Abstract:The simultaneous sorption behavior and characteristics of cadmium (Cd) and sulfamethoxazole (SMX) on rice straw biochar were investigated. Isotherms of Cd and SMX were well modeled by the Langmuir equation (R 2 >0.95). The calculated maximum adsorption parameter (Q) of Cd was similar in single and binary systems (34 129.69 and 35 919.54 mg/kg, respectively). However, the Q of SMX in a binary system (9 182.74 mg/kg) was much higher than that in a single system (1 827.82 mg/kg). The presence of Cd significantly promoted the sorption of SMX on rice straw biochar. When the pH ranged from 3 to 7.5, the sorption of Cd had the characteristics of a parabola pattern with maximum adsorption at pH 5, while the adsorption quantity of SMX decreased with increasing pH, with maximum adsorption at pH 3. The amount of SMX adsorbed on biochar was positively correlated with the surface area of the biochar, and the maximum adsorption occurred with d 250 biochar (biochar with a diameter of 150-250 μm). Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) showed that the removal of Cd and SMX by rice straw biochar may be attributed to precipitation and the formation of surface complexes between Cd or SMX and carboxyl or hydroxyl groups. The results of this study indicate that rice straw biochar has the potential for simultaneous removal of Cd and SMX from co-contaminated water.

No abstract

Dimeric zirconium benzyl and amide complexes supported by an imidazolone framework have been successfully synthesized and fully characterized. The amide complexes were found to be effective catalysts for intramolecular hydroamination of primary and secondary amines.

d,l-lactide (LA) was first successfully ringopening polymerized in melt by Schiff base complexesSchiff base], which were prepared by Schiff base ligand derived from salicylidene and L-aspartic acid and corresponding acetates. The effects of various complexes, the molar ratio of K[ML]nH 2 O/LA, the polymerization temperature, and time were studied in detail. The results show that all complexes studied have the ability to initiate the ring-opening polymerization of d,l-lactide in melt. More than 90% high polymerization conversion and narrow molecular weight distribution (MWD) can be obtained very easily. However, the Ni(II) complex shows better catalytic property than other complexes on the polymerization and the molecular weight (MW) of poly(d,l-lactide) (PLA) produced. With a rise in temperature and a prolongation of time, the MW of PLA decreased remarkably. The MW of PLA prepared by all complexes is not very high, which might be related to the crystalline water of complexes. X-ray study indicated that PLA produced by Ni(II) complex is an amorphous polymer.

No abstract