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  • Author: Elwira Tomczak x
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Application of ANN to the Sorption Equilibrium Modelling of Heavy Metal Ions on Clinoptilolite

The latest achievements in the field of mathematical modelling include the application of artificial neural networks (ANN). A growing interest in the ANN is confirmed by the number of publications devoted to the applicability of ANN in chemical, process and environmental engineering. A recent dynamic development of ANN provided an efficient and universal tool that is used to solve many tasks, including modelling, approximation and identification of objects. The initial step of applying the network to a given process consists in the determination of weights of the proposed neural network structure. This is performed on the basis of training data. A network that is properly trained allows correct information to be obtained on the basis of other data which have not been used in the network training. In most cases the network training is performed on the basis of a known mathematical model. However, the training of a network can be also performed using experimental data. In this paper, the sorption isotherms were predicted by means of a multilayer perceptron (MLP). Calculations were made using a training program written in Matlab, which took advantage of the Lavenberg-Marquardt procedure. In the last decade a growing interest is observed in inexpensive and very cheap adsorbents to remove heavy metal ions. Clinoptilolite is the mineral sorbent extracted in Poland used to remove heavy metal ions from diluted solutions. Equilibrium experiments were carried out to estimate sorptivity of a clinoptilolite and its selectivity towards Cu(II), Zn(II) and Ni(II) ions for multicomponent solution. Calculations with the use of MLP enabled description of sorption isotherms for one, two and three ions which were present at the same time in the solution. The network also enabled an analysis of sorption of the single ion, taking into account the effect of its concentration.

Abstract

The azo dye and plant-derived sorbent system was investigated in this paper. Direct Orange 26 azo dye was acquired from Boruta-Zachem Kolor Sp. z o.o. Chemically modified granulated corncobs obtained from Chipsi Mais Germany were used as the biosorbent. The changes in the dye and sorbent concentrations with time were measured and used for further calculations. The experiments were carried out in a laboratory fixed bed column. Breakthrough curves were plotted for different initial concentrations, volumetric flow rates and bed heights. Sorption dynamics was described by a model presented in the literature. It was demonstrated that Infrared analysis of the system allows to determine the nature of the dye-sorbent bond. It was found that corncobs can be used as a promising sorbent material.

Abstract

Azo dye-plant sorbent system was investigated in the paper. Direct Orange 26 and Reactive Blue 81 azo dyes were sourced from Boruta-Zachem Kolor Sp. z o.o. Mechanically and chemically modified rye straw was used as a “low-cost” biosorbent. During experiments, dye concentration changes in the solution and sorbent in time were measured at constant temperature until equilibrium was reached. Sorption equilibrium was described by 2-parameter (Freundlich, Langmuir) and 3-parameter (Redlich-Peterson and Radke-Prausnitz) equations widely used in adsorption studies. Characteristic coefficients of equations were determined and the proposed approximations of the results of experimental studies were evaluated statistically. Higher sorption capacity was obtained for Direct Orange 26 than for Reactive Blue 81.

Abstract

The sewerage network in Poland, built in the early 20th century, has been losing its original water-tightness and flow capacity. To bring these characteristics back, rehabilitation works are performed. The initial capacity of sewers can be restored without affecting the urban environment thanks to the trenchless technology. The sewer subjected to rehabilitation receives a new internal leakproof layer capable of preventing groundwater infiltration as well as sewage leaks, which can contaminate the environment. This paper intends to compare the trenchless technology with traditional open cut trench excavation. In the study, two variants of trenchless rehabilitation were considered: one performed with the help of GRP panels and the other using cured-in-place pipe (CIPP) lining. Flow velocities and flow rates in the sewers before and after rehabilitation were compared. Also, selected economic and environmental aspects of sewer rehabilitation methods were examined.

Abstract

This article describes a method for producing polymeric membranes by adding carbon nanostructures in the form of graphene oxide (GO). The reference membrane (having typical composition) was formed via phase inversion, using polyvinylidene fluoride (PVDF) dissolved in dimethylacetamide (DMAC). The polymeric matrix was additionally enriched with a plasticizer, i.e. polyethylene glycol (PEG). Afterwards, graphene oxide ultrasonically dispersed in dimethylacetamide was added to basic matrix. The membranes were further compared with one another by measuring their contact angle and hydrodynamics. The results were compared with the literature reports. The transport properties of the membranes were assessed with experimental ultrafiltration equipment (KOCH Membrane System). Also, their permeate flux and mass transfer resistance were determined.

Abstract

It was examined if buckwheat hull has a potential to be used to adsorb heavy metal ions Zn(II), Cd(II), Co(II), Cu(II), Ni(II) from water. The research involved experiments aimed at the determination of sorption kinetics taking into consideration changes of concentration in a solution and sorbent over time. According to the literature data, kinetics is described with the use of pseudo first-order equations. Application of fractional derivatives for the description of sorption kinetics enables the development of the generalised sorption kinetics equation. Result analysis with this concept requires making a computational procedure using gamma functions and infinite series. Kinetics description using fractional derivatives will be equations with two parameters ie fraction of derivative α and the kinetics constant K dependent on the analysed sorbent-adsorbate system.

Abstract

This paper evaluates ceramic membrane performance and fouling mechanisms in the ultrafiltration of model oil-in-water solutions with addition of NaCl. First, the work estimated the effect of main process parameters, i.e. transmembrane pressure, cross-flow velocity and NaCl content in the feed on oil rejection and permeate flux using 23 experimental design. The ultrafiltration experiments were carried out using pilot installation with commercial tubular ceramic 300 kDa membrane. Ultrafiltration data obtained using experimental design technique was used to determine the regression coefficients of polynomial equations. These equations give information on non-conjugated as well as conjugated effects of two operating parameters and one feed parameter on ceramic membrane performance in ultrafiltration process of model oil-in-water-NaCl solutions. Moreover, these equations can help to determine optimal conditions for ultrafiltration process from the point of view of membrane permeability and selectivity. Next, ultrafiltration results were analyzed using resistance-in-series model. It was found that the process is membrane resistance limited. It was also stated that, resistance caused by reversible fouling is greater than irreversible fouling resistance. Finally, pore blocking models based on modified Hermia’s equation were used to determine membrane fouling mechanism responsible for permeate flux decline with ultrafiltration time. In investigated system ceramic membrane fouling was caused by complete and intermediate pore blocking mechanisms.