TiO2/ZSM-5m光催化耦合过硫酸盐降解焦化尾水的研究

以具有介孔结构的沸石分子筛ZSM-5m负载纳米TiO2制备出复合型光催化剂,用扫描电镜、比表面及孔径分析仪和X射线衍射对形貌和结构进行表征,通过序批试验考察了TiO2/ZSM-5m/过硫酸盐体系深度降解焦化生化处理出水中残余有机污染物(ROPs)的效果和机理.结果表明,在COD初始平均浓度为352mg/L,TiO2/ ZSM-5m投加量为1.6g/L,pH值为3.0,C(Na2S2O8)为0.8g/L,常温下反应180min,COD出水平均浓度为76.3mg/L,去除率达到78.2 %,在上述优化条件下可达到现行污染物排放标准.ROPs光催化符合Langmuir-Hinshelwood模型,推测具有微介双孔结构的催化剂表面电子易被S2O82-俘获,降低空穴与电子的复合率,促进了·OH 和SO4-·形成,对ROPs的吸附和光降解有较大的强化作用.用GC-MS对处理前后废水中的污染物进行测定以揭示降解与转化规律,发现苯类特征污染物能有效降解,但产生的中间产物明显增多.     

紫外/过硫酸盐工艺降解水中氯贝酸的研究

采用紫外/过硫酸盐（UV/PS）工艺去除水中典型PPCPs类物质氯贝酸（CA）.考察了氯贝酸初始浓度、PS投加量、溶液初始pH值、碳酸氢根离子浓度、氯离子浓度和腐殖酸（HA）投加量共计6种因素对UV/PS工艺去除氯贝酸的影响.结果表明：UV/PS工艺降解氯贝酸与准一级动力学模型相符（R²>0.95）,准一级反应速率常数随氯贝酸初始浓度增加而减小.在一定的范围内,随着PS投加量的增加,氯贝酸的降解速率快速增加.不同的pH值环境对氯贝酸的降解有一定影响,溶液pH值从酸性到碱性再到强碱性的过程中,UV/PS工艺对氯贝酸的降解速率呈先加快后减慢的趋势.溶液中的碳酸氢根离子和氯离子都会对UV/PS工艺降解氯贝酸产生抑制作用,且两者对该反应的抑制作用大小关系为HCO₃^->Cl^-.HA的存在对UV/PS工艺去除氯贝酸有抑制作用.     

碳纳米管活化过二硫酸盐降解偶氮染料酸性橙7

采用碳纳米管（CNT）活化过二硫酸盐（PS）降解偶氮染料酸性橙7（AO7）.考察了PS浓度、CNT投加量、初始pH值、温度等反应条件对AO7降解效果的影响.结果表明,当初始pH为7、n（PS）/n（AO7）为20、CNT投加量为0.2g/L时,AO7在反应480min后可以被完全脱色去除.随着PS剂量、CNT投加量和温度的升高,AO7的去除率也逐渐增加,中性条件下最有利于AO7的去除.AO7降解反应主要发生在CNT表面,且反应活化能Ea为46.76kJ/mol.通过紫外-可见分光光谱、气相色谱-质谱（GC-MS）和TOC分析表明,AO7分子偶氮键和萘环结构断裂,生成含苯环类物质,最终矿化为CO₂和H₂O.     

Acute toxicity of potassium permanganate to Caspian roach Rutilus rutilus caspicus in two size classes and under different aeration conditions

Caspian roach, Rutilus rutilus caspicus, might experience potassium permanganate (PM) toxicity, because it is common and widely used disinfectant in fish rearing and propagation centers in Iran. Thus, acute toxicity (24-h-LC₅₀) of PM was determined on Caspian roach in two size classes (small and large groups), under aerated and non-aerated conditions, using static non-renewal system. 24-h-LC₅₀ for PM in Caspian roach was 3.2, 3, 3.2, and 2.8?mg?L^?1 in large-aerated, large-non-aerated, small-aerated, and small-non-aerated groups, respectively. Results indicated that aeration was led to decrease in PM toxicity, regardless of size class. However, large fish showed more tolerance to PM toxicity compared to small ones, under non-aerated condition. It is concluded that aeration could decrease the toxicity of PM that seems to be due to the increase in PM degradation, derived from increase in water turbulence. It is suggested that 96-h-LC₅₀ may be more suitable to determine the effects of fish size on PM toxicity than 24-h-LC₅₀.     

