改性沸石对低浓度氨氮废水的动态吸附

采用氯化钠溶液对甘肃白银天然沸石改性,以低浓度氨氮(NH4+-N)废水为处理对象,对比了天然沸石和改性沸石的动态吸附特性并绘制穿透曲线,利用Origin软件对实验数据分析处理,得出穿透曲线的通式。结果表明:在相同条件下,改性沸石的穿透时间和吸附饱和时间都比天然沸石的长约1.5倍;沸石经氯化钠改性后,对NH4+-N的吸附速率和饱和吸附量都明显提高,吸附性能显著改善。Origin软件对水溶液中NH4+-N的吸附穿透曲线的Logistic模型回归式具有较高的精度,该模型可以很好地反映沸石吸附剂的动态吸附过程。     

A novel nano-sized Co3O4@C catalyst derived from Co-MOF template for efficient Hg0 removal at low temperatures with outstanding SO2 resistance

Environmental Science and Pollution Research - Co3O4 is a promising Hg0 removal catalyst for industrial application. Operating temperature and low sulfur resistance are two of the main problems...     

低浓度氨氮废水的离子交换法脱氮

分别研究了沸石的等温吸附模型,改性沸石在交换柱中的穿透与再生,通过化学沉淀法对再生废液中氨氮的回收等。结果显示:60～80目单位重量天然斜发沸石对氨氮的饱和交换容量为4.15 mg/g;30 mg/L的氨氮废水经过交换柱后沸石的穿透吸附容量和平衡吸附容量分别为:4.50 mg/g和4.757 mg/g。化学再生后,用化学沉淀法使再生废液中氨氮由202 mg/L降到16.3 mg/L。     

改性沸石吸附低浓度氨氮废水及其脱附的研究

采用氯化钠溶液对浙江某地天然沸石改性,以低浓度氨氮废水为处理对象,比较了天然沸石和改性沸石的吸附等温线、吸附动力学和动态吸附,并进行了改性沸石的动态脱附研究.结果表明,沸石的平衡吸附量随着平衡浓度的增大而增大;Freundlich方程比Langmuir方程更好地描述沸石吸附低浓度氨氮废水的行为,改性沸石比天然沸石具有更...     

低浓度三氯生废水的电化学去除效能

以钌铱电极做阳极、石墨片做阴极,建立了电化学反应器处理三氯生模拟废水,重点考察了电流密度、pH、电解质硫酸钠浓度对电化学反应器去除水中微量三氯生效能的影响规律。研究发现,随着电流密度增大,三氯生去除率会有所提高,但存在一定限度;总体上酸性或碱性条件下的处理效果优于中性条件,电解质浓度过高或过低都不利于三氯生的去除。计算出不同电解质浓度和电流密度下的能耗,探讨了三氯生的电化学去除机制。电化学反应器对三氯生模拟废水有较好的处理效果,当三氯生初始浓度为4 mg·L-1、电流密度为10 mA·cm-2、电解质Na2SO4浓度为0.025 mg·L-1、中性条件下反应时间2 h,三氯生去除率达70.7%,能耗为26.4 kWh·g-1。     

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pH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。     

Adsorption properties of regenerative materials for removal of low concentration of toluene

A specific type of material, activated carbon fiber (ACF), was modified by SiO₂, and the final products ACF-x were obtained as ACF-12.5, ACF-20, ACF-40, and ACF-80 according to different dosages of tetraethoxysilane (TEOS). The modified material on the ACF surface had a significant and smooth cover layer with low content of silica from scanning electron microscope (SEM) image. The modified ACF-x showed the stronger hydrophobicity, thermal stability, and adsorption capacity, which had almost no effect in the presence of water vapor and no destruction in multiple cycles. ACF-20 was proven as the most efficient adsorbent in humid conditions. The dual-function system composed of the regenerative adsorbents and the combustion catalyst would be efficient in consecutive toluene adsorption/oxidation cycles, in which the combustion catalyst was prepared by the displacement reaction of H₂PtCl₆ with foam Ni. Therefore, the adsorption/catalytic oxidation could be a promising technique in the indoor air purification, especially in the case of very low volatile organic compound (VOC; toluene) concentration levels.

Implications: Exploring highly effective adsorptive materials with less expensive costs becomes an urgent issue in the indoor air protection. ACF-20 modified by SiO₂ with Pt/Ni catalysts shows stronger hydrophobicity, thermal stability, and adsorption capacity. This dual-function system composed of the regenerative materials and the combustion catalyst would be a promising technique in the indoor air purification, especially in the case of removal of very low concentration of toluene.     

