Papers by Keyword: Sorption

Abstract: The principal coke modification possibility with butyl potassium xanthate was revealed. It was shown that the modified coke exhibits sorption properties with respect to nickel ions compared to untreated coke, traditionally used for melting. The influence degree of various factors on the sorption capacity of the modified coke was established.

Abstract: Contaminated water purification from products of anthropogenesis activity remains one of the main problems that chemists and ecologists are facing nowadays. The main mass of pollutants in the form of toxic compounds of heavy metals is made by insufficiently purified and untreated sewage from the mining and machine-building industries. Industrial sewage treatment has become one of the most common technological processes, thus the issues of its improvement and optimization are especially relevant.

Abstract: The magnetic particles of iron oxides are promising materials for the purification of water from ions of heavy metals and radionuclides. Their advantage compared to other sorbents is the ability to extract by applied magnetic field, which greatly simplifies the task of extraction, separation and processing in cleaning technologies. The aim of this work is investigation of temperature and concentration of iron in the solution effect on the phase composition, nanoparticle size and their magnetization. Phase magnetite in the sample increases with increasing temperature and the magnetization decreases slightly with increasing the initial concentration of iron in solution. We found that regardless of the conditions of deposition formed spherical particles whose average size ranges from 7 to 15 nm. The sorptive capacity of the particles is virtually independent of the phase composition and for cobalt is about 18 mg/g. For sorption-based material magnetic particles Fe3O4 recommended to carry out the deposition process at a temperature not lower than 80°C. The concentration of iron in solution must be within 0,15–0,3M. The particles obtained contain in their composition at least 90 wt.% of magnetite phase and are characterized by a magnetization in the range of 65–70 A·m2/kg. Also in the paper is comparing efficiency of extraction and sorption capacity for cobalt particles by different phase of magnetite and hematite.

Abstract: Sorption and desorption of moisture in epoxy composites reinforced with triangular and V-shaped bar fillers were studied. Epoxy was reinforced with vinyl ester bar assemblies fabricated according to 4 varied factors: bar orientation relative to diffusion direction (pointed or base side), bar alignment (parallel or staggered), spacing between bars (1 or 5 mm), and bar cross-sectional shape (triangular or V-shaped). Unlike previous studies, the bar fillers were initially coated with small amount of epoxy resin to improve wetting during fabrication of composites. Moisture uptake and loss of composites during one-side exposure to water vapor (50% relative humidity at 60°C) and hot air (60°C), respectively, were monitored with time. Experimental results show weight change of composites during moisture sorption and desorption varies linearly with square root of exposure time. Diffusion coefficients of composites were determined by assuming the material to be semi-infinite and fitting a mathematical solution to Fick’s second law of diffusion to weight change data. Results show diffusion coefficient of composites during moisture sorption is increased when bars are oriented pointed relative to diffusion direction, aligned parallel, spaced at 1 mm, and has triangular cross-sectional shape. However, during desorption, the diffusion coefficient is increased when base side of bars are exposed and when the bars are aligned staggered. The observed effects of factors on moisture diffusion coefficients of epoxy composites during sorption and desorption are discussed in relation to path length, available diffusion area, and status of epoxy/vinyl ester interphase before and after moisture sorption in composites.

Abstract: Devonian, and Quaternary clays of Latvia together with additive of sawdust after plastic moulding of pellets were used. Partial oxidation of sawdust and formation of active carbon after thermal shock at temperature 800°C were determined. The main clay mineral in all of clays was hydromica with some difference in the structure. Obtained materials with bulk density 1.1 g/cm³ as sorbent for different chemicals such as iodine and methylene blue was used. Dependence of sorption ability of pellets on the type of used clay (clay minerals) was determined. XRD for the determination of phase compositions, nitrogen absorption for the pore size distribution, SEM for the analysis of structure and nanoscale Zetasizer for the determination of surface charge were used.

