Removal of cationic pollutants from water by xanthated corn cob: optimization, kinetics, thermodynamics, and prediction of purification process

The removal of Cr(III) ions and methylene blue (MB) from aqueous solutions by xanthated corn cob (xCC) in batch conditions was investigated. The sorption capacity of xCC strongly depended of the pH, and increase when the pH rises. The kinetics was well fitted by pseudo-second order and Chrastil’s model. Sorption of Cr(III) ions and MB on xCC was rapid during the first 20 min of contact time and, thereafter, the biosorption rate decrease gradually until reaching equilibrium. The maximum sorption capacity of 17.13 and 83.89 mg g-1 for Cr(III) ions and MB, respectively was obtained at 40 °C, pH 5 and sorbent dose 4 g dm-3 for removal of Cr(III) ions and 1 g dm-3 for removal of MB. The prediction of purification process was successfully carried out and the verification of theoretically calculated amounts of sorbent was confirmed by using packed-bed column laboratory system with recirculation of the aqueous phase. The wastewater from chrome plating industry was successfully purified, i.e. after 40 min concentration of Cr(III) ions was decreased lower than 0.1 mg dm-3. Also, removal of MB from the river water was successfully carried out and after 40 min removal efficiency was about 94 %

Predicting the capability of carboxylated cellulose nanowhiskers for the remediation of copper from water using response surface methodology (RSM) and artificial neural network (ANN) models

This study observed the influence of temperature, initial Cu(II) ion concentration, and sorbent dosage on the Cu(II) removal from the water matrix using surface-oxidized cellulose nanowhiskers (CNWs) bearing carboxylate functionalities. In addition, this study focused on the actual conditions in a wastewater treatment plant. Conductometric titration of CNWs suspensions showed a surface charge of 54 and 410 mmol/kg for the unmodified and modified CNWs, respectively, which indicated that the modified CNWs provide a relatively high surface area per unit mass than the unmodified CNWs. In addition, the stability of the modified CNWs was tested under different conditions and proved that the functional groups were permanent and not degraded. Response surface methodology (RSM) and artificial neural network (ANN) models were employed in order to optimize the system and to create a predictive model to evaluate the Cu(II) removal performance of the modified CNWs. The performance of the ANN and RSM models were statistically evaluated in terms of the coefficient of determination (R2), absolute average deviation (AAD), and the root mean squared error (RMSE) on predicted experiment outcomes. Moreover, to confirm the model suitability, unseen experiments were conducted for 14 new trials not belonging to the training data set and located both inside and outside of the training set boundaries. Result showed that the ANN model (R2 = 0.9925, AAD = 1.15%, RMSE = 1.66) outperformed the RSM model (R2 = 0.9541, AAD = 7.07%, RMSE = 3.99) in terms of the R2, AAD, and RMSE when predicting the Cu(II) removal and is thus more reliable. The Langmuir and Freundlich isotherm models were applied to the equilibrium data and the results revealed that Langmuir isotherm (R2 = 0.9998) had better correlation than the Freundlich isotherm (R2 = 0.9461). Experimental data were also tested in terms of kinetics studies using pseudo-first order and pseudo-second order kinetic models. The results showed that the pseudo-second-order model accurately described the kinetics of adsorption

Chromium(III) ion removal from aqueous solutions by a submerged hollow-fiber adsorber

Przedstawiono wyniki badań skuteczności hybrydowego układu sorpcyjno-membranowego w usuwaniu jonów metali ciężkich (na przykładzie Cr3+) z modelowych roztworów wodnych. Wykazano, że w reaktorze tego typu możliwe jest połączenie procesu adsorpcji z separacją na membranach kapilarnych zanurzonych w oczyszczanym roztworze. Stwierdzono, że układ z membranami zanurzonymi, pracujący w warunkach poniżej krytycznego strumienia permeatu, pozwala na uzyskanie dużej wydajności przy niskim zużyciu energii. W badaniach oceniono wpływu intensywności napowietrzania, ciśnienia transmembranowego i zawartości sorbentu na wydajność procesu usuwania jonów chromu(III) z roztworów wodnych. Zaproponowano również adsorpcję z użyciem taniego odpadowego biosorbentu - łupin orzeszków ziemnych, jako alternatywę dla tradycyjnych adsorbentów węglowych. Układ taki może być konkurencyjny w stosunku do klasycznych sposobów oczyszczania wody i ścieków z uwagi na minimalne koszty prowadzenia procesu.The aim of this work was to determine the efficiency of the hybrid membrane-sorption system for the removal of heavy metal ions (Cr3+ being the case in point) from model aqueous solutions. It has been demonstrated that this type of reactor enables the adsorption process to be combined with a separation process involving capillary membranes submerged in the solution being treated. When operated under conditions below the critical flux of the permeate, the submerged membrane system provides high removal efficiency at low energy demand. The experiments were aimed at evaluating the influence of aeration rate, trans-membrane pressure and sorbent concentration on the efficiency of Cr(III) ion removal from aqueous solutions. The use of peanut shells, a low-cost waste biosorbent, was proposed as an alternative to conventional carbon adsorbents. Owing to the very low operating costs involved, the treatment mode described above may become competitive with the classical methods of water and wastewater treatment

Absorption kinetics of VOC in a membrane capillary contactor

Oczyszczanie gazów procesowych i powietrza stanowi istotny aspekt działań zmierzających do ograniczenia emisji zanieczyszczeń do środowiska. Kluczowym zagadnieniem dla rozwiązania w/w problemu jest poszukiwanie nowych rozwiązań procesowych i aparaturowych w zakresie wychwytu zanieczyszczeń ze strumieni gazu. Poniższa praca przedstawia wyniki badań nad absorpcją lotnych związków organicznych (ŁZO) z wykorzystaniem kapilarnego kontaktora membranowego. Badania kinetyki absorpcji w układzie aceton/woda w kapilarnym kontaktorze membranowym pozwoliły na wyznaczenie współczynników wnikania masy po stronic gazu i cieczy a tym samym na określenie optymalnych warunków pracy absorbera membranowego.The air and flue gases purification is an essential aspect of decreasing pollutants emission. A key issue to solve this problem is a search for new processes and apparatuses designs in the field of gas stream impurities capturing. The paper presents research results dealing with the absorption of volatile organic compounds in a membrane capillary contactor. The acetone/water absorption kinetics' experiments with the use of membrane capillary contactor allowed one to determine the gas and liquid side mass transport coefficients, and therefore enabled the selection of optimal operating conditions for membrane absorption process

CFD methods and Flory-Huggins theory utilization in mathematical modeling of water-ethanol pervaporation process

Rozdział mieszaniny woda-etanol ma duże znaczenie dla wielu gałęzi przemysłu. Powszechnie stosowane techniki rozdziału tego układu posiadają szereg wad. Jedną z alternatyw jest proces perwaporacji. W celu upowszechnienia stosowalności perwaporacji podjęto próbę modelowania wspomnianego układu. W tym celu wykorzystano model Flory-Hugginsa, I prawo Ficka oraz metody CFD. Otrzymane wyniki pozwoliły ocenić wpływ polaryzacji na transport masy w perwaporacji.Separation of water-ethanol mixture is of great significance for many branches of industry. Separation techniques commonly used to separate above-mentioned mixture have many drawbacks. Pervaporation is one of alternatives. To make this process more applicable a mathematical model was created. The Flory-Huggins theory, first Fick's law and CFD methods were used in this model. Modeling results enable one to asses the influence of concentration polarization on mass transfer in pervaporation