Porous dye affinity beads for nickel adsorption from aqueous solutions: A kinetic study

We investigated a new adsorbent system, Reactive Red 120 attached poly(2‐hydroxyethyl methacrylate ethylene dimethacrylate) [poly(HEMA–EDMA)] beads, for the removal of Ni²⁺ ions from aqueous solutions. Poly(HEMA–EDMA) beads were prepared by the modified suspension copolymerization of 2‐hydroxyethyl methacrylate and ethylene dimethacrylate. Reactive Red 120 molecules were covalently attached to the beads. The beads (150–250 μm), having a swelling ratio of 55% and carrying 25.5 μmol of Reactive Red 120/g of polymer, were used in the removal of Ni²⁺ ions. The adsorption rate and capacity of the Reactive Red 120 attached poly(HEMA–EDMA) beads for Ni²⁺ ions was investigated in aqueous media containing different amounts of Ni²⁺ ions (5–35 mg/L) and having different pH values (2.0–7.0). Very high adsorption rates were observed at the beginning, and adsorption equilibria were then gradually achieved in about 60 min. The maximum adsorption of Ni²⁺ ions onto the Reactive Red 120 attached poly(HEMA–EDMA) beads was 2.83 mg/g at pH 6.0. The nonspecific adsorption of Ni²⁺ ions onto poly(HEMA–EDMA) beads was negligible (0.1 mg/g). The desorption of Ni²⁺ ions was studied with 0.1M HNO₃. High desorption ratios (>90%) were achieved. The intraparticle diffusion rate constants at various temperatures were calculated as k_20°C = 0.565 mg/g min^0.5, k_30°C = 0.560 mg/g min^0.5, and k_40°C = 0.385 mg/g min^0.5. Adsorption–desorption cycles showed the feasibility of repeated use of this novel adsorbent system. The equilibrium data fitted very well both Langmuir and Freundlich adsorption models. The pseudo‐first‐order kinetic model was used to describe the kinetic data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:5056–5065, 2006     

A model to predict the solubility and permeability of gaseous penetrant in the glassy polymeric membrane at high pressure

In this work, the transport properties of gaseous penetrant through several dense glassy polymeric membranes are studied. The nonequilibrium lattice fluid (NELF) in conjunction with the modified Fick's law and dual mode sorption model was used to simulate the gas transport in glassy polymeric membranes. The approach is based on the sorption, diffusion, in which solubility is calculated based on the NELF model, and diffusion coefficient is obtained from the product thermodynamic coefficient and molecular mobility. The governing equation is solved by the finite element method using COMSOL multi-physics software. The developed model for gas permeability of glassy polymeric membrane can be applied in a wide range of pressure and temperature. The comparison of the calculated permeability and solubility of gasses with the experimental data represented the ability of the developed model. Increasing feed gas temperature increases the gas permeability, while this variation leads to lower gas solubility in the glassy polymeric membranes. The effect of feed temperature and pressure on permeability and solubility is investigated, and the experimental data from literature are described by the developed model. A good prediction of the experimental data can be observed over the considered condition.     

Preparation of a cellulose acetate/organic montmorillonite composite porous ultrafine fiber membrane for enzyme immobilization

Four types of fibrous membranes based on cellulose acetate (CA)—CA membranes with nonporous fibers, CA/organic montmorillonite (O‐MMT) membranes with nonporous fibers, CA membranes with porous fibers, and CA/O‐MMT membranes with porous fibers—were prepared by electrospinning, and then, they were used for enzyme immobilization. The surface morphologies of the composite fibrous membranes were investigated with scanning electron microscopy and transmission electron microscopy. The optimum pH was 3.5 for all of the immobilized enzymes, and the optimum temperature was 50 °C. Compared with the free enzyme, the immobilized enzyme showed better stability for pH and temperature changes. Moreover, the addition of O‐MMT and the pores on the fibers improved the storage stability and the operational stability. Among the four kinds of fibrous membranes, the CA/O‐MMT membranes with porous fibers showed the best stability for the immobilized enzymes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43818.     

