突变灰盖鬼伞过氧化物酶降解刚果红的响应面法优化分析简

酶法降解偶氮染料刚果红是一个复杂的过程,受温度、pH、酶量、刚果红浓度和双氧水浓度显著影响。为研究各因素及因素间交互作用对刚果红降解影响,提高刚果红的降解率,分别使用单因素法和响应面分析法对刚果红降解条件进行了优化。单因素实验结果显示灰盖鬼伞过氧化物酶降解刚果红的最适条件为：pH 5.0、32℃、酶量4.98 U、双氧水0.1 mmol/L、刚果红20 mg/L,此时刚果红最高降解率为34.84%。然后选双氧水浓度、刚果红浓度和灰盖鬼伞过氧化物酶量作为3个因素,通过中心组合设计实验,用响应面法对刚果红降解进行优化分析,最后得到一个拟合度良好的二次多项方程模型（R²=0.9900）。方差分析结果显示,刚果红浓度和酶量是影响最显著的因素,双氧水与酶以及染料与酶之间的交互作用极显著。响应面分析优化后的反应体系为：双氧水浓度0.15 mmol/L,刚果红浓度为27.21 mg/L,酶为2.0 7 U,在此条件下,刚果红降解率达58.13%。     

基于智能优化算法的河流水质模型参数的优化简

为探索河流水质模型参数新的求解方法,根据有限的实测数据,分别应用免疫进化优化算法和免疫进化优选的捕食搜索算法,对河流水质模型计算公式中的多参数进行优化。将优化得到的计算公式用于国内外若干河流的河段中DO浓度值的拟合,并与实测结果进行了比较。结果表明,将免疫进化优化算法或免疫进化优选的捕食搜索算法优化得到的水质模型参数精度不仅较高,而且相对稳定,从而为河流水质模型参数的优化提供了一种新方法。     

MCM-41介孔分子筛的合成及其对铜离子的吸附性能简

以微硅粉为硅源,CTAB和PEG-6000为模板剂,合成MCM-41介孔分子筛。采用XRD、N₂吸附-脱附曲线、FTIR以及TEM表征了其结构、比表面积、孔径分布及晶体形貌,并且以该样品为吸附剂,对含Cu²⁺的溶液进行了静态吸附实验。结果表明,以微硅粉为硅源成功合成了具有典型六方排列孔道结构的MCM-41,其比表面积为869.5 m²/g,孔容为0.97 cm³/g,平均孔径为3.3 nm;溶液pH为5~6时,MCM-41对Cu²⁺的去除效果最好;MCM-41对Cu²⁺的最大吸附吸附容量36.3 mg/g;MCM-41对Cu²⁺的吸附性能符合Langmuir吸附方程的特征。动力学研究表明,该过程符合准二级动力学模型。     

3种生物质炭对活性艳蓝KN-R的吸附简

选择由玉米秸秆、稻壳和稻草秸秆在825℃制成的生物质炭作为吸附剂,通过模拟实验,研究其对溶液中活性艳蓝KN-R的吸附特性,考察了pH值、时间、溶液初始浓度和生物质炭用量对吸附效果的影响。结果表明,当pH为2.0时,玉米秸秆炭和稻壳炭对活性艳蓝的吸附量均达到最大,而pH对稻草秸秆炭的影响不大;三者达到吸附平衡的时间分别为180、300和360 min,最大吸附量分别为114.05、54.60和68.19 mg/g。等温吸附过程可以用Langmuir方程来描述;动力学实验表明,吸附过程更符合拟二级动力学模型;热力学数据分析发现,吸附过程是自发进行的吸热过程。     

水生植物酸碱预处理对厌氧发酵联产氢气-甲烷的影响简

采用酸碱预处理乌梁素海典型沉水植物龙须眼子菜和挺水植物芦苇,通过厌氧发酵动力学分析、还原糖变化及微观结构解析,研究酸碱预处理对水生植物厌氧发酵联产氢气-甲烷的影响。实验结果表明,酸碱预处理后水生植物厌氧发酵联产氢气-甲烷两阶段累积产气量、氢气及甲烷含量均显著提高,酸处理效果优于碱处理。采用0.5 mol/L HCl预处理龙须眼子菜效果最佳,最大氢气、甲烷含量分别达42.65%和52.82%,产氢气速率为4.118 mL/h,产甲烷速率最高达14.199 mL/h。芦苇经1 mol/L HCl预处理效果最佳,最高氢气、甲烷含量分别为32.22%和65.26%。扫描电镜微观结构分析表明,酸碱预处理可显著破坏芦苇、龙须眼子菜的纤维素结构,有效增加植物与微生物接触面积,有利于厌氧发酵联产氢气-甲烷工艺的快速启动和稳定运行。     

