A pair of novel Tb^III-based enantiomers, [Tb（dbm）·Lss] （1） and [Tb（dbm）3.LRR] （2） （where Lss=（＋）-4,5-pinene bipyridine, LRR= （-）-4,5-pinene bipyridine, dbm=dibenzoylmethanate）, were synthesized and characterized based on single crystal X-ray diffi＇action, elemental analysis, FT-IR, TG and CD spectra. X-ray diffraction analysis showed that both the complexes crystallized in monoclinic crystal system with P21 chiral space group. The Tb^III ion was eight-coordinated by six O atoms of three dbm ligands and two N atoms fi-om one chiral ligand Lss or LRR. The CD spectra revealed that complexes 1 and 2 were enantiomers. Thermogravimetric analysis results indicated that 1 and 2 were thermally stable up to 246 ℃.
The aim of the present work was to produce a polyaluminium ferric silicate chloride （PAFSiC） coagulant from acidic and alkaline wastewater of purifying graphite by roasting, and subsequently to evaluate coagulation efficiency of the reagent by treating surface water from the Yellow River as well as municipal wastewater in comparison with the conventional coagulant polyaluminium chloride （PAC）. The PAFSiC coagulant was prepared by co-polymerization. The effects of （Al＋Fe）/Si molar ratio, OH/（Al＋Fe） molar ratio （i.e., γ value）, coagulant dosage and pH value of test suspension on the coagulation behavior of FAFSiC and the stability of the PAFSiC were also examined. Results showed that PAFSiC performed more efficiently than PAC in removing turbidity, chemical oxygen demand （COD）, and total phosphate （TP）. The PAFSiC with a γ value of 2.0 and （Al＋Fe）/Si ratio of 5 （PAFSiC 2.0/5） showed excellent coagulation effect for both turbidity and COD, while PAFSiC 1.0/5 was the best for TP. The optimum coagulation pH range of PAFSiC 2.0/5 was 5.0–9.0, slightly wider than that of PAC （6.0–8.0）. The process can be easily incorporated into high-purity graphite production plants, thereby reducing wastewater pollution and producing a valuable coagulant.
Xiaoxia Niu Xili Li Jihong Zhao Yigang Ren Yanqin Yang
