粉煤灰制备高纯分子筛及对氨氮的去除

结合碱熔处理和引入晶种的方法,用粉煤灰制备出高纯的分子筛。运用XRD,SEM和BET等技术手段对制备的纯分子筛的晶体类型,形貌结构和物理参数等进行表征。通过续批实验,研究了p H值,投加量和初始氨氮浓度对氨氮去除的影响。实验结果表明,这些实验参数对于制备的分子筛去除氨氮有着重要的影响。其动力学行为非常符合准二级动力学方程。Langmuir方程能较好描述分子筛对氨氮的等温吸附过程,相关系数为0.9919。因此,利用粉煤灰制备高纯分子筛可以高效去除氨氮并达到"以废治废"的价值。     

不同硅铝比的ZSM-5型沸石分子筛吸附水中Cu2＋离子的研究

考察了3种不同硅铝比的ZSM-5沸石分子筛（25H、38H和50H，25、38和50为硅铝比）对水中Cu2＋的吸附过程及其影响因素。结果表明，3种材料均能有效吸附去除水中Cu2＋离子，动力学符合假二阶动力学模型，吸附等温线符合Langmuir吸附等温式。3种材料吸附速率及吸附容量顺序为：25H〉50H〉38H，其中，25H最大吸附容量达到12．83mg／g。投加量由0．8g／L增加至2．0g／L，材料对Cu2＋吸附去除率由87．0％增加至97．5％。考察水中常见阳离子对吸附的干扰作用，结果表明，干扰离子的影响顺序为：Pb2＋〉K＋〉Na＋〉Mg2＋；随着干扰离子浓度的增大，材料对Cu2＋的去除率显著下降。硅铝比及晶粒形貌均对沸石分子筛吸附Cu2＋有较大影响，小的孔径不利于Cu2＋的吸附，低硅铝比有利于Cu2＋在分子筛上的吸附。     

用煤矸石合成4A沸石分子筛处理氨氮废水

以煤矸石为原料，采用碱熔一水热法合成4A沸石分子筛。由于煤矸石中铝、硅主要以高岭土形式存在，其活化过程是合成4A沸石分子筛关键环节。为提高4A沸石分子筛钙离子的交换能力，增加对模拟废水氨氮的去除率，实验考察了碳酸钠与煤矸石质量比、活化温度、活化时间、晶化温度和晶化时间对4A沸石分子筛钙离子交换能力的影响，同时也考察了模拟废水的pH、4A沸石分子筛加入量及吸附时间对氨氮去除率的影响。结果表明，最佳工艺条件为，碳酸钠与煤矸石质量比为0．9、活化温度为800％、活化时间1．5h、晶化温度90％和晶化时间3h。合成4A沸石分子筛的钙离子交换能力为310mg／g，在pH为6的100mL模拟氨氮废水中加入6g4A沸石分子筛吸附40min后，废水中氨氮的去除率达到86％。通过最佳工艺条件合成4A沸石分子筛，在处理氨氮废水方面具有一定的应用前景。     

矸石基X型分子筛对水中Co2+、Cu2+、Cd2+和Cr3+的去除

以煤矸石为原料,采用碱熔后水热合成法制备X型分子筛并进行XRD、SEM、BET和Zeta电位分析。研究其对水中Co2+、Cu2+、Cd2+和Cr3+4种离子的吸附性能,包括吸附等温线、吸附动力学以及初始金属离子浓度、pH值对吸附性能的影响。所合成的矸石基X型分子筛的BET比表面积为676.02 m2/g,微孔孔容为0.263 cm3/g。吸附实验表明,矸石基X型分子筛能有效去除上述4种离子,同时实现煤矸石的资源化和金属离子的去除。4种离子的平衡吸附量均随初始浓度的增大而增大,相同条件下平衡吸附量的大小顺序为Cd2+>Cr3+>Cu2+>Co2+。准二级动力学模型能很好地描述4种离子的吸附动力行为。Langmuir模型对Co2+、Cu2+和Cd2+吸附的拟合较Freundlich模型高,说明其主要表现为物理吸附过程。4种离子的吸附速率均由液膜扩散和颗粒内扩散共同控制。     

