Characterization of metal adsorption kinetic properties in batch and fixed-bed reactors

Copper adsorption kinetic properties in batch and fixed-bed reactors were studied in this paper. The isothermal adsorption experiments showed that the copper adsorption capacity of a granular activated carbon (Filtrasorb 200) increased when ionic strength was higher. The presence of EDTA diminished the adsorption. An intraparticle diffusion model and a fixed-bed model were successfully used to describe the batch kinetic and fixed-bed operation behaviors. The kinetics became faster when the solution pH was not controlled, implying that the surface precipitation caused some metal uptake. The external mass transfer coefficient, the diffusivity and the dispersion coefficient were obtained from the modeling. It was found that both external mass transfer and dispersion coefficients increased when the flow rate was higher. Finally effects of kinetic parameters on simulation of fixed-bed operation were conducted.     

仲钨酸铵生产中钨渣的污染特性分析

采集了14家仲钨酸铵（APT）生产企业生产过程中产生的钨渣,分别采用HJ/T299—2007《固体废物 浸出毒性浸出方法 硫酸硝酸法》和GB 5085.3—2007《危险废物鉴别标准 浸出毒性鉴别》附录S推荐的方法分析了钨渣中重金属的浓度及浸出浓度,并研究了钨渣的污染特征。结果表明,钨渣中重金属浓度服从正态分布,浓度较高的重金属为Cu、Zn和类金属As,其最大值分别为6 260、25 000和26 900 mg/kg,平均值分别为3 510、4 560和5 640 mg/kg;浸出浓度较大的是Pb、As和Hg,其最大值分别为33.6、26.2和0.85 mg/L,超出GB 5085.3—2007中规定的相应限值的6.72、5.24和8.5倍,超标率分别为14.3%、21.4%和42.9%;钨渣中As、Mo和Hg是特征污染物,应作为危险废物进行管理。     

两相均流板对弯管中气固两相运动分布特征的影响

针对燃煤电厂烟气污染物脱除系统设备入口弯管内的气固两相分布不均的问题,提出一种两相均流板,采用CFD数值模拟的方法对比分析了安装两相均流板与常规导流装置的弯道内气流速度分布、颗粒质量浓度分布以及弯管进出口压差变化特征。结果表明：在弯管内安装两相均流板较安装导流板/三角翼挡板更优,既可以使气固两相均匀分布又可以有效降低系统的压阻,克服了常规均流装置气固两相均流效果不佳、阻力大等缺点,在较低的压阻下解决燃煤电厂烟气污染物脱除系统入口气固两相混合不均匀的问题,有效提高污染物脱除效率。     

The fractionation and geochemical characteristics of rare earth elements measured in ambient size-resolved PM in an integrated iron and steelmaking industry zone

Environmental Science and Pollution Research - Improved understanding of the fractionation and geochemical characteristic of rare earth elements (REEs) from steel plant emissions is important due...     

NiFe2O4/ZnAl-LDH吸附去除水中Cr(VI)

采用共沉淀法合成磁性复合材料NiFe2O4/ZnAl-LDH,通过静态吸附试验考察复合材料去除水中Cr（VI）的性能,系统地研究了溶液初始pH值、吸附剂投加量、吸附时间和温度等因素对Cr（VI）去除效果的影响。结果表明,当溶液初始pH值为2、初始Cr（VI）浓度为50 mg·L-1、吸附剂投加量为4 g·L-1时,吸附过程在240 min内达到平衡,此时Cr（VI）的去除率为89.5%。动力学和吸附等温式的研究表明：NiFe2O4/ZnAl-LDH吸附Cr（VI）的过程符合准二级动力学和Langmuir等温吸附模型。热力学参数表明该吸附过程为自发、放热的反应过程,低温有利于吸附剂对Cr（VI）的吸附。吸附剂经4次再生后对Cr（VI）仍有83.1%的去除率,且其在外加磁场的作用下能快速与水溶液分离,因此NiFe2O4/ZnAl-LDH可作为去除水中Cr（VI）的良好吸附剂。     

