Further investigation into ICP-induced elemental fractionation in LA-ICP-MS using a local aerosol extraction strategy

The increased size of aerosol agglomerates or particles because of the reduced carrier gas velocity on the ablation site deteriorates the vaporization of aerosol particles in ICP, which induces similar elemental fractionation to laser ablation-induced fractionation.

Diffusion and Equilibrium Adsorption Coefficients of Aromatic Hydrocarbon Species in Capillary Columns

This study focuses on a mathematical description of elution of aromatic species in a 30 m×0.25 mm×0.25 μm BPX5 capillary column. Experimental studies involve the detection of chemical species at the capillary column outlet. Using the recorded peaks, statistical moments of different orders are calculated for both toluene and naphthalene. Modeling studies involve a laminar flow model with an equilibrium coefficient (Ks) and a solute diffusion coefficient in the stationary phase (Ds). Model validation is developed by performing experiments at different carrier gas velocities and GC oven temperatures. Under the conditions, neither the first statistical moment (M1) nor the second statistical moment (M2) is affected by the carrier gas velocity. Thus, the interface equilibrium coefficients (Ks) and the diffusion coefficients (Ds) solely depend on the solute and the capillary column polymer coating properties. Furthermore, the statistical moments of different orders show that the proposed interface equilibrium based model in the “narrow bore” 30 m×0.25 mm×0.25 μm BPX5 capillary column is adequate for aromatic species such as toluene and naphthalene.

Study on Thermal Regeneration for Caffeine-Saturated Activated Carbon

Waste activated carbon (AC) containing caffeine was produced during the process of the production for caffeine. The process of treatment caffeine-saturated AC using thermal regeneration was explored and factors on the regeneration of activated carbon were investigated. The optimum conditions obtained were: temperature is 650 °C, the regeneration time is 180 min, the carrier gas velocity is 0.002 m/s, carbon layer thickness is 0.1 m. Under these conditions, activated carbon regeneration efficiency reached 90.3%. In addition, the pore structure of activated carbon before and after regeneration was characterized and the activated carbon surface area and pore size distribution under optimum conditions were determined by the adsorption isotherms.