HNO_3改性活性炭对染料橙黄G的吸附研究

利用HNO_3改性后的活性炭为吸附材料,对染料橙黄G废水进行吸附处理。研究了活性炭投加量、反应时间和盐浓度对活性炭吸附橙黄G的影响,并研究了该吸附过程的吸附等温线和吸附动力学。结果显示:0~10 min是染料的快速吸附阶段,当活性炭投加量达到2.5 g/L时,40 min时橙黄G的去除率达到95.5%;高浓度盐类存在对吸附影响不明显。吸附过程符合Langmuir吸附等温方程,吸附数据可用伪二级吸附动力学方程拟合。     

Synthesis,crystal structure,photodegradation kinetics and photocatalytic activity of novel photocatalyst ZnBiYO4

ZnBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO4 were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–Vis diffuse reflectance.ZnBiYO4 crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO4 were a = b = 11.176479  and c = 10.014323 . The band gap of ZnBiYO4 was estimated to be 1.58 e V. The photocatalytic activity of ZnBiYO4 was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiYO4 had higher catalytic activity compared with N-doped Ti O2 under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO4 or N-doped Ti O2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 min-1for ZnBiYO4 and N-doped Ti O2, respectively. After visible light irradiation for 220 min with ZnBiYO4 as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO2-4and NO-3, and evolution of CO2 revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatography–mass spectrometry. The ZnBiYO4/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems.     

Novel extractive colorimetric and UV spectrophotometric estimation of etizolam in bulk and tablet by forming ion association complex with methyl orange and bromocresol green

A novel, sensitive, and rapid UV spectrophotometric and colorimetric method was developed for estimation of etizolam (ETZ) in bulk and tablet. The UV spectrophotometric method (method I) is based on quantitative estimation of ETZ using 0.1N NaOH as the solvent which exhibits maximal absorption at 378 nm. Colorimetric methods (method II and III) were based on the formation of color complex in association with ions between basic nitrogen of the drug with methyl orange (MO) and bromocresol green (BCG) in acidic medium. The formed color complexes were quantitatively extracted with chloroform and measured at 509 nm for Drug–MO complex and at 442 nm for Drug–BCG complex, respectively. Beer's law was obeyed over the linear ranges 2–16 µg/ml (method I), 5–45 µg/ml (method II), and 2–20 µg/ml (method III). The correlation coefficient (r²) for ETZ was 0.999, 0.997, and 0.998 for method I, II, and III, respectively. All methods were successfully applied for the assay of the drug in tablet. The % purity was found to be 98.52 (method I), 98.72 (method II), and 99.18 (method III). These developed methods were fully validated with % relative standard deviation (RSD) for accuracy less than 2 for all methods. The % RSD of the intra-day and inter-day variations was found to be less than 2%. The limit of detection and quantitation were as follows: 0.108 µg/ml and 0.327 µg/ml (method I), 0.24 µg/ml and 0.75 µg/ml (method II), 0.1 µg/ml and 0.5 µg/ml (method III) indicating marked method sensitivity. Empirical evidence from all three methods concludes that developed methods are simple, sensitive, and reliably validated for useful routine quality control analysis of ETZ.     

多壁碳纳米管结构对复合光催化剂催化效果的影响

采用溶胶凝胶法制备了多壁碳纳米管负载纳米TiO₂的复合光催化剂（TiO₂/MWCNTs）,以偶氮类染料甲基橙为目标污染物,在自制的光催化反应器上进行了光催化降解反应实验。主要研究同一甲基橙初始浓度（C₀)下,多壁碳纳米管不同管长和管径对复合光催化剂催化效果的影响。结果表明：该降解反应可用一级反应动力学方程描述,反应速率常数k随着多壁碳纳米管管长和管径的增大而增大;与纯纳米TiO₂相比,复合光催化剂对甲基橙的降解率提高了6％～18％,反应速率常数为前者的1.19～2.11倍;采用复合光催化剂的甲基橙光降解溶液自行沉降分离效果较好,静止沉降60 min后达到沉降平衡,剩余浊度为8.5 NTU,下降了90.6％。     

Evaluation of mutagenicity associated with Escherichia coli inactivation in UV-treated orange juice

UV radiation is an alternative technology for the elimination of pathogenic micro-organisms in liquid food. The objectives of this work were to investigate mutagenesis using the Ames test in : (1) fresh squeezed orange juice submitted to UV radiation doses required to achieve 5 and 10 log₁₀ reductions of different strains of Escherichia coli serotype O157:H7 at two temperatures, and (2) commercial pasteurized orange juice submitted to thermal treatment.

Two histidine-auxotrophic strains, Salmonella Typhimurium TA98 and TA97a, were used in the Ames test with and without metabolic activation.

In commercial pasteurized orange juices, mutagenesis was not observed with S. Typhimurium TA98 strain with and without metabolic activation, but high mutagenic effect was observed using TA97a with metabolic activation.

