A monometallic (Ni 2+ , 1) and a bimetallic (Ni 2+ -Sm 3+ , 2) complexes based on the Salen-type Schiff-base ligand H 2 L (H 2 L ¼ N,N 0 -bis(3-methoxysalicylidene)ethylene-1,2-diamine) were synthesized and characterized by FT-IR, ESI-MS and X-ray crystallography. The catalysis results showed that the two complexes with different active species, could efficiently catalyze the bulk solvent-free melt ringopening polymerization (ROP) of L-lactide with moderate molecular weights and narrow molecular weight distributions. Especially, for the bimetallic complex 2, the involvement of rare ions effectively passivated the catalytic behavior on the ROP of L-lactide, while was in favor of the increase of polymeric molecular weights (M n ) and the polymerization controllability.

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The quality of the clays and over all halloysite are mostly associated with minor amounts of ferruginous impurities content, since this element gives an undesirable reddish color to the halloysite mineral. Hence, finding out the modes of occurrence of iron in halloysite is of prime importance in the value addition and optimum utilization of halloysite. In order to analyze the occurrence of iron impurities in halloysite, Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were combined with wet chemical analysis methods to study the low-grade halloysite. The results indicated that the mineral phases of iron impurities in the concentrates are mainly composed of amounts of magnetite, goethite and hematite. Two types of occurrences for iron impurities have been found. One is single crystalline mineral consist in the halloysite, which contains three different phases of Goethite FeO(OH) (44.75%), Magnetite Fe3O4 (27.43%) and Hematite Fe2O3 (31.96%). The other is amorphous Fe-Al-Si glial materials. This study is of significance in the theoretical research on the halloysite mineralogy and in the developmental practice of halloysite in coal measures.