粉煤灰基地质聚合物水热原位转化NaP型沸石分子筛的研究

以固体废弃物粉煤灰基地质聚合物为基本骨架,通过水热合成法将其原位转化为自支撑Na P型沸石分子筛型体,并研究了水热过程中碱液浓度、碱液体积、水热温度和水热时间对NaP型沸石分子筛结晶程度、形貌和机械强度的影响,得到粉煤灰基地质聚合物原位转化Na P型沸石分子筛型体的适宜条件为水热温度100℃、NaOH浓度2.0mol/L、NaOH体积50 m L、水热时间24 h。所得Na P型沸石分子筛型体的抗压强度为23.21 MPa,BET比表面积为50.46 m~2/g,已达到工业生产P型沸石的水平。该法工艺简单,环境友好,可控成型。在此方法的基础上通过改变原料配比和反应条件,可以合成其他类型的沸石分子筛型体。     

偏高岭土基地质聚合物原位水热合成P型沸石分子筛的研究

本文以偏高岭土基地质聚合物(SiO_2/Al_2O_3=3.2)为基体,通过水热合成法将其原位转化成P型沸石分子筛。研究水热温度、NaOH浓度及水热时间对P型沸石分子筛的结晶程度及形貌的影响,得到偏高岭土基地质聚合物原位合成P型沸石分子筛的适宜条件为:水热温度100℃,NaOH浓度2.0 mol/L,水热时间24 h。该法工艺简单,环境友好,可控成型。在此方法的基础上通过改变原材料和反应条件,可以合成其他类型的沸石分子筛。     

石英裂变径迹蚀刻条件的对比实验研究

通过 40%的 HF溶液、KOH饱和溶液和 19 mol/L的 NaOH溶液这三种常用方法对大、小颗粒石英进行裂变径迹蚀刻实验的对比发现,用环氧树脂固定的小颗粒石英样品,不宜用 KOH饱和溶液(150 ℃)和 19 mol/L的 NaOH溶液(沸点,约 120 ℃)作为裂变径迹的蚀刻剂,宜用 40%的 HF溶液;三种方法均适宜于大颗粒石英,但不同的蚀刻方法蚀刻效率不同, 40%的 HF溶液(29 ℃)的蚀刻效率最高,且操作简单、安全性高.40%的 HF溶液最佳蚀刻时间为: 温度在 4 ℃左右(冬季)时为 40 min,温度在 29 ℃左右(夏季)时为 30 min,可在全年室内常温条件下操作.     

改性红辉沸石去除水溶液中氨氮的初步研究

文章研究了采用酸、碱、盐改性红辉沸石和加热活化红辉沸石对改性红辉沸石去除水溶液中氨氮的影响效果。实验结果表明：（1）用红辉沸石去除溶液中氨氮的实验条件选择如下：1搅拌时间为30min;2沸石粒度为40～60目;3沸石用量为2g;4氯化氨溶液浓度为40mg/L;5氯化氨溶液用量为80ml。（2）采用高温活化对提高红辉沸石去除氨氮效率的作用不明显。（3）酸和碱改性对提高红辉沸石去除氨氮的效率有一定的作用,其中盐酸改性的红辉沸石去除氨氮效率为16.2%,硫酸改性的红辉沸石去除氨氮效率为13.1%,碱改性的红辉沸石去除氨氮效率为25.6%。（4）盐改性对红辉沸石去除水溶液中氨氮的影响效果巨大：经盐改性后,去除率由9.6%升高至72.6%。     

粉煤灰的火法改性及其在废水处理中的应用

应用正交实验设计理论,在粉煤灰中添加助熔剂(Na2CO3),在800~900℃的高温下熔融,然后与NaOH溶液混合进行火法改性。多种实验方式对比得知,火法改性粉煤灰是废水中重金属最好的吸附剂。火法改性后粉煤灰处理废水的最优改性产品配比为:原状粉煤灰与Na2CO3的比例为1∶2;所用NaOH的浓度为1 mol/L;烘干温度为100℃。改性前后的扫描电镜照片及X射线衍射图的对比分析结果表明,粉煤灰的吸附性孔道随温度升高而增多,温度达300℃时为最佳,其比表面积增大,同时产生新的矿物相(A型和Na-P型沸石),吸附能力提高。而温度高于300℃时,吸附孔道被烧得塌陷或堵死,因而降低了吸附率。     

