Removal studies

Fig. 24. Laboratory cell for H2S removal study. Schematic diagram for assembled cell with A12Oj ring.

O Grady J, Losikoff A, Poiley J, Fickett D, Oliver C. Virus removal studies using nanofiltration membranes. Dev Biol Stand 1996 88 319-326. 

Hg2+ Removal Studies using Synthesized Metal Sulfides... 

Hg2 Removal studies using particle-size-mediated synthesized metal sulfides. 

Because porphyrins bind metal cations avidly, we found it necessary to protect the porphyrin stoppers by complexation prior to template removal studies. The sequence of reactions are shown schematically in Figure 2.31.61... 

Dianions derived from sulfur and oxygen containing polycyclic systems have not been reported until very recently. The weak carbon-sulfur bond could discourage attempts to prepare such dianions. Sulfur removal studies by alkali metals were successful due to the properties of the carbon-sulfur bond 182,183). Reductive alkylation studies on model compounds which are relevant to sulfur containing systems demonstrated the stability of hydrocarbon dianions 182). A spectroscopic study performed under mild conditions afforded the characterization of sulfur and oxygen containing dianions 184 186). Benzo[b]thiophene, (73), 1,3-diphenylbenzo[c]thiophene (74) and l,3-diphenylbenzo[c]furan (75) form the respective dianions at low temperature. 

In order to evaluate the utility of the removal model for additional metals, additional removal studies were conducted using Chromium and Cobalt in place of copper. Chromium removal was studied using solutions made by dissolving CrO, in dilute H2SO4 to produce solutions with chromium concentrations of 80 ppm. The oxidation state of the chromium in the resulting solutions was not determined. Intraparticle diffusivities of Cr, Co", and Cu were calculated with the removal model, and are compared in Figure 7. The removal model for Dowex XFS 4195.02 appears to be generally applicable to most metals. 

Huge amounts of liquid byproduct and waste effluents in the fertilizer industry contain various heavy metals, some of which are highly toxic. Cd, Cu, and Zn are commonly encountered in these effluents and are selected for selective removal studies using liquid membrane systems [1-7, 14-17]. Below, experimental and calculated data, obtained for Cd, Cu, and Zn separation, are used for the BAHLM process design considerations. 

Another appUcation of membrane processes for MTBE removal studied in literature is the pervaporation, which represents an alternative to the stripping process discussed in chapter 3. Hydrophilic pervaporation is commonly used for the absolutation of alcohol which forms an azeotropic mixture at high ethanol content [128]. By the vaporization of the mixture through a thin membrane layer, the azeotrope is cleaved and water is evaporated leaving the pure ethanol in the retentate. 

Another empirical parameter that has been used in wet removal studies is the scavenging ratio defined as the ratio of species concentration in collected precipitation divided by that in air ... 

In the above sequence, sulfate is the most-preferred anion for strong-base-anion (SBA) resins and it will eventually displace ions with lower selectivity from the resin. Monovalent arsenate, H2ASO4, and bicarbonate have low affinity for the resin. Arsenious acid, H3ASO3, is the least preferred it simply passes through the resin because it s not ionic. This resin selectivity sequence, which had been suggested by Horng (23) based on his As(V)-removal studies was confirmed by other studies (3,4,19-21). 

J Simms, J Upton, J Barnes. Arsenic removal studies and the design of a 20,000 m per day plant in the UK. American Water Works Association Inorganic Contaminants Workshop, Albuquerque, NM, 2000. 

Polycyclic aromatic hydrocarbons (PAHs), representative HOCs, are very hydro-phobic and have quite low aqueous solubUity. The solubilization/desorption and partitioning of PAHs in soil-water systems have been extensively studied using solubUity-enhancing solutions such as surfactants and cosolvents to achieve effective removal of PAHs from contaminated sites. Recently, a number of laboratory studies on the electrokinetic removal of PAHs have appeared, evaluating the effect of enhancing solution and electrokinetic variables. The field remains underresearched in comparison with metal removal studies. 

Apart from the hydrogen-removal studies, reactions in which O2 has to be removed, e.g. NO and CO2 decomposition, are of environmental interest. The membrane materials used for this purpose are mixed oxides such as zirconias [90, 91] and perovskites [92]. 

SUMMARY OF HETEROATOM REMOVAL STUDIES Fart A - Study Related to Real Systems... 

A CU3AS target irradiated with protons contains both Se and As, formed via As(p,n) Se and As(p,pn) As reactions, respectively. Detailed removal studies as a function of temperature revealed that [ As] AS2O3 is removed at 600° C, whereas for removal of radioselenium, a temperature of about 1,100°C is required. Thus, by a two step thermochro-matographic treatment, it is possible to separate radioselenium from the matrix. 

The production cost and reusability of the adsorbents are the most effective parameters for the sorbents in the wastewater treatment systems. Therefore, reusability of the super absorbent hydrogel was also evaluated for the Cr (VI) ions removal studies. During these studies, the optimized super absorbent hydrogel A2 adsorption condition, (initial ion concentration), which can provide maximum ion removal, was used. 

Removal studies for GE from Pt catalysts are still under investigation. Mitigation strategies will likely include flushing the FG with water to remove Cl , and incorporating anion-exchange units (Abd Elhamid et al., 2006). Pt-alloys also have been reported to recover more completely from Cl-poisoning as reported by Steinbach et al. (2007). 

Sujana, M.G. Anand, S. (2011) Fluoride removal studies from contaminated ground water by using bauxite. Desalination, 267, 222-221. 

The advantage of DBBP over the other 2 carriers was evident and this carrier was selected for the subsequent As removal studies. It was suggested that pol5nnerization between CTA and DBBP occurred spontaneously at all CTA/DBBP ratios studied (Ballinas et al., 2004). A t)q)ical PIM used in this work was composed of 8 wt% CTA and 92 wt% DBBP. Hence, the intermixing between the two components is crucial for the formation of a stable membrane. Otherwise, the... 

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