Simultaneous determination of estrogenic odorant alkylphenols,chlorophenols, and their derivatives in water using online headspace solid phase microextraction coupled with gas chromatography-mass spectrometry

A simple online headspace solid-phase microextraction (HS-SPME) coupled with the gas chromatography-mass spectrometry (GC-MS) method was developed for simultaneous determination of trace amounts of nine estrogenic odorant alkylphenols and chlorophenols and their derivatives in water samples. The extraction conditions of HS-SPME were optimized including fiber selection, extraction temperature, extraction time, and salt concentration. Results showed that divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was the most appropriate one among the three selected commercial fibers, and the optimal extraction temperature, time, and salt concentration were 70 °C, 30 min, and 0.25 g/mL, respectively. The developed method was validated and showed good linearity (R ²?>?0.989), low limit of detection (LOD, 0.002–0.5 μg/L), and excellent recoveries (76–126 %) with low relative standard deviation (RSD, 0.7–12.9 %). The developed method was finally applied to two surface water samples and some of these target compounds were detected. All these detected compounds were below their odor thresholds, except for 2,4,6-TCAS and 2,4,6-TBAS wherein their concentrations were near their odor thresholds. However, in the two surface water samples, these detected compounds contributed to a certain amount of estrogenicity, which seemed to suggest that more attention should be paid to the issue of estrogenicity rather than to the odor problem.     

热活化过硫酸钾降解呋虫胺

以新烟碱类杀虫剂呋虫胺为目标污染物,以过硫酸钾为氧化剂,研究不同热活化条件下过硫酸钾对呋虫胺降解率的影响。实验结果表明:呋虫胺的降解率与溶液中过硫酸钾的浓度成正比;随着温度的升高,呋虫胺的降解率也逐渐升高;虽然中性时呋虫胺的降解率稍高于酸性和碱性时的降解率,但pH的变化对呋虫胺的降解率影响不大;Cl-和HCO3-对反应的影响比较复杂,当溶液中的Cl-和HCO3-的浓度低于5 mmol/L时,均促进呋虫胺的降解,而浓度升高时则抑制呋虫胺的降解;通过添加自由基捕获剂发现,该反应体系中同时存在·SO4-和·OH,但起主要作用的是·SO4-。     

常温还原铁氧体法处理含铬废水

实验探究了常温还原铁氧体法处理含铬废水的最优工艺条件,研究了不同亚铁盐及氨氮和COD对处理效果的影响,对沉淀进行了化学分析与材料表征。实验表明,在n(Fe2+):n(Cr6+)=6,共沉淀pH=10.0,还原时间为2 min,共沉淀时间为15 min条件下,处理含铬废水可达最好效果,总铬浓度从1 600 mg/L降至1.5 mg/L以下,符合国家《污水综合排放标准》(GB 8978-1996)的要求,实现了常温条件下铁氧体法对含铬废水的处理。对于不同亚铁盐,氯化亚铁处理废水的性能要强于硫酸亚铁,沉降速率快且沉淀致密。一般浓度的氨氮(50 mg/L)与COD(500 mg/L)对处理效果没有明显影响。对沉淀进行酸稳定性分析和XRD表征,确定生成了稳定的含铬复合铁氧体。     

聚醚砜小球负载Comamonas sp.(bdq06)生物降解水中的喹啉

以聚醚砜为原料制备了一种具有多孔道的小球载体,负载睾丸酮丛毛单孢菌(bdq06)降解水中喹啉。制备的小球直径约3 mm,表面光滑,存在厚度约20μm的致密层。经过浸蚀去掉致密层后,露出粗糙表面,有助于细菌粘附和生殖。同时出现大量直径约1.5μm的孔道,且由外向内,孔径逐渐增大,细菌可以通过表层孔进入球内生殖。在pH为5、10和温度为40℃的条件下,负载菌的小球对水中喹啉的降解效果优于游离菌。小球具有良好的溶胀性和机械强度,经过多次重复使用后,球形完整而未破裂,细菌在球表面大量生殖形成生物膜,显著提高降解效率,能够在1 h内完全降解100 mg/L喹啉。以聚醚砜为原料制备的小球在废水处理中具有潜在应用前景。