13X沸石处理含赖氨酸废水的实验研究

用合成的13X沸石对废水中氨基酸(赖氨酸)进行静态吸附实验,研究了pH、温度、吸附时间、沸石用量等对吸附率的影响,结果表明,室温下沸石对赖氨酸的吸附平衡时间为30min,pH=pKa1=2.2时,赖氨酸在沸石上的吸附效果最好,吸附率大于82%,饱和吸附量达51.73mg.g-1。吸附等温线近似呈直线型,表明离子交换机制是沸石吸附氨基酸的主要方式。对已饱和吸附的沸石用饱和氯化钠溶液进行再生实验,赖氨酸的解吸率大于95%,沸石可重复使用。实验研究表明可用13X分子筛处理含氨基酸废水,为实际处理含氨基酸废水提供了可行性依据。     

新型洗涤助剂—4A沸石的合成及其在洗涤剂中的应用

摘要本文介绍了用福建龙岩东宫下高岭土,经选矿、煅烧、晶化、过滤、干燥成功地合成新型洗涤助剂——4A沸石的工艺条件。高岭土经煅烧使其脱羟形成具有反应活性的无定型非晶质偏高岭石,偏高岭石在氢氧化钠溶液中反应一定的时间即形成4A沸石。我们合成的4A沸石的主要技术指标为:钙交换容量290—316(mgCaCO_3/g沸石),白度>85％,平均粒度4μm。我们合成的4A沸石应用于洗涤剂工业,取得了良好效果。在肥皂中。可以用3％的沸石代替4％的脂肪酸钠,在超浓缩洗衣粉中,可以用4A沸石代替其中5％的三聚磷酸钠。     

利用钾长石粉水热合成13X沸石分子筛的实验研究

对综合利用钾长石提钾工艺中的重要高附加值副产品13X沸石分子筛的合成进行了实验研究。对福建沙县的钾长石粉加入配料NaCO3进行焙烧实验，确定培烧的最佳工艺参数为：钾长石粉：NaCO3=1：1．30(摩尔比)，焙烧温度为845℃，焙烧时间为150min；优化的水热合成条件为M2O／SiO2(mo1)=1．50，H2O／M2O(mo1)=40．0，合成时间为8h，晶种加入量为9．0％。对合成样品化学成分分析、X射线物相分析、红外光谱分析、扫描电镜分析表明，合成13X沸石分子筛结晶完好，性能优良．水热反应经由溶解水合反应和聚合浓缩反应两大阶段。     

二氧化锰改性粉煤灰制备及其对地下水中砷的吸附特性

高砷地下水在我国广泛分布,开发绿色高效的除砷材料对于促进地区发展和保障居民饮用水安全具有重要意义.采用共沉淀法结合NaOH水热处理技术制备了二氧化锰改性粉煤灰吸附材料MFA150,并研究其对地下水中As(Ⅲ)和As(Ⅴ)的吸附特性.结果表明,NaOH水热处理破坏了原始粉煤灰的玻璃体结构,且在这一过程中生成沸石相,粉煤灰比表面积由1.30 m²/g增加至40.26 m²/g.在负载MnO₂后,MFA150比表面积达到148.82 m²/g.此外,吸附材料表面-OH的含量显著增加,为As(Ⅲ)和As(Ⅴ)提供了更多的吸附活性位点.MFA150对As(Ⅲ)和As(Ⅴ)的吸附过程符合Elovich模型和Freundlich模型.在中性条件下MFA150对As(Ⅴ)和As(Ⅲ)的吸附量分别达到2.55 mg/g和9.71 mg/g,酸性条件更有利于吸附.溶液中共存的HCO₃^-和PO₄^3-会抑制As(Ⅲ)和As(Ⅴ)的吸附,...     

