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The two retention models, the linear solvent strength model (LSS) and the quadratic relationship, in addition to artificial neural network (ANN) approach, were compared in their ability to predict the retention behaviour of common cations (Li, Na, NH4, K, Mg, and Ca) in isocratic ion chromatography using the methanesulfonic acid (MSA) eluent. Over wide variations in the MSA concentration, the quadratic model shows a quite good prediction power. LSS can be used only for monovalent cations and in the proximity of the experimental design point. ANN fails to predict the retention for the data not included in the training set. To find the optimal conditions in the experimental design, the normalized resolution product as a chromatographic objective function was employed. The optimum MSA concentration in the eluent on a Dionex CS12 column was found to be 18 mM, with the total analysis time of less than 10 min. [Projekat Ministarstva nauke Republike Srbije, br. III43009]

Interpretive retention modeling was utilized to optimize the isocratic ion chromatographic (IC) separation of the nine anions (formate, fluoride, chloride, nitrite, bromide, nitrate, phosphate, sulfate, oxalate). The carbonate-bicarbonate eluent was used and separation was done on a Dionex AS14 ion-exchange column. The influence of combined effects of two mobile phase factors, the total eluent concentration (2 - 6 mM) and the carbonate/bicaronate ratio from 1:9 to 9:1 (which corespondent to pH range 9.35 - 11.27), on the IC separation was studied. The multiple species analyte/eluent model that takes into account ion-exchange equilibria of the eluent and sample anions was used. In order to estimate the parameters in the model, a non-linear fitting of the retention data, obtained at two-factor three-level experimental design, was applied. To find the optimal conditions in the experimental design, the normalized resolution product as a chromatographic objective function was employed. This criterion includes both the individual peak resolution and the total analysis time. A good agreement between experimental and simulated chromatograms was obtained. [Projekat Ministarstva nauke Republike Srbije, br. III43009]

This paper presents the extraction of major and trace elements from a coal sample, in deionized water, by using three different extraction techniques. Rotary mixing and ultrasonic extraction were examined for different extraction times, while the microwave assisted extraction was performed at different temperatures. Metal concentrations (Na, K, Ca, Mg, Al, Fe, Mn, Be, Cd, Co, Cr, Hg, As, Ni, Se, Sb and Pb) in a solution were determined by employing the inductively coupled plasma atomic emission spectrometry; whereas the results obtained for Na, K, Ca and Mg were compared employing ion chromatography. Comparing the rotary and ultrasonic-assisted extraction it is shown that the former is more efficient for the determination of Fe, Na and Pb, whereas the latter one has proven more efficient for the determination of Co and Cr ions. Microwave-assisted extraction has proven the most efficient method for any elements tested in coal. In addition, sequential extraction of elements was done using microwave digestion. The results of sequential extraction experiments indicated associations of investigated elements with a mineral phase and organic matrix. Sequential extraction provided information on possible leaching of As, Cd, Co, Cr, Ni, Pb, Fe and Mn in environmental conditions. [Projekat Ministarstva nauke Republike Srbije, br. 172030]

Ultrapure water with minimum contents of impurities is used for the preparation of steam in thermal power plants. More recently it has been found that the corrosion process is also influenced by sodium ions, chloride ions, and all forms of silicon in water. At higher temperatures and under high pressure the less soluble compounds of silicon are extracted, which form deposits on the walls of the boiler, the piping system and the turbine blades. Silicon is found in water in the form of different types (species) which are characterized by specific physical and chemical properties. Distinctions can be made between highly reactive species of ionic (silicate anions) and molecular forms (silicic acid) and relatively inert types (suspended, colloidal, and polymerized silicon). The determination of various forms of silicon in water is a complex analytical task. This paper covers relevant research in the field of silicon specification analysis. Maintaining the unchanged, original composition of silicon species during various stages of analysis (sample collection, storage, and conservation) has been given special attention. A large number of methods and procedures have been developed for the analysis of species of silicon, including chromatographic, spectroscopic and electrochemical techniques and combinations thereof. The techniques used for determining both the total amount and individual forms of silicon have been singled out. There is also an overview of the coupled techniques used most frequently in practice by using the methodology which involves preliminary separation of species and then individual specification. The paper offers an overview of analytical properties, advantages and disadvantages of the most representative analytical methods developed specifically for the analysis of silicon species in ultrapure water. The most important studies focusing on the silicon species in water have been highlighted and presented in detail. The determination of silicon content in water is of great importance because of various effects of silicon species (corrodibility and toxicity) and the selection of methods for the efficient removal of silicon from water.

