Surface properties of the mixed oxides of iron and silica

Mustafa, S.; Dilara, B.; Nargis, K; Akhtar, Naeem; Shahida, P.

doi:10.1016/s0927-7757(02)00025-0

Cited by 144 publications

(56 citation statements)

References 22 publications

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“…Understanding such fundamental properties are essential in the proper modeling and risk-analysis of plutonium storage in underground geological repositories. Point of zero charge (PZC) measurements were conducted on the Mn-substituted goethite using the powder addition method [16,17]. This method was chosen because of two distinct advantages: the process is fast, and it requires a small amount of mineral compared to other methods, such as potentiometric titration [18] and mass titration [19].…”

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confidence: 99%

Molecular interactions of plutonium(VI) with synthetic manganese-substituted goethite

Schwaiger

Booth

et al. 2010

Ract

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SummaryPlutonium(VI) sorption on the surface of well-characterized synthetic manganese-substituted goethite minerals (Fe 1-x Mn x OOH) was studied using X-ray absorption spectroscopy. We chose to study the influence of manganese as a minor component in goethite, because goethite rarely exists as a pure phase in nature. Manganese X-ray absorption near-edge structure measurements indicated that essentially all the Mn in the goethite existed as Mn(III), even though Mn was added during mineral synthesis as Mn(II). Importantly, energy dispersive X-ray analysis demonstrated that Mn did not exist as discrete phases and that it was homogeneously mixed into the goethite to within the limit of detection of the method. Furthermore, Mössbauer spectra demonstrated that all Fe existed as Fe(III), with no Fe(II) present. Plutonium(VI) sorption experiments were conducted open to air and no attempt was made to exclude carbonate. The use of X-ray absorption spectroscopy allows us to directly and unambiguously measure the oxidation state of plutonium in situ at the mineral surface. Plutonium X-ray absorption near-edge structure measurements carried out on these samples showed that Pu(VI) was reduced to Pu(IV) upon contact with the mineral. This reduction appears to be strongly correlated with mineral solution pH, coinciding with pH transitions across the point of zero charge of the mineral. Furthermore, extended X-ray absorption fine structure measurements show evidence of direct plutonium binding to the metal surface as an inner-sphere complex. This combination of extensive mineral characterization and advanced spectroscopy suggests that sorption of the plutonium onto the surface of the mineral was followed by reduction of the plutonium at the surface of the mineral to form an inner-sphere complex. Because manganese is often found in the environment as a minor component associated with major mineral components, such as goethite, understanding the molecular-level interactions of plutonium with such substituted-mineral phases is important for risk assessment purposes at radioactively contaminated sites and long-term underground radioactive waste repositories. Previous work by Kaplan et al.[4] using laboratory and lysimeter studies showed that > 95% of plutonium migrating from a purposefully placed solid Pu IV (NO 3 ) 4 source remained within 1.25 cm of the source over an 11 year period under natural environmental conditions at the Department of Energy (DOE) Savannah River Site (SRS).Such work on large-scale environmental systems is an important part in uncovering essential components of the soil and mineral composition that controls plutonium redox chemistry. However, individual sorption and redox processes must also be tested on well-characterized model mineral phases that properly represent individual environmental In nature, manganese is rarely found as a pure mineral phase. It is often found as a minor component associated with major mineral phases, such as goethite. As a model to these environmental minerals, we have synthesiz...

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Molecular interactions of plutonium(VI) with synthetic manganese-substituted goethite

Schwaiger

Booth

et al. 2010

Ract

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“…0 and 231.5 nm) [15,16]. The pH of point of zero charge (pH PZC ) for TSPA-AgNO 3 was detected using the pH equilibrium method as described in the reference work [17]. Solution pH was measured with a Sartorius PB-10 pH meter.…”

Section: Methodsmentioning

confidence: 99%

Silver (I)-coordinated bis(trimethoxysilylpropyl)amine Polycondensate for Adsorptive Removal of Iodide from Aqueous Solutions

Zhang

et al. 2016

MATEC Web Conf.

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Abstract.Silver-coordinated bis(trimethoxysilylpropyl)amine polycondensate (TSPA-AgNO 3 ) was prepared and used to adsorb iodide ions in aqueous solutions. Batch adsorption studies were performed to investigate the effects of pH, temperature and coexisting NaCl on adsorption behavior. The results show that TSPA-AgNO 3 is easy to prepare and remarkably efficient in adsorbing iodide in water, especially in acidic solutions. Furthermore, increased temperature accelerated the adsorption, while coexisting NaCl inhibited the adsorption. TSPA-AgNO 3 also proved to be chemically stable in simulated environmental situations, which reveals a promising potential for applying this method to the disposal of radioactive iodide in environment water.

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“…The industrial granular activated carbon used in the present work was obtained from typical market and its properties such as the point of zero charge (PZC) and iodine number (Mustafa et al, 2002 andMatsumura et al, 1997) are determined equal to 3 and 1330.24 mg g , respectively (with cylindrical shape and average diameter and length of 4 and 7 mm, respectively). The Basic yellow 2, was obtained from Aldrich company and used without further purification.…”

Section: Methodsmentioning

confidence: 99%

Removal of C.I.Basic yellow 2 from aqueous solution by adsorption onto granular activated carbon using an on-line spectrophotometric analysis system: Kinetic and equilibrium study

2013

Global NEST Journal

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The adsorption of Basic yellow 2 (BY2), from aqueous solutions onto Granular activated carbon (GAC) and its adsorption kinetics at different concentrations, GAC masses, initial pH values and temperatures were studied. The adsorption process was followed by an on-line spectrophotometric analysis system, which consisted of UV-spectrophotometer, a designed spectrophotometric cell, peristaltic pump and a glassy reactor. The effect of initial dye concentration, mass of GAC, initial pH and temperature on adsorption was studied over 60 min adsorption period. The results showed that at first the removal percent of BY2 increases with the increase in initial concentration, then the trend is reversed. The results also showed that removal percent of BY2 at pH i around 7 is more than acidic pH i . Also the removal percent of BY2 increases with the increase in mass of GAC and temperature. For kinetic study, the obtained data were treated according to various kinetic models. The results showed that first order kinetic model is fitted to experimental data better than second order and intraparticle diffusion models. The Freundlich, Langmuir, Redlich-Peterson and BET adsorption models were applied to describe the equilibrium isotherms. Type 1 Langmuir isotherm and non-linear Redlich-Peterson isotherm seemed to be the best-fitting models for the experimental results with similar values of coefficient of determination.

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Surface properties of the mixed oxides of iron and silica

Cited by 144 publications

References 22 publications

Molecular interactions of plutonium(VI) with synthetic manganese-substituted goethite

Molecular interactions of plutonium(VI) with synthetic manganese-substituted goethite

Silver (I)-coordinated bis(trimethoxysilylpropyl)amine Polycondensate for Adsorptive Removal of Iodide from Aqueous Solutions

Removal of C.I.Basic yellow 2 from aqueous solution by adsorption onto granular activated carbon using an on-line spectrophotometric analysis system: Kinetic and equilibrium study

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