Methods were developed to determine OH reaction rates for medium-weight organophosphorus pesticides in the gas phase. A 57-L chamber was constructed that utilized xenon arc irradiation (>290 nm) to photolyze the OH precursor, methyl nitrite. Experiments were performed at elevated temperatures ranging from 60 to 80 degrees C to minimize wall sorption. Solid-phase microextraction (SPME) sampling ...

Crystalline cellulose chemically modified through a reaction with sodium trimetaphosphate (STMP) in an acidic or basic condition yielded Cel-P4 and Cel-P10. These phosphated solids were characterized by elemental analysis, X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) at the solid state for phosphorus nucleus and disper...

Natural lignocellulosic fiber epicarp extracted from the babassu coconut (Orbignya speciosa) was chemically modified through reaction with molten maleic anhydride without solvent, with incorporation of 189.34 mg g of carboxylic acid groups into the biopolymer structure. The success of this reaction was also confirmed by the presence of carboxylic acid bands at 1741 and 1164 cm in the infrared s...

In the environment, chemical reactions at the mineral/water interface occur over a range of temporal scales, ranging from microseconds to years. Many important mineral surface processes (e.g., adsorption, oxidation-reduction, precipitation) are characterized by a rapid initial reaction on time-scales of milliseconds to minutes, and are often limited by the formation of secondary mineral phases....

The sorption and desorption behaviors of Eu(III) from aqueous solutions with cation exchange resins containing carboxyl groups (D155 resin) were studied in terms of varied Eu(III) concentration, adsorbent dosage, pH, contact time and temperature. Batch shaking sorption experiments were carried out to evaluate the performance of D155 resin in the removal of Eu(III) from aqu...

Results are presented from 1 year batch experiments where K-rich hyperalkaline pH 13.5 young cement water (YCW) was reacted with sediments to investigate the effect of high pH, mineral alteration, and secondary mineral precipitation on (90)Sr sorption. After reaction with YCW, Sr sorption was found to be greater than 75% in all samples up to 365 days and 98% in a sample reacted for 365 days at ...

It has been demonstrated both thermodynamically and experimentally that fuel-cell grade hydrogen can be produced by a one-step sorption enhanced water gas shift (SEWGS) process at about 500 oC, where the water gas shift (WGS) catalyst and the CO2 sorbent are highly integrated. A synthetic CaO-based mixed oxide sorbent was also assessed, which showed a good CO2 capture capacity and stability in ...

The role of biochar as a soil amendment on the transport of acetamiprid, a widely used neonicotinoid pesticide, is little known. We conducted saturated column experiments to examine cotransport of acetamiprid and silica nanoparticles (NPs) in pure and biochar-amended sands. Retention of acetamiprid was minor in the pure sand, whereas application of biochar in the sand significantly increased re...

Experiments were conducted to compare the sorption and desorption of phenanthrene and its primary degradation product, 1-hydroxy-2-naphthoic acid (HNA), in estuarine sediment, humic acid (HA) and humin. Ionic composition, ionic strength (0.4 M) and pH (7.6) were employed to mimic native estuarine pore water at the sediment-water interface. Sorption to whole sediment and organic matter (OM) frac...

cleanup. Major compounds that have been shown to increase the solubility and thus the mobility of nutrients Mobile organic sorbents (MOS) such as dissolved and colloidal and contaminants are surfactants (Edwards et al., 1991; phase organic matter control flow of water and transport of solutes in soils. We studied the effect of MOS on contaminant fate by systematic Haulbrook et al., 1993; Rahman...