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The aim of this study is to investigate the possibilities of removing lead, cadmium, and zinc from air by sorption natural wool fibers (NWF), thus evaluating possible application of the wool materials in direct protection of air from the influence of heavy metals. Metal detection was done (before and after the sorption process) by potentiometric stripping analysis. Sorption experiments were done in two ways: by immersing NWF in model solutions (prepared by the working standard solutions and deionized water), and by immersing NWF in solutions of sediments from the air. The influence of mass sorbent, sorption time, pH, and temperature on the sorption of lead, cadmium, and zinc were experimentally examined. Effectiveness of lead, cadmium, and zinc sorption by applying natural wool fibers is shown as the sorption capacity (a ratio between metal concentration before and after sorption and sorbent mass). Sorbent of 0.1 g NWF mass in neutral environment collects: after 10 min 23,9% of lead, 19,0% of cadmium, and 21,3% of zinc; whereas after 30 min 71.5% of lead, 69.6% of cadmium, and 69.4% of zinc. NWF of the same mass in acidic environment shows lower sorption capabilities, for pH 4.5 the effective sorption is: 68.6% of lead, 66.8% of cadmium, and 66.6% of zinc; whereas for pH 2.1 NWF sorption is 54.6% of lead, 53.2% of cadmium, and 52.9% of zinc. Optimal pH range for application of this sorption during the experiment material is 4.5-7.0. The sorption was made in solutions with pH 2.1 due to potentiometric stripping analysis application conditions. Temperature significantly impacts the tested material sorption characteristics. When temperature slightly increases, regardless of the inflicted damage, NWF keeps its functionality. When temperature is higher than 60°C, the sorbent effectiveness is reduced. The NWF sorption capacity is lowest at 100°C: for lead 11.63 μg g−1, for cadmium 8.18 μg g−1, and for zinc 9.41 μg g−1. Results of the experimental research have shown that a high degree of removal (about 70%) can be achieved provided that the mass of the sorbent rages from 0,06−0,1 g, contact time is long enough (30 min), and that there are no significant effects of temperature and pH. |
