Search results

Filters

  • Journals
  • Keywords
  • Date

Search results

Number of results: 12
items per page: 25 50 75
Sort by:

Abstract

The possibility of the application of nontraditional method of greenhouse gas utilization by the injection of CO2 (sequestration) into porous geological deposits, treated as unconventional gas collectors, requires the fulfillment of basic criteria such as the impact on the environment and long term storage. The important issue is the physical behavior of the deposit during the porous structure saturation phase by carbon dioxide. What should be mentioned first and foremost is: the availability of CO2 transport along the porous structure and adsorption capacity. The work presents the results of water vapor sorption on coal samples from selected Hard Coal Mines of a differentiated carbon content. The received results were presented in the form of sorption and desorption isotherms performed in a temperature of 303 K. It was additionally described with a BET adsorption isotherm. Based on sorption data, a specific surface area was calculated, in accordance with BET theory. The amount of the adsorbed water vapor molecules for the analyzed coal samples was dependent on the degree of metamorphism. The obtained isotherms can be described as type II according to the BET classification. Volumetric type apparatus -adsorption- microburette liquid was used for the sorption experiments. Water vapor sorption in relation to coals allows for the quantitative determination of primary adsorption centers as a measure of adsorbed molecule interconnections with the adsorbent surface. Based on the BET adsorption equation, out of water vapor isotherms, the amount of adsorption active centers, which potentially may take part in CO2 adsorption in coal seams during injection of this gas, was determined. The sorption capacity of coals is determined by the degree of metamorphism, which also has very large impact on the sorption capacity of the deposit.
Go to article

Abstract

The sorption isotherm and sorption kinetics of NH4+ by the Fen River reservoir sediment were investigated for a better understanding of the NH4+ sorption characteristics and parameters. The results showed that Q (adsorption content) increased with the increase of Ceq (equilibrium concentration), sorption isotherms could be described by Freundlich equation (R2 from 0.97 to 0.99). Cation exchange capacity (CEC) had a significant correlation with the parameters K and n (R2 was 0.85 and 0.95, respectively). The ENC0 (Ceq as Q was zero) of S1, S2, S3 and S4 was 1.25, 0.57, 1.15 and 1.14 mg L-1, respectively, and they were less than the NH4+ concentrations in reservoir water. The sediments released NH4+ to the Fen River reservoir water and acted as a pollution source, in the form of complex and heterogeneous adsorbents. The NH4+ adsorption kinetic process was composed of ‘fast’ and ‘slow’ reaction patterns and could be fitted using both Elovich equation and Pseudo second-equation. More than one-step may be involved in the NH4+ sorption processes, and interior diffusion was not dominant ion action.
Go to article

Abstract

The trigeneration systems for production of cold use sorption refrigeration machines: absorption and adsorption types. Absorption systems are characterized namely by better cooling coefficient of performance, while the adsorptive systems are characterized by the ability to operate at lower temperatures. The driving heat source temperature can be as low as 60-70 °C. Such temperature of the driving heat source allows to use them in district heating systems. The article focuses on the presentation of the research results on the adsorption devices designed to work in trigeneration systems.
Go to article

Abstract

This study was undertaken to determine the effectiveness of biosurfactants - saponin, tannin and rhamnolipids JBR 515 and 425, for the removal of cadmium, zinc and copper from activated sludge immobilized in 1.5% sodium alginate with 0.5% polyvinyl alcohol. We also established the impact of pH value on biosorbent regeneration with the analyzed biosurfactants and determined the critical micelle concentration (CMC) in solutions containing the biosorbent and biosurfactant and in exact samples with heavy metals. Saponin exhibited the highest effectiveness of metals leaching at pH 1-5, and rhamnosides at pH 5-6. In addition, the study demonstrated a significant effect of the ratio of biosorbent mass to washing agent volume (m/V) on the effectiveness of metals leaching. Of the biosurfactants analyzed, saponin was ca. 100% effective in leaching zinc and copper. The effectiveness of the other biosurfactants was lower and depended on the metal being leached
Go to article

Abstract

The evaluation of threats connected with the presence of methane in coal seams is based on our knowledge of the total content of this gas in coal. The most important parameter determining the potential of coal seams to accumulate methane is the sorption capacity of coal a. It is heavily influenced by the degree of coalification of the coal substance, determined by the vitrinite reflectance R0 or the content of volatile matter V daf. The relationship between the degree of coalification and the sorption capacity in the area of the Upper Silesian Coal Basin (USCB) has not been thoroughly investigated, which is due to the zonation of methane accumulation in this area and the considerable changeability of methane content in various localities of the Basin. Understanding this relationship call for in-depth investigation, especially since it depends on the analyzed reflectance range. The present work attempts to explain the reasons for which the sorption capacity changes along with the degree of coalification in the area of Jastrzębie (the Zofiówka Monocline). The relationship between parameters R0 and V daf was investigated. The authors also analyzed changes of the maceral composition, real density and the micropore volume. Furthermore, coalification-dependent changes in the sorption capacity of the investigated coal seams were identified. The conducted analyses have indicated a significant role of petrographic factors in relation to the accumulation properties of the seams located in the investigated area of USCB.
Go to article

Abstract

In the last decade a growing interest was observed in low-cost adsorbents for heavy metal ions. Clinoptilolite is a mineral sorbent extracted in Poland that is used to remove heavy metal ions from diluted solutions. The experiments in this study were carried out in a laboratory column for multicomponent water solutions of heavy metal ions, i.e. Cu(II), Zn(II) and Ni(II). A mathematical model to calculate the metals' concentration of water solution at the column outlet and the concentration of adsorbed substances in the adsorbent was proposed. It enables determination of breakthrough curves for different process conditions and column dimensions. The model of process dynamics in the column took into account the specificity of sorption described by the Elovich equation (for chemical sorption and ion exchange). Identification of the column dynamics consisted in finding model coefficients β, KE and Deff and comparing the calculated values with experimental data. Searching for coefficients which identify the column operation can involve the use of optimisation methods to find the area of feasible solutions in order to obtain a global extremum. For that purpose our own procedure of genetic algorithm is applied in the study.
Go to article

