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The sorption capacity of bone char was tested on the removal of copper, nickel and cadmium ions, from aqueous solutions. The Freundlich and Langmuir models were applied to the adsorption isotherms. The equilibrium data fitted well with the Langmuir model and the maximum loading capacities showed the following affinity order: Cu2+ (1.093 mmol g–1 at pH i 3, and 0.884 mmol g–1 at pH i 4) > Cd2+ (0.760 mmol g–1 at pH i 3, and 0.690 mmol g–1 at pH i 4) > Ni2+ (0.453 mmol g–1 at pH i 3, and 0.225 mmol g–1 at pH i 4). The kinetic data follow a diffusion model in the film and inside particles. A sorption mechanism based on ion exchange, attack by protons of the carbonate and hydroxide positions in the apatite lattice, and also on the adsorption of protons on the basic active sites of carbon, is proposed to explain the heavy metals removal and the pH decreasing in solution.

The modification of the chemical structure of the cotton fibers was carried out in basic medium using succinic anhydride in pyridine. The anhydride monomer was added to cotton fiber, previously activated by sodium hydroxide or potassium permanganate solution, by graft polymerization that was followed by using the parameters, i.e., monomer concentration, pyridine concentration, modification time and temperature. The graft yield was characterized by back-titration and FTIR analysis. The adsorption capacity of the graft cotton was performed on the removing of methylene blue from aqueous solutions. Adsorption isotherms were studied by the Freundlich, Langmuir and Temkin models. The kinetics data follow a second order model and the cellulose support grafted showed an adsorption capacity of 710 mg g−1, which means an improvement of about 40% in comparison with the cellulose support raw material.

This work relates a study on a medieval coin found during archaeological works carried out at the site of Senhora do Castelo in Urros (Torre de Moncorvo, Portugal). The artefact has been identified as a coin of D. Afonso IX of Leon (1155–1188). The substratum showed composition typical of bullion, Cu-Ag (30–33%) with minor elements (1% Pb + 0.2% Sn + 0.4% Zn). The corrosion products developed on the coin during the archaeological burial was studied by means of optical microscopy (OM), scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS), energy dispersive X-ray fluorescence (EDXRF), and X-ray diffraction (XRD). The results show the presence of cuprite, atacamite, chalcocite, native silver, silver oxide and silver sulphide on the outer layers of the coin, which allows deducing the importance of the environment in the corrosion phenomena.