共查询到20条相似文献，搜索用时 125 毫秒
1.
采用化学氧化还原-中和-絮凝沉淀法处理电镀废水中铬,研究了还原pH值、絮凝pH值、絮凝剂的用量、沉降时间对处理效果的影响.还原六价铬的最佳pH在2.0～2.2之间时,絮凝最佳pH值为9时,加入PAM,絮凝时间为0.5小时絮凝效果最好,处理后的Cr浓度最小. 相似文献
2.
电镀综合废水成分更加复杂,而新颁布的排放标准更为严格,这导致传统处理工艺存在困难。本研究采用电芬顿．吸附还原沉淀组合工艺,在试验验证基础上进行了方案设计和成本分析。结果表明,电芬顿．吸附还原沉淀组合工艺处理电镀综合废水可确保出水水质稳定达到《电镀污染物排放标准》（GB21900-2008）中表3要求,与传统工艺相比具有投资低、运行成本低等优点,具有推广应用价值。 相似文献
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设R和r分别是正三角形的外接圆和内切圆的半径，则有公式：R=2r.我们把这个平面几何公式引伸到空间，就得到如下的重要定理.定理：正四面体的外接球半径R及内切球半径r之间存在关系式：R=3r.证明：如图，设P为正四面体A—BCD的中心，连结AP并延长交△BCD于点H，则H为△BCD的中心，并且PA=R，PH=r,PH⊥面BCD，由体积公式得：VA－BCD=VP－BCD＋VP－CDA＋VP－DAB＋VP－ABC=4VP－BCD，∴S△BCD·AH=S△BCD·PH，即AH=4PH，∴R＋r=4r,从而R=3r.由上述证法易得：推论1：正四面体的棱长为a，外接球半径为R,则R=a.… 相似文献
4.
硼泥处理电镀废水中铬(Ⅵ)的研究 总被引：5，自引：0，他引：5
本文采用硫酸亚铁还原,硼泥絮凝沉降的方法处理电镀废水中的铬（Ⅵ）．控制还原时的ｐＨ值为 ３．５～５．５,铬（Ⅵ）：硫酸亚铁：硼泥二１：２０：１４０（重量比）,铬（Ⅵ）去除率达９９％以上．对于铬（Ⅵ）浓度小于１０００ｍｇ／Ｌ的废水,经一次处理,就可以达到国家的排放标准． 相似文献
5.
以炉灰脱色剂对还原蓝分散红染料的印染废水进行脱色处理研究，结果表明，在常温常压下，炉灰脱色剂在5min左右可使印染废水(pH=4～14)中的红色脱除率达98．673％，蓝色脱除率达91．598％，使废水由深蓝色变为无色，废水CODCr脱除率达56．210％．本脱色剂不仅价廉易得，处理设备简单，操作方便，以废治废，对印染废水无需进行pH值的调整，而且炉灰经焙烧再生后可多次重复利用，减少二次污染． 相似文献
6.
硫酸亚铁法处理电镀含氰废水的试验研究 总被引：4，自引：0，他引：4
熊正为 《湖南科技学院学报》2007,28(9):49-52
对硫酸亚铁法处理电镀含氰废水进行了试验研究，探讨了硫酸亚铁除氰的原理及其去除效果。试验结果表明：用硫酸亚铁法处理电镀含氰废水，氰化物的去除率可达97％左右，而且处理费用低，操作简便，具有广泛的应用前景。 相似文献
7.
高砷酸性废水除砷新工艺 总被引：3，自引：0，他引：3
刘琦 《洛阳工业高等专科学校学报》2005,15(1):10-11,27
对高含砷废水(砷含量为10000mg／L左右)采用分步、催化氧化后絮凝沉淀的处理方法。一步处理：采用石灰乳，调pH=3～4去除SO4^2-；二步处理：采用NaOH溶液使PH=9～10的范围，回收重金属；三步处理：加入催化剂-活性炭和Fe^2 通入空气氧化，使溶液中的As(Ⅲ)和Fe^2 氧化成As(V)和Fe^3 ，然后用石灰乳控制pH=6-9，使高价砷酸根与Fe^3 生成难溶的FeAsO4沉淀。经过上述处理后溶液中的砷小于0．5mg/L。 相似文献
8.
本文研究了Ni(Ⅱ－HSA结合时，金属中心的结构，发现在等防子点PH＝5．2附近，NIⅡHSA结合时仅存在一个四方平面构型的金属中心，这与生理PH时的双金属中心结构是不同的，用PH效应可以解释这种差异的存在。 相似文献
9.
白福琴 《延安教育学院学报》1995,(1)
在分析化学教科书中[1－3]，对于中和滴定法指示剂的选择一般总认为：只要指示剂变色范围全部或部分处于化学计量点附近的PH突跃范围内，便能满足滴定分析对准确度的要求。对于前者，很容易理解，而且被大量的实验事实所证实，无须赘述，对于后者，有时出现与实验事实不相符合的现象，本文就此作一点讨论。例如以0．1000mol·1－1的HCl溶液滴定20．00ml·0．1000mol·1－1NaOH溶液，化学计量点PH=7．0，PH突跃范围为4．3～9．7。选用变色范围部分处于PH突跃范围的百里酚酞（9．4～10.6）计指示剂。滴定至溶液蓝色正好褪去为终点，此时… 相似文献
10.
聚丙烯酰胺的合成与研究 总被引：1，自引：0，他引：1
穆志坚 《南通职业大学学报》2001,15(2):21-23
采用过硫酸钾－氮三丙酰胺引发体系，进行丙烯酰胺水溶液聚合，考察了溶液PH值，温度等工艺对产物分子量，转化率及聚合物溶解性能的影响，在PH＝8，60℃时，氨水滴加7滴时，可得到分子量为62．00E4聚丙烯酰胺及转化率为98．94％。 相似文献
11.
罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
12.
Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
13.
邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
14.
Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
18.
陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
19.
Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
20.
YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 相似文献