Influence of anionic surfractants on Zn2+ and Sr2+ uptake by ivy (Hedera helix L.) leaves

Surfactants are frequently used as adjuvants for improving the efficiency of foliar applied fertilizers, pesticides and other biologically active substances. In our paper we used detached leaves of ivy (Hedera helix L.) for the study of the influence of anionic surfactants sodium dodecylsulfate (SDS) and sodium dicyclohexyl sulfosuccinate (DCSS) on zinc and strontium uptake by leaf surface and transport by radiotracer technique with 65ZnCl2 and 85SrCl2. Accumulated amounts of Zn2+ and Sr2+ ions by the surface of detached intact ivy leaves were 5.0 and 1.1 μg/g, respectively. Ivy leaves pretreated for 24 h in 1 mM SDS or DCSS solutions accumulated approx. twice more Zn and five time more Sr than non treated leaves. Pretreatment with surfactants increased mobility of zinc and strontium in leaf tissues. Separate experiments showed that both SDS and DCSS were sorbed onto the leaf tissue reaching equilibrium within several hours of immersing leaf blades to surfactant solutions. The process can be described in terms of partition equilibria P = [C]leaf/[C]solution with log P = 1.396 within surfactant concentration studied Co ≤ 100 μmol/L. The mechanism of action of surfactants on metal ion uptake is discussed.

Removal of Pb(II), Zn(II), Sn(II) and Cu(II) Ions from Aqueous Solutions by Linear Alternating Poly(4,4'-biphenol oxalate) Oligomer

Poly(4,4′-biphenol oxalate) oligomer was synthesized and characterized by FT-IR, elemental analysis XRD and thermal analysis. The capability of the oligomer to take away Pb(II), Zn(II), Sn(II) and Cu(II) metal ions from aqueous solutions was considered by the known batch and column techniques in terms of concentration, pH value, contact time and temperature. The results indicated that a high initial rate of metal-ion uptake by the oligomer was observed throughout the first 30 minutes, which enlarged slightly amid rising the pH value and then reached its greatest value at pH=5.00 for Pb(II) and Zn(II), pH=4.00 for Cu(II) and pH=6.00 for Sn(II). The oligomer exhibited a high metal-ion uptake capacity to Pb(II) and Zn(II), but a little metal-ion uptake capacity to Cu(II) and Sn(II). Linearized forms of the Langmuir, Freundlich and Dubinin–Radushkevich adsorption isotherms were used to investigate the experimental equilibrium concentration data of Pb(II), Zn(II), Cu(II) and Sn(II). ΔG values demonstrated that the adsorption process of these metal ions on the oligomer is favored while the ΔH values indicated that this process is endothermic. On the other hand, the entropy of the process is positive. In addition to batch experiments, column experiments were performed, where the metal ions were efficiently recovered by treatment of the metal-loaded oligomer with 1.0 M HNO3, 1.0 M HCl and 0.5 M EDTA. The best results were obtained with 1.0 M HNO3 solution.

Adsorption of Copper from aqueous solution by chitosan using molecular imprinting technology

In nature chitosan is a plentiful polymer with high heavy metal ion uptake capacity due to chitosan’s functional groups that chelate with the positive surfaces of heavy metal ions. In this study, epichlorohydrin was used as a crosslink to prepare the copper-imprinted chitosan as a pattern to enable the selectivity property and increase adsorption capacity. The effects of the cross-linker, PH, initial concentration and time were examined in this study to identify the optimum amount of each to remove copper metal ions from waste water by imprinted chitosan. This composite was characterized by Fourier-transform infrared spectroscopy (FTIR) test to determine the existence of copper ions in chitosan crosslinked with epichlorohydrin. Scanning electron microscopy (SEM) tests were also done to compare the surfaces of crosslinked chitosan and the removal of copper by imprinted chitosan. PH adsorption was tested from 3 to 7 and the initial concentration and time investigated were between 10 and 100 mg/l and 0 and 120 minutes respectively. The maximum capacity to adsorb was found to be at PH 7, initial concentration of 100mg/l at 90 minutes with 0.1 gr chitosan. Ultimately, the maximum adsorbent amount achieved for effective Cu(II) removal was 74.37 mg/g.

Biosorption of nickel using mixed cultures of Pseudomonas aeruginosa and Bacillus subtilis

<p class="p1"><span class="s1"> </span>Biosorption of Ni(II) was investigated in this study using dead biomass of gram positive (<strong><em>Bacillus subtilis</em></strong>) and gram negative (<strong><em>Pseudomonas aeruginosa</em></strong>).The effects of pH, initial adsorbent dosage, initial metal ion concentration, contact time and temperature were studied in batch experiment. A contact time of 40 min, pH 5.0 and temperature 30<span class="s2">o</span>C were found to be optimum. Nickel removal decreased from 77 to 45% as the concentration increased from 50 to 250 mg/L. The Ni(II) removal increased from 45 to 75% as adsorbent dose increased from 0.25 to 1.5 g/L. The Langmuir and freundlich models for dynamics of metal of metal ion uptake proposed in this work fit the experimental data reasonably well. The adsorption capacity (Q<span class="s2">o</span>) calculated from Langmuir isotherm was 89.08 mg for Ni (II).<span class="Apple-converted-space"> </span></p>