Abstract: Oily water was treated with porous ceramic granules and immobilized microorganisms. Floating granules with bulk density of 0.63-0.66 g cm^-3 were used. The sorption of motor oil was investigated for dry and wetted granules. Respiration experiments showed that microorganisms immobilized on floating ceramic carrier and treated with oily water were influenced by agitation of liquid. The treatment of oily water with low salinity (1-9 g L^-1) showed that oil removal efficiency decreased after increasing water salinity. Likewise, oil removal efficiency decreased from 12 to 9% per gram of ceramic carrier after increasing the spill of oil from 9 to 35 g per square meter. Porous granules with immobilized microorganisms can be used in cases with insignificant oil pollution or for pretreatment of wastewater before feeding it into a wastewater treatment plant.

Abstract: Long–lived ¹³⁴Cs and ¹³⁷Cs isotopes with half-cycle of 2.06 and 30 years respectively refer to the most dangerous and wide-spread radionuclides in ecological facilities. The efficient way of removing cesium radioisotopes from the living environment is to bind them into the compounds insoluble in water. This paper presents the findings on the sorption properties of synthetic nanostructured calcium aluminosilicates (CAS) with AI:Si correlation equal to 2:2, 2:6, 2:10 and obtained in CaCI₂—AICI₃—КОН--SiO₂—H₂O multiple-component system. An isotherm investigation of cesium ion sorption produced from aqueous solution with Cs+1 from 0.2 till 6.0 mmol/L-1 concentration was carried out. Maximum sorption capacity of calcium aluminosilicates (CAS) as well as Langmuir constant was defined. The kinetics data was received and the activation energy of cation exchange in the process of sorption was estimated. The impact of 1% КCI + 6% NaCI saline background on the values of interfacial distribution coefficient (Kd) and recovery rate of cesium ions were determined.

Abstract: This work was done to assess the arsenate (AsV ) removal from the model solution by sorbents based on Fe-oxide. Two samples were compared in sorption properties, synthetically prepared Fe-oxide and bentonite/iron oxide (ratio 2:1). The effect of pH and initial metal ion concentration was investigated. The optimum pH for arsenic adsorption by both samples was found to be about 3.0. The adsorption increased very significantly with decreasing pH for both samples. The Fe-oxide sample achieved the maximum adsorption capacity 24,1 mg.g-1 AsV at pH 3, composite sample 14,1 mg.g -1 AsV at pH 3. The adsorption of AsV on Fe-oxide sample increased with the increasing initial metal ion concentration up to 40 mg/l and then equilibrium was established, by contrast of bentonite/Fe-oxide sample shown no significant change at this concentration range.

Abstract: А new polyethyleneimine sulfur-containig exchanger network structure with static exchange capacity of 0.1 N solution of HCl 4.7 mEq/g was obtained by polycondensation of glycidyl methacrylate, methyl methacrylate and phosphoric acid. Sorption of copper (II) and zinc (II) ions was studied and investigated in static conditions from model solutions of sulfates of copper and zinc, in dependence on their concentration and pH, as well as their contact time with the ion-exchanger. Found that the magnitude of the sorption capacity of the ion exchanger for ions of copper (II) at pH 3.6 CuSO4 solution is 4.03 mg / g. It has been established that zinc ion (II) is absorbed best by the sorbent at pH 4.06. In these conditions the sorption capacity of the sorbent for copper ions (II) and zinc (II) respectively equal to 0.8225 mmol / g (Cu) and 0.8305 mmol / g (Zn). The sorption ability new sulfur-containing ionite with respect to copper ions (II) and zinc (II) is significantly higher than for industrial ionite of KU-2x8.

Abstract: This study is devoted to the synthesis of calcium-deficient carbonated hydroxyapatite and the modeling study of its sorption capacity for heavy metal ions on the example of Pb²⁺. Sorption of Pb²⁺ ions was investigated in physiological conditions. It was found that the synthesized calcium-deficient carbonated hydroxyapatite is nanosized and has an excellent sorption capacity for Pb²⁺ ions – up to 588 mg/g. Characterization of the solid particles after sorption by XRD and FTIR methods showed that in the sorption process, a new crystal phase of hydroxypyromorphite was formed. Also, the sharp decrease of pH in the initial period when the material is exposed to the heavy metal solution was explained. This effect is attributed to the fast formation of the surface complex =POPb⁺, followed by the dissociation of structural water molecules in the surface layer of the material under the influence of the adsorbed lead ions.