Porous carbon is an excellent absorbent for pollutants in water. Here, we report a breakthrough in performance of porous carbon based on lignin prepared using sodium lignosulfonate (SLS), potassium carbonate and melamine as precursor, activator and nitrogen source, respectively. A series of characterization tests confirmed that in-situ nitrogen doping greatly enhanced porous structure, resulting in a specific surface area of 2567.9 m2 g?1 and total pore volume of 1.499 cm3 g?1, which is nearly twice that of non-nitrogen-doped porous carbon. Moreover, adsorption experiments revealed that at 303 K, the saturated adsorption capacity of chloramphenicol was as high as 713.7 mg g?1, corresponding to an improvement of 33.7%. Further, the prepared porous carbon exhibited a strong anti-interference against metal ions and humic acid. The adsorption process was confirmed to be an endothermic reaction dominated by physical adsorption, indicating that an increase in temperature is conducive to adsorption. The results of this study show that nitrogen-doped lignin-based porous carbon prepared by in-situ doping is a promising material to significantly alleviate water pollution owing to its low cost, excellent pore structure and good adsorption properties.
Four typical coastal sites (rocky shore, sandy shore, mud flat shore, and artificial harbor) at the Yellow Sea were chosen to investigate the spatial and seasonal variations in bacterial communities. This was accomplished by using terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR amplified 16S rDNA fragments. Two kinds of tetrameric restriction enzymes, HhaI and MspI, were used in the experiment to depict the bacterial community diversity in different marine environments. It was found that the community compositions digested by the two enzymes separately were different. However, the results of bacterial community diversity derived from them were similar. The MDA analysis results of T-RFLP profiles coming from HhaI and MspI both exhibited a significant seasonal community shift for bacteria and a relatively low spatial variation among the four locations. With HhaI as the sample, the pair wise T-tests also revealed that variations were minor between each pair of marine environments, with R ranging from 0.198 to 0.349. However, the bacterial community structure in the mud flat site depicted a larger difference than each of the other three sites (R ranging from 0.282 to 0.349). 相似文献
Preparation of activated carbon from sewage sludge is a promising way to dispose of sewage sludge as well as to produce a low-cost adsorbent for pollutant removal. This research work aimed to optimise the condition for activated carbon preparation from anaerobically digested sewage sludge with the additive coconut husk. The sewage sludge sample was mixed with the additive coconut husk. The preparation condition variables investigated involved the concentration of the ZnCl2 solutions, heating temperature, dwell time and heating rate in pyrolysis and the mixing ratio of coconut husk to sewage sludge. Surface area, pore size distribution, aqueous phenol adsorption capacity and the production yield of the final products were determined and compared. Experimental results revealed that low concentrations of ZnCl2 solution tended to improve the microporosity of the final product. Heating temperature had a considerable impact on the surface area, pore size distribution and phenol adsorption capacity of the final products, whereas dwell time and heating rate performed comparatively insignificantly. The effect of increasing the mixing ratio of coconut husk to sewage sludge was principally to increase the microporosity of the final products. The activated carbon with the highest BET surface area was produced with the activation of 5 M ZnCl2 solution and, thereafter, pyrolysis at a heating temperature of 500 degrees C for 2 h with a heating rate of 10 degrees C/min. The mixing ratio of 1:4 in terms of coconut husk to sewage sludge based on their dried weights was found to be most cost effective. 相似文献
PCB levels in fish (collected from local rivers), atmosphere and human milk samples have been studied to determine the exposure levels of PCBs for local residents and e-waste workers in Guiyu, a major electronic waste scrapping center in China. The source appointment and correlation analyses showed that homologue composition of PCBs in 7 species of fish were consistent and similar to commercial PCBs Aroclor 1248. PCB levels in air surrounding the open burning site were significantly higher than those in residential area. Inhalation exposure contributed 27% and 93% to the total body loadings (the sum of dietary and inhalation exposure) of the local residents, and e-waste workers engaged in open burning respectively. Total PCB concentrations in human milk ranged from N.D. to 57.6 ng/g lipid, with an average of 9.50 ng/g lipid. The present results indicated that commercial PCBs derived from e-waste recycling are major sources of PCBs accumulating in different environmental media, leading to the accumulation of high chlorinated biphenyls in human beings. 相似文献