Compartmental analysis of metals in waterpipe smoking technique.

BACKGROUND: The number of waterpipe tobacco smokers has been increasing worldwide. Smokers can be exposed to a number of toxicants, some of which are metals. The aim of this study is to quantitatively determine if the water filtration stage of the waterpipe smoking process successfully decreases exposure to Bi, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, V, and U. METHODS: Four samples of commercially available tobacco (Moassel) were compared in terms of the total amount of metal contained within the fresh tobacco sample and the amount of metal distributed into each compartment of the waterpipe after a smoking session. RESULTS: For all metals analysed, the concentration of metal 'filtered' out during the water bubbling stage is around 3% (±1%) of the total metal. CONCLUSIONS: It can be concluded that this small fraction would not protect the user against exposure to the majority of the potentially toxic metals.

Improving the adsorption efficiency of phenolic compounds into olive wood biosorbents by pre-washing with organic solvents: Equilibrium, kinetic and thermodynamic aspects.

The adsorption properties of olive wood (OW) toward phenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2-nitrophenol, 4-nitrophenol and 2,4-dinitrophenol, were improved by washing OW with some organic solvents (ethanol, tetrahydrofuran, ether, dichloromethane or hexane). Adsorption isotherms were classified according to Giles and Smith classification, in which L2-shape was obtained after OW washing. The adsorption data were modeled using Langmuir and Freundlich isotherm equations and it was found that adsorption capacity and affinity have increased after OW washing. Thermodynamic (ΔG°, ΔH° and ΔS°), kinetic and intra-particle diffusion parameters were estimated before and after OW washing. It was found that the adsorption of phenols on OW was of physical nature, spontaneous, exothermic and followed second order rate equation. After OW washing, adsorption spontaneity has increased. Both pore diffusion and kinetic resistances have most likely affected the adsorption process. The results presented in this work suggested that washing OW with any one of the tested solvents would enhance uptake of the tested phenols into OW sorbent. Discussing some economical and environmental aspects suggested that the use of ethanol might be preferred.

Separation and flame atomic absorption spectrometric determination of total chromium and chromium (III) in phosphate rock used for production of fertilizer.

Due to the commercial value of phosphate rock (PR) as a fertilizer precursor, it is necessary to investigate its heavy metals content. Chromium (Cr) may present as Cr(III) or Cr(VI) in PR; but quantitative differentiation between them is not an easy task. This is due to possible interconversion of Cr species during the digestion/leaching process. In this work, ultrasound digestion (USD) of PR was optimized (300 mg PR, 4.0 mL of 4.0 mol L(-1) nitric acid, 15 min sonication) for the sake of leaching Cr species prior to their determination by flame atomic absorption spectroscopy. Using multi-walled carbon nanotube (MWCNT) as adsorbent, solid phase extraction (SPE) was used to separate Cr(III) from the digestate at pH 9, while total Cr was estimated after reducing Cr(VI) into Cr(III). The optimum USD/SPE method gave LOQ and LOD of Cr(III) of 0.96 mg kg(-1) and 0.288 mg kg(-1), respectively. The method sensitivity was 1.44×10(-3) AU kg mg(-1) within the studied Cr concentration range (5-400 mg kg(-1)). The USD/SPE method was validated by analyzing lake sediments LKSD-4 certified reference material, and by comparison with classical digestion method (CD). Application of USD/SPE on Jordanian PR samples gave total Cr rang 29.1-122.0 mg kg(-1) (±1.4-6.3), while Cr(III) ranged between 23.8 and 101.7 mg kg(-1) (±1.3-5.5). AFPC Rock Check Program samples gave total Cr range 238.9-394.7 mg kg(-1) (±11.5-24.1), while Cr(III) ranged between 202.4 and 335.8 mg kg(-1) (±11.4-18.3). These results were very close to the results obtained by the CD method.