以海泡石为载体的双金属多相类芬顿催化剂的制备及表征

以活性艳蓝为目标污染物,以改性海泡石为载体,以Fe(NO3)3浓度、MnSO4浓度、尿素浓度、水浴温度、煅烧温度与煅烧时间为影响因素,优化了均匀沉淀法制备双金属多相类芬顿催化剂的工艺条件,并利用SEM、XRD、FTIR对催化剂进行了表征.结果表明,随铁离子浓度的增大,所制得催化剂金属离子活性越高.少量的锰掺杂可抑制Fe2O3粒径的增长,提高催化剂的活性.尿素浓度增大,使得晶粒的生成速率愈快,有利于生成细小、均匀的金属颗粒.利用Box-Behnken实验得出催化剂制备的最佳工艺条件为:硝酸铁浓度为0.18 mol.L-1,硫酸锰浓度为0.05 mol.L-1,尿素的浓度为1.0 mol.L-1,海泡石的投加量为40 g.L-1,水浴温度为100℃,煅烧温度为370℃,煅烧时间为3 h.SEM表明本实验所采用的海泡石为α型海泡石,可作为良好的催化剂载体;在催化剂制得后,FTIR图谱显示海泡石的纯度得到提高,并出现了Fe-O的吸收峰.XRD图谱表明,在催化剂表面铁离子主要以α-Fe2O3和γ-Fe2O3的形式存在.     

Decolorization and kinetics of photo oxidizing cationic blue X-GRL by UV/H2O2 system

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CuO/AOCF类Fenton催化剂的制备及光催化性能

以偕胺肟纤维(AOCF)为载体,采用配位-沉淀法研制了一种新型的类Fenton催化剂CuO/AOCF.用SEM、EDS和XRD对CuO/AOCF的表面形貌、晶体结构和表面成分进行分析,结果显示:CuO纳米颗粒均匀分布在AOCF表面.以活性红染料为目标降解物及其去除率为评价指标,考察CuO/AOCF与H_2O_2组成类Fenton催化剂的光催化性能.结果表明:在氙灯光照作用下,0.6 g·L~(-1)CuO/AOCF、2 m L·L~(-1)H_2O_2、反应时间为80 min,活性红溶液几乎完全被降解.对比同质量粉体CuO,CuO/AOCF对光催化性能有着更好的促进作用.CuO/AOCF重复使用5次后降解率仍能大于80%.动力学研究表明,该类Fenton催化降解反应遵循一级反应动力学规律.     

介质阻挡放电等离子体对亚甲基蓝的降解

研究了介质阻挡放电等离子体降解亚甲基蓝溶液过程。考察了放电电压、亚甲基蓝溶液初始浓度、初始pH值对降解率的影响和降解过程中亚甲基蓝溶液pH值的变化。结果表明:100mg/L的亚甲基蓝溶液在放电频率为10.5kHz,电压为22kV,pH值为5.68的实验条件下,降解40min后,亚甲基蓝降解率为99.8%。对降解产物进行气质联用分析,亚甲基蓝降解产物中存在甲苯、乙烷基环戊烷、苯并噻唑等物质。     

花状软锰矿的超声合成及其对亚甲基蓝的脱色性能

首次通过操作简便成本低廉的超声方法合成花状软锰矿(MWs).采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)以及能量散布分析仪(EDS)等测试手段对其结构和形貌进行表征.研究了MWs对偶氮染料亚甲基蓝(MB)的脱色性能,考察pH值、反应时间、MWs投加量以及MB初始浓度等影响因子对脱色效果影响.结果表明,MWs对MB具有优良的脱色性能,90min达到近100%的脱色率,无需使用H2O2或者UV灯和超声等其它辅助设备,这明显优于其他催化剂,如Mn3O4/H2O2需3h达到99.7%最大脱色率、ZnS/CdS在光照下需6h最大脱色率仅为73%、硫改性的TiO2光照下需4h才能达到近100%的脱色率.     

A National Assessment of the Potential Linkage between Soil,and Surface and Groundwater Concentrations of Phosphorus

A meta‐analysis of three national databases determined the potential linkage between soil and surface and groundwater enrichment with phosphorus (P). Soil P was enriched especially under dairying commensurate with an increase in cow numbers and the tonnage of P‐fertilizers sold. Median P concentrations were enriched in surface waters receiving runoff from industrial and dairy land uses, and in groundwater beneath dairying especially in those aquifers with gravel or sand lithology, irrespective of groundwater redox status. After geographically pairing surface and groundwater sites to maximize the chance of connectivity, a subset of sites dominated by aquifers with gravel and sand lithology showed increasing P concentrations with as little as 10 years data. These data raise the possibility that groundwater could contribute much P to surface water if: there is good connectivity between surface and groundwater, intensive land use occurs on soils prone to leaching, and leached‐P is not attenuated through aquifers. While strategies are available to mitigate P loss from intensive farming systems in the short‐term, factors such as enriched soils and slow groundwater may mean that despite their use, there will be a long‐term input (viz. legacy), that may sustain surface water P enrichment. To avoid poor surface water quality, management and planning may need to consider the connectivity and characteristics of P in soil‐groundwater‐surface water systems.     

