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391.
以苯胺、甲醛为原料,在不同的反应条件下,以不同的配比合成了一系列的苯胺缩聚物.用失重法研究了在温度、酸浓度、缓蚀剂加入量等影响因素下,苯胺-甲醛聚合物缓蚀剂对A3钢缓蚀效果,结果表明合成的苯胺-甲醛聚合物具有优良缓蚀性能,并得出其适宜的应用条件。 相似文献
392.
生物电化学系统固定二氧化碳同时产生乙酸和丁酸 总被引:1,自引:0,他引:1
生物电化学系统用于微生物电合成,可原位利用污水中的能量将二氧化碳固定,并生产有机物.通过构建生物电化学系统,利用混合菌作电催化剂还原二氧化碳生成乙酸和丁酸.设定阴极电势-0.75 V(vs Ag/AgCl),10 d的反应周期内,乙酸最大积累浓度为251.89 mg/L;丁酸从第3天开始生成,最大积累浓度为89.42 mg/L.系统总电子回收率可达85.04%.电化学分析表明生物阴极具有良好的催化活性.PCR-DGGE分析生物阴极主要菌群为醋酸杆菌属(Acetobacterium)和拟杆菌属(Bacteroides).本研究证明了生物阴极具有以二氧化碳为原始底物合成乙酸,并进一步延伸碳链合成中链脂肪酸的能力,对进一步开发微生物电合成技术具有重要参考价值. 相似文献
393.
沱江是四川省内重要水系,也是长江上游重要支流.沱江既是流域内纳污河流,也是工农业生产用水和居民饮用水水源.本文在沱江流域采集表层沉积物样品46个,研究了9种合成麝香的污染水平和分布特征.在所有沉积物中均检出佳乐麝香(HHCB)和吐纳麝香(AHTN),浓度范围分别为0.736—25.0 ng·g-1(中值为3.68μg·g-1)和0.320—24.4 ng·g-1(中值为1.55 ng·g-1),研究结果揭示出.生活污水排放对沱江沉积物的影响.Pearson相关性分析表明HHCB与AHTN有显著正相关(r=0.894,P<0.01),说明它们具有相似来源和环境地球化学行为.沉积物中AHTN和HHCB实测浓度远低于各化合物对应的预测无效应浓度,风险熵值远小于1,表明其生态风险有限. 相似文献
394.
以Bi(NO3)3和Na2WO4为原料,采用水热法合成了可见光催化剂Bi2WO6,并采用X射线衍射仪和BET法对其进行了表征。考察了合成温度、Bi2WO6加入量、邻氯苯酚(2-CP)浓度、溶液pH等对2-CP光催化降解效果的影响。实验结果表明:在加入140℃下合成的Bi2WO6催化剂1g/L、原始pH(pH=5.85)、可见光光照210min的条件下,对质量浓度为20mg/L的2-CP溶液进行处理,2-CP去除率最高为97.2%;添加少量H2O2对2-CP的降解有促进作用。 相似文献
395.
396.
Levels of synthetic musk fragrances in human milk from three cities in the
Yangtze River Delta in Eastern China 总被引:2,自引:0,他引:2
Xiaolan Zhang Gaofeng Liang Xiangying Zeng Jing Zhou Guoying Sheng Jiamo Fu 《环境科学学报(英文版)》2011,23(6):983-990
Synthetic musks are used as additives in many household products. After absorption into the human body, they accumulate and
their concentrations in human milk reflect both the mother and her infant’s exposure level. Concentrations of four synthetic musks,
musk xylene (1-tert-butyl-2,6-dimethyl-2,4,6-trinitrobenzene, MX), musk ketone (4-tert-butyl-2,6-dimethyl-3,5-dinitroacetophenone,
MK), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[
]-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-
tetrahydronaphthalene (AHTN), were determined in human milk samples collected from Shanghai, Wuxi, and Shaoxing in Eastern
China. The four synthetic musks were found in most samples analyzed, with HHCB the dominant component followed by MX. The
median (mean) values for HHCB, AHTN, MX and MK concentrations were 63 (82), 5 (12), 17 (24) and 4 (9) ng/g lipid weight,
respectively. These data suggested the total synthetic musk contamination was low, and the distribution percentage was HHCB > MX
> AHTN MK. The relative high ratio of nitro to polycylic musk indicated that nitro musks were still widely used. The musk
concentrations in these cities were not significantly different from each other (p > 0.05). Principal components score plots were
obtained, which showed similar exposure sources. The amount of total synthetic musks in human milk were not associated with
mother’s age, although HHCB was significantly correlated with AHTN (p < 0.05). Daily ingestion of HHCB, AHTN, MX and MK for
infants from human milk were estimated as (2526 2926), (370 524), (7391 832), and (277 462) ng/day, respectively. Those
doses were 1–2 orders of magnitude below the provisional tolerable daily intakes. 相似文献
397.
Simultaneous removal of ammonium and phosphate by zeolite synthesized
from coal fly ash as influenced by acid treatment 总被引:5,自引:0,他引:5
ZHANG Bao-hu WU De-yi WANG Chong HE Sheng-bing ZHANG Zhen-ji KONG Hai-nan 《环境科学学报(英文版)》2007,19(5):540-545
Zeolite synthesized from fly ash (ZFA) without modification is not efficient for the purification of NH4+ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 (≥0.9 mol/L) resulted in a limited maximum phosphate immobilization capacity (PIC). It was concluded that through a previous mild acid treatment (e.g. 0.01 mol/L of H2SO4), ZFA can be used in the simultaneous removal of NH4+ and P at low concentrations simulating real effluent. 相似文献
398.
通过生物测试,研究了加乐麝香和重金属镉在模拟城市径流和清水条件下对大型水蚤(Daphnia magna)的单一、联合毒性效应.结果表明,在单一毒性效应试验中,当暴露时间为24,48h时,加乐麝香和镉在模拟城市径流条件下的EC50值分别为2.455,1.187mg/L以及0.384,0.304mg/L;在清水试验条件下的EC50值分别为0.533,0.189mg/L以及0.359,0.244mg/L.2种污染物在模拟城市径流条件下EC50值均高于清水条件下的EC50值.采用毒性1∶1试验测定2种污染物联合毒性效应,当暴露时间为24,48h时,在清水条件下AI>0,二者联合毒性效应表现为协同效应;在模拟城市径流条件下,AI<0,联合毒性效应为拮抗效应. 相似文献
399.
400.