IR and raman spectra of two layered aluminium phosphates Co(en)3Al3P4O16.3H2O and

An effective and novel pore sealing agent to enhance the corrosion resistance performance of Al coating in artificial ocean water

A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH₄H₂PO₄: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH₄)₃Al₅H₆(PO₄)₈.18H₂O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al₃(PO₄)₂(OH)₃(H₂O)₅) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance.

Activation of Firmiana Simplex leaf and the enhanced Pb(II) adsorption performance: equilibrium and kinetic studies

Although various biosorbents have been reported effective to purify wastewaters containing heavy metals, the high tendency to decomposition in the environment makes them unsuitable for long-term persistent utilization. In this paper, a simple and new activation method was proposed to mineralize the Firmiana Simplex leaf (FSL) into an enhanced adsorbent for Pb(II) removal from aqueous solution. The leaves activated at various temperatures were characterized with BET N(2) adsorption test, FT-IR test and XRD test. After activation, the mass percent of inorganic components (including whewellite, quartz, phosphate and calcite) increased and the specific surface area increased from 0.08283 to 9.32 m(2)g(-1) with the increasing activation temperature (AT) from 100 to 400 degrees C. Proper activation temperature (200 degrees C) helps to preserve the beneficial groups (amine and carboxyl). The affinities of the adsorbents towards Pb(II) were increased with increasing AT from 300, 100, 200 to 400 degrees C according to the adsorption isotherms. The adsorbent activated at 200 degrees C (AL2) was found most suitable for Pb(II) adsorption regarding the high yield efficiency (36.52%), high Pb(II) adsorption capacity (136.7 mg g(-1) by Langmuir model), high adsorption affinity (H type isotherm) and rapid adsorption rate (within 20 min by kinetic study). The Pb(II) removal efficiency of AL2 was obviously affected by the solution pH rather than by the adsorbent dosage. The adsorption was viewed as a chemical process based on IR spectra along with a physical process based on the correlation between the average pore size of the adsorbent and the adsorption capacity. The activation method proposed in this paper was proved effective and potentially applicable in the treatment of Pb(II) polluted wastewaters.