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Freundlich Isotherm (freundlich + isotherm)
Selected AbstractsComparison of Cd, Cu, and Zn toxic effects on four marine phytoplankton by pulse-amplitude-modulated fluorometryENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2005Ai-Jun Miao Abstract The toxic effects of Cd, Cu, and Zn on four different marine phytoplankton, Dunaliella tertiolecta, Prorocentrum minimum, Synechococcus sp., and Thalassiosira weissflogii, were examined by comparing the cell-specific growth rate, pulse-amplitude-modulated (PAM) parameters (maximum photosystem II quantum yield ,M and operational quantum yield ,'M), chlorophyll a content, and cellular metal concentration, over a 96-h period. The calculated no-observed-effect concentration (NOEC) based on both cell-specific growth rate and two PAM parameters (,M and ,'M) were mostly identical. Thus, these PAM parameters and cell-specific growth rate were comparable in their sensitivities as the biomarkers for trace metal toxicity to marine phytoplankton. The cyanobacteria Synechococcus sp. was the most sensitive species among the four algal species tested because of its higher cell surface to volume ratio. The toxicity of the three tested metals followed the order of Cd > Cu > Zn based on the cellular metal concentration of the four algae at the NOEC. The cellular metal bioaccumulation followed the same Freundlich isotherm for each metal regardless of the algal species, indicating that the metal accumulation was a nonmetabolic process under high ambient metal concentrations and that the cell surface metal binding was comparable among the different species. For all the algae examined in our study, the bioaccumulation potentials of Cu and Zn were similar to each other, while the Cd bioaccumulation was much lower under environmentally realistic metal concentration. [source] Protein stabilisation of Chardonnay wine using trisacryl and bentonite: a comparative studyINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2009Johannes De Bruijn Summary The stabilisation of a Chilean Chardonnay wine by SP-Trisacryl-M and bentonite was investigated, evaluating protein, polyphenol and polysaccharide adsorption, turbidity and wine quality. The wine could be stabilised by adding at least 0.3 kg m,3 of bentonite or 12 kg m,3 of trisacryl, removing 95% and 76% of the wine proteins, respectively. The protein adsorption data for bentonite and trisacryl were fitted using the Freundlich isotherm. The wine protein adsorption isotherm on trisacryl was unfavourable. Protein removal from Chardonnay by trisacryl in a packed column at continuous operation was about 50% during the first 70 bed volumes (BV) of treated wine and decreased progressively until the end of the treatment (100 BV). The adsorbents showed a higher selectivity for proteins than for polyphenols and polysaccharides. A sensorial panel could not detect statistically significant differences between the bentonite and trisacryl treatments of wine at P , 0.05. [source] Comparative studies of Oryza sativa L. husk and chitosan as lead adsorbentJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2006Mohamed Mohamed Daud Zulkali Abstract The adsorption capacity of two low-cost adsorbents, Oryza sativa L. husk and chitosan, was studied. Lead solution was used as the adsorbate. The effect of initial lead concentration, pH, temperature, weight of adsorbent, particle size and contact time on lead uptake was investigated. It was found that the isotherm data were well described by the Freundlich isotherm for both adsorbents. The adsorption capacities of rice husk and chitosan were 5.69 and 8.31 mg g,1, respectively. It was shown that chitosan was more effective than rice husk. Copyright © 2005 Society of Chemical Industry [source] ADSORPTION CHARACTERISTICS OF CROCIN IN THE EXTRACT OF GARDENIA FRUITS (GARDENIA JASMINOIDES ELLIS) ON MACROPOROUS RESINSJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2009BIN YANG ABSTRACT To study resin adsorptions and investigate the differences between processes in crude extracts and microfiltrates, the adsorption characteristics of crocin in the extract of Gardenia jasminoides Ellis on 10 macroporous styrene-divinylbenzene (SDVB) resins were investigated. Ground gardenia fruit was extracted with water and the crude extract was partially purified by microfiltration. The crude extract and microfiltrate were mixed with the 10 resins until the adsorption of crocin reached equilibrium on resins. The adsorption followed the pseudo-second-order kinetics closely, but the data also fitted the first-order and intraparticle diffusion models. Furthermore, the Freundlich isotherm was found suitable for describing the equilibrate adsorption data. XAD-1180, HP20, HPD-100A and AB-8 stood out as the best performing resins in terms of their adsorptive capacities and selectivities for crocin. The thermodynamics of the adsorption process was shown to be spontaneous and exothermal in nature, and controlled by physical rather than chemical mechanisms. Adsorption with SDVB resins in conjunction with microfiltration was found to be an efficient process for the purification of crocin in gardenia extract. PRACTICAL APPLICATIONS Macroporous resins have been industrially applied in