TiO2/PVDF共混微滤膜的制备及其吸附胆红素的研究

胆红素是一种内源性毒素,当人体肝脏系统受损或代谢受阻时,则在体内累积,引起高胆红素血症,其具有神经毒性,严重时甚至会危及生命。无机纳米材料作为胆红素吸附剂越来越受到关注,但也存在因团聚而吸附效率降低、因颗粒过小而容易泄漏的问题。以聚偏氟乙烯(PVDF)为基膜原料,掺杂纳米TiO₂颗粒,DMAc为溶剂、PVP为致孔剂,通过干湿相转化法,制得TiO₂/PVDF共混微滤膜。当铸膜液中PVDF浓度为10%(质量)、TiO₂含量为1%(质量)、PVP含量为6%(质量)时,制备的TiO₂/PVDF共混微滤膜的胆红素特异性吸附显著。电镜照片及EDX能谱发现,该膜内部及孔隙中均匀分布TiO₂颗粒,颗粒无团聚现象。实验还考察了胆红素初始浓度、吸附时间、吸附温度、pH等吸附条件的影响。     

Preferential adsorption in polymer/solvent-1 /solvent-2 solutions by infrared spectroscopy

IR spectroscopy is shown to be a suitable technique for preferential adsorption studies in the following solvent-1/solvent-2/polymer systems: poly(N-vinylcarbazole) and polyacenaphthene in nitrobenzene/dioxane, nitrobenzene/ tetrahydrofuran, and nitrobenzene/cyclohexanone. Values of the preferential adsorption parameters derived from the Schultz-Flory theory agree with those from IR when both solvents in the ternary system are considered to be good solvents for the polymer. In the systems studied, the relative adsorptions of solvent-1 and solvent-2 by the polymer depend on the solvent mixture composition. The number of adsorbed molecules and their performance are correlated with the ternary interaction parameters, X_m3, and the Mark-Houwink-Sakurada exponent, a′. The adsorption changes observed are greater in those systems in which tetrahydrofuran was present.     

Removal of phenol from aqueous solutions by adsorption onto polymeric adsorbents

Phenolic compounds are one of the most representative pollutants in industrial wastewater, and efficient removals of them have attracted significant concerns. In this study, several commercial and new synthetic polymers (acrylonitrile, 1,3‐butadiene, and styrene copolymer (ABS), styrene, acrylonitrile copolymer (SAN), poly(vinyl chloride) (PVC), poly(methyl methacrylate) (PMMA), poly(tert‐butyl acrylate) (ptBA)) with special functionalities were evaluated for their ability to remove phenol from an aqueous solution. Equilibrium studies were conducted in the range of 20–100 mg/L initial phenol concentrations, 3–11 pH solutions, and a temperature range of 25–65°C. The results showed that (styrene, 1,3‐butadiene) copolymer (SAN) gave the best adsorption capacity among all of the polymers tested. The solution temperature, phenol concentration, and agitation rate played a significant role in influencing the capacity of the adsorbents toward phenol molecules. An increase in solution temperature led to a significant increase in the adsorption capacity of SAN. The percentage of adsorption decreased when initial concentration of phenol increased. However, the percentage removal of phenol was observed to increase with agitation. Removal of phenol using polymeric microbeads is difficult to investigate under high and low pH values because it requires a lot of acid or base to adjust the pH values in the adsorption media. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A semi‐empirical cell voltage model for polymer electrolyte/methanol systems: Applicability of the group contribution method

A new group contribution model is established to describe the cell voltage of a direct methanol fuel cell as a function of the current density. The model equation is validated with experimental data over a wide range of methanol concentrations and temperatures. The proposed model focuses on very unfavorable conditions for cell operation, that is, low methanol solution concentrations and relatively low cell temperatures. The proposed group contribution method includes a methanol crossover effect that plays a major role in determining the cell voltage of a direct methanol fuel cell. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Radiation‐induced GMA/DMAA graft copolymerization onto porous PE hollow‐fiber membrane

Radiation‐induced graft copolymerization is a powerful technique to prepare a grafted chain with the desired properties pending onto the trunk material. In this work, a polyethylene hollow‐fiber membrane was modified by this technique. The monomers glycidyl methacrylate (GMA) and N,N‐dimethylacrylamide (DMAA) were cografted onto macroporous polyethylene hollow fiber with a grafting degree in the order of 200%. DMAA/GMA cografted membranes were compared to GMA grafted ones for the introduction of an amino acid as a specific ligand. Grafted membranes with a copolymer composition between 0 and 2 DMAA/GMA were prepared by soaking them in solutions of different mixtures of monomers. Copolymers were characterized by FTIR and their composition was estimated by the analysis of the ratio of carbonyl signals. Copolymers with a higher proportion of DMAA showed improved hydrophilic properties and higher conversion rates of epoxy groups on phenyalanine ligands than those of the GMA grafted ones. However, copolymers with a DMAA/GMA ratio higher than 1 showed a detrimental effect on the pure water flux. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1646–1653, 2003     

