Metal Ion Exchange by Natural Zeolites

The influence of pretreatment on the capacity and selectivity of natural zeolite for Zn2+ and Mn2+ ions has been studied. Natural tuff (sample 1), consisting mainly of zeolite clinoptilolite, was converted into the Na+ form by conditioning with 2 M NaCl at 22 °C (sample 2) and 70 °C (sample 3), respectively. Simultaneously, 0.26, 0.31, 0.38 mmol Zn2+ and 0.20, 0.23, 0.30 mmol Mn2+ were taken up by 1.00 g of zeolite samples 1, 2 and 3, respectively. The results show that zeolites converted to the Na+ form at 70 °C possess the highest capacity for metal ions. For all the zeolite samples tested, zinc was more selectively removed than manganese. The amount and composition of exchangeable cations as well as their impact on ion-exchange performances of zeolite in the process of Zn2+ and Mn2+ removal were determined

Ion Chromatographic Analysis of Anion from Slag Elution

Anions from blast furnace slag (F~, Cl", Br", NO3, NO2 and SO|") significantly influence the environment, human health, and the stability of structures. Particular attention is paid to reactions between the slag and the solution of the anions in question (of defined concentration) in the duration of 1 hour to 30 days. The anions were determined by means of the ion chromatographic analysis modified for different proportions of anions in eluents. The results of elution within reactions between slag and media point to the inertness of the system. The fluoride saturation factors of the system were experimentally determined and calculated with the help of distribution coefficients

Aqueous Leachate from Electric Furnace Slag

In manufacturing manganese and carbon steel in the basic electric arc furnace, 70 to 80 kg of slag per tonne of steel is produced, whereas the grey cast production results in 30 to 40 kg of slag per tonne of grey cast. Such large slag volumes require special care for their disposal at landfills near steel and rolling mills. It is therefore necessary to examine the chemical stability of slag under various conditions. The paper reports examinations of the chemical and phase composition of slag, as well as the number of anions and cations. The number of anions and cations in water eluates was determined in order to define the influence of such material on the environment. The phase composition of slag was determined by the X-ray diffraction method. Eluated anions (F-, Cl-, NO2-, Br-, NO3- and SO42-) were determined by ion-chromatographic analysis. Eluated cations (Na+, K+, Ca2+ and Mg2+) were established by spectrometric atom absorption. Changes in pH, conductivity and chemical composition of water eluates were monitored for 96 hours. The results have shown that the examined slag material could, with regard to its chemical and phase composition, constitute a stable Fe-Mn-Ca silicate material. However, elution of the examined components, along with the change in conductivity and pH value, implies that slag is not chemically inert and that therefore the problem of slag disposal has to be approached paying special attention on its potential impact on the environment

Isolation of Yttrium and Strontium from Soil Samples and Rapid Determination of 90Sr

A procedure of yttrium and strontium separation from calcium and other cations has been developed for rapid determination of 90Sr in soil samples. The procedure involves yttrium, strontium and other cations bound on cation exchanger AMBERLITE IR-120, separtion of yttrium and strontium from other cations, e.g. potassium, calcium, sodium, barium, on anion exchangers AMBERLITE CG-400 or DOWEX AG 1 × 8 with 0.25 mol l-1 HNO3 in alcohol mixture as eluent, separation of yttrium from strontium on cation exchanger DOWEX 50 × 8 with 3 mol l-1 HNO3, and determination of 90Sr on the low-level gas-flow β-counter and by Cherenkow counting on the liquid-scintillation counter. It has been shown that this procedure might be successfully applied in rapid determination of 90Sr, in a timesaving manner and without application of strong, concentrated acids. The method is appropriate for determination of the water soluble fraction of 90Sr in different kinds of environmental samples (milk, water, wine, vegetables, etc.) with some modification of the sample preparation procedure

The Phase Composition of Electric Furnace Slag

Elementary and phase composition as well as micrography of the electric furnace slag were examined. The base of slag is made from phases containing Fe, Mn and Ca. Grains differ in size and shape, they cling together to form bigger or smaller agglomerates, depending on separated fractions. Relative distribution of identified phases in separated fractions is presented and the possibility of phase separation by means of successive fragmentation and sieve analysis was noticed. The slag defined in that way could find application in cement production and construction industry. The electric furnace slag deposits which pollute the water and ground as well as disfigure the environment can thus be reduced

Evaluation of Croatian Clinoptiloliteand Montmorillonite-rich Tuffs for Ammonium Removal

In this Study, the ability of a Croatian clinoptiloliteand montmorillonite-rich tuffs to take up ammonium from aqueous Solutions was investigated. Montmorillonite tuff was converted into the Na+ and H+ form by treatment with Na2CO3 (w = 3-5%) and the solution of H2SO4 (w = 15%). The properties of clay modified in this way were investigated as well. The results show that the clinoptilolite tuff efficiency for ammonium removal is far superior (by 45-50%) to the removal efficiency of montmorillonite tuff. Treatment of montmorillonite tuff with Na2CO3 resulted in a slight improvement of its ammonium exchange efficiency. Acid modification of montmorillonite tuff causes a considerable decrease of ammonium exchange. Maximum loadings in ammonium exchange in clinoptilolite tuff, montmorillonite tuff, alkaline modified montmorillonite tuff, and acid modified montmorillonite tuff, as calculated by the Langmuir equation, are 1.20, 0.54, 0.64, and 0.21 mmol g-1 NH4+, respectively

