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481.
粉煤灰深度处理低浓度的磷 总被引:1,自引:0,他引:1
为了探讨低浓度磷吸附的方法,比较了粉煤灰、煤质活性炭和粉煤灰碎砖块颗粒这3种价廉易得的吸附材料的除磷效果。经对比确定以粉煤灰为吸附剂,研究了反应时间、粉煤灰投加量以及溶液p H对深度除磷效果的影响。同时为了解粉煤灰高效除磷原理,利用SEM和XRD对其表面形状、所含元素及其内部结构进行了表征。结果表明,粉煤灰比煤质活性碳和粉煤灰砖砖块颗粒的除磷效果更好,去除率高达98.9%;SEM和XRD表征结果显示,由于粉煤灰表面积较大、表面能高、含有Si—O—Si和Si—O—Al—O偶极键及铝、铁和钙的氧化物,使得粉煤灰对低浓度的磷有着高效的去除率;吸附磷后的粉煤灰表面形成了一层絮状物,经EDS分析显示其组成以钙磷沉淀为主;1 g粉煤灰对1 mg/L的磷酸盐溶液在p H=10、反应时间60 min时表现出最佳吸附性能。 相似文献
482.
Reef blocks made from stabilized oil ash were taken from the sea after five years in the ocean to examine the chemical behaviour of calcium. Experiments included (1) determination of the calcium leaching rate and a comparison with the rate for unexposed blocks to test the validity of a diffusion model for predicting long term (5 years) leaching rates, (2) determination of the effect of biological cover (shell) on the leaching rate, (3) determination of the leaching rate of the core of exposed reef blocks, (4) determination of the calcium content in 'ring areas' - regions of discoloration observed in sectioned exposed reef blocks, and (5) determination of the leachable fraction of the total calcium in exposed reef blocks. Results showed the presence of a pronounced calcium discontinuity zone located 3-7 cm from the outside surface of the reef blocks. Cumulated calcium release rates ranged from 2.81-3.14 μmol cm-2 day-1 for original unexposed reef blocks and the core of exposed (in the ocean for five years) blocks, respectively, to 0.47-0.50 μmol cm-2 day-1 for outside (facing sea water) surfaces of exposed reef blocks. Tank leaching studies also showed that the presence or absence of hard biological cover (shells) had little or no effect on the calcium release rate. the diffusion model normally used in modelling the chemical behaviour of calcium cannot be used to predict the long term (five years) leaching of calcium. the core of the exposed blocks released calcium at a rate similar to new, unexposed reef block material. Overall, it appears that the calcium discontinuity zone is probably responsible for restricting the release of calcium and hence the failure of the diffusion model. 相似文献
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吕志超 《辽宁城乡环境科技》2007,27(2):17-18,42
洁净型煤的推广使用是有效控制煤烟型污染的一种重要手段,采用在原煤中添加化学药剂,重新加工成型的方法,达到降尘、固硫、节能的目的。通过推广使用,有效的降低二氧化硫、烟尘的产生量和排放量,减少对城市大气环境的污染,达到煤的热量高效、清洁利用。 相似文献
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根据屋顶电除尘器二次烟尘的特点,针对其清灰不彻底的问题,通过工程实践经验,设计了一种可动喷水清灰装置,在实践中应用良好,值得借鉴 相似文献
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Use of zeolitized coal fly ash in the simultaneous removal of ammonium and phosphate from aqueous solution 总被引:1,自引:0,他引:1
Wu Deyi Hu Zhanbo Wang Xinze He Shengbing Kong Hainan 《Frontiers of Environmental Science & Engineering in China》2007,1(2):213-220
Discharge of wastewater containing nitrogen and phosphate can cause eutrophication. Therefore, the development of an efficient
material for the immobilization of the nutrients is important. In this study, a low calcium fly ash and high calcium fly ash
were converted into zeolite using the hydrothermal method. The removal of ammonium and phosphate that coexist in aqueous solution
by the synthesized zeolites were studied. The results showed that zeolitized fly ash could efficiently eliminate ammonium
and phosphate at the same time. Saturation of zeolite with Ca2+ rather than Na+ favored the removal of both ammonium and phosphate because the cation exchange reaction by the NH4
+ resulted in the release of Ca2+ into the solution and precipitation of Ca2+ with PO4
3− followed. An increase in the temperature elevated the immobilization of phosphate whereas it abated the removal of ammonium.
Nearly 60% removal efficiency for ammonium was achieved in the neutral pH range from 5.5 to 10.5, while the increase or decrease
in pH out of the neutral range lowered the adsorption. In contrast, the removal of phosphate approached 100% at a pH lower
than 5.0 or higher than 9.0, and less phosphate was immobilized at neutral pH. However, there was still a narrow pH range
from 9.0 to 10.5 favoring the removal of both ammonium and phosphate. It was concluded that the removal of ammonium was caused
by cation exchange; the contribution of NH3 volatilization to immobilization at alkaline conditions (up to pH level of 11.4) was limited. With respect to phosphate immobilization,
the mechanism was mainly the formation of precipitate as Ca3(PO4)2 within the basic pH range or as FePO4 and AlPO4 within acidic pH range. 相似文献