A series of energy-and time-efficient enhanced microwave syntheses (EMS) of polyaniline (PANI) have been performed and are discussed herein. The syntheses were performed at different microwave power levels while keeping the reaction system at a constant temperature of 24 ± 1 °C, with the samples extracted after 10 min of reaction. Molecular weights were determined with GPC (gel permeation chromatography) and showed that the molecular weight of the microwave-generated materials depends on applied power: the higher the power level, the greater the molecular weight. The chemical structure was investigated by FTIR and UV−vis spectroscopy, while the morphology was imaged using scanning electron microscopy (SEM). FTIR and UV−vis spectroscopy confirmed the formation of PANI, and SEM indicated the presence of a mixed morphology, with a prevalence of nanofibers with different aspect ratios. The conductivity of the samples (ca. 3−3.5 S cm −1 ) was found to be relatively independent of microwave power levels. Surface area measurements were carried out using Brunauer−Emmett−Teller (BET) method, with samples synthesized using EMS showing higher surface areas when compared with conventionally synthesized PANI. The fact that molecular weight depends on applied power implies that microwaveenhanced synthesis can be used to fine-tune PANI reaction conditions, directing it toward specific properties.

The objective of this study is to evaluate natural and artificial radioactivity levels in 18 different samples of medicinal herbs from Serbian market. The activity concentrations of (238)U, (232)Th, (40)K, and (137)Cs were measured using gamma spectroscopy system with a high-purity germanium detector. The activity concentrations of (238)U, (232)Th, (40)K, and (137)Cs were found to be in a range of 0.6-8.2, 1.7-15.1, 126-1243.7, and 0.3-8.8 Bq/kg, respectively. The annual whole body doses from ingestion of (137)Cs and natural radionuclides for an adult person who consumed herbal tea from these medicinal herbs were found to be 2.5-469.9 nSv for (137)Cs, 0.7-9.7 nSv for (238)U, 0.3-2.8 nSv for (232)Th, and 1026.0-10,132.0 nSv for (40)K. These doses are not hazardous to public health. The obtained results were compared with correspondent studies conducted worldwide.

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The kinetics of isothermal adsorption of nicotine from an aqueous solution onto hydrophobic zeolite type USY was investigated. The adsorption isotherms of nicotine on zeolite type USY were measured in the temperature range from 298 to 322 K. Specific shape parameters of the adsorption degree curves were determined. The changes in the specific shape parameters of the adsorption degree curves with temperature and the kinetic parameters of nicotine adsorption (E a, ln A) were determined. The kinetic model of nicotine adsorption, [1 − (1 − α)1/2] = kt, was established by using the model-fitting method. It was found that the nicotine adsorption was a kinetically controlled process which was determined by the rate of bidimensional movement of the boundary layer of the adsorption phase. Nicotine is most probably chemisorbed onto the acidic centers of zeolite type USY.