溶解性微生物产物在GO/PVDF杂化膜面的污染行为

为了解析溶解性微生物产物（SMP）在GO/PVDF杂化膜面的污染特性,对膜片进行了宏观污染实验,并采用耗散石英微晶天平（QCM-D）从微观角度分析了SMP在自制镀膜芯片上的吸附规律和污染层结构变化.结果表明,GO含量为0.5wt%的膜污染恢复率最高（79.95%）,抗污染能力最强.QCM-D实验发现,GO含量为0wt%镀膜芯片表面SMP吸附量最大,污染较为严重.膜片亲水性越强,吸附频率变化越小,抗污染能力越强.此外,GO含量为0.5wt%镀膜芯片表面的污染物结构比较疏松和柔软,其他膜表面的污染物结构较为坚硬和致密.     

有机改性蒙脱土对萘的吸附机制和影响因子

我国场地土壤中多环芳烃（PAHs）污染或PAHs-重金属复合污染是常见的污染类型,对公众健康与环境构成巨大威胁.本研究利用耗散型石英晶体微天平（QCM-D）技术和批量吸附实验,探究实验室制备的2种有机改性黏土对萘的吸附机制,以及萘与Cu²⁺共存时黏土颗粒吸附情况.结果表明,25℃时,十六烷基三甲基溴化铵改性蒙脱土（CTAB-SMF）的吸附等温线符合Freundlich模型（R²>0.92,n>1）,说明其对萘的吸附位点具有多样性,在较高萘平衡浓度（c_e=1 mmol ·L^-1）下吸附分配系数K_d为SMF的13.4倍;3-巯基丙基三甲氧基硅烷改性蒙脱土（TMSP-SMF）的吸附等温线符合Langmuir模型（R²>0.96）,在较高萘平衡浓度（c_e=1 mmol ·L^-1）下吸附分配系数K_d为SMF的1.14倍.说明2种有机改性黏土对萘的吸附效果优于SMF颗粒.3种黏土颗粒对萘的吸附焓在-30~-10 kJ ·mol^-1之间,均为自发物理吸附.溶液离子强度升高抑制了SMF吸附萘,但对改性黏土吸附萘无显著影响.萘平衡浓度较低（c_e=0.1 mmol ·L^-1）时,Cu²⁺的存在使TMSP-SMF对萘的吸附效果增加了3倍;同时萘能促进2种改性黏土对Cu²⁺的吸附.本研究通过原位在线QCM-D检测了黏土对萘的吸附机制,结果与批量吸附实验结果一致：CTAB-SMF对萘的吸附位点主要为黏土层间的改性剂基团,TMSP-SMF则位于黏土颗粒表面的改性剂基团.本项研究结果显示,QCM-D技术是一种有效的原位在线表征黏土膜吸附有机污染物的方法,2种有机改性的黏土颗粒可作为应用于PAHs或PAHs-重金属复合污染场地的修复材料.     

GO-TiO2改性中空纤维膜的制备条件及抗污染性能研究

以氧化石墨烯(GO)与纳米二氧化钛(TiO_2)为改性剂,采用界面聚合法与抽滤吸附结合,对聚偏氟乙烯中空纤维超滤膜(简称原膜)进行表面改性,得到新型纳米改性膜(简称GO-TiO_2改性膜).研究改性膜的制备工艺条件及其对腐殖酸(HA)的吸附截留性能与抗污染特性.结果表明:(1)最佳制备工艺条件为:钛酸丁酯2 m L、GO 1 mg、间苯二胺1%(质量分数)、间苯二胺浸泡时间8 min、均苯三甲酰氯0.2%(质量分数)、均苯三甲酰氯浸泡时间10 min;(2)亲水性提高显著,亲水性表面为GO-聚酰胺-TiO_2复合结构,改性膜接触角由80.6°±1.8°下降到38.6°±1.2°;(3)抗污染性能提高明显.改性膜通量总衰减率由改性前的51.2%下降到35.6%,过滤周期约为原膜的2.5倍;反冲洗后膜通量恢复率由69%提高到96%.     

Atomic force microscopy study on the microtopography of natural organic matter and newly formed hydrous MnO2

To understand the water purification mechanism of potassium permanganate as a coagulation-aid during the preoxidation process, the microtopography of its reductive products, the newly formed hydrous manganese dioxide and the aged hydrous manganese dioxide, was investigated. The morphology of natural organic matter (NOM) adsorbed by the newly formed hydrous manganese dioxide was also compared with that of NOM alone. By using the tapping mode atomic force microscopy (AFM), the observation results show that the newly formed hydrous manganese dioxide possess a perforated sheet (with a thickness of 0–1.75 nm) as well as some spherical particle structures compared with the hydrous manganese dioxide with 2 h aging time, which demonstrated that the newly formed hydrous manganese dioxide had a large surface area and adsorption capacity. When 1 mmol/L newly formed hydrous manganese dioxide was added, the microtopography of NOM molecules shifted from a loosely dispersed pancake shape (with adsorption height of 5–8.5 nm) to a densely dispersed and uniform spherical structure. These results provide a valid proof that it is the perfect adsorption capability of the newly formed hydrous manganese dioxide that might result in the coagulation aid effect of potassium permanganate preoxidation. Translated from Environmental Science, 2006, 27(5): 945–949 [译自: 环境科学]     

CeO2改性MnOx/Al2O3的低温SCR法脱硝性能及机制研究

采用凝胶溶胶法制备大比表面积的Al2O3载体,等体积浸渍法配制负载MnOx和CeO2组分的CeO2-MnOx催化剂.以NH3为还原剂,一定的空气流速及合适的气体配比的条件下,考察所制备的催化剂在70～300℃范围内低温SCR法的脱硝性能及机制,同时分别对催化剂进行BET、XRD、SEM等表征实验,研究催化剂的理化性质....