the recovery and purification of some products from plant extracts. However, there is a lack of understanding of the adsorption process and many of the applications are based on empirical data rather than on predicable models. Therefore, the development of reliable mathematical models that can accurately describe and predicate experimental data of adsorption would be extremely helpful in understanding the adsorption process as well as optimizing the design of adsorption systems. [source] Removal of arsenic from simulated groundwater by GAC-Fe: A modeling approachAICHE JOURNAL, Issue 7 2009P. Mondal Abstract A study on kinetics and equilibrium is presented on the adsorption of arsenic species from simulated groundwater containing arsenic (As(III):As(V)::1:1), Fe and Mn in concentrations of 0.188 mg/L, 2.8 mg/L and 0.6 mg/L, respectively, by iron impregnated granular activated charcoal (GAC-Fe). Also presented is the interaction effect of As, Fe and Mn on the removal of arsenic species from water, which simulates contaminated groundwater. Among conventional models, pseudo second-order kinetic model and Freundlich isotherm were adequate to explain the kinetics and equilibrium of adsorption process, respectively. However, in comparison to conventional isotherm empirical polynomial isotherm provided a more accurate prediction on equilibrium specific uptakes of arsenic species. Effects of initial concentrations of As, Fe and Mn on the removal of total arsenic (As(T)), As(V) & As(III) have been correlated within the error limit of ,0.2 to +5.64%. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Kinetic and Statistical Studies of Adsorptive Desulfurization of Diesel Fuel on Commercial Activated CarbonsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2008M. Muzic Abstract Diesel fuel desulfurization by different commercial activated carbons was studied in a batch adsorber. Experiments, carried out to determine the sulfur adsorption dependency on time, were used to perform kinetic characterization and to screen the best performing activated carbon. The equilibrium characterization of the adsorption process was also performed. The statistical study of the process was undertaken by way of a two-level one-half fractional factorial experimental design with five process parameters. Individual parameters and their interaction effects on sulfur adsorption were determined and a statistical model of the process was developed. Chemviron Carbon SOLCARBTM C3 was found to be the most efficient adsorbent. The kinetic pseudo-second order model and Freundlich isotherm are shown to exhibit the best fits of experimental data. The lowest achieved sulfur concentration in treated diesel fuel was 9.1,mg kg,1. [source] Sorption Removal of Pb(II) from Solution by Uncalcined and Calcined MgAl-Layered Double HydroxidesCHINESE JOURNAL OF CHEMISTRY, Issue 10 2007Shu-Qin ZHANG Abstract Layered double hydroxide (LDH) with a Mg/Al molar ratio of 1:1 was synthesized by using a co-precipitation method and its calcined product (CLDH) was obtained by calcination of the MgAl-LDH at 500 °C. The sorption removal of Pb2+ from solution was investigated, finding that both LDH and CLDH show good sorption ability and they could be used as a new type of environmental sorbent for the removal of Pb2+ from water. The sorption kinetics and the sorption isotherms of Pb2+ on both LDH and CLDH can be described by the pseudo-second order kinetics and Freundlich isotherm, respectively, under the studied conditions. The sorption amounts of Pb2+ on LDH and CLDH are independent of pH in a pH range of about 3,10. The presence of NaNO3 may inhibit the sorption ofPb2+ on LDH while hardly affect that on CLDH. The sorption mechanism of Pb2+ on LDH and CLDH may be attributed to the surface precipitation and the surface complex adsorption. The surface complex adsorption may be further distinguished to the chemical binding adsorption forming the inner-sphere surface complexes and the electrostatic binding adsorption forming the outer-sphere surface complexes. The sorption mechanism of Pb2+ on LDH may be attributed to the surface precipitation and the electrostatic binding adsorption, while that on CLDH may be attributed to the surface precipitation and the chemical binding adsorption. [source] Adsorption Behavior of Potassium Ion on Planting MaterialsCHINESE JOURNAL OF CHEMISTRY, Issue 9 2007Dechprasitthichokea Paunpassanan Abstract Characterization of planting materials used as adsorbent has been studied in order to compare potassium ion adsorption on two types of planting materials, which are a fired planting material (FPM) made from a mixture of 4 kinds of wastes (bottom ash, flue gas desulfurization (FGD) gypsum, paddy soil and sawdust) formed and fired at 850 °C and the commercial planting material called "hydroball" (HDB) bought from Jatujak market, Bangkok. The physical characteristics of both types of planting materials indicate that the FPM has a larger specific surface area than the HDB. The factors affecting potassium adsorption on both the planting materials such as an equilibration time and some solid/solution ratios were investigated. The suitable equilibration time for the adsorption to reach an equilibrium on the FPM and HDB is one and two hours, respectively. The