Removal of sulfadiazine from aqueous solution on kaolinite

The adsorption of sulfadiazine onto kaolinite clay as an alternative adsorbent was examined in aqueous solution, hnpacts of the contact time, pH, temperature, ionic strength and coexistent surfactants on the adsorption process were evaluated. The pH significantly influenced the adsorption process, with adsorption being promoted at lower pH due to the cation exchange mechanism. Decreasing ionic strength in the solution was favorable for adsorption, and the addition of cationic and anionic surfactants had negative effects on the adsorption capacity of sulfadiazine on kaolinite. Kinetic experiments showed that the adsorption followed the pseudo-second-order model. The equilibrium adsorption was well described by both Freundlich and Dubinin-Radushkevich （DR） models. According to the DR model, the adsorption mechanism was determined by cationic exchange and weak physical forces. The thermodynamic study showed that sulfadiazine adsorption onto kaolinite was a sponta- neous and endothermic reaction.     

液氨泄漏事故的处置要点有哪些？

液氨,因其价廉的特点在制冰和冷藏行业得到广泛使用。液氨,是一种有刺激臭味的无色有毒气体,极易溶于水,水溶液呈碱性,易液化,一般液氨可作致冷剂,接触液氨可引起严重冻伤。氨气爆炸极限为15．7～27．4％。因此、氨气与空气或氧气混和会形成爆炸性混合物,储存容器受热时也极有可能发生爆炸。氨气能侵袭湿皮肤、粘膜和眼睛,可引起严重咳嗽、支气管痉挛、急性肺水肿,甚至会造成失明和窒息死亡。     

氯气职业病危害及防护对策

氯气（Cl2）在氯碱生产工艺中,由直流电电解饱和食盐水溶液所制取,是重要的化工原料。它用途极广,主要有杀菌消毒、纸浆纤维漂白、矿物氯化法精炼等,用于无机合成方面,如漂白剂（漂白粉、漂白精及次氯酸钠）、三氯化铝、氯化磷、农药、三氯化铁、照相氯化银、氯化钾、合成盐酸、     

杂质对硝酸铵水溶液临界爆炸温度的影响

利用自制装置对含杂质的硝酸铵水溶液临界爆炸温度进行测试研究.结果表明,Cl-单独作用在一定程度上抑制硝酸铵溶液的热分解,提高了其临界爆炸温度;pH值一定时,随着Cl-浓度的增大,硝酸铵水溶液的临界爆炸温度呈指数形式降低;Cl-浓度一定时,pH值越小,硝酸铵水溶液的临界爆炸温度越低;油脂会降低硝酸铵溶液的热稳定性.该结果...     

两种生物炭的制备及其对水溶液中四环素去除的影响因素

以中药材三桠苦药渣和玉米秸秆为原料,分别在400、600和800℃下热解制备生物炭,并研究其对水溶液中四环素的去除及其影响因素.利用元素分析、傅里叶红外光谱(FT-IR)、比表面积分析(BET)、X射线衍射(XRD)、扫描电子显微镜(SEM)等方法对制备的生物炭进行表征;并探究热解温度、生物炭添加量、初始溶液浓度、吸附时间、溶液pH、离子强度、环境温度等因素对生物炭去除水溶液中四环素的影响;通过吸附动力学和等温吸附平衡探究两种原料制备的生物炭对溶液中四环素的吸附行为.结果表明,生物炭对四环素的吸附性能随制备温度的升高而增加,800℃制备的三桠苦药渣生物炭(EIBC800)具有最佳吸附性能.生物炭添加量、溶液pH、离子强度、吸附时间对800℃制备的三桠苦药渣生物炭(EIBC800)和玉米秸秆生物炭(CSBC800)吸附水溶液中四环素影响较大,吸附时环境温度对吸附的影响大小依赖于抗生素质量浓度.EIBC800和CSBC800对四环素的吸附行为均符合准二级动力学方程(R~2分别为0. 954 0和0. 835 5),等温吸附符合Freundlich方程(R~2分别在0. 899 1～0. 957 9和0. 973 6～0. 994 6之间),主要吸附过程为化学吸附,且吸附过程均是自发吸热的过程.通过以两种原料所制备的生物炭吸附性能对比,EIBC800吸附抗生素的能力比CSBC800更强,说明中药渣在制备生物炭去除水环境中的抗生素具有较好的应用前景.     

