堇青石负载Pd和过渡金属氧化物催化剂的表征及其对CO的催化氧化活性

以堇青石蜂窝陶瓷(CC)为载体,采用浸渍法制备了堇青石负载Pd和过渡金属混合氧化物催化剂,记作Pd-M-Mn(M=Cu,Co,Fe,Ni)/CC。实验结果表明:Pd-Co-Mn/CC催化剂的催化活性最高;随着Pd负载量的增加,CO转化率提高;当Pd负载量为1.00%时,反应温度为150℃时CO转化率达到98%,200℃时CO转化率达到100%;在反应温度150℃条件下,Pd-Co-Mn/CC催化剂(Pd负载量1.00%)的CO转化率在前30h内小幅度下降,随后稳定在90%以上,反应100h后,催化剂表面颜色由黑色变为棕褐色。     

碱式硫酸铝溶液中SO42-的测定

建立了以铬黑T为指示剂,乙二胺四乙酸二钠反滴定过量BaCl₂的碱式硫酸铝溶液中SO₄^2-的测定方法。实验确定的操作条件为：待测试样稀释后ρ（SO_4^2-）为0.025 ~0.100 g/L,BaCl₂过量率为25%~100%,并且在加入BaCl₂前将试样煮沸,三乙醇胺加入量为0.10 L/L。该法回收率在98.90%~100.72%,相对标准偏差小于1%。测定方法准确,可靠,且操作简便、快速。     

循环式超声强化光催化降解双酚A

设计了一种循环式超声强化光催化反应器,以TiO2作为光催化剂,研究了超声功率、TiO2加入量、循环液流速和空气流量对双酚A(BPA)降解效果的影响。实验结果表明:超声与光催化过程在循环式超声强化光催化反应器中实现了较好的协同效应;在初始BPA质量浓度为20.0mg/L、超声功率为600W、TiO2加入量为7g/L、循环液流速为4.05×10-2m/s、空气流量为200mL/min的条件下,反应150min后,BPA降解率可达90.5%,溶液中剩余BPA质量浓度仅为1.8mg/L,反应240min后TOC去除率可达84.5%。     

Motility of Pseudomonas aeruginosa in saturated granular media as affected by chemoattractant

To examine and quantify the effects of glass beads and chemoattractant on bacterial motility in granular media, we examined the motile behavior of P. aeruginosa in a saturated granular medium and quantified the effects of glass beads and the presence of a chemoattractant. By recording individual cell trajectories in microfluidic channels under a high-speed confocal microscope, we directly measured the cell's run direction and corresponding run-length, speed and turn angle. Bacterial run speed increased in the presence of chemoattractant in both aqueous and granular media. But it decreased in glass-beads compared to in aqueous media due to the restricted pore geometry and interactions between bacteria and grain surfaces. Notably, the relatively higher frequency distribution at turn angles of 170° decreased dramatically, while the smaller peak at 70° increased and became dominant on a bimodal distribution, showing more bacteria changed directions at smaller turn angles rather than reverse their swimming directions. Additionally, the presence of glass beads also decreased the chemotactic velocity and random motility by similar proportions due to the restrictive geometry and the interactions between bacteria and glass beads surface. Our study indicates that the swimming parameters measured from aqueous media cannot be directly adopted in models for predicting bacteria travel in granular media.     

The dissipation rates of trichlorfon and its degradation product dichlorvos in cabbage and soil

The residual levels and dissipation rate of trichlorfon, and its degradation product, dichlorvos, in cabbage crops and the soil in which these were grown, were determined by gas chromatography at two geographically distant experimental sites, one in Kunming and one in Beijing, China. Trichlorfon was applied at two dosages (900 g ai ha⁻¹ and 1350 g ai ha⁻¹). Maximum final residues of trichlorfon in soil and cabbage were 1.23 mg kg⁻¹ and 1.81 mg kg⁻¹ respectively at Kunming, and 0.35 mg kg⁻¹ and 0.70 mg kg⁻¹ respectively at Beijing. However, the final residues of dichlorvos in both cabbage and soil was only 0.04 mg kg⁻¹ at Kunming, and only 0.03 mg kg⁻¹, or “not detectable”, at Beijing. The mean half-life of trichlorfon in cabbage was 1.80 d with a dissipation rate of 90% over 5 d, while that in soil was 3.05 d with a dissipation rate of 90% over 14 d at one experimental site. The dissipation rates of trichlorfon and its degradation product dichlorvos at the two experimental sites were different, suggesting that degradation of these pesticides was affected by local soil characteristics and climate. When applied at both the recommended dosage and at 1.5 times this, no detectable residues of either trichlorfon or dichlorvos were found in soil or cabbage at harvest. Although trichlorfon can easily degrade into dichlorvos, which is highly toxic to humans and other animals, the observed low residual levels of dichlorvos suggest that trichlorfon is safe when applied at the recommended dosage.     