Development of a generic process model for membrane adsorption

In this work, a generic model describing the dynamic adsorption behaviour of proteins on membrane adsorbers over complete purification cycles under consideration of module geometry and of the interaction between multiple transport mechanisms is developed.A general rate model for membrane adsorption, in which the interaction between multiple phenomena, like mass transfer and adsorption kinetics are considered, is formulated. Hereby, the implemented isotherms describe the influence of eluting agents on the adsorption behaviour, so that complete purification cycle (loading, washing and elution operation) can be simulated.Using the developed model the theoretical influence of relevant transport phenomena, operating conditions and process scale on affinity and ion exchange membrane adsorption of proteins are investigated. An example on ion exchange membrane adsorption illustrates the possibility to predict scale up effects occurring in configurations of multiple membrane adsorber modules. The obtained simulation results are in accordance with experimental observations reported in literature.     

Optimization of kinetic data for two‐stage batch adsorption of Pb(II) ions onto tripolyphosphate‐modified kaolinite clay

BACKGROUND: Most adsorption studies consider only the adsorption of pollutants onto low cost adsorbents without considering how equilibrium and kinetic data can be optimized for the proper design of adsorption systems. This study considers the optimization of kinetic data obtained for the removal of Pb(II) from aqueous solution by a tripolyphosphate modified kaolinite clay adsorbent. RESULTS: Modification of kaolinite clay with pentasodium tripolyphosphate increases its cation adsorption capacity (CEC) and specific surface area (SSA) from 7.81 to 78.9 meq (100 g)^?1 and 10.56 to 13.2 m² g^?1 respectively. X‐ray diffraction patterns for both unmodified and tripolyphosphate‐modified kaolinite clay suggest the modification is effective on the surface of the clay mineral. Kinetic data from the batch adsorption of Pb(II) onto the tripolyphosphate‐modified kaolinite clay adsorbent were optimized to a two‐stage batch adsorption of Pb(II) using the pseudo‐second‐order kinetic model. Mathematical model equations were developed to predict the minimum operating time for the adsorption of Pb(II). Results obtained suggest that increasing temperature and decreasing percentage Pb(II) removal by the adsorbent enhanced operating time of the adsorption process. The use of two‐stage batch adsorption reduces contact time to 6.7 min from 300 min in the single‐stage batch adsorption process for the adsorption of 2.5 m³ of 500 mg L^?1 Pb(II) under the same operating conditions. CONCLUSION: Results show the potential of a tripolyphosphate‐modified kaolinite clay for the adsorption of Pb(II) from aqueous solution and the improved efficiency of a two‐stage batch adsorption process for the adsorption of Pb(II) even at increased temperature. Copyright © 2009 Society of Chemical Industry     

Removal of phosphate by adsorption onto oyster shell powder—kinetic studies

Kinetic studies on the removal of phosphate by adsorption onto oyster shell powder have been investigated at 24 °C. The results showed that the equilibrium occurred in 10 min and the equilibrium data followed the Freundlich isotherm. Freundlich constants were found to be k_f, 1.4 × 10^?2, and n, 0.71. The phosphate removal was not influenced by pH over the range 5.0–10.5. Continuous agitation studies at 24 °C and 530 rpm reached equilibrium after 7.7 days, when 24 g dm^?3 of oyster shell powder reduced the phosphate concentration from 50 to 7.0 mg dm^?3. The Lagergren rate constant for the slow adsorption process was observed to be 3.81 × 10^?4 dm³ min^?1. Comparison with calcium carbonate, GR grade, showed that oyster shell powder and CaCO₃ behave more or less in the same way. Copyright © 2004 Society of Chemical Industry     

Removal of trace quantities of co from H2 using temperature‐swing‐adsorption

A method for the removal of trace quantities (0.2 to 10 ppm) of carbon monoxide in commercial hydrogen using a temperature‐swing‐adsorption system with 0.5 wt% Pt/Al₂O₃, adsorbent has been investigated. The adsorbent could be regenerated by treatment with air at 200°C to 250°C or by treatment with hydrogen at 270°C. The breakthrough curves have been described by a model which considers both the external‐film resistance and the intraparticle diffusion resistance. The model has been validated at the high gas velocities expected in a commercial plant.     

