High Saturation Capacity Research Articles

High-performance magnetic chicken bone-based biochar for efficient removal of rhodamine-B dye and tetracycline: competitive sorption analysis.

Magnetic chicken bone-based biochar (MCBB) was successfully prepared and efficiently adsorbed rhodamine-B (RB) dye and tetracycline (TC) in multi-component systems. The magnetisation value, surface area, and pHpzc of the MCBB were found to be 66.5 emu/g, 328 m2/g, and 8.3, respectively. RB has higher saturation capacity (96.5 mg/g) and occupies more active sites on MCBB, thus limiting the sorption of TC with lower saturation capacity (63.3 mg/g). Langmuir isotherm suitably describes the sorption process in a single-component system; however, the multi-component system was well fitted to the Sheindorf-Rebhun-Sheintuch model. The selectivity factor values confirmed that MCBB had higher adsorption affinity toward RB than TC. The intraparticle diffusion model played a significant role in the sorption process. The MCBB can be easily desorbed with base-spiked H2O and reused without loss in stability or structural integrity.

Hypothetically Quantifying Flood Vulnerability in a Reservoir Tributary Employing 3-Dimensional Geomorphological Terrain Related Covariants, a Stochastic Iterative Quantitative Interpolator and a Space-time Global Circulation Model Paradigm

Deaths from flooding in the United States are preventable with the right planning maps and mitigation. This research is revolutionary as it forecast the most vulnerable flooding areas of higher population regions by incorporating future precipitation projections, soil classifications, a 3-dimensional (3-D) digital elevation model (DEM) and the Geographic Information System (GIS) kriging algorithmic iterative interpolation tool to determine the optimal geolocations where storm water drainage detention or retention and improvements should occur. Firstly, utilizing spatial tools and a global circulation models (GCMs), precipitation was mapped to determine high vulnerability areas for future potential flooding. A robust semi variogram, geospatial explanatory locations of precipitation were then parsimoniously constructed for a sample site in Hillsborough County, Florida. Overlaying this data on 3-D temporal geomorphological terrain related elevation models, high risk flooding areas were geolocated employing geospectrotemporal geospatial techniques. For this region, two-thirds of the precipitation occurs during the summer months; therefore, June, July and August were analyzed. Furthermore, just focusing on one month, e.g., August, would not take into account antecedent ecogeohydrology conditions which impact run off volume and flooding. Soil characteristics such as capillary action, permeability and drainage porosity were considered as some soils have a high water-holding saturation capacity and poor infiltration capability, increasing flooding. Finally, extracting forecasted slope coefficient from 3-D models were examined to determine if they were feasible to help extract geolocations where there is prevalent standing water during wet season.

Removal of Eu3+, Ce3+, Sr2+ and Cs+ ions from radioactive waste solutions by modified activated carbon prepared from coconut shells

The modified surface of activated carbon (MSAC) was prepared from the agricultural byproduct coconut shells, by physical and chemical activation processes, and it was tested for the treatment of simulated radioactive waste solutions included some metal ions, namely Europium, Cerium, Strontium, and Cesium. The structural morphology and composition of the modified surface activated carbon coconut shells (MSAC) were evaluated by SEM, XRD, FTIR, XRF, and elemental analysis. The solubility experiments show that the prepared sorbent (MSAC) has reasonably good chemical stability. The influence of solution pH, contact time, adsorbent dosage, adsorption temperature, initial metal ion concentration and interfering substances such as sodium chloride salt and ethylenediaminetetraacetic acid (EDTA), on the adsorption performance of Eu3+, Ce3+, Sr2+ and Cs+ ions on to the prepared sorbent (MSAC) were examined by batch technique. The saturation capacity of the MSAC for the studied metal ions was found to be very high as compared to the break-through capacity, and it was found to be 136.84, 85.55, 69.85 and 60.00 mg g -1 for Eu3+, Ce3+, Sr2+ ,and Cs+ ions, respectively. Using the Van,t Hoff linear plot, the thermodynamic parameters, ΔHo, ΔSo ,and ΔGo were also evaluated. . Results show that studied sorbent (MSAC) is efficient to remove more than 98.43, 90.7, 38.65, and 37.4%, of Eu 3+, Ce 3+, Sr 2+ and Cs + ions respectively, at 180 min equilibrium time. The developed sorbent is considered as a good replacement technology for removal of Eu3+, Ce3+, Sr2+ ,and Cs+ ions from radioactive waste solutions due to its low-cost , good efficiency, high saturation capacity, as well as easy handling with no or small amount of secondary sludge.