Comment on "Removal of heavy metals from aqueous solution by carbon nanotubes: adsorption equilibrium and kinetics" by Li, Y. H., Di, Z.C., Luan, Z.K., Ding, J., Zuo, H., Wu, X.Q., Xu, C.L. and Wu, D.H.

Recently, Li et al. (Li, 2004 ) published the paper entitled as above. In section 2.2: Adsorption kinetics,authors mentioned three kinetic models, the first-order rate equation, pseudo-second-order rate equation, and secondorder rate equation citing a secondary reference (Benguella,2002). However, there are mistakes occurred in this reference(Ho,2004a).     

Effect of electron beam irradiation on the degradation of monochlorophenols in aqueous solution

Electron beam was successfully used for the degradation of 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP) in aqueous solutions in this research. The effect of radiation dose on substrate degradation and dechlorination of solutions with concentration of 50mg/L was investigated. The effect of initial concentration, pH and presence of oxygen was also investigated. The concentration of 2-CP and 4-CP remaining in solution after irradiation were measured by HPLC. The results showed that increased radiation dose led to increased degradation of the chlorophenols and increased CI^- yield. Deaeration was also found to significantly increase the rate of degradation of chlorphenols in water while degradation and dechlodnation under alkaline condition was lower than at low to neutral pH.     

Photocatalytic degradation of dye effluent by titanium dioxide pillar pellets in aqueous solution

Photocatalytic oxidation (PCO) process is an effective way to deal with organic pollutants in wastewater which could be difficult to be degraded by conventional biological treatment methods. Normally the TiO2 powder in nanometre size range was directly used as photocatalyst for dye degradation in wastewater. However the titanium dioxide powder was arduous to be recovered from the solution after treatment. In this application, a new form of TiO2(i. e. pillar pellets ranging from 2.5 to 5.3 mm long and with a diameter of 3.7 mm) was used and investigated for photocatalytic degradation of textile dye effluent. A test system was built with a flat plate reactor(FPR) and UV light source(blacklight and solar simulator as light source respectively) for investigating the effectiveness of the new form of TiO2. It was found that the photocatalytic process under this configuration could efficiently remove colours from textile dyeing effluent. Comparing with the TiO2 powder, the pellet was very easy to recovered from the treated solution and can be reused in multiple times without the significant change on the photocatalytic property. The results also showed that to achieve the same photocatalytic performance, the FPR area by pellets was about 91% smaller than required by TiO2 powder. At least TiO2 pellet could be used as an alternative form of photocatalyst in applications for textile effluent treatment process, also other wastewater treatment processes.     

Comparison of quartz sand, anthracite, shale and biological ceramsite for adsorptive removal of phosphorus from aqueous solution

The choice of substrates with high phosphorus adsorption capacity is vital for sustainable phosphorus removal from waste water in constructed wetlands. In this study, four substrates were used： quartz sand, anthracite, shale and biological ceramsite. These substrate samples were characterized by X- ray diffractometry and scanning electron microscopy studies for their mineral components （chemical components） and surface characteristics. The dynamic experimental results revealed the following ranking order for total phosphorus （TP） removal efficiency： anthracite 〉 biological ceramsite 〉 shale 〉 quartz sand. The adsorptive removal capacities for TP using anthracite, biological ceramsite, shale and quartz sand were 85.87, 81.44, 59.65, and 55.98 mg/kg, respectively. Phosphorus desorption was also studied to analyze the substrates＇ adsorption efficiency in wastewater treatment as well as the substrates＇ ability to be reused for treatment. It was noted that the removal performance for the different forms of phosphorus was dependent on the nature of the substrate and the adsorption mechanism. A comparative analysis showed that the removal of particulate phosphorus was much easier using shale. Whereas anthracite had the highest soluble reactive phosphorus （SRP） adsorptive capacity, biological ceramsite had the highest dissolved organic phosphorus （DOP） removal capacity. Phosphorus removal by shale and biological ceramsite was mainly through chemical adsorption, precipitation or biological adsorption. On the other hand, phosphorus removal through physical adsorption （electrostatic attraction or ion exchange） was dominant in anthracite and quartz sand.