highest amounts of potassium ion adsorbed on both the planting materials were obtained when the solid/solution ratio was 1:15. The adsorption behavior on both the planting materials tends to correspond with the Freundlich isotherm. [source] The effect of surface,solute interactions on the transport of solutes through porous materialsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2009D. A. Rose Summary We have investigated the effect of differences in surface charge, valency of ion, solute concentration, solution flux and physical structure on the leaching and uptake of individual ions from simple solutions flowing through porous materials. We studied the miscible displacement of solutions of four salts (KBr, K2SO4, CaBr2 and CaSO4) having different cation : anion ratios separately through three inert materials (ballotini, pumice and ceramic) and two sizes of a reactive material (sepiolite) over several ranges of concentration (c) and at many pore-water velocities (v) under steady vertical saturated flow. Breakthrough curves of individual effluent ions (K+, Br,, Ca2+ and SO42,) were analysed by CXTFIT 2.0 to optimize transport parameters (retardation factor, R; dispersion coefficient, K) assuming that transport was governed by the convective,dispersion equation. In the inert materials, R did not differ significantly from 1 irrespective of c. In sepiolite, R was < 1 for anions and > 1 for cations, and became more extreme as c decreased. R varied with the valency of the anions, as predicted by diffuse double layer theory, and with that of the cations by a simple charge balance. Freundlich isotherms, reconstructed from R values, described the sorption of the cations and exclusion of the anions. For the inert materials, K did not depend on the ion or c and increased monotonically with v. For sepiolite, K also increased with v and with small but non-significant differences between ions and concentrations. The K(v) functions were consistent with Passioura's theory of dispersion in aggregated media, and the transport was reversible as R and K values did not depend on whether the media were being leached or resalinized. The effective dispersion coefficient of an ion is K* = K/R so, although K(v) appears to be unaffected by ion or concentration of solute in sepiolite, K*(v) will be affected. Thus, the controlling factor of these surface,solute interactions is R. [source] A comparative adsorption study of copper on various industrial solid wastesAICHE JOURNAL, Issue 10 2004Archana Agrawal Abstract The adsorption behavior of Cu on three solid waste materials,sea nodule residue (SNR), fly ash (FA), and red mud (RM),was investigated. The effects of various parameters, such as pH of the feed solution, contact time, temperature, adsorbate and adsorbent concentration, and particle size of the adsorbent, were studied for optimization of the process parameters. Adsorption of copper increased with increasing time, temperature, pH, and adsorbate concentration, and decreased with increasing initial copper concentration. The equilibrium data fit well with the Langmuir and Freundlich isotherms in the case of SNR, but not on RM and FA, because there was no appreciable effect of temperature on the metal removal on these two adsorbents. The adsorption of copper on SNR followed first-order kinetics involving the surface complex formation mechanism on the charged surface. Under the optimized conditions the adsorption capacity for copper was found to be 19.65 mg/g of SNR, 1.98 mg/g of FA, and 2.28 mg/g of RM. Thus the adsorption capacity of SNR was found to be more than that of activated carbon, thus making it suitable for the treatment of industrial effluents to reduce the level of copper within the permissible limits for its land disposal (3 mg/L) according to ISI guidelines. © 2004 American Institute of Chemical Engineers AIChE J 50: 2430,2438, 2004 [source] Adsorption, absorption, and biological degradation of ammonia in different biofilter organic mediaBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2007Estela Pagans Abstract A tailor-made apparatus called ammoniometer, which is a batch mode respirometer applied to the study of ammonia biodegradation in biofilter media, has been used to evaluate adsorption, absorption, and biodegradation in five different organic materials (compost, coconut fibre, bark, pruning wastes, and peat) obtained from full-scale biofilters in operation in several waste treatment plants. The results showed that absorption could be represented by a Henry's law linear equation, with values of the Henry coefficient significantly higher (from 1,866 to 15,320) than that of pure water (1,498). Adsorption data were successfully fitted to Langmuir and Freundlich isotherms and maximum adsorption capacity varies from 1.06 to 1.81 mg NH3/g dry media. Ammonia biodegradation rates for each organic material were also calculated. Biodegradation rates varied from 0.67 to 7.82 mg NH3/kg media/d depending on the material tested. The data obtained showed important differences in the behaviour of the biofilter organic media, which has important implications in the design and modelling of these systems. Biotechnol. Bioeng. 2007;97: 515,525. © 2006 Wiley Periodicals, Inc. [source] | |||||||||||||||||||||||||