Abstract

The removal of organic dyes from industrial wastewater remains a problem, both technically and economically. In this study, Yarrowia lipolytica yeast cells were isolated from poultry meat and immobilized using alginate. The immobilized Yarrowia lipolytica yeast was used as biosorbent to remove methylene blue (MB) dye from synthetic effl uent water. The results show that maximum adsorption capacity under optimum conditions was 66.67 mg∙g-1. The equilibrium adsorption data fi tted well onto the Freundlich adsorption isotherms with R2 >0.99. Adsorption kinetics was of pseudo-second order process suggesting that the adsorption was a chemisorption. FTIR spectra identifi ed typical absorption bands of a biosorbent. Sorption of MB dye on Yarrowia lipolytica yeast cells was exothermic with weak sorption interaction.
Go to article

Abstract

The compost derived from cellulosic material coming from the Public Utility Company in Zabrze (Poland) was investigated for its capability for adsorbing acid dyes from aqueous solution at various concentrations of the dyes and the compost dosages. Four acid dyes were investigated: Acid Red 18 (AR-18), Acid Blue 9 (AB-9), Acid Green 16 (AG-16) and Acid Black 1 (ABk-1). The adsorption isotherms were determined by comparing the experimental data with the isotherm models (Freundlich, Langmuir and Dubinin–Radushkevich models). The sorption capacity of the compost depended on the initial concentrations of dyes in the solution, compost dosage, and on the structure of dyes. The maximum sorption capacities of the compost for adsorbing particular dyes may be ordered as follows: ABk-1 > AG-16 > AB-9 > AR-18. The amounts of bound and the percentages of removed acid dyes from effluent depended on the adsorbent dosage. The growth of the dye removal percentages with growing adsorbent mass may be attributed to the growth of the adsorbent uptake surface with growth of the adsorbent mass. The dyes were bound onto the surface of compost through the electrostatic interaction between the surface (negatively charged at pH > pHPZC) and the dye cations (AG-16), and/or through the hydrogen bond between the functional groups of the humic matter in compost (–OH, –COOH) and the functional surface groups of AR-18, AB-9 and ABk-1 dyes (–OH, –NH2 ). At the experiment conditions, the Freundlich and Dubinin-Raduskevich adsorption isotherm models fitted the equilibrium data very well (much better than the Langmuir one). The values of 1/n in the Freundlich equation and E in the Dubinin-Raduskevich one indicate the favourable adsorption. The studied compost may be used as a low-cost sorbent for the removal of acid dyes from wastewater released by textile industries. However, elevated values of chemical oxygen demand (COD) in the final solutions may enhance the solubility of humic compounds.
Go to article

Abstract

In this review, research carried out on sorption-enhanced steam methane reforming (SESMR) process is presented and discussed. The reactor types employed to carry out this process, fixed packed bed and fluidized bed reactors, are characterized as well as their main operating conditions indicated. Also the concepts developed and investigations performed by the main research groups involved in the subject are summarized. Next the catalysts and CO2 sorbents developed to carry out SE-SMR are characterized and the relationships describing the reaction and sorption kinetics are collected. A general approach to model the process is presented as well as results obtained for a calculation example, which demonstrate the main properties of SE-SMR.
Go to article

Abstract

The knowledge about membrane contactors is growing rapidly but is still insufficient for a reliable designing. This paper presents a new type of membrane contactors that are integrated with one of the following ways of separation by using absorbents, micelles, flocculants, functionalized polymers, molecular imprints, or other methods that are based on aggregation. The article discusses methods for designing multi-stage cascade, usually counter-current. At every stage of this cascade, relevant aggregates are retained by the membrane, while the permeate passes freely through membrane. The process takes place in the membrane boundary layer with a local cross-flow of the permeate and the retentate. So the whole system can be called a cross-counter-current. The process kinetics, k, must be coordinated with the permeate flux, J, and the rate of surface renewal of the sorbent on the membrane surface, s. This can be done by using ordinary back-flushing or relevant hydrodynamic method of sweeping, such as: turbulences, shear stresses or lifting forces. A surface renewal model has been applied to adjust the optimal process conditions to sorbent kinetics. The experimental results confirmed the correctness of the model and its suitability for design of the new type of contactors.
Go to article

Abstract

The results of researches of sorption processes of surface layers of components of sand moulds covered by protective coatings are presented in the hereby paper. Investigations comprised various types of sand grains of moulding sands with furan resin: silica sand, reclaimed sand and calcined in temperature of 700oC silica sand. Two kinds of alcoholic protective coatings were used – zirconium and zirconium – graphite. Tests were performed under condition of a constant temperature within the range 30 – 35oC and high relative air humidity 75 - 80%. To analyze the role of sand grains in sorption processes quantitavie moisture sorption with use of gravimetric method and ultrasonic method were used in measurements. The tendency to moisture sorption of surface layers of sand moulds according to the different kinds of sand grains was specified. The effectiveness of protective action of coatings from moisture sorption was analyzed as well. Knowledge of the role of sand grains from the viewpoint of capacity for moisture sorption is important due to the surface casting defects occurrence. In particular, that are defects of a gaseous origin caused by too high moisture content of moulds, especially in surface layers.
Go to article

This page uses 'cookies'. Learn more