Micro-electro-mechanical systems (MEMS) are miniturized devices that can sense the environment, process and analyze information, and respond with a variety of mechanical and electrical actuators. MEMS consists of mechanical elements, sensors, actuators, electrical and electronics devices on a common silicon substrate. Micro-electro-mechanical systems are becoming a vital technology for modern society. Some of the advantages of MEMS devices are: very small size, very low power consumption, low cost, easy to integrate into systems or modify, small thermal constant, high resistance to vibration, shock and radiation, batch fabricated in large arrays, improved thermal expansion tolerance. MEMS technology is increasingly penetrating into our lives and improving quality of life, similar to what we experienced in the microelectronics revolution. Commercial opportunities for MEMS are rapidly growing in broad application areas, including biomedical, telecommunication, security, entertainment, aerospace, and more in both the consumer and industrial sectors on a global scale. As a breakthrough technology, MEMS is building synergy between previously unrelated fields such as biology and microelectronics. Many new MEMS and nanotechnology applications will emerge, expanding beyond that which is currently identified or known. MEMS are definitely technology for 21st century.

The sorption of inorganic arsenic species, As(III) and As(V), from water by sepiolite modified with hydrated iron(III) oxide was investigated at 25 °C through batch studies. The influence of the initial pH value, the initial As concentrations, the contact time and types of water on the sorption capacity was investigated. Two types of water were used, deionized and groundwater. The maximal sorption capacity for As(III) from deionized water was observed at initial and final pH value 7.0, while the bonding of As(V) was observed to be almost pH independent for pH value in the range from 2.0 to 7.0, and the significant decrease in the sorption capacity was observed at pH values above 7.0. The sorption capacity at initial pH 7.0 was about 10 mg gˉ1 for As(III) and 4.2 mg gˉ1 for As(V) in deionized water. The capacity in groundwater was decreased by 40 % for As(III) and by 20 % for As(V). The Langmuir model and pseudo-second order kinetic model revealed good agreement with the experimental results. The results show that Fe(III)-modified sepiolite exhibits significant affinity for arsenic removal and it has a potential for the application in water purification processes. [Projekat Ministarstva nauke Republike Srbije, br. III 45019, III 43009 i TR 37010]

Arsenic exists in the form of various chemical species differing by their physicochemical behavior, in toxicity, bioavailability and biotransformation. The determination of arsenic species is an important issue for environmental, clinical and food chemistry. However, differentiation of these species is a quite complex analytical task. Numerous speciation procedures have been studied that include electrochemical, chromatographic, spectrometric and hyphenated techniques. This review comprehends the relevant research in the field of arsenic speciation analysis with novel applications and significant advances. Stability of arsenic species and each of the analytical steps (sample collection, storage, preservation, extraction) of the arsenic speciation methods was particularly evaluated. Analytical validation and performance of these methods are also reviewed.

The aim of this study is to investigate the possibilities of removing lead, cadmium, and zinc from air by sorption natural wool fibers (NWF), thus evaluating possible application of the wool materials in direct protection of air from the influence of heavy metals. Metal detection was done (before and after the sorption process) by potentiometric stripping analysis. Sorption experiments were done in two ways: by immersing NWF in model solutions (prepared by the working standard solutions and deionized water), and by immersing NWF in solutions of sediments from the air. The influence of mass sorbent, sorption time, pH, and temperature on the sorption of lead, cadmium, and zinc were experimentally examined. Effectiveness of lead, cadmium, and zinc sorption by applying natural wool fibers is shown as the sorption capacity (a ratio between metal concentration before and after sorption and sorbent mass). Sorbent of 0.1 g NWF mass in neutral environment collects: after 10 min 23,9% of lead, 19,0% of cadmium, and 21,3% of zinc; whereas after 30 min 71.5% of lead, 69.6% of cadmium, and 69.4% of zinc. NWF of the same mass in acidic environment shows lower sorption capabilities, for pH 4.5 the effective sorption is: 68.6% of lead, 66.8% of cadmium, and 66.6% of zinc; whereas for pH 2.1 NWF sorption is 54.6% of lead, 53.2% of cadmium, and 52.9% of zinc. Optimal pH range for application of this sorption during the experiment material is 4.5-7.0. The sorption was made in solutions with pH 2.1 due to potentiometric stripping analysis application conditions. Temperature significantly impacts the tested material sorption characteristics. When temperature slightly increases, regardless of the inflicted damage, NWF keeps its functionality. When temperature is higher than 60°C, the sorbent effectiveness is reduced. The NWF sorption capacity is lowest at 100°C: for lead 11.63 μg g−1, for cadmium 8.18 μg g−1, and for zinc 9.41 μg g−1. Results of the experimental research have shown that a high degree of removal (about 70%) can be achieved provided that the mass of the sorbent rages from 0,06−0,1 g, contact time is long enough (30 min), and that there are no significant effects of temperature and pH.