负载型Mn-Ce／TiO2催化剂的制备及其低温脱硝活性

以成型TiO2作为载体,通过浸渍法制备了Mn-Ce／TiO2低温SCR催化剂,并系统研究了制备方法、煅烧条件、活性组分担载量、Mn含量等参数对催化剂催化还原NO性能的影响。结果表明,煅烧温度的升高会促使活性组分结晶度的提高,从而引起催化活性的降低,在500℃和600℃下所得Mn-Ce／TiO2催化剂活性组分为无定型态,表现出较高的脱硝活性。活性组分担载量的增加有利于催化活性的提高。Mn含量对Mn-Ce／TiO2催化剂的活性有较大影响,当Mn／（Mn＋Ce）摩尔比为40％和85％时,催化剂活性最高。     

低温条件下BAF+SPD组合工艺对滇池入湖河水的脱氮效果

为缓解湖泊富营养化问题,需进一步降低入湖河流氮的含量。针对滇池流域新运粮河的低C/N水质特征,研究了冬季低温条件下的微曝气生物滤池（BAF）及固相反硝化（SPD）组合异位脱氮工艺。结果表明,BAF+SPD组合工艺启动挂膜阶段,约3周后,NH₄⁺-N的去除率达80%以上,而反硝化细菌增殖相对缓慢,约5周后,NO₃^--N的去除率达80%以上;稳定运行的低温阶段,除降雨时间外,NH₄⁺-N平均去除率达80%,出水NH₄⁺-N浓度<1 mg/L;NO₃^--N平均去除率达到85%以上,出水NO₃^--N浓度<1 mg/L;TN平均去除率达80%以上,出水TN浓度<2 mg/L,主要水质指标达到国家地表水Ⅴ类标准。     

利用UVC去除低浓度苯的实验研究

探讨了不同实验参数对苯的UVC去除效果的影响,获得了苯的去除率与苯的初始浓度、气体流量、相对湿度和氧气含量等参数之间的关系。数据表明,在实验条件范围内,苯的去除率的倒数与苯初始浓度、气体流量之间为线性关系;苯的去除率随相对湿度的增加呈现先升高后缓慢降低的关系,最佳相对湿度值在30%～50%之间;苯的去除率随氧气量的增加而缓慢增加;波长为185+254 nm的UV与254 nm的UV相比净化效果更为理想。还分析了苯降解产生的中间产物,探讨了苯的降解机理。     

利用UVC去除低浓度丁烷的实验研究

探讨了不同实验参数对丁烷在UVC下去除效果的影响,获得了丁烷的去除率与丁烷的初始浓度、气体流量、相对湿度、氧气含量等参数之间的关系。数据表明：在实验条件范围内,丁烷的去除率随其初始浓度和气体流量增大而减小;丁烷的去除率随相对湿度的增加呈现先快速升高后缓慢降低的关系,最佳相对湿度值在40%～60%之间;丁烷的去除率随氧气...     

PCDD/F removal at low temperatures over vanadium-based catalyst: insight into the superiority of mechanochemical method

Environmental Science and Pollution Research - The high toxicity and low volatility of PCDD/Fs prevent detailed study of their catalytic degradation removal characteristics. In this study,...     

Applying hexagonal nanostructured zeolite particles for acetone removal

This study examines the performance of a new adsorbent, hexagonal nanostructured zeolite particles (HNZP) for acetone adsorption and compares the results with that of commercial mobil synthetic zeolite-5 (ZSM-5) type zeolite. The HNZP is a pure siliceous adsorbent with different values of pore diameter and surface area being adjustable by the manufacturing condition. The results indicate that a slight increase in the average pore diameter (d) of HNZP from 2 to 2.5 nm leads to an increase in the acetone adsorption capacity, although its surface area is decreased, in which case (d = 2.5 nm) the adsorption capacity of fresh HNZP is better than that of ZSM-5 zeolite. Even for the fresh HNZP (d = 2 nm) of which the adsorption capacity is less than that of the ZSM-5 zeolite at relative humidity (RH) of 0%, its adsorption capacity is not deteriorated after repeated regeneration, but the adsorption capacity of regenerated ZSM-5 zeolite decays markedly. Thus, after only one regeneration, the adsorption capacity of HNZP (d = 2 nm) becomes better than that of the ZSM-5 zeolite. The decrease in the adsorption capacity of regenerated ZSM-5 zeolite might be because of its aluminum content that catalyzes the acetone into coke and, thus, blocks the adsorption sites. Furthermore, result on the moisture effect shows that because the pure siliceous HNZP was more hydrophobic than the ZSM-5 zeolite, the acetone adsorption efficiency of fresh HNZP (d = 2 nm) is better than that of ZSM-5 zeolite at RH = 50%.     

