Removal of Parabens from Aqueous Solution Using β-Cyclodextrin Cross-Linked Polymer

The removal of four parabens, methyl-, ethyl-, propyl-, and benzyl-paraben, by β-cyclodextrin (β-CD) polymer from aqueous solution was studied. Different β-CD polymers were prepared by using two cross-linkers, i.e., hexamethylene diisocyanate (HMDI) and toluene-2,6-diisocyanate (TDI), with various molar ratios of cross-linker. β-CD-HMDI polymer with molar ratio of 1:7 and β-CD-TDI polymer with ratio 1:4 gave the highest adsorption of parabens among the β-CD-HMDI and β-CD-TDI series, and were subsequently used for further studies. The adsorption capacity of β-CD-HMDI is 0.0305, 0.0376, 0.1854 and 0.3026 mmol/g for methyl-, ethyl-, propyl-, and benzyl-paraben, respectively. β-CD-TDI have higher adsorption capacities compared with β-CD-HMDI, the adsorption capacity are 0.1019, 0.1286, 0.2551, and 0.3699 mmol/g methyl-, ethyl-, propyl-, and benzyl-paraben respectively. The parameters studied were adsorption capacity, water retention, and reusability. Role of both cross-linker in adsorption, hydrophobicity of polymers, and adsorption capacity of different parabens were compared and discussed. All experiments were conducted in batch adsorption technique. These polymers were applied to real samples and showed positive results

Composition of higher molecular weight organic matter in smoke aerosol from biomass combustion in Amazonia

Smoke particulate matter was sampled by high volume filtration from a controlled burn of forest litter in the northern forest reserve of INPA about 70 km north of Manaus, Amazonas. The extract of the filter was separated after methylation into hydrocarbon, ketone, carboxylic acid ester and polar fractions and then analyzed by gas chromatography and gas chromatography-mass spectrometry. The total lipid extract yield was ∼13 mg/m3 of smoke. The major organic components of the smoke particles were straight-chain aliphatic and triterpenoid compounds from vegetation wax, biopolymers, and gum/resin. Polynuclear aromatic hydrocarbons (PAH) from the combustion process were found at high levels and aromatized derivatives from natural product precursors were also important components. Petroleum hydrocarbons representing urban and vehicular emissions were not detectable. The n-alkanes ranged from C19 to C35, with a carbon number maximum (Cmax) at C29/C31 and an odd-to-even carbon predominance > C25 (CPI20-35 = 3.6). Terminal olefins (n-alk-1-enes) were also present and ranged from C17 to C35, with a Cmax at C22 and an even-to-odd carboon predominance (CPI17-35 = 0.8). The n-alkanes are derived mainly from vegetation wax and the alk-1-enes with other oxygenated compounds (e.g., ketones, acids, triterpenoids) are thermal alteration products from gum/resin and biopolymers. These alteration products coupled with the PAH are the tracers for biomass combustion. © 1995

A study of the physical, chemical, and optical properties of ambient aerosol particles in Southeast Asia during hazy and nonhazy days

10.1029/2005JD006180Journal of Geophysical Research D: Atmospheres11110