氯化镁复配硫酸铝混凝性能及絮体特性

在研究氢氧化镁混凝特性的基础上,复配氯化镁和硫酸铝作为混凝剂,以高岭土配水水样为研究对象,运用iPDA在线监测技术对混凝过程絮体形成进行监测,探讨了单独使用氯化镁和硫酸铝以及二者复配使用的混凝效果和絮体特性,确定复配使用的各种条件。结果表明,对于浊度20 NTU,pH 11.5的高岭土配水水样,氯化镁、硫酸铝最佳投加量分别为7.2 mg/L(Mg2+计)和3 mg/L(Al3+计);硫酸铝跟氯化镁复配使用时,先投加硫酸铝,间隔30 s后投加氯化镁,混凝效果较好;在镁离子最佳投加量7.2 mg/L时,铝和镁最佳质量比在1∶3~1∶2之间;镁铝复配时其FI值明显大于单独作用时,即絮体尺寸大小:二者复配硫酸铝氯化镁,而且复配条件下Zeta电位值在零电势左右浮动,浮动范围小,更利于聚集沉淀;镁铝复配时发生了协同效应,弥补了单独使用氯化镁混凝过程的不足。     

干式厌氧消化过程挥发酸对硫酸盐还原菌的影响

在牛粪干式厌氧消化过程中,通过添加不同挥发酸(乙酸、丙酸、丁酸),考察消化稳定阶段,挥发性脂肪酸的分布特征,挥发性脂肪酸酸组成变化对硫酸盐还原菌(SRB)的影响,微生物种群组成和种群间关系。实验结果表明,挥发性脂肪酸对SRB还原速率的贡献依次为:丙酸丁酸乙酸。相比乙酸和丁酸,添加一定量的丙酸,更有利于激活SRB的活性,从而加强SRB与产甲烷菌(MB)的种间协同,保证厌氧系统的稳定运行。     

Effect of temperature and particle size on the thermal desorption of PCBs from contaminated soil

Thermal desorption is widely used for remediation of soil contaminated with volatiles, such as solvents and distillates. In this study, a soil contaminated with semivolatile polychlorinated biphenyls (PCBs) was sampled at an interim storage point for waste PCB transformers and heated to temperatures from 300 to 600 °C in a flow of nitrogen to investigate the effect of temperature and particle size on thermal desorption. Two size fractions were tested: coarse soil of 420–841 μm and fine soil with particles <250 μm. A PCB removal efficiency of 98.0 % was attained after 1 h of thermal treatment at 600 °C. The residual amount of PCBs in this soil decreased with rising thermal treatment temperature while the amount transferred to the gas phase increased up to 550 °C; at 600 °C, destruction of PCBs became more obvious. At low temperature, the thermally treated soil still had a similar PCB homologue distribution as raw soil, indicating thermal desorption as a main mechanism in removal. Dechlorination and decomposition increasingly occurred at high temperature, since shifts in average chlorination level were observed, from 3.34 in the raw soil to 2.75 in soil treated at 600 °C. Fine soil particles showed higher removal efficiency and destruction efficiency than coarse particles, suggesting that desorption from coarse particles is influenced by mass transfer.     

Probing the distribution and contamination levels of 10 trace metal/metalloids in soils near a Pb/Zn smelter in Middle China

The horizontal and vertical distribution patterns and contamination status of ten trace metal/metalloids (Ag, Bi, Co, Cr, Ge, In, Ni, Sb, Sn, Tl) in soils around one of the largest Chinese Pb–Zn smelter in Zhuzhou City, Central China, were revealed. Different soil samples were collected from 11 areas, including ten agricultural areas and one city park area, with a total of 83 surface soil samples and six soil cores obtained. Trace metal/metalloids were determined by inductively coupled plasma–mass spectrometry after digestion by an acid mixture of HF and HNO₃. The results showed that Ag, Bi, In, Sb, Sn, and Tl contents decreased both with the distance to the Pb–Zn smelter as well as the soil depth, hinting that these elements were mainly originated from the Pb–Zn smelting operations and were introduced into soils through atmospheric deposition. Soil Ge was influenced by the smelter at a less extent, while the distributions of Co, Cr, and Ni were roughly even among most sampling sites and soil depths, suggesting that they were primarily derived from natural sources. The contamination status, as revealed by the geo-accumulation index (I _geo), indicated that In and Ag were the most enriched elements, followed by Sb, Bi, and Sn. In general, Cr, Tl, Co, Ni, and Ge were of an uncontaminated status.     

As(V)在金红石TiO_2颗粒表面吸附特性及机理

通过静态动力学和热力学吸附实验,研究了温度、共存离子以及溶质的初始浓度对As(V)在金红石TiO2颗粒表面吸附的影响,探讨了As(V)在金红石TiO2颗粒表面吸附特性及机理。结果表明,在As(V)初始浓度为10 mg/L,pH为7的条件下,25℃时的吸附量0.41 mg/g高于30℃时的吸附量0.31 mg/g,As(V)在金红石TiO2上的吸附为放热过程。CaCl2和MgCl2的添加对As(V)在金红石TiO2表面吸附起到明显的促进作用。T=25℃,Ca2+或Mg2+浓度为10 mmol/L时,As(V)吸附量分别为0.64和0.56 mg/g,Ca2+比Mg2+对As(V)吸附促进作用强。As(V)在金红石TiO2的吸附等温线符合Frendlich方程,Lagergren二级动力学方程能较好地描述As(V)在金红石TiO2颗粒表面吸附的动力学过程。