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Removal of arsenic from wastewater using iron compound: Comparing two different types of adsorbents in the context of LCA 总被引:1,自引:0,他引:1
Gjergj Dodbiba Teiji Nukaya Yousuke Kamioka Yuji Tanimura Toyohisa Fujita 《Resources, Conservation and Recycling》2009,53(12):688-697
A study was carried out in order to compare the environmental performance of two different types of adsorbents in removing arsenic (As) from wastewater. A FeCl3-based adsorbent and a poly-Fe-based adsorbent were first synthesized and their abilities in adsorbing As from wastewater were investigated in terms of the adsorption density and the rate of adsorption. Here, it should be noted that the main material being used in the synthesis of the poly-Fe-based adsorbent was a waste product, known as polyferric sulfate or poly-Fe in short, which exits the manufacturing process of titanium dioxide.Both adsorbents were then compared in the context of life-cycle assessment (LCA). In other words, the experimental results (i.e. the value of the adsorption density and the rate of adsorption) were input into the LCA model in order to assess the environmental performance of each adsorbent in removing arsenic. An estimate for the environmental burden of each option was finally calculated as the sum of the depletion of abiotic resources (ADP), the global warming potential (GWP), the acidification potential (AP), the photo-oxidant formation potential (POCP), the eutrophication potential (EP), and the human toxicity potential (HTP). The main finding of this study was that the adsorption of arsenic by using the poly-Fe-based adsorbent is more attractive treatment option in the environmental protection point of view than the adsorption by using the FeCl3-based adsorbent, which generates a relatively larger environmental burden. 相似文献
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为了废弃桑枝的资源化,利用3-氯-2-羟丙基三甲基氯化铵(CTA)对桑枝进行醚化改性制备桑枝基吸附剂,通过正交实验优化了吸附剂的制备条件。采用制备的吸附剂吸附水中阴离子染料日落黄,研究了pH值、吸附剂投加量、吸附时间和吸附温度对吸附效果的影响,测定了日落黄在吸附剂上的吸附等温线。结果表明,制备吸附剂的最佳工艺条件为CTA与桑枝粉的质量比为0.5,NaOH与桑枝粉的质量比为1.0,微波功率为300 W,反应时间为3 min。制备的吸附剂对质量浓度为50 mg/L的日落黄的最大吸附去除率达92.0%。日落黄在吸附剂上的等温吸附线可用Langmuir方程和Freundlich方程来描述,饱和吸附容量为18.21 mg/g,吸附易于进行。吸附速率数据可以用准二级吸附动力学方程拟合,说明日落黄在吸附剂上的吸附以化学吸附为主。 相似文献
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采用某洗煤厂的煤矸石和天然粘土石灰石作为主要原料,添加适量的氯化铝制备吸附剂对Zn~(2+)进行吸附,运用SEM技术对吸附剂进行了表征,研究了不同因素对Zn~(2+)去除率的影响,并探讨了吸附机理。实验结果表明:当反应温度为20℃、振荡时间为70 min、废水pH为6、吸附剂投加量为0.5 g时,Zn~(2+)去除率达到96.28%。煤矸石复合吸附剂对Zn~(2+)的吸附符合准二级动力学方程,在高浓度时符合Langmuir等温吸附模型低浓度时符合Freundlich等温吸附模型,且吸附是易发生的。 相似文献
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A trimetal oxide was developed as a fluoride adsorbent by coprecipitation of Fe(II), Al(III) and Ce(IV) salt solutions with a molar ratio of 1:4:1 under alkaline condition. The material retained amorphous structure and maintained relatively stable fluoride adsorption performance at calcination temperatures lower than 600 degrees C. The optimum pH range for fluoride adsorption was 6.0-6.5 and the adsorbent also showed high defluoridation ability around pH 5.5-7.0, which is preferable for actual application. A high fluoride adsorption capacity of 178 mg g(-1) was acquired under an equilibrium fluoride concentration of 84.5 mg l(-1), adsorbent dose of 150 mg l(-1) and pH 7.0. The adsorption isotherm could be better described by the two-site Langmuir model than the one-site model, suggesting the existence of two types of active sites on the adsorbent surface. Coexistence of high concentrations of phosphate or arsenate only led to partial inhibition of fluoride adsorption, which further suggests the existence of heterogeneous adsorption sites. Sulfate and chloride did not affect fluoride adsorption, and nitrate influenced it only when the concentration of NO(3)(-)-N exceeded 50 mg l(-1). A high desorption efficiency of 97% was achieved by treating fluoride loaded Fe-Al-Ce oxide with NaOH solution at pH 12.2. A column experiment using the adsorbent fabricated into 1mm pellets was performed at an initial fluoride concentration of 5.5 mg l(-1), space velocity of 5h(-1) and pH of 5.8, and 2240 bed volumes were treated with the effluent fluoride under 1.0 mg l(-1). 相似文献
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This study focuses on the effects of pH and fluoride at different molar ratios of fluoride to Al (RF:Al) on the removal of cadmium (Cd2+) and phosphate by Al coagulation. Fluoride at RF:Al ≥ 3:1 inhibits the removal of Cd over wide Al dose ranges from 5 to 10 mg/L as Al. The removal of phosphate decreases significantly at high RF:Al of 10:1 whereas at lowered RF:Al (i.e., ≤ 6:1), an adverse effect is observed only at insufficient Al doses below 2 mg/L. Fluoride shows inhibitive effects towards the removal of Cd at pH 7 and 8 and that of phosphate at pH 6. Fluoride decreases the ζ-potential in both systems, and the decreasing extent is positively correlated to the elevated RF:Al. The Al fluoride interactions include the formation of Al–F complexes and the adsorption of fluoride onto Al(OH)3 precipitates, i.e., the formation of Al(OH)nFm. Al–F complex formation inhibits Al hydrolysis and increases residual Al levels, and a more significant increase was observed at lower pH. Al–F complexes at high RF:Al complicate the coagulation behavior of Al towards both negative and positive ionic species. Moreover, fluoride at low RF:Al shows little effect on Al coagulation behavior towards Cd2 + and phosphate, and the spent defluoridation adsorbent, i.e., aluminum (Al) hydro(oxide) with adsorbed fluoride at RF:Al of below 0.1:1, may be reclaimed as a coagulant after being dissolved. 相似文献
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废水处理中的几种廉价吸附剂 总被引:18,自引:0,他引:18
介绍了废水处理中具有良好实际应用价值的几种性能良好的廉价吸附(粉煤灰、混炭和膨润土等),对它们的作用机理、处理效能及应用前景进行了分析。 相似文献