and Greening Program. The most affected environmental factors can be the sources of water, soil, but also air

As(V) adsorption using MFe2O4 (M=Cd2+, Ni2+) ferrite nanoparticles

The paper present the possibilities of arsenic removal from aqueous solutions using as adsorbent MFe2O4 (M=Cd2+, Ni2+) ferrite nanoparticles due to the affinity of arsenic towards iron ions. The ferrites were obtained after a heating treatment of the cadmium respectively nickel ferrioxalate coordination compounds, as precursors, at 500oC. From the two studied adsorbent material the nickel ferrite developed a higher maximum adsorption capacity (132 µg As(V)/g of ferrite) than the cadmium ferrite (109 µg As(V)/g of ferrite) in the removal process of As(V) from aqueous solutions. In both cases the equilibrium between the adsorbent and adsorbate was achieved in 60 minutes

The role of temperature in the bioaccumulation processes of mangan from surface water, in species Salvinia natans (L.) All.

In this article we wanted to demonstrate the influence that temperature has on the processes of manganese accumulation in the species Salvinia natans (L.) All. In order to reach the proposed objective, different concentrations of manganese present in the water were tested at different temperature levels (15°, 25° and 35° C) and the samples of plant material were analyzed at different time intervals (0h, 24h, 72h and 120h)

Studies on column adsorption of arsenic (V) from a real water on dehpa-impregnated XAD-8 resin

Arsenic contamination of drinking water is a widespread problem of international interest. Arsenic is released from the soil through natural processes or due to human activities. In the paper was studied the possibility of removal of arsenic from drinking water using a column filled with Amberlite XAD-8 resin impregnated with di-(2-ethylhexyl) phosphoric acid (DEHPA). The efficiency of arsenic removal from water was established by studying the dependence of arsenic residual concentration and arsenic removal degree on the volume of the water passed over the adsorbent material. The adsorption process had an efficiency of -90% and the arsenic residual concentration was smaller than 10 pg/L. The studies concerning the influence of other ions present in water (Na+, K+, Ca2+, Mg2+, Fen+, Mnn+, NO2", N H /, NO3', PO43', CF) showed that these ions do not interfere with arsenic adsorption process