利用粉煤灰和电石渣制备形貌可控的硅酸钙晶须

粉煤灰和电石渣是重要的污染物,本文选用粉煤灰和电石渣为原料,通过水热合成法,制备了硅酸钙晶须材料,探讨了合成温度、保温时间、水固比和反应浓度等条件对生成产物晶须性能的影响,通过XRD和SEM等手段表征晶须的形貌和结构特征。结果表明,以工业品为原料时,温度控制在250℃左右,时间控制在30~50 h才能生成晶须产物。反应体系水固比应控制在40∶1且最佳反应浓度应控制在0.05 mol/L。不同类型的表面活性剂对硬硅钙石型硅酸钙晶须的形貌、长度和长径比都有影响。。     

Effect of some additives on synthesis of zeolite from coal fly ash

Hydrothermal conversion of fly ash into zeolites was conducted and the effects of the addition of sodium halide and waste solutions produced after zeolitization of fly ash, as well as the adjustment of the Si/Al ratio prior to synthesis process on the formation and cation exchange capacity (CEC) of zeolite product were evaluated. Both the addition of NaCl and NaF ameliorated the crystallinity and CEC of synthesized zeolite, but NaF had a better improvement effect. Na⁺ was considered to enhance the crystallization of zeolite, while F⁻ favored the dissolution of fly ash. The type of zeolite formed depended on the Si/Al ratio of the starting material prior to the nucleation and crystallization of zeolite. The adjustment of the Si/Al ratio of fly ash by addition of Na₂SiO₄ and Al(OH)₃ changed the type and CEC of zeolite. Waste solutions contained large amount of Si and little Al due to the formation of a zeolite named NaP1 in zeolite terminology with the Joint Committee of Powder Diffraction Standard (JCPDS) code of 39-0219. The alkalinity decreased largely. As a result, the CEC value of zeolite products synthesized with waste solution as alkali source decreased. The supplementation of new alkali to adjust the alkalinity of waste solution could enhance the CEC of synthesized product. It was concluded that: (1) addition of sodium halide and adjustment of the Si/Al ratio prior to synthesis can improve the quality of zeolite; (2) waste solutions produced following the zeolitization of fly ash can be reused as an alkali source in the activation of fly ash; zero-emission of waste solution in the synthesis of zeolite from fly ash is possible.     

含氟废水的粉煤灰处理实验研究

进行了影响粉煤灰处理含氟废水的各种条件实验，（pH、水灰比、氟浓度、振荡平衡时间），结果表明最佳处理条件是pH值为2．5、水灰比为小于20、氟浓度小于500mg/l、振荡平衡时间大于2．5h，并研究了粉煤灰处理含氟废水的机理，给出了其吸附等温式。     

Synthesis of Zeolite a from Natural Ca-Bentonite Using a Direct Alkali Hydrothermal Approach

Ca-bentonite can be converted into zeolites A through hydrothermal alkaline treatment by varying the synthetic parameters. This study focuses on the effect of initial Si/Al molar ratio, NaOH concentration on the type of formed zeolite A. The Ca-bentonite (China, Fuxin)were mixed with an aqueous NaOH solution, Al(OH)3 powder and hydrothermally treated at about 90 ℃,12 h. Different types of zeolites (zeolite X, P, and A),sodalite were synthesized after the treatment. Zeolites were characterized and quantified by means of XRD and SEM analysis. Zeolite A predominantly formed with 0.5≤Si/Al≤2.0 was produced and zeolite X, P formed with Si/Al>2.0 under the 2.2mol/LNaOH concentration; Sodalite was also formed under high NaOH molarities. Shape of zeolite A is show the cube by the SEM micrograph.     

Characterization of activated carbon obtained from Saudi Arabian fly ash

This study investigated the potential application of heavy oil burning fly ash as a precursor to prepare activated carbon. The raw fly ash obtained from a power plant is cleaned by nitric acid/hydrochloric acid and activated at 550–800 °C with hold times of 30 and 60 min to obtain fly ash activated carbon. The phosphoric acid is used as a chemical agent to improve the surface characteristics of the cleaned fly ash. The effects of process variables such as amount of chemical reagents, activation time and temperature were investigated according to two-levels full factorial design. The resultant activated carbons were characterized in terms of Brunauer, Emmett and Teller surface area and total and pore volume. The maximum specific surface area was found of 148.30 m²/g at 800 °C temperatures with 60 min holding time. The test showed that the surface area and pore volumes of the material are also significantly enhanced by the activation process.     