粉煤灰合成NaX型分子筛的表征及其对Fe~（2＋）离子的吸附研究

以高温碱熔融处理粉煤灰合成了NaX型沸石分子筛,考察了不同水热晶化温度对产物结果的影响,用粉末XRD、XRF、SEM和FT-IR等手段对产品进行了表征,结果表明,以粉煤灰为原料用水热合成法合成微孔分子筛时,在晶化温度为90℃时能得到晶形较好的NaX型分子筛。同时考察了NaX分子筛的用量、时间和pH值等因素对Fe2＋离子的吸附影响,在25 mL Fe2＋离子浓度为2×103 mg/L的溶液中,当吸附剂用量为0.2 g,吸附时间为2 h,吸附效率达到最大值（36.41%）,而随着溶液pH值的升高其吸附效率显著增大。     

粉煤灰合成NaX型分子筛的表征及其对Fe2+离子的吸附研究

以高温碱熔融处理粉煤灰合成了NaX型沸石分子筛，考察了不同水热晶化温度对产物结果的影响，用粉末XRD、XRF、SEM和FT-IR等手段对产品进行了表征，结果表明，以粉煤灰为原料用水热合成法合成微孔分子筛时，在晶化温度为90℃时能得到晶形较好的NaX型分子筛。同时考察了NaX分子筛的用量、时间和pH值等因素对Fe2+离子...     

粉煤灰合成沸石去除城市暴雨径流中氨氮

采用粉煤灰为原料,通过耦合碱熔-两步合成法制得3种合成沸石产品,并以合成沸石制备大粒径的功能填料。通过氨氮吸附速率实验和等温吸附实验探讨了合成沸石及功能填料的氨氮吸附速率和最大吸附容量(Qm),以功能填料构建模拟人工快速渗滤系统,研究其对城市暴雨径流中氨氮的去除效果。结果表明,合成沸石对氨氮的吸附速率极快,5min去除率约达到75%,氨氮最大吸附容量为11.36～16.13 mg/g;功能填料对氨氮的最大吸附容量有所下降,但氨氮吸附速率仍较快,应用于模拟人工快速渗滤系统时能在较高的水力负荷下快速去除城市暴雨径流中的氨氮。碱处理再生法更适于进行合成沸石功能填料原位再生,氨氮吸附容量一次再生率达到67%～87%。     

粉煤灰水热合成Y型沸石及其表征

针对固体废弃物粉煤灰的资源化利用问题,探索合成Y型沸石的实验方法。以燃煤锅炉产生的粉煤灰为实验对象,经过筛分、研磨、高温煅烧和酸浸等预处理方法来提高硅铝含量。将预处理后的粉煤灰加碱煅烧后与氢氧化钠水溶液混合,水热合成Y型沸石。结果表明:粉煤灰经过750℃煅烧1.5 h可以去除约15%的碳;用4 mol·L~(-1)的盐酸在90℃下处理2 h,粉煤灰中的铁、钙和硫等杂质可以分别减少约63.1%、87.3%和79.6%;粉煤灰预处理后的质量减少约51%;预处理后的粉煤灰经过加碱熔融处理,其中的石英和莫来石晶相物质被完全破坏,生成了新的晶相物质;当预处理粉末/碱的质量比为1∶1.2时,熔融产物经过水热反应(温度95~105℃、时间12~24 h)可以生成纯度良好、形貌规则的八面棱柱体Y型沸石;粉煤灰合成Y型沸石的BET等效比表面积可达389.44 m~2·g~(-1),孔容为0.348 mL·g~(-1),并具有优良的热稳定性。粉煤灰经过适当处理,可以在不外加硅、铝化学试剂以及模板剂情况下水热合成结晶度良好的Y型沸石。     

微孔分子筛的合成及其去除水中氨氮的实验研究

以廉价的天然矿物岩石作为主要原料,采用水热晶化法合成了微孔分子筛。分子筛有效孔径约为0.9 nm,BET比表面积583m2/g,阳离子交换容量(CEC)316 meq/100 g。将其用于水体中氨氮的去除,实验结果表明,分子筛对氨氮的吸附速率较快,吸附时间为20 min时,吸附基本达饱和;分子筛对氨氮的最大吸附量可达11.6 mg/g,其吸附规律很好地符合Fruendlich吸附等温式;在有干扰离子如Ca2+、Mg2+、Al3+和Fe3+等存在的情况下,仍能优先选择吸附NH4+,且吸附率几乎没有变化。动态吸附柱实验的效果好于静态实验,出水12 h内去除率均>85％;饱和了氨氮的分子筛,用氢氧化钠溶液洗脱再生,解吸率达92％,再生后的分子筛与原分子筛相比吸附率几乎没有降低。     