Dissipation of carbendazim and chloramphenicol alone and in combination and their effects on soil fungal:bacterial ratios and soil enzyme activities

The dissipation of carbendazim and chloramphenicol alone and in combination and their effects on soil fungal:bacterial ratios and soil enzyme activities were investigated. The results revealed that carbendazim dissipation was little affected by chloramphenicol, whereas chloramphenicol dissipation was found to be retarded significantly by the presence of carbendazim. The inhibitory effect of carbendazim on the fungal:bacterial ratios was increased by the presence of chloramphenicol, and the inhibitory effect of chloramphenicol on neutral phosphatase was increased by the presence of carbendazim. Carbendazim increased soil catalase and urease activities, but this increase was partially diminished by the presence of chloramphenicol. Little interaction was observed between carbendazim and chloramphenicol with regard to their influence on soil invertase. The results obtained in this study suggest that combinations of fungicides and antibiotics may alter the compounds’ individual behaviors in soil and their effects on soil enzymes.     

混凝一气浮控制三卤甲烷生成势的研究

研究了混凝一气浮工艺对不同分子量区间三卤甲烷生成势（trihalomethanes formation potential,THMFP）的去除效果及絮体形态对THMFP去除效果的影响。结果表明,混凝一气浮工艺以去除大分子量区间THMFP为主,对小分子量区间THMFP的去除效果较差。UV254值与THMFP值的线性相关系数为0．9449,UV254值可以较好地反映THMFP的含量。絮体的分形维数为1．17～1．2时,孔隙率较大,可增加絮体对THMFP的活性吸附空间,且絮体相对密度较小,可增强同向絮凝作用,增加絮体和THMFP的接触概率,有利于气浮对THMFP的去除。     

Variation of low molecular weight organic acids in precipitation and cloudwater at high elevation in South China

To investigate the sources and chemical behaviors of carboxylic acids in Southern China, precipitation and corresponding cloudwater samples were collected in an acid rain-prone area of Mount Heng. The carboxylic acid levels in the samples were measured, and the concentration patterns were evaluated with respect to temporal and seasonal variations. Formic and acetic acids were predominant among the carboxylic acids identified for both precipitation and cloudwater. Most of the organic acids in the precipitation had a clear seasonal pattern, reaching higher levels during the warm season; these higher levels were attributed to the stronger source strength of biogenic emissions during this season. The cloud–fog samples did not display a similar trend. A distinctive diurnal pattern in carboxylic acids was only observed in the precipitation samples during the warm season. In cloud–fog, the ratio of formic to acetic acid differed considerably with time, with these values varying little in the precipitation samples. This result indicates that the organic acids in precipitation originate consistently from primary sources throughout the entire period, while those in cloud are mainly associated with direct emissions in the earlier stage and with secondary sources in the later period.     

固硫灰渣深度处理焦化废水的实验研究

选用同硫灰渣深度处理经生化处理后焦化废水,采用分光光度计法评价焦化废水的处理效果,采用XRD、XRF、SEM和IR等分析材料的成分、结构和微观形貌等.结果表明,固硫灰渣用量60 g/L、吸附时间15 min,焦化废水的脱色率可达94.22%,COD从原水的76.01 mg/L降低到处理后的5.76 mg/L,NH+4-...     

稻秆对铜绿微囊藻抑制作用的研究

研究了稻秆浸出液对铜绿微囊藻生长的抑制作用.研究表明,稻秆浸出液中含有的化学物质抑制了铜绿微囊藻的生长繁殖.稻秆浸泡时间的延长,有利于提高浸出液的抑藻效果,但浸泡时间过长则无益于抑藻效果提高,浸泡时间为15 d时,抑制率能高达75.99%.稻秆浸出液投加量达7.5%以上具有显著的抑藻效果.不同部位的水稻秸秆浸出液对铜绿...