Textural properties vs. CEC and EGME retention of Na–X zeolite prepared from fly ash at room temperature

Zeolite Na–X (FAU type) was synthesized from F-class fly ash in simple and economical way. Several months of storage of fly ash in NaOH solution, at room temperature, without any prior treatment, results in the production of material with ca. 50% content of Na–X zeolite. The most efficient reaction takes place at (OH)⁻ activity of 0.1–0.15 mol (OH)⁻/g of ash and at S/L ratio of 33 to 67 g/dm³. Higher S/L value causes an accelerating dissolution–crystallization equilibrium attainment. Cl⁻ ion acts as the inhibitor of this reaction.     

Utilisation of fly ash in a geopolymeric material

Finding means of utilising waste products is a very important field of research at the moment. In this study, fly ash, a waste product of the electricity and petrochemical industries, was investigated as a basic ingredient of a new geopolymeric material. The similarity of fly ash to natural pozzolans has encouraged the use of this waste product in the synthesis of geopolymers, which, in turn, can best be viewed as consisting of a polymeric Si–O–Al framework. Manufacturing of the geopolymers was conducted by mixing fly ash, kaolinite, sodium silicate solution, NaOH and water. The samples were cured at 40, 50, 60 and 70 °C for different time intervals (6, 24, 48 and 72 h). The optimum condition was found to be at 60 °C for a period of 48 h. Compressive strength measurements show a maximum strength of almost 8 MPa after 28 days. Infrared spectroscopic measurements were obtained of the samples after 7 and 28 days. X-ray diffraction measurements show quartz as the main constituent with the largest part of the geopolymer structure being amorphous and glass-like.     

Compression Behavior of Mine Tailings Amended with Cementitious Binders

The objective of this study was to evaluate the effect of fly ash amendment on the compression behavior of mine tailings. Natural and synthetic (i.e., laboratory prepared) mine tailings were used to assess the effects of tailings composition and tailings solids content on compressibility. Three types of off-specification fly ashes and Type I–II Portland cement were used as cementitious binders. Tailings-fly ash mixtures were prepared at solids content of 60–75% (water content = 33–67%), water-to-binder ratios of 2.5 and 5, and were cured for 0.1 days (2 h), 7, and 28 days. Bi-linear compression curves on semi-log plots were observed in most of the binder-amended tailings specimens. The break in slope on the compression curve was identified as the breaking stress, whereupon cementitious bonds were broken. The breaking stress increased with an increase in fly ash content, which was attributed to a lower water-to-binder ratio and void volume-to-binder volume ratio that produced more effective particle bonding. Breaking stress also increased with an increase in CaO content and CaO-to-SiO₂ ratio of fly ash, which resulted in more effective bonding between particles. The effect of curing time on the breaking stress of fly ash amended specimens was characterized by (1) an increase in breaking stress via increase in curing time and cementitious bond formation or (2) a constant breaking stress with curing time due to competing mechanisms during loading. Specimens cured under a vertical stress showed an increase in breakings stress with applied load water removal prior to cementitious bond formation that reduced the water-to-binder ratio and led to more effective cementation.     

