不同条件下低温低浊水混凝试验研究

为了保证饮用水水质并实现节能降耗,宁夏宁东水厂采用调节原水pH值,投加高锰酸钾的方式来强化常规处理工艺。结果表明,调节pH值对于处理偏碱性的低温低浊水具有良好的净化效果。当原水pH值调节为中性时,混凝效果达到最优;适当使用聚丙烯酰胺可以优化混凝效果,但由于聚丙烯酰胺具有毒性,在实际运行中要慎重使用;高锰酸钾预氧化可有效提高低温低浊水的处理效果,对于提高冬季低温低浊水处理效果具有重要影响;通过滤池反冲洗水回流的方法．可以提高原水中颗粒物的数量．有助于提高水处理过程中颗粒碰撞效率,改善混凝效果。     

高锰酸钾与粉末活性炭联用处理低温低浊水研究

考察了高锰酸钾与粉末活性炭联用对宁夏宁东水厂冬季低温低浊水的处理效果。结果表明,单独使用高锰酸钾做助凝剂,聚合氯化铝作为混凝剂时,随着高锰酸钾投加量的增加,浊度去除率呈现先增加后减小的趋势,当高锰酸钾投加量达到0．5mg／L时,浊度去除率最高,出水CODMn和UV254的去除率随高锰酸钾投加量的升高而上升;UV254的去除率随着粉末活性炭投加量的增加而升高,当粉末活性炭投加量大于30mg／L时,其对浊度的去除率无明显影响;高锰酸钾与粉末活性炭联用可以明显提高低温低浊水的浊度和UV254的去除率,在我国冬季北方低温低浊水处理中具有广泛的应用前景。     

碳酸钙沉淀法检测混浊原水中“两虫”的研究

对于混浊水源水中"两虫"的检测,选定有效的浓缩富集及分离纯化方法尤为重要。滤囊/滤芯富集—免疫磁分离(IMS)组合方法对混浊水源水的预处理效果较好,但成本过高。为此,研究了碳酸钙沉淀法对某混浊河水中"两虫"的浓缩富集效果,并对浓缩后样品比较了密度梯度离心法和免疫磁分离法的分离纯化效果。结果发现,利用碳酸钙沉淀法可有效实现水中"两虫"的富集;从分离纯化效果来看,Percoll—蔗糖密度梯度离心方法对贾第鞭毛虫和隐孢子虫的平均回收率分别可达72.3%和39.5%,相对标准偏差分别为10.8%和11.9%;与国标方法中免疫磁分离方法的效果相当,但可显著降低分析成本。因此,碳酸钙沉淀—密度梯度离心组合技术用于混浊水源水中"两虫"的检测具有较好的应用前景。     

新型纳米平板陶瓷膜在纸箱生产废水回用中的工程应用

采用混凝沉淀+水解酸化+MBR+活性炭吸附组合工艺来回用纸箱厂废水。MBR膜采用的是新型纳米平板陶瓷膜。介绍了各处理段的工艺特点、构筑物的设计尺寸、设备选型等,并对新型纳米平板陶瓷膜的清洗进行了介绍。系统运行一年,出水水质稳定,优于≤城市污水再生利用城市杂用水水质≥GB/T 18920-2002表1中的城市绿化排放标准,即BOD5≤20 g/L,浊度≤10 NTU,色度≤30,并分析了本工程的处理成本及所产生的经济效益。     

Construction of BiVO4 microspheres sensitized TiO2 NTAs for the enhanced photocatalytic mineralization of organic dyes

In the present work, BiVO₄ microspheres were deposited on TiO₂ NTAs via the solvothermal method using urea as the mineralizer. The binary heterojunction formation significantly enhanced the solar response region and intensity, and the electron transfer path was built at the interface of two semiconductors, which was the main reason for the enhanced photoelectrochemical and photocatalytic performances. The S-2 electrode prepared with urea concentration of 2 mol/L displayed the high visible light photocurrent of 73.76 μA/cm² and photovoltage of −0.30 V. Furthermore, the S-2 photocatalyst also showed excellent photocatalytic decoloration ability of MO, RhB and MB dyes, and the corresponding decomposition efficiencies were 55.82%, 41.62% and 89.90% under solar irradiation. Except for the organic dyes, Cr(VI) ions also could be reduced into Cr(III), and the photocatalytic efficiency achieved 74.05% after 3 h solar irradiation. The active group and photocatalytic mechanism were proposed to illuminate the essential reason. The experimental results indicated that the novel BiVO₄/TiO₂ NTAs with binary heterojunction are attractive photocatalysts for the dyeing and printing water treatment.     

Self-assembled cubic-hexagonal perovskite nanocomposite as intermediate-temperature solid oxide fuel cell cathode

Self-assembly is an emerging strategy for preparing composite cathodes with good oxygen electrochemical reduction activity and congenital chemical compatibility for intermediate-temperature solid oxide fuel cell (IT-SOFC). Here we report that a self-assembled BaCo_0.6Zr_0.4O_3-δ (BZC-BC) nanocomposite is prepared through one-pot glycine-nitrate process and exhibits high cathode performance. The BZC-BC nanocomposite is composed of 62 mol% cubic perovskite BaZr_0.82Co_0.18O_3-δ (BZC) as an ionic conductor and 38 mol% hexagonal perovskite BaCo_0.96Zr_0.04O_2.6+δ (12H-BC) as a mixed ionic and electronic conductor. The BZC-BC nanocomposite has the pomegranate-like particles aggregated with a larger number of nanoparticles (50-100 nm) which greatly enlarge the three-phase boundary sites. The BZC-BC nanocomposite exhibits a thermal expansion coefficient of 12.89 × 10⁻⁶ K⁻¹ well-matched with that of Ce_0.8Gd_0.2O_3-δ (12.84 × 10⁻⁶ K⁻¹) electrolyte. The high electro-catalytic activity of BZC-BC nanocomposite cathode for oxygen reduction is reflected by the low polarization resistances of oxygen ions incorporation at cathode/electrolyte interface (0.02823 Ω cm²), oxygen species diffusion (0.03702 Ω cm²) and oxygen adsorptive dissociation (0.07609 Ω cm²) at 700 °C. The single cell with BZC-BC nanocomposite cathode achieves the maximum power density of 1094 mW cm⁻² at 650 °C and shows good stability under 25 h run.     

Molecular sieves as catalysts for aromatic bromination

Ring bromination of alkylbenzenes at room temperature was effectively performed on aromatic substrates catalyzed by zeolite 13X or mordenite after introduction of iron(III) ions. Other zeolites and ions were also studied. Almost quantitative yields of p- and o-bromo derivatives without dibromo or side-chain derivatives were obtained after 3–4 h when the reaction was performed in the dark. Bromination of benzene was not complete even at reflux temperature. The catalyst may be recycled many times for practical applications.     

Catalytic activity of aluminium form of Y-type zeolites for the Claus reaction

Y-type zeolites modified with aluminium and activated at temperature below 470 K has bee found to be an effective catalyst for the Claus reaction. The activity of this modified form is higher than that of NaY pretreated under the same conditions. The basic OH groups are believed to be active centers involved in the catalytic process. Removal of these groups by means of high-temperature treatment or fluorination of the sample brings about a considerable decrease in the catalytic activity.