UV radiation did not affect the stability of ascorbic acid in aqueous solution. However, degradation of ascorbic acid was observed when UV treatment was performed on squeezed orange juice, following first order kinetics.

UV treatment required to achieve 5 log₁₀ reductions (1.5 J/cm²) did not show a mutagenic effect with and without metabolic activation using the tested strains, but a higher UV radiation dose necessary to produce 10 log₁₀ reductions (3.0 J/cm²) showed mutagenicity with metabolic activation.     

树脂纳米零价铁催化过硫酸钠降解甲基橙的研究

采用树脂负载零价纳米铁（NZVI-resin）作为铁源,活化过硫酸钠,产生硫酸根自由基氧化降解偶氮染料甲基橙。考察了温度、NZVI-resin加入量、pH值及过硫酸钠的浓度等因素对甲基橙降解率的影响,并对其降解动力学规律作了初步探讨。结果表明：降解反应遵循准一级反应动力学,在pH=3.0、Fe0=0.2 g.L-1、Na2S2O8=1.33 g.L-1的条件下,30 mg.L-1的甲基橙溶液降解率为99.7%。     

皂化改性橘子皮生物吸附剂对重金属离子的吸附

以生物废料橘子皮(OP)为原料,经乙醇、氢氧化钠处理,得到改性橘子皮生物吸附剂SOP,将其用于对重金属离子Cu2+、Pb2+、Cd2+、Zn2+和Ni2+的吸附。研究了溶液pH、吸附时间和重金属离子初始浓度对SOP吸附性能的影响。结果表明,重金属离子在生物吸附剂上的吸附速率快,符合准二级动力学方程。SOP对重金属离子的吸附等温线符合Lang-muir模型,根据Langmuir模型计算SOP对Cu2+、Pb2+、Cd2+、Zn2+和Ni2+的饱和吸附量分别为56.82、152.4、66.27、33.90和23.02 mg/g,均高于改性前。常见阳离子的存在对重金属离子吸附的影响较小,改性后的橘子皮生物吸附剂可以再生重复使用4次以上,是性能良好的重金属离子吸附剂。     

核桃果皮基活性炭对甲基橙和酸性品红的吸附性能

采用氯化锌活化法制得核桃果皮基活性炭吸附甲基橙和酸性品红,考察了吸附时间,p H,吸附质初始浓度对吸附性能的影响及吸附热力学和动力学性质。结果表明,核桃果皮基活性炭是吸附甲基橙和酸性品红染料的理想材料;延长吸附时间,去除率和吸附量增加,最佳吸附时间为6 h;减小p H值,去除率和吸附量增加。p H为6时,2种染料的去除率达95%以上,吸附效果较好;增大吸附质初始浓度,去除率降低,吸附量增大,当甲基橙初始浓度为180 mg/L时,吸附基本达到饱和;甲基橙的吸附属于单层吸附,酸性品红的吸附属于多层吸附行为。准二级动力学方程均能较好地解释2种染料的吸附动力学行为。     

磁性活性炭的制备及其对水中甲基橙的吸附

活性炭被广泛应用于水处理领域,然而吸附饱和后难以分离和再生的缺点却限制了其应用。本研究采用化学共沉淀法将铁氧化物和活性炭进行复合,制备出同时具有磁分离性能和较强的吸附性能的磁性活性炭复合材料,并对制备的复合材料进行表征,考察其对水中甲基橙的吸附性能。结果表明,制备的磁性活性炭的比表面积为666.72 m2/g,平均孔径为3.16 nm,具有良好的磁性能,在外加磁场下能快速地从溶液中分离出来且磁性能相对稳定,铁氧化物对活性炭吸附性能的影响不大。在温度为25℃、p H为5、吸附剂用量为3 g/L的情况下,吸附3 h后,该磁性活性炭对甲基橙的吸附率可达99.1%,预示着该磁性活性炭在水处理方面具有潜在的应用前景。     

Mn-N/TiO_2光催化剂的制备及甲基橙的降解

采用溶胶-凝胶法制备了新型Mn-N共掺杂纳米TiO_2复合光催化剂(Mn-N/TiO_2),采用EDX,SEM,UV-Vis,XRD技术对其进行了表征,并将其用于水中甲基橙的可见光催化降解,考察了制备条件对其光催化性能的影响。表征结果显示:Mn-N/TiO_2光催化剂的粒径约为25 nm,且分散性较好;Mn-N共掺杂可增强TiO_2在可见光区域的吸收。实验结果表明:Mn-N/TiO_2的最佳制备条件为硝酸锰、尿素、无水乙醇、冰醋酸与钛酸四丁酯的摩尔比分别为0.000 6,0.24,10,6,焙烧温度400℃;采用最佳条件下制得的Mn-N/TiO_2于可见光下催化处理初始质量浓度为60 mg/L的甲基橙溶液60 min,甲基橙的降解率达92%。