A simple and efficient method for separation and determination of dimethylarsenate DMAs(V) was developed in this work. Two resins, a strong base anion exchange (SBAE) resin and iron-oxide coated hybrid (HY) resin were tested. By simple adjusting pH value of water at 7.00, DMAs(V) passed through the HY column without any changes, while all other arsenic species [inorganic arsenic and monomethylarsonate, MMAs(V)] were quantitatively bonded on HY resin. The resin capacity was calculated according to the breakthrough points in a fixed bed flow system. At pH 7.00 the HY resins bonded more than 4150 μg g-1 of As(III), 3500 μg g-1 of As(V) and 1500 μg g1 of MMAs(V). Arsenic adsorption behavior in the presence of impurities showed tolerance with the respect to potential interference of anions commonly found in natural water. DMAs(V) was determined in the effluent by ICP-MS. The detection limit was 0.03 μg L?1 and relative standard deviation (RSD) was between 1.1?7.5 %. Proposed method was established performing standard procedures: with external standard, certified reference material and the standard addition method.

Inorganic arsenic removal from water using low-cost adsorbents is presented in this paper. Selective removal of As(III) and As(V) from water was performed with natural materials (zeolite, bentonite, sepiolite, pyrolusite and limonite) and industrial by-products (waste filter sand as a water treatment residual and blast furnace slag from steel production); all inexpensive and locally available. Kinetic and equilibrium studies were realized using batch system techniques under conditions that are likely to occur in real water treatment systems. The natural zeolite and the industrial by-products were found to be good and inexpensive sorbents for arsenic while bentonite and sepiolite clays showed little affinity towards arsenic. The highest maximum sorption capacities were obtained for natural zeolite, 4.07 mg As(V) g-1, and waste iron slag, 4.04 mg As(V) g-1.

Coastal area surrounding the river Ibar, in the area between cities of Kosovska Mitrovica and Leposavić in the north of Kosovo and Metohija, is occupied with seven industrial waste dumps. These dumps were all part of the exploitation and flotation refinement of raw mineral materials, metallurgic refinement of concentrates, chemical industry, industrial refinement and energetic facilities of Trepča industrial complex. The existing waste dumps, both active and inactive, are of heterogenic chemical composition. Its impact on the river water is shown by the content of heavy metals found in it. Removal of lead, cadmium and zinc would be economically unrewarding, regardless of the technology used. Wooden plant that prevails in this area is white willow. This work is focused on the removal of heavy metals (Pb, Cd and Zn) from the water of the river Ibar using white willow. Roots of the willow are cultivated using the method of water cultures in an individual solution of heavy metals and river water sample. The preparation of the samples for analysis was performed by burning the herbal material and dissolving ashes in the appropriate acids. The concentrations of metals were determined by the stripping analysis. In the investigated heavy metal solutions the biomass increase is 25.6% in lead solution, 27.3% in cadmium and 30.7% in zinc solution. The increase of biomass in nutritional solution, without the heavy metals, is 32.4% and in river water sample 27.5%. The coefficient of bioaccumulation in solutions with heavy metals is 1.6% in lead solution, 1.9% in cadmium and 2.2% in zinc solution. Heavy metals accumulation is 18.74 μg of lead, 20.09 μg of cadmium and 22.89 μg of zinc. The coefficient of bioaccumulation of the water samples, that contained 44.83 μg/dm3 of lead, 29.21 μg/dm3 of cadmium and 434.00 μg/dm3 of zinc, during the period of 45 days, was 30.3% for lead, 53.4% for cadmium and 3.9% for zinc. The concentrations of accumulated metals from the river water are 19.01 μg of lead, 21.85 μg of cadmium and 23.96 μg of zinc in grams dry matter. The obtained results indicate that the willow can contribute to the decontamination of moderately contaminated river water from Pb, Cd and Zn.

A suppressed ion chromatography (IC) technique, using a carbonate/hydrogen carbonate or a hydroxide eluent, has been evaluated as a monitoring tool for the detection of major anions (F-, Cl-, NO3-, PO43- and SO42-) in ultra pure water and condensed steam from thermal power plants. An electrical conductivity detector with an anion-exchange column (IonPac AS14), an auto self-regenerating suppressor (ASRS), and an isocratic high-pressure pump system were used for the detection of low concentrations of inorganic anions. It was shown that the suppressed IC technique provides a suitable means for preventing possible damage to generating equipment in power plants. The detection limits of the method for the anions of interest were < 0.3 μg/L.