整体蜂窝陶瓷催化剂催化氧化法脱除低浓度VOCs的实验研究

本文讨论了目前有机污染物脱除的各种方法 ,并将催化活性组分担载在经Al2 O3 修饰的整体蜂窝陶瓷支撑体上 ,制备了催化氧化法脱除低浓度有机污染物 (VOCs)ZDL - 1催化剂 ,在固定床反应器进行了连续工艺条件实验。结果表明 ,ZDL 1催化剂具有低温启动性能好、脱除VOCs的效率高、稳定性好的突出优点 ,且床层压降低。为ZDL 1催化剂应用于不同过程脱除VOCs提供基础     

负载型Mn-Ce/TiO2催化剂的制备及其低温脱硝活性简

以成型TiO₂作为载体,通过浸渍法制备了Mn-Ce/TiO₂低温SCR催化剂,并系统研究了制备方法、煅烧条件、活性组分担载量、Mn含量等参数对催化剂催化还原NO性能的影响。结果表明,煅烧温度的升高会促使活性组分结晶度的提高,从而引起催化活性的降低,在500℃和600℃下所得Mn-Ce/TiO₂催化剂活性组分为无定型态,表现出较高的脱硝活性。活性组分担载量的增加有利于催化活性的提高。Mn含量对Mn-Ce/TiO₂催化剂的活性有较大影响,当Mn/（Mn+Ce）摩尔比为40%和85%时,催化剂活性最高。     

110离子交换树脂担载催化剂净化低浓度PH3

以110丙烯酸系阳离子交换树脂作为载体,Pd(Ⅱ)-Cu(Ⅱ)为主催化剂,制成担载型过渡金属催化剂。以N₂为载气,对反应温度、氧含量、催化剂用量3个因素进行催化氧化净化低浓度PH₃研究。实验结果表明,在氧含量为3.7%,温度为72℃时,催化剂的催化活性较高;PH₃净化效率随催化剂用量增大而提高。在优化后的实验条件下,考察催化剂以CO为载气时催化剂对PH₃的净化效率,虽然净化效果比以N₂为载气时差,但反应较稳定,持续时间较长,有较好的抗杂毒性,且催化剂具有再生性能。     

110离子交换树脂担载催化齐净化低浓度PH3

以110丙烯酸系阳离子交换树脂作为载体,Pd（Ⅱ）-Cu（Ⅱ）为主催化剂,制成担载型过渡金属催化剂。以N2为载气,对反应温度、氧含量、催化剂用量3个因素进行催化氧化净化低浓度PH3研究。实验结果表明,在氧含量为3．7％,温度为72℃时,催化剂的催化活性较高;PH3净化效率随催化剂用量增大而提高。在优化后的实验条件下,考察催化剂以CO为载气时催化剂对PH3的净化效率,虽然净化效果比以N2为载气时差,但反应较稳定,持续时间较长,有较好的抗杂毒性,且催化剂具有再生性能。     

活性炭纤维低温脱除模拟烟气中的VOC

采用H2O2浸渍的修饰方法对ACF进行化学改性,并利用氮吸附等温线和XPS（X-ray photoelectron spectroscopy）的方法对ACF样品进行表征。通过在反应床上开展吸附实验,由此测定改性前后ACF脱除VOC（甲苯作为VOC的代表物）的效果,同时考察氧气、温度、水蒸气等因素对ACF脱除甲苯的影响。研究发现,改性使得ACF样品比表面积和孔容略有降低,但表面含氧官能团含量增加,吸附甲苯的能力也因此增强。当模拟烟气中O2浓度为5%时,ACF脱除VOC效果达到最佳,超过5%之后,氧的促进效果不再明显;温度40℃为最佳吸附温度;当烟气中加入水蒸气时,ACF对VOC的脱除效率降低。     

高表面氧MnOx/类水滑石催化剂常温催化低浓度甲醛的性能

常温催化氧化技术是去除室内低浓度甲醛(HCHO)的一种有效方法,其中过渡金属氧化物锰基催化剂在催化降解方面性能优异,相较于贵金属催化剂,具有成本低、活性高、稳定性良好、应用前景广等优点。采用共沉淀法制备了类水滑石载体和锰基/类水滑石催化剂,将类水滑石与锰基氧化物相结合用于常温催化氧化,克服了锰基氧化物常温条件下因大量吸附水蒸气而导致稳定性降低的缺点,同时研究考察了载体组成、煅烧温度、氧化锰负载量等对催化剂常温催化氧化性能的影响,并通过XRD、SEM、BET、EPR、XPS等技术对催化剂进行了微观表征。结果表明,当类水滑石中n(Mg)∶n(Al)=4∶1,氧化锰负载量 (质量分数) 为40%,煅烧温度为200 ℃时,所述MnO_x/Mg₄Al₁催化剂性能最佳,其48 h甲醛去除率高达98.5%,甲醛质量浓度由1.000 mg·m^-3降至0.015 mg·m⁻³。类水滑石载体表面存有大量羟基基团,有利于吸附低浓度甲醛及中间产物进而利于催化剂催化氧化性能提升。通过XPS分析可知,相较于MnO_x催化剂,MnO_x/Mg₄Al₁催化剂中O_β/(O_α+O_β)相对含量比例由35.7%提升至88.0%,表面氧含量(O_β)大幅提升,其在甲醛常温催化氧化过程中发挥着极其重要作用。本研究结果可为常温催化氧化甲醛提供参考。