采空区大掺量粉煤灰无机固化泡沫制备及特性研究

煤矿采空区漏风是引发煤火灾害的重要原因,传统充填堵漏材料易干裂,流动性差,成本高,因此研发出有效充填封堵漏风通道的新型材料十分必要。通过单因素变量法,以材料流动度、初凝时间、抗压强度为指标进行配比优选,研发出大掺量粉煤灰无机固化泡沫充填堵漏新材料。同时,利用红外光谱、X射线衍射仪、扫描电镜表征材料的水化过程。结果表明∶基于泡沫均匀度、发泡倍数、半衰期及析水率等参数,优选出十二烷基硫酸钠(SDS)∶辛癸基葡糖苷(APG)=1∶1,黄原胶(XG)∶瓜尔胶(GG)=1∶1的水基泡沫。研发的大掺量粉煤灰无机固化泡沫,其初凝时间与粉煤灰掺量、水灰比、泡沫掺量成正比;流动度与水灰比成正比,与粉煤灰掺量成反比,随泡沫掺量增加先上升后缓慢降低;抗压强度随粉煤灰掺量增加呈先增加后减小趋势,与水灰比和泡沫掺量呈反比关系。综合评价指标确定粉煤灰掺量为60%、水灰比为0.6、泡沫与复合浆液体积比为1∶1时,材料流动度好,为15.9 cm,初凝时间适中,为5 h,抗压强度高,28 d达到1.5 MPa。该材料的水化产物是钙矾石(AFT)以及C-S-H凝胶,由水泥先发生水化反应生成Ca(OH)2,后与粉煤灰反应生...     

Lead Removal from Aqueous Solution by Natural and Pretreated Zeolites

Hazardous metal cations enter water through the natural geochemical route or from the industrial wastes. Their separation and removal can be achieved by adsorptive accumulation of the cations on a suitable adsorbent. In the present work, toxic Pb(II) ions are removed from water by accumulating it on the surface of natural zeolite in three different forms; one untreated and two treated samples, one sample treated with 2 M HCI solution and other is treated with 3 M NaOH solution. Natural zeolite is mainly composed of clinoptilolite, and mordenite, with amount of non-zeolite phase (smectite and illite) and C and CT opal. The adsorption experiments are carried out using a batch process in environments of different pH, initial Pb(II) concentration, interaction time and amount of zeolites. Treated zeolite samples show high exchange capacity for Pb(II) compared to untreated sample, however, acid-treated sample shows an exceedingly good exchange capacity. Equilibrium data fitted well with the Langmuir isotherm model with maximum adsorption capacity of 115, 126, and 132 mg g⁻¹ of untreated natural zeolites, alkali-treated zeolites and acid-treated zeolites respectively. The rates of adsorption were found to confirm to pseudo-first order kinetic with good correlation and the overall rate of lead ions uptake.     

粉煤灰增强回填碱渣工程特性的试验研究

碱渣与饱和卤水混合制成浆体回填到盐矿废弃盐腔可同时解决碱渣处理问题和地下废弃盐腔存在的地质隐患。回填碱渣强度是影响充填效果的重要因素。因此,为了提高回填碱渣强度,采用掺入粉煤灰制成复合碱渣对其强度特性进行改良。针对不同粉煤灰掺合比的碱渣开展了组成、力学和细观试验。研究结果表明：（1）掺入粉煤灰能明显改善碱渣的强度,使其黏聚力、内摩擦角都大幅提高,抗剪强度大幅增加;（2）粉煤灰掺合比越大,增强效果越明显,但强度并非随掺合比呈线性变化,对黏聚力而言,在0～20%内的掺合比下增加速度最快,而对内摩擦角则在20%～30%的掺合比区间增加最快,对抗剪强度而言,0～20%的掺合比内增加最明显;（3）粉煤灰掺入还可显著改善碱渣的压缩固结特性,使其固结系数大幅提高,从而提高碱渣固结速度,缩短充填工期,其中在0～10%的掺合比内对压缩固结特性改善最显著;（4）矿物组成分析表明,粉煤灰掺入改变了矿物组成,使得亲水性矿物含量急剧锐减,进而改变了其沉积特性。而细观分析则表明,粉煤灰掺入使碱渣从絮凝团细观结构变成了粉煤灰充当骨架的充填结构,且粒间支撑和拉联效应明显。从增强效果提高、压缩固结特性增强、控制成本和工期综合分析表明,最优掺合比为20%左右,建议工程中以不高于20%的掺合比作为实用掺合比即可取得较为理想的充填增强效果。该研究为揭示碱渣增强机制及废弃盐腔碱渣充填工艺优化提供了有益参考。