Investigation of adsorption of lead,mercury and nickel from aqueous solutions onto carbon aerogel

Recently a new form of activated carbon has appeared: carbon aerogel (CA). Its use for the removal of inorganic (and especially metal ions) has not been studied. In the present study, the adsorption of three metal ions, Hg(II), Pb(II) and Ni(II), onto carbon aerogel has been investigated. Batch experiments were carried out to assess adsorption equilibria and kinetic behaviour of heavy metal ions by varying parameters such as agitation time, metal ions' concentration, adsorbent dose and pH. They facilitated the computation of kinetic parameters and maximum metal ion adsorption capacities. Increasing the initial solution pH (2–10) and carbon concentration (50–500 mg per 50 cm³) increases the removal of all three metal ions. A decrease of equilibrium pH with an increase of metal ion concentration led us to propose an adsorption mechanism by ion exchange between metal cations and H⁺ at the carbon aerogel surface. Carboxylic groups are especially involved in this adsorption mechanism. Langmuir and Freundlich isotherm models were used to analyse the experimental data of carbon aerogel. The thermodynamics of the metal adsorption was also investigated for the practical implementation of the adsorbent. The sorption showed significant increase with increase of temperature. Kinetics models describing the adsorption of Hg(II), Pb(II) and Ni(II) ions onto carbon aerogel have been compared. Kinetics models evaluated include the pseudo‐first order and second order model. The parameters of the adsorption rate constants have been determined and the effectiveness of each model assessed. The result obtained showed that the pseudo‐second order kinetic model correlated well with the experimental data and better than the pseudo‐first order model examined in the study. Mass transfer coefficients obtained can be useful in designing wastewater treatment systems or in the development of environmental technologies. Copyright © 2005 Society of Chemical Industry     

A study of the rheological behavior of high‐temperature polymer electrolyte membrane solutions

The viscosity behavior of various compositions of polymer electrolyte membrane solutions, which are later hydrolyzed into proton conducting membrane film for fuel cells, is characterized. Using the Carreau‐Yasuda model and time–temperature superposition, an empirical model relating the viscosity as a function of temperature and shear strain rate has been developed for several membrane solution compositions. It is observed that the viscosity of the non‐Newtonian membrane has a strong correlation to the membrane's inherent viscosity (a property determined during membrane synthesis). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A simple model for a non-isothermal adsorption column

A simple analytic solution has been derived for the temperature response of a non-isothermal adsorption column in which a small concentration of an irreversibly adsorbed species is removed. The model is shown to provide a reasonable representation of the experimentally observed behaviour of an ethanol drying column using 3A molecular sieve as the moisture selective adsorbent.     

Variation of intraparticle diffusion parameter during adsorption of p‐chlorophenol onto activated carbon made from apricot stones

The adsorption of para‐chlorophenol onto an active carbon made from waste apricot stones has been studied. The batch kinetic adsorption processes have been measured for a range of system variables including agitation rate, initial concentration of para‐chlorophenol, mass of carbon and particle size of carbon. The extent of adsorption is reported as plots of solid phase concentration against the square root of time. An intraparticle diffusion parameter is used to describe the mass transfer within the adsorbent. This parameter varies with the square root of time and can be related to the type of structure which occurs within an activated carbon. A correlation is proposed relating the process variable with the intraparticle diffusion parameter in each of the three mass transfer regions. Copyright © 2003 Society of Chemical Industry     

Synthesis and adsorption properties of nanocrystalline ferrites for kinetic modeling development

Nanocrystalline ferrites are known to be used in different applications, including industrial wastewater management. For environmental water issues, one of the most widely applied techniques is the adsorption of pollutants. The adsorption capacity of Congo red (CR) dye on different MFe₂O₄ (M = Co²⁺, Mg²⁺, Mn²⁺, Ni²⁺, and Zn²⁺) ferrites, synthesized by coprecipitation method, was determined. Specific isotherms and kinetic models were used to characterize the adsorption process. Interesting results were obtained for MgFe₂O₄ with adsorption capacity ranging from 39% up to 70% dependent on the initial dye concentration. Furthermore, an artificial intelligence model based on neural network was developed in order to model the adsorption rates followed by the generation of 3D adsorption rate models for each type of synthesized ferrite. These models were obtained in order to provide information about the particle-dye system`s kinetics at various initial CR concentration. Specific techniques were used to characterize the functionalized magnetic particles.