Defect creation in metal-organic frameworks for rapid and controllable decontamination of roxarsone from aqueous solution

Given the great harm to the human health of organic arsenic compounds (OACs), developing highly efficient adsorbents with both rapid adsorption rate and high saturation capacity is paramount important. Herein, Zr-based metal-organic frameworks (MOFs) of UiO-66 have been successfully exploited for the efficient decontamination of a typical organic arsenic compound of roxarsone (ROX) from aqueous solution. The influences of the most significant parameters such as contact time, adsorbate concentration, pH as well as ionic strength on the adsorption of ROX were investigated. The amount of missing-linker defects in UiO-66 was systematically tuned by changing the concentration of modulator in the reactants. The presence of the defects not only resulted in the dramatically enhanced porosity, but also induced the creation of ZrOH groups which served as the main active adsorption sites for efficient ROX sequestration. As a result, adsorptive capacity of ROX over UiO-66 could be improved to 730mg/g, which was much higher than those of many reported adsorbents. Meanwhile, the adsorption equilibrium time could be reduced to as short as 30min. These merits, combined with their excellent stability, prefigure the great potentials of these defect-tunable UiO-66 MOFs as adsorbents for the efficient removal of various OACs from the polluted water.

Binding of Functionalized Paramagnetic Nanoparticles to Bacterial Lipopolysaccharides And DNA

Magnetite and metallic cobalt-based nanoparticles with sizes ranging from 10 to 300 nm and surface-functionalized with poly(hexamethylene biguanide) (PHMBG) are introduced as capable lipopolysaccharide (LPS)-sequestering agents. The nanoparticles efficiently bind to whole E. coli cells and can be used to separate the cells effectively from suspension using a magnet. A fluorescence dye displacement assay shows strong affinities of the nanoparticles for lipid A, the glycolipid component of LPS responsible for septic shock. The particle-lipid A affinity is of the same order of magnitude or higher than that of polymyxin B. The affinity of smaller (< 50 nm) magnetite particles modified with PHMBG to lipid A is several-fold higher than that of their larger counterparts (> 100 nm) due to their higher surface area to volume ratio. The nanoparticles possess high saturation capacity for double-stranded lambdaDNA from E. coli, with which particle-polyelectrolyte complexes are formed. The PHMBG-modified nanoparticles are potent bactericides, inhibiting E. coli viability and growth at concentrations at < or = 10 microg/mL.

Performance assessment and isotherm modeling of dye uptake by h3po4 and zncl2 modified activated carbon animalis from poultry droppings

Activated carbon animalis was prepared from poultry droppings by H3PO4 and ZnCl2 activation at 5 and 15 minutes dwells time. Four different isotherms were used to model data obtained from adsorption of textile dye from waste water. Applicability of the models followed the trend; Langmuir (R2 = 0.87-0.989) > Radushkevich – Dubinin (R2=0.731-0.973)> Frendhich (R2=0.735-0.967) > Temkin (R2=0.742-0.951). The Langmuir separation factor (RL) revealed thefavorable nature of the adsorption. Samples, activated at longer time with ZnCl2 gave the best quality carbon with high saturation capacity (qD), high mean free energy (ED) and high maximum capacity (qm), but least adsorption energy (BD). Adsorption was majorly monolayer on uniform strategies, with no transmigration of adsobate. The overall results in this assessment indicate that percentage dye removal ranged between 28-63.60%, 38-76.00%, 33.58-50.40% and 24.83-76.00% for pd/A/5, pd/A/15, pd/z/5 and pd/z/15 respectively. This is an indication that, the Poultry waste biomass can be a good precursor for generating adsorbent for uptake of multicomponent organic solute.Keywords: Isotherm modeling, activated carbon, poultry dropping, textile dye

High saturation capacity of activated carbons prepared from mesophase pitch in the removal of volatile organic compounds

A series of binderless activated carbon monoliths (ACMs) have been prepared from petroleum pitch and using KOH as activating agent. Characterization shows that these activated carbons combine a large “apparent” surface area (up to S BET ∼ 3000 m 2/g) together with a well-developed narrow micropore size distribution. Dynamic column adsorption experiments using different volatile organic compounds (VOCs), ethanol and benzene, show that these activated carbons prepared from mesophase-based materials exhibit a superior saturation capacity compared to conventional carbon materials. The total amount adsorbed reaches values as high as 18 g/100 g AC and 40 g/100 g AC, for ethanol and benzene, respectively. These are the best results reported in the literature. The total amount adsorbed for both molecules correlates with the total volume of narrow micropores, thus confirming the pore size specificity required for the adsorption of VOC molecules. Regeneration studies show that ethanol can be easily desorbed at room temperature by flowing clean air through the adsorbent whereas benzene requires a further heating for complete desorption/regeneration.