巯基酯化壳聚糖的合成及对Cd2＋的去除性能研究

采用化学方法，研究了以巯基甲壳质制备巯基酯化壳聚糖的最佳合成方案。研究表明，巯基甲壳质的脱乙酰条件（包括时间、温度、氢氧化钠浓度）影响其产物巯基酯化壳聚糖对重金属镉离子的吸附效果。当脱乙酰时间为2h，温度为160℃，氢氧化钠浓度为20％时，20mg的合成产物对30mLCd2＋浓度为20mg／L水样的去除率最高，达到85．46％，其对镉离子的吸附量达到28．5mg／g。通过对产物进行红外分析发现，巯基甲壳质中出现脂基特征峰值，脱乙酰后脂基并没有消失，证明最后的产物为巯基酯化壳聚糖。     

碱熔融法合成NaA和NaX型粉煤灰沸石的品质表征

以粉煤灰为原料采用碱熔融法合成了2种单一沸石矿物种的NaA和NaX型沸石,并对产物的结构、性能和应用指标进行了详细表征.经x射线衍射和IR光谱分析,表明合成产物是无杂晶生成的NaA和NaX型沸石相;在扫描电镜观察下,产物分别具有NaA和NaX型沸石的立方体和八面体晶体骨架结构.DTA分析表明了合成产物中沸石水的存在,且产物热稳定性较好.通过对比,粉煤灰合成的NaA和NaX型沸石的比表面积达到了相应商品沸石的66.9%和83.6%;孔容为41.1%和70.2%;阳离子交换容量(CEC,cation exchange capacity)为82.93%和84.31%.通过比较化学组成表明,大规模应用合成产物不会对环境造成危害.     

Utilization of fly ash to improve the quality of the acid mine drainage generated by oxidation of a sulphide-rich mining waste: column experiments

The production of Acid Mine Drainage (AMD) as a result of the oxidative dissolution of sulphides is one of the main pollution problems affecting natural watercourses in mining environments with sulphide-rich residues. In this work, the generation of AMD was prevented by means of the addition of fly ash to sulphide-rich residues in non-saturated column experiments. A column experiment filled with a pyrite-rich sludge with artificial irrigation leached acid drainages (pH approx. 2) containing high concentrations of sulphate, iron and other metals. However, non-saturated column experiments filled with pyritic-rich sludge and fly ash drained leachates characterized by alkaline pH (pH up to 10), low sulphate concentration, and lack of iron and other metals in solution. The pyrite oxidative dissolution at high pH, as a consequence of the leaching of fly ash, favours the metal precipitation inside the column (mainly iron), the coating of pyrite grains, and the attenuation of the oxidation process, resulting in a great improvement in the quality of the leachates.     

The role of ammonia on mercury leaching from coal fly ash

The Federal Clean Air Interstate Rule issued in March 2005 will result in many power plants employing ammonia-based technologies to control NO(x) emission. The Clean Air Mercury Rule, issued at the same time, will encourage many power plants to use various technologies to remove mercury from flue gas, generating fly ashes that contain elevated concentrations of mercury. Ammonia forms relatively strong complexes with mercury compared to most other cationic elements and, therefore, may change the leaching characteristics of mercury. Understanding the impact of ammonia on the leaching of mercury from fly ash is critical in predicting the potential environmental impact of future fly ash. Batch methods were used to investigate the ammonia impact on mercury leaching from fly ash under different pH conditions. The results indicated that mercury leaching without external ammonia addition is not significant. However, ammonia addition increased mercury leaching in the alkaline pH range, due to the formation of less adsorbable mercury-ammonia complexes. Washed ash released more mercury than the raw ash if the ammonia concentration is the same, mainly due to the dissolution of some ash components during washing which exposed more mercury on ash surface. Mercury adsorption data indicated that more than 90% of available mercury was adsorbed by fly ash even in the presence of 1000 mg l(-1) ammonia addition.     

Alumina as a model support in the formation and dechlorination of polychlorinated dibenzo-p-dioxins and dibenzofurans

Alumina was studied as a model matrix for formation and dechlorination reactions of PCDDs and PCDFs. Only small differences in PCDD and PCDF formation were found between de-novo synthesis on alumina and on fly ash. The amounts of PCDDs and PCDFs formed on acidic alumina were much larger than on neutral and alkaline alumina. OCDD and OCDF were rapidly dechlorinated on basic alumina.     

