Arsenic sorption on mechanically activated minerals such as magnetite Fe3O4 (Kiruna, Sweden) and olivine (Mg,Fe)2SiO4 (Ǻheim, Norway) has been studied and compared in this work. Experiments were carried out with non-activated and mechanically activated samples. The activation of both minerals was performed in a planetary mill at different milling conditions. The specific surface area and conseq...

The sorption kinetics of the divalent metals Zn, Co, Ni, and Cd to hematite were studied in single sorbate systems with high sorbate/sorbent ratios (from 1.67 to 3.33mol sorbate/mol sorption sites) in 10mM Na-piperazine N,N'-bis 2-ethane sulfonic acid (Na-PIPES) solution at pH 6.8. The experimental data showed a rapid initial sorption (half-time about 1min) followed by slower sorption that cont...

Rates of biodegradation of sorbed chemicals are usually lower in soil than in aqueous systems, in part because sorption reduces the availability of the chemical to microorganisms. Biodegradation, sorption, and diffusion occur simultaneously and are tightly coupled. In soil, the rate of biodegradation is a function of a chemical's diffusion coefficient, sorption partition coefficient, the distan...

The organic-inorganic hybrid material of polyaniline/titanium(IV) (PANI/Ti(HPO4)2) was synthesized by an oxidative polymerization reaction. The PANI/Ti(HPO4)2 was applied to remove Re(VII). The size of Ti(HPO4)2 nanoplates has no obvious effect on the sorption capacity. The effects of various environmental factors (such as pH, extra anions (NO3(-) and MO4(2-)) and temperature) on Re(VII) sorpti...

In zeolites, diffusion is often accompanied by a reaction or sorption which in turn can induce temperature inhomogeneities. Monte Carlo simulations of Lennard–Jones atoms in zeolite NaCaA are reported for the presence of a hot zone presumed to be created by a reaction or chemior physi-sorption site. These simulations show that the presence of localized hot regions can alter both kinetic and tra...

Introduction: Many kinetic studies have shown that sorption of metals on natural materials results in the formation of metal precipitates. However, the influence of temperature on the kinetic formation of these metal precipitates has not been studied. The effect of temperature on reaction rates is well known and important in understanding reaction mechanisms. For most reactions, the increase in...

The kinetics of mixed Ni-Al layered double hydroxide (LDH) precipitate formation on a soil clay fraction was monitored using X-ray absorption fine structure (XAFS) spectroscopy. The kinetic behavior was monitored at pH 6.0, 6.8, and 7.5 in order to determine the effect of reaction pH on precipitate formation. XAFS analyses were performed on a Ni-reacted whole soil at pH 7.5 to determine the eff...

The interaction of sulfonamide antimicrobial agents with smectite clay minerals and humic acid (HA)-clay complexes was investigated in batch experiments to assess the influence of adsorbed humic acid on sulfonamide sorption. Soil HA-clay complexes were produced at HA:clay ratios of 1:5, 1:50, and 1:100 (w/w). Vibrational and electronic spectroscopy indicated the preferential adsorption of polar...

The transport and fate of many contaminants in subsurface systems can be influenced by several rate-limited processes, such as rate-limited sorption, diffusional mass transfer, and transformation reactions. Identification of the controlling process in such systems is often difficult, and is confounded by the possible influence of additional factors such as nonlinear or hysteretic sorption. We p...