This study offers some insight into the significance of water quality control in thermal power plants. In order to maintain high reliability indices in thermal plants and to realize the expected lifetime of these plants, high water quality should be accomplished. Also, the working tools of the analyst in thermal power plants and the types of problems, which help in solving daily tasks, are discussed. The difficulties the analyst might face are indicated. This review considers the implementation of standard control and diagnostic parameters crucial for water quality in all segments of a water-steam system. The subject of this paper was to analyze anion traces in the water-steam cycle, using a modern, highly sensitive instrumental method the method of ion chromatography (1S). Thus, the possibility of monitoring ionic species that can cause corrosion processes in the water-steam system is examined.

The quality of life depends on water quality. Good water quality and the rational use of water are an absolute need of the new millennium. Although it is an ecological and health priority to prohibit the contamination of water and water protection, it is a responsibility for environmental engineers and chemists to develop and apply effective methods for monitoring and controlling of water quality, and at that way prevent ecological and technological catastrophe on time. In this paper modern methods and process for monitoring, control and detection of cyanide in water and wastewater are presented. Recent developments in instrumental techniques and treatment for determination of this toxic substance in water are described, particularly the methods according to green analytical aspects.

The subject of this paper was to consider the possibilities of economical paper production with rationalization of water consumption. In accordance with the principles of viable development. The pulp & paper industry has had to face global market needs and strict regulation concerning the environment. The basic motive was to provide consistent and high product quality, which is competitive on the market. The pulp & paper industry is one of the largest consumers and pollutants of natural resources. In that light, the rationalization of raw material, water, energy and chemicals consumption with minimization of environmental impact is essential. The European directive on environmental protection obliges producers of pulp & paper to decrease the volume of wastewater and to increase the efficiency treatment. Pulp and paper industry in Serbia and Montenegro will also be faced with the demands for environmental protection. Numerous examples of water consumption rationalization and improvement of water quality in the pulp & paper industry could be found in different literature sources. It is necessary to increase water system closure and implement up-to-date treatment methods. The possibilities for water consumption rationalization, in a real system the paperboard mill UMKA, were examined.

Strict ecological legislation, especially in highly developed countries, imposed requirements for the purification of industrial effluents and the need for efficient oil clean up after sea and inland water spills. Although numerous processes have been developed, the application of sorbents is still one of the most efficient methods to remove heavy metal ions, dyes and crude oil from water. Recently, special attention was paid to sorbents based on natural fibres. A review of studies concerning the sorption properties of wool is presented in this paper. The presence of various functional groups on the wool fibre surface contributes to the efficient sorption of heavy metal ions and dyes. A hydrophobic, scaly surface and fibre crimp strongly influence the high sorption capacity of wool for oil. Wool has great sorption potential even as a recycled material. Accordingly, it can be used as a viable substitute to commercially available synthetic sorbents that show poor biodegradab ility.

In order to maintain high reliability indices in thermal power plants and to realize the expected lifetime of these plants, high water quality should be accomplished. Also, an insight in the working tools of the analyst in thermal power plants and into the types of problems, which help in solving daily tasks, is given. This review considers the implementation of standard control parameters crucial for the indication of water quality in all segments of a water-steam system. A concept of modernization of the system for analytical control and monitoring in the water-steam cycle is suggested.

In this paper modern methods and techniques for water purification are described. Good water quality and the rational use of water are an absolute need of the new millennium. The quality of life depends on water quality. Although it is an ecological priority to prohibit the contamination of water, it is a responsibility for environmental engineers and chemists to develop and apply effective methods for water purification. Beside well-known methods and techniques, it is necessary to create new methods for water purification and treatment. Water recycling is especially important. Plants with membrane separation technologies enable savings in fresh water with high efficiency. Methods for monitoring and controlling processes and water protection should be developed simultaneously with the development of techniques for the methods for purification.

The interactions of n-hexane, benzene, chloroform, and tetrahydrofuran with dried (amorphous) chromia (I) and chromia heated at 1073 K (crystalline) (II), both obtained from a colloidal dispersion, and a commercially available chromia (III) were studied by inverse gas chromatography (IGC) under finite surface coverage conditions. The isotherms, in the temperature range 383 – 423 K, were used to estimate the surface area, the adsorption energy distribution, the isosteric heat of adsorption, and the spreading pressure on the surfaces of the solids. The uniformly reduced adsorption ability of the heated chromia was attributed to the dehydroxylation of the surface at the higher temperatures. Both solids showed an increased affinity toward chloroform molecules, as a result of strong acid-base interaction.

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Copyright of Chemical Industry / Hemijska Industrija is the property of Association of Chemical Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)