锡冶炼含砷烟尘低温陶瓷固化技术

以锡冶炼过程中排放的含砷烟尘为研究对象,对浸出特性和低温陶瓷胶凝材料对其的固化效果进行了研究。结果表明,含砷烟尘As、Cu和Zn毒性浸出浓度分别为6 783、167和224 mg/L,严重超过国家毒性浸出鉴别标准值。其经低温陶瓷胶凝材料固化处理,当含砷烟尘掺量小于40%,自然养护3 d,As、Cu和Zn毒性浸出浓度急剧降低,且低于国家标准值。XRD和SEM分析表明,低温陶瓷胶凝材料在复合化学激发剂作用下,反应生成类沸石水化铝硅酸盐矿物(Al-O-Si);固化体中Ca-Fe-As-O盐是As固化的主要矿物相。Cu2+、Zn2+替换铝硅酸盐聚合物结构中的Na+、K+保持平衡电荷。胶凝材料水化产物填充于材料颗粒间,使其连接成一致密整体,有效降低了有害物质的毒性浸出浓度。     

Zeolitic bagasse fly ash as a low-cost sorbent for the sequestration of <Emphasis Type="BoldItalic">p</Emphasis>-nitrophenol: equilibrium,kinetics, and column studies

Purpose  

The purpose of the research is to investigate the application of bagasse fly ash, a sugar industry solid waste for the synthesis of zeolites and their behavior for the sorption of p-nitrophenol (p-NP).     

火力发电厂粉煤灰干燥特性研究

介绍了利用实验台对粉煤灰的干燥特性进行试验研究的情况 ,给出了粉煤灰的干燥曲线、干燥速率曲线和粉煤灰平衡湿含量计算式 ,分析了在干燥过程中粉煤灰的阻力特性 ,为粉煤灰干燥装置的工业化设计提供了理论依据     

垃圾焚烧飞灰浸出特性及固化试验的研究

垃圾焚烧飞灰残留有重金属元素和二恶英等物质而被认为是危险废物,必须对之进行稳定化处理.通过试验研究分析了国内首家自主开发成功的广东省东莞市某回转窑垃圾焚烧发电厂垃圾焚烧飞灰的化学成分及矿物组成,研究了飞灰的浸出毒性,考察了水泥固化焚烧飞灰的效果,并与熔融/玻璃固化进行了比较.研究表明,该焚烧飞灰中重金属Cd的浸出毒性严重超标,并且随pH值的减小而增大,水泥固化效果随龄期的增大而更加显著.熔融/玻璃固化的效果优于水泥固化,但其经济性有待提高.     

Improving phosphate removal of sand infiltration system using alkaline fly ash

Septic tank effluent is customarily disposed of by soil infiltration. Coarse, sandy soil such as those found in Perth, Western Australia, exhibit low attenuation capabilities for phosphate (PO4(3-)) during effluent infiltration. Amendment of such soil with different amounts of alkaline precipitator and lagoon fly ashes was investigated as a means of reducing phosphorus (P) leakage to ground water. Alkaline precipitator fly ash possessed the highest P sorption capacity in terms of its Langmuir and Freundlich isotherm parameters during initial batch tests. The test materials were repeatedly contacted with fresh PO4(3-) solutions over 90 contacting cycles to gain a better indication of long-term P sorption capability. Again, precipitator fly ash exhibited higher P sorption capacity than lagoon fly ash and Spearwood sand. Column studies assessed the influence of various application rates of alkaline precipitator and lagoon fly ashes on the P removal of septic tank effluent. Septic tank effluent was applied at the rate of 4 cm/day to the column for 12 weeks. Concentrations of P were monitored in the column effluent. All the fly ash columns were more efficient in reducing P migration compared to the sand column. Increased levels of fly ash in the soil columns resulted in increased P attenuation. Lagoon fly ash was inferior to precipitator fly ash for P removal; high application rates of fly ash caused clogging of the infiltration bed apparently due to their lower permeability. It is reasoned that 5-15% precipitator fly ash, and less than 30% lagoon fly ash could be added to coarse sands to produce an infiltration bed, which would result in a better quality effluent than can be obtained with untreated sand alone.