Steam activation,characterisation and adsorption studies of activated carbon from maize tassels

In this paper, steam-produced activated carbon (STAC) from maize tassel (MT) was evaluated for its ability to remove basic dye (methylene blue MB) from aqueous solution in a batch adsorption process. The equilibrium experiments were conducted in the range of 50–300 mg/L initial MB concentrations at 30°C, for effect of pH, adsorbent dosage and contact time. The experimental data were analysed by Langmuir, Freundlich and Temkin isotherm models of adsorption. Freundlich adsorption isotherm was found to have highest value of R²(R²=0.97) compared to other models of Langmuir and Temkin having (0.96 and 0.95 respectively). STAC has a high adsorptive capacity for MB dye (200 mg/g) and also showed favourable adsorption for the dye with the separation factor (R_L<1) for the dye-activated carbon system. The kinetic data obtained were analysed using pseudo first-order kinetic equation and pseudo second-order kinetic equation. The experimental data fitted well into pseudo second-order kinetic equation, as demonstrated by the high value of R².     

铁阳极电凝聚处理活性黑KN-B染料废水动力学分析

采用铁为阳极的原位电凝聚方法处理活性黑KN-B染料废水。以活性黑KN-B在特征吸收波长600nm和255nm的吸光度变化为分析指标,考察了电流密度、染料溶液初始pH值、电介质浓度及种类、温度、染料浓度等影响因素对染料废水脱色过程及脱色速率常数的影响。同时根据化学反应动力学理论对其脱色的动力学过程及脱色机理进行了初步探讨与分析。实验结果表明:染料溶液的脱色反应符合一级反应动力学过程;电流密度、染料浓度、染料溶液初始pH值及电解质的种类及浓度对一级反应速率常数影响显著,而染料溶液温度对一级反应速率常数的影响较小;染料废水的脱色过程是电凝聚和染料还原共同作用的过程。     

不同来源溶解性有机质在光辐射下产生活性氧基团能力的差异

溶解性有机质(DOM)在光辐射下可以吸收光能产生活性氧物质(Reactive oxygen species, ROS),如单线态氧(~1O_2),羟基自由基(HO·)及激发三线态DOM(~3DOM~*)等,这些ROS对污染物的光化学反应起着重要的作用.本实验在254 nm紫外光辐射下,利用特征ROS探针化合物,探究4种不同来源土壤DOM光致产生ROS能力的差异.通过XAD-8树脂分组将2种不同来源DOM分成5个组分,进一步探究DOM结构对ROS生成的影响.研究发现,来源于黄褐土、潮土的DOM分别产生~1O_2、HO·的能力较强,而来源于黄褐土的富里酸及潮土的胡敏酸产生~3DOM~*的能力较强,说明不同来源DOM在光辐射下产生ROS的能力不同.紫外光谱分析表明,分子量较大、腐殖化程度较高的腐殖酸产生ROS的能力较强,且富里酸与胡敏酸对ROS生成的影响存在差异.整体来看,2种腐殖酸的不同分组组分对ROS生成的影响趋势相似,水与乙醇组分所产生的影响非常小,低pH值组分对ROS生成的影响比高pH值大.结合红外光谱分析,研究发现,低pH值组分的腐殖酸羧基含量较高,脂肪族官能团含量低,含氧量高,可能具有较高的光化学活性,有利于ROS的生成.此外,2种腐殖酸不同组分对ROS生成的影响存在差异,说明DOM结构中官能团的可解离程度对ROS生成具有一定影响.     

微量元素对白腐真菌的生长影响和抑制酵母菌效果的研究

采用振荡培养方式研究了微量元素对白腐真菌生长以及在非灭菌环境下对液体培养基抑制酵母菌的影响,结果表明,在灭菌环境培养方式下投加含有铁元素的微量元素液体培养基培养的菌丝球大小和数量均优于不含铁但含有其它微量元素液体培养基,而不含铁的液体培养基又优于不投加任何微量元素液体培养基;如果采用灭菌环境培养后在非灭菌环境降解染料方式,则不含微量元素和含其它微量元素但不含铁的液体培养基培养的白腐真菌在非灭菌环境对染料的脱色效果与灭菌环境得到的结果基本相当,而铁浓度为3.5 mg/L液体培养基培养的白腐真菌的脱色效果不如灭菌环境得到的结果,并且镜检发现铁浓度为3.5 mg/L液体培养基中感染的酵母菌的量要多于不含铁元素液体培养基和不投加任何微量元素培养体系.微量元素铁在抑制酵母菌生长方面具有很重要的作用,同时铁元素又是白腐真菌生长所必需的,只要在不影响白腐真菌生长的前提下,合理调控培养基中的铁浓度,就有可能达到抑制酵母菌的目的.