Method for isolation of floating fetal RBCs from maternal circulation based on their inherent magnetic property

Isolation of floating fetal cells from maternal circulation has immense potential in diagnosing of various genetic alterations in the developing fetus. Currently, non-invasive fetal cell isolation methods include fluorescence/magnetic activated cell sorting that use antibodies specific to fetal cells. Apart from being complex and expensive the biggest challenge associated with these cell sorting methods is low concentration of fetal cells in maternal peripheral blood. In order to make the complete process much simpler and effective, we propose a novel method for isolation of floating fetal cells that uses a continuous flow of maternal blood for effectively harvesting a higher fetal cell volume compared to any other existing method. The isolation mechanism is based on the difference in the magnetic susceptibility of fetal hemoglobin (HbF- α 2 γ 2) and maternal hemoglobin (HbA- α 2 β 2). HbF has high oxygen saturation capacity (diamagnetic) compared to HbA (paramagnetic), and this difference in saturation is further enhanced by presence of 2,3-bisphosphoglycerate (2,3-BPG). When placed in magnetic field, these cells get separated based on the difference ( p ≤ 0.001) in their magnetophoretic mobility. This separation method may also be used for detection of fetomaternal hemorrhages and also treatment of Rh incompatibility.

Mesoporous-molecular-sieve-supported Polymer Sorbents for Removing H2S from Hydrogen Gas Streams

A series of sorbents with a linear polyethylenimine (PEI) supported on the mesoporous molecular sieves, including MCM-41, MCM-48 and SBA-15, have been prepared and used to remove H2S from a model gas containing 0.40 v% of H2S and 20 v% H2 in N2 gas. The sorption was conducted in a fixed-bed system at a temperature range of 22–75 °C, a GHSV range of 337–1,011 h−1 and atmospheric pressure. The effects of the operating temperature, GHSV, the amount of PEI loading and the different molecular sieve supports were studied. A reduction in the temperature and GHSV improves the sorption performance of the supported PEI sorbents. A synergetic effect of the SBA−15 support and PEI on the H2S sorption performance was observed. Loading 50 wt% PEI on SBA-15 gave the best breakthrough capacity, while loading 65 wt% PEI on SBA-15 had the highest saturation capacity. The mesoporous molecular sieve with large pore size and three-dimensional channel structure favors increasing the kinetic capacity of the supported PEI sorbent. In addition, the developed sorbents can be regenerated easily at mild conditions (temperature range of 75–100 °C) and have excellent regenerability and stability. The results indicate that the mesoporous-molecular-sieve-supported polymer sorbents are promising for removing H2S from hydrogen gas streams.

Modeling the Transient Adsorption Process of Ternary Mixtures on Nanoporous Zeolitic Adsorbents in Batch Systems

Transient adsorption process of a hypothetical ternary mixture constituted by a fast diffusing‐weak adsorbing (C1), a low diffusing‐strong adsorbing (C2), and a high saturation capacity species (C3) on zeolite adsorbents in a batch system was modeled by the Maxwell‐Stefan formulation in combination with the IAST mixture isotherm. When the Henry constant of C2 and C3 were K 2=K 3, the transient adsorption selectivity (S i,j ) defined with the weakest‐adsorbing species used as a reference becomes higher for C3 in comparison with C2, during the entire lapse of contact time. The influence of the gas phase pressure and mixture composition on the transient adsorption selectivities basically depends on the behavior of the equilibrium selectivities (S i,j eq ). The transient response of the fractional coverage (θ i ) of C1 within the zeolite overshoots its equilibrium value. In comparison to the single adsorption profiles, the component with the highest saturation capacity (C3) is the only species of the ternary mixture that maintains its fractional coverage practically unmodified. When K 2 >K 3, a cross‐over between the corresponding equilibrium selectivities can occur with pressure. The use of the model based on experimental data is discussed.

Adsorption Isotherms of Aspartame on Commercial and Chemically Modified Divinylbenzene−Styrene Resins at Different Temperatures

The equilibria of adsorption of aspartame in an aqueous solution on a commercial resin and three chemically modified Amberlite XAD-2 resins were measured at different temperatures within the range (0 to 35) °C. The functional groups, introduced by nucleophilic substitution in the aromatic rings of the divinylbenzene−styrene matrix, were bromine (−Br), bromoethyl (−CH2CH2Br), and chloromethyl (−CH2Cl). All of the isotherms showed a nonlinear and favorable shape with decreasing adsorption capacity as the temperature increased. The chloromethylated resin, and, to a lesser degree, the bromoethylated resin, increased the adsorption capacity for aspartame compared to Amberlite XAD-2. At 35 °C, the chloromethyl resin showed up to a 280% higher saturation capacity than the commercial adsorbent. The experimental equilibrium data were fitted to the Langmuir, Freundlich, Langmuir−Freundlich, Redlich−Peterson, and Toth models. Toth and Langmuir−Freundlich isotherms provided very good fittings for all of the resins over the temperature range studied, whereas the Langmuir and Redlich−Peterson equations were less accurate, although the average errors were, in general, below 10% with respect to the measured values.

