Competitive heavy metal adsorption on pinecone shells: Mathematical modelling of fixed-bed column and surface interaction insights.

Pinecone shells are assessed as a cost-effective biosorbent for the removal of metal ions Pb(II), Cu(II), Cd(II), Ni(II), and Cr(VI) in a fixed-bed column. Influent concentration, bed height, and flowrate are studied to improve efficiency. The breakthrough data is well fitted by the Sips adsorption model, suggesting a surface complexation mechanism, with maximum adsorption capacities of 11.1 mg/g for Cu(II) and 66 mg/g for Pb(II). In multimetal solutions, the uptake sequence at breakthrough and saturation is Pb(II) > Cu(II) > Cd(II). Characterization via FTIR and XRD reveals carboxyl and hydroxyl functional groups interacting with metal ions. Ca(II) does not compete with Pb(II), Cu(II), and Cd(II) adsorption, highlighting the ability of pinecone to adsorb heavy metals via surface complexation. Its application in the treatment of industrial effluents containing Cu(II), Ni(II), and Cr(VI) is explored. The study investigates bed media regeneration via eluting adsorbed metal ions with hydrochloric acid solutions. The potential of pinecone shells as an efficient biosorbent for removing toxic metal ions from industrial wastewater is emphasized. These findings enhance our understanding of the adsorption mechanism and underscore the fixed-bed column system's applicability in real-world scenarios, addressing environmental concerns related to heavy metal contamination of industrial effluents.

Assessment of the conformational profile of bombesin by computational methods.

In the present work, the results of a computational study aimed at assessing the conformational profile of bombesin are reported. The conformational space of the peptide was sampled by means of a 4 µs accelerated molecular dynamics simulation in water, using an explicit solvent model. The results were analyzed using Principal Component Analysis to get essential information on peptide fluctuations, along with cluster analysis to characterize different conformations in the sample. Analysis of the results suggests that the peptide adopts helical structures at the C-terminus that tend to unwind at the end of the peptide chain, since there are many structures exhibiting only two turns of a helix at the central segment of the peptide. In addition, the peptide also adopts hairpin turn structures at the N-terminus. Results of the simulation were confronted with available NMR results in a 2,2,2-trifluoroethanol/water (30% v/v) solution. Distances deduced form NOEs experiments only provide support to the presence of helical conformations that represent the most populated structures in the simulation. The absence of other conformations in the NMR experiments can be explained to be due to the α-helix enhancing nature of the solvent used in the experiments.