Aqueous Leachate from Electric Furnace Slag

In manufacturing manganese and carbon steel in the basic electric arc furnace, 70 to 80 kg of slag per tonne of steel is produced, whereas the grey cast production results in 30 to 40 kg of slag per tonne of grey cast. Such large slag volumes require special care for their disposal at landfills near steel and rolling mills. It is therefore necessary to examine the chemical stability of slag under various conditions. The paper reports examinations of the chemical and phase composition of slag, as well as the number of anions and cations. The number of anions and cations in water eluates was determined in order to define the influence of such material on the environment. The phase composition of slag was determined by the X-ray diffraction method. Eluated anions (F-, Cl-, NO2-, Br-, NO3- and SO42-) were determined by ion-chromatographic analysis. Eluated cations (Na+, K+, Ca2+ and Mg2+) were established by spectrometric atom absorption. Changes in pH, conductivity and chemical composition of water eluates were monitored for 96 hours. The results have shown that the examined slag material could, with regard to its chemical and phase composition, constitute a stable Fe-Mn-Ca silicate material. However, elution of the examined components, along with the change in conductivity and pH value, implies that slag is not chemically inert and that therefore the problem of slag disposal has to be approached paying special attention on its potential impact on the environment

Isolation of Yttrium and Strontium from Soil Samples and Rapid Determination of 90Sr

A procedure of yttrium and strontium separation from calcium and other cations has been developed for rapid determination of 90Sr in soil samples. The procedure involves yttrium, strontium and other cations bound on cation exchanger AMBERLITE IR-120, separtion of yttrium and strontium from other cations, e.g. potassium, calcium, sodium, barium, on anion exchangers AMBERLITE CG-400 or DOWEX AG 1 × 8 with 0.25 mol l-1 HNO3 in alcohol mixture as eluent, separation of yttrium from strontium on cation exchanger DOWEX 50 × 8 with 3 mol l-1 HNO3, and determination of 90Sr on the low-level gas-flow β-counter and by Cherenkow counting on the liquid-scintillation counter. It has been shown that this procedure might be successfully applied in rapid determination of 90Sr, in a timesaving manner and without application of strong, concentrated acids. The method is appropriate for determination of the water soluble fraction of 90Sr in different kinds of environmental samples (milk, water, wine, vegetables, etc.) with some modification of the sample preparation procedure

Influence of X-ray Radiation on the Phase Composition and Morphology of Electric Furnace Slag, Clinker, and Plaster

The effect of X-ray irradiation upon the structure and morphology of samples of clinker, plaster, and electric furnace slag was studied. Slag was obtained in the process of austenite manganese steel casting. The research objective was to determine the stability of these materials under radiation. The changes that occurred were analyzed by X-ray diffraction and scanning electron microscopy. The diffractograms show changes in the profile, number, relative intensity of diffraction lines, and measured width values at half the maximum height. The micrographs show swelling and cracking of grains. As the radiation time was prolonged, this phenomenon became more evident, which points to the apparent change in the size and shape of the slag, clinker, and plaster grains, i.e. the elementary components of cement

APPLICATION OF NATURAL ZEOLITES IN ENVIRONMENT PROTECTION

U ovome radu sažeta su istraživanja i vlastita iskustva o mogućnosti iskorištavanja svojstava prirodnog zeolita kod završnog stupnja obrade vode za uklanjanje tragova metalnih iona kao kroma, srebra i arsena. Arsen prisutan u prirodnim vodama je genetskog podrijetla zbog procesa razlaganja minerala kojim prolaze podzemne vode. Ostali ispitivani metalni ioni su uglavnom antropogenog podrijetla zbog utjecaja kemijske, tekstilne i metalurške industrije. Rezultati istraživanja pokazali su da je efikasnost uklanjanja arsenovih iona na željezom modificiranim zeolitima za niže koncentracijsko područje do 100 %, kromovih iona za koncentracijsko područje 0,5-20 mg/L od 40 do 60 % ovisno o modifikaciji zeolita, a srebrovih iona za koncentracijsko područje 5-120 mg/L od 55 do 70 % ovisno o nalazištu prirodnog zeolita.The paper summarizes the findings and our own experience regarding exploitation of the properties of natural zeolite in the final processing of water to remove traces of metal ions like chromium, arsenic and silver. Arsenic present in natural waters is of genetic origin and is due to the process of decomposition of minerals in groundwater. Other examined metal ions are mainly of anthropogenic origin and come from the chemical, textile and metallurgical industries. The results showed that the efficiency of arsenic removal using iron modified zeolites for the lower concentration range is up to 100%, for chromium ions in concentration range from 0.5 to 20 mg/L is 40 to 60% depending on the modification of zeolites, and for silver ions in concentration range from 5-120 mg/L from 55 to 70% depending on the deposit of the natural zeolite