Grafting of Molecularly Imprinted Polymer Films on Silica Supports Containing Surface-Bound Free Radical Initiators

Silica particles containing surface-bound free radical initiators have been used as supports for the grafting of thin films of molecularly imprinted polymers (MIPs). This technique offers a means of fine-tuning the layer thickness for improved kinetic properties or enhanced capacity in chromatographic or sensor applications. Thus prepared MIPs imprinted with l-phenylalanine anilide, have been characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), elemental analysis, fluorescence microscopy, and scanning electron microscopy (SEM), providing evidence concerning the reproducibility in each step and the quantity and quality of the grafted films. The chromatographic properties of the materials have been investigated with respect to the average layer thickness of the polymer on the surface, the solvent, the support pore diameter, the cross-linker concentration, and the composition of the mobile phase. For the porous particles, the column efficiency depended strongly on the amount of grafted polymer. Thus, polymers grafted as thin films (ca. 0.8 nm as average film thickness) on silica with 10 nm average pore diameter showed the highest column efficiency giving plate numbers (N) for the imprinted enantiomer of ca. 700 m-1 and for the antipode ca. 24 000 m-1. This resulted in baseline resolutions on a 33 mm long column in less than 5min. On the other hand the sample load capacity and separation factor increased up to 7.0 nm layer thickness and dropped again for larger amounts of grafted polymer. A support with an average pore diameter of 100 nm and a 3.8 nm layer thickness showed a far higher saturation capacity than values previously determined for the conventional monolithic materials.

Separation of Hydroxycitric Acid Lactone from Fruit Pectins and Polyhydroxyphenols on Poly(4-Vinylpyridine) Weak-Base Resin

Poly(4-vinylpyridine) (PVP) has been used for the separation of hydroxycitric acid lactone (HCAL) from polyhydroxyphenols and fruit pectins, as the study has relevance to the problem of extraction of the antiobesity substance hydroxycitric acid from Garcinia cambogia fruits, a rich source of the acid. PVP has been used both in free-base form and in protonated or salt form as a sorbent, while catechol and pyrogallol have been used as representative polyhydroxyphenols. Though the protonated form, used as PVP(HCl), has a low sorption capacity (96 mg/g dry resin) and low selectivity for pectin (at pH 8), its higher, but comparable, sorptions (at pH 8) of HCAL, catechol, and pyrogallol, with respective saturation values of 354, 349, and 366 mg/g dry resin, coupled with high selectivity for the hydroxyphenols, make the sorbent unsuitable for the desired separation of HCAL. On the other hand, PVP free-base resin has significantly high sorption of HCAL as compared to catechol and pyrogallol in mildly acidic media (pH 1.8–2.8), the respective saturation values being 576, 206, and 303 mg/g dry resin, but the free-base resin also shows high saturation capacity (500 mg/g dry resin) for pectin. However, at low substrate concentrations (1 g/L) or relatively low pH (2), pectin has an order of magnitude lower sorption than HCAL, making separation of the latter possible on PVP free-base resin. Column operation using PVP free-base resin with influent maintained at pH 1.8, followed by stripping with less than the theoretical amount of alkali, produces good separation and high yield of HCAL from the mixed influent. Reillex HP, a macroporous PVP resin, used in free-base form, has relatively fast kinetics for HCAL sorption, with a t 1/2 value of about 5 minutes and diffusivity of the order of 10−6 cm2/s.

Preparative separation of taxol in normal- and reversed-phase operations

A method is described that separates taxane compounds from crude extracts under either reversed- or normal-phase conditions using a Zorbax-based bonded material, “SW-Taxane”. A crude plant extract of Taxus canadensis and five standard taxane compounds were separated. The method provides high selectivity and recoveries of compounds from a taxol extract in the isocratic mode. Under normal-phase conditions, the packing material has shown significantly greater selectivity of taxol-related compounds than bare silica and most other commercially available silica-based bonded materials. Reversed-phase separations on the column, are also superior compared to typical C 8 separations. In addition, a loading study demonstrates that this phase has a high taxol saturation capacity due to its large surface area.