ABSTRACT
Biochar derived from chicken manure, as an effective metal adsorbent, was prepared through a pyrolysis method at different pyrolytic temperatures (200, 400, 600, and 800 °C). The physicochemical characteristics of chicken manure biochar (CMB) and its lead (Pb2+) adsorption mechanisms were studied by batch adsorption experiments, DTA/TGA, XRD, SEM-EDS, FTIR and an analysis of the composition of their mineral ash. Results showed that the best-fit for the Pb2+ adsorption data was achieved using a Langmuir isotherm and a pseudo-second-order model. The maximum adsorption capacities of Pb2+ increased with increasing of pyrolytic temperatures of the CMB, being 180.21, 200.80, 239.59, and 242.57 mg g-1, respectively, for CMB-200, CMB-400, CMB-600 and CMB-200. Although Pb2+ adsorption on CMB revealed that adsorption was controlled by multiple mechanisms, (e.g. surface complexation, ion exchange, surface precipitation, electrostatic attraction, physical adsorption, and co-precipitation), the ion exchange and surface precipitation played a dominant role in Pb2+ sorption. Using CMB for the removal of Pb from water is proposed as an effective, environmentally protective, novel approach.
ABSTRACT
Objective: To compare the molecular weight of sodium hyaluronate in the injection determined by three methods. Methods:Viscometry was used to determine the molecular weight of sodium hyaluronate. The molecular weight and its distribution ( Mw/Mn) was measured by size exclusion chromatography ( SEC) and the combination of multi-angle laser light scattering instrument and size exclusion chromatography( MALLS-SEC) . Results:The results of MALLS-SEC were close to those of viscometry, and Mw/Mn was obtained simultaneously. The average value of molecular weight of three batches of samples was 991962, 1007438 and 990232 with RSD of 6. 5%, 4. 6% and 2. 2%, respectively(n=4). The average value of Mw/Mn was 1. 6, 1. 6 and 1. 6 with RSD of 7. 2%, 3. 2% and 3. 2%, respectively(n=4). Conclusion:MALLS-SEC shows better accuracy and precision, and can be used in the quali-ty control of sodium hyaluronate samples.
ABSTRACT
The gross enrollment proportion of Chinese higher education has achieved 17% in 2003.Higher education has entered into popular phase.It indicates that Chinese higher education has made great progress;meanwhile,it also brings lots of problems.This paper would analyze higher education from three aspects: educatee,university and society.It demonstrates that the development of Chinese higher education has exceeded the bearable degree of current society and the recruiting enlargement speed should be controlled.
