Equilibrium study of Cr (VI) removal from aqueous solution by stalks from three tobacco species (Nicotiana) grown in Bulgaria

摘要

Agricultural and processing activities generate enormous amounts of tobacco waste, and the stalks left afterharvesting of the leaves constitute a significant share. The stalks of common tobacco (N. tabacum L.) wereconsidered a promising source for processing and recycling, but very little is known about the properties of thestalks from other Nicotiana species. The aim of the present study was to examine the performance of stalkpowders from three Nicotiana species grown side-by-side in Bulgaria for the ability to remove Cr (VI) ions fromaqueous solutions. The characterization of applied biosorbents was conducted by FTIR analysis. Batch experiments were carried out and the effects of different adsorption process parameters were determined. Maximumremoval efficiencies of 99.13 ± 0.55%, 98.33 ± 0.58% and 95.00 ± 0.50% for N. tabacum, N. rustica L. and N. alataLinkOtto, respectively, were obtained at pH 3.0, adsorbent dosage 5 g/L, initial Cr (VI) concentration 10 mg/L,temperature 25.0 ± 0.5oC, agitation speed 200 rpm and contact time 60 min. The Langmuir and Freundlich models fitted well the equilibrium isotherms experimental data. Based on the values determined for the maximum adsorption capacity, the powder from N. alata stalks was found to have higher affinity (9.87 mg/g) for Cr (VI)ions than those obtained from N. tabacum (8.38 mg/g) and N. rustica (6.96 mg/g) stalks.