Tissue nutrient concentrations in aquatic macrophytes: comparison across biophysical zones,surface water habitats and plant life forms

Aquatic plant tissue (nitrogen) N and phosphorus (P) concentrations, together with the N:P ratio in general, respond poorly to ambient nutrient supply. The variability in plant tissue nutrient concentrations appears to be highly conditioned by taxonomic (mostly species) effects. The significant role that other attributes of the surrounding environment may have in modifying the degree of taxonomic dependence on plant nutrient concentration is yet to be tested with a broader characterisation of plant life forms (bryophytes, helophytes, hydrophytes), so as to investigate implications for ecosystem processes. Plant samples (378) were collected across 65 sites spanning a wide range of aquatic habitats (lotic and lentic) and biophysical zones (floodplain, glacial terraces, mountains) located in NE Scotland. Significant differences in plant tissues N, P and the N:P were found after grouping sampling sites by either habitat or biophysical zones; the latter even after removing the largest taxonomic effect. The range in plant tissue N and P was relatively wide within habitats and zones, reflecting the high species diversity of the studied area. As a group, bryophytes had smaller N and P concentrations, and consequently wider biomass C:N and C:P ratios, a situation which may impose constraints on the flow of energy through food-webs of the mountain and bog areas where they dominate.     

过硫酸盐缓释材料释放性能及机理

采用过硫酸钾、水泥、砂和水按照一定配比均匀混和后,于立方体模具中成型制备过硫酸盐缓释材料(A₁、A₂、A₃、A₄),参照欧盟标准化组织制定的NEN 7375水槽试验方法,分8个阶段更换浸取液连续浸泡缓释材料,考察过硫酸盐缓释材料的释放性能,并初步探讨其缓释机理. 结果表明:过硫酸盐缓释材料在浸泡初期释放速率较大,短时间内释放速率迅速降低,之后缓慢降低;4种配比缓释材料的过硫酸盐释放特性均满足二级动力学方程;砂的含量水平是影响过硫酸盐释放特性的主要因素之一,砂含量较高的A₄材料的传质阻力小,传质系数(K)为58.11mg/(d·g),释放过硫酸钾的速率较快;砂含量低的A₁、A₂材料传质阻力大,传质系数分别为14.59、17.11mg/(d·g),过硫酸钾释放速率较慢. 该研究中过硫酸盐缓释材料最长释放时间可达159.08~501.44d,能够有效实现有效组分过硫酸盐的缓慢释放. 总体上,浸泡初期释放机理表现为标准扩散过程,后期为损耗扩散过程.      

高锰酸钾强化混凝处理化工废水生化尾水

高锰酸钾氧化技术是提高混凝工艺去除有机污染物的有效途径之一。与其他方法相比,采用高锰酸钾氧化法作为混凝工艺的前处理工艺具有反应速度快、处理效率高、适用范围广等优点。实验采用高锰酸钾强化混凝处理生化尾水,考察了高锰酸钾投加量、反应时间、反应pH以及不同混凝剂组合的因素的影响。结果表明,COD,TOC,UV254等污染物的去除率随着高锰酸钾投加量的增加而增加;在高锰酸钾投加量小于12 mg/L时,反应时间不应大于40 min;高锰酸钾对有机物的去除存在最优的pH,pH在6~7范围内,有机物去除率较高;高锰酸钾与不同混凝剂组合工艺相比于单独投加高锰酸钾或直接混凝剂混凝,COD去除率明显提高。高锰酸钾与聚合氯化铝组合混凝工艺对有机污染物的去除效果较其他组合工艺好。     

超声-Fe2+-K2S2O8/NaHSO3体系降解罗丹明B

采用超声促进、Fe²⁺活化的K₂S₂O₈/NaHSO₃联合体系（US-Fe²⁺-K₂S₂O₈/NaHSO₃体系）降解罗丹明B（RhB）。考察了RhB模拟废水脱色效果的影响因素,并研究了不同处理方法的协同效应,推测了反应机理。实验结果表明：在反应温度25 ℃、初始pH 5.18、超声功率250 W、K₂S₂O₈溶液（4.91 mmol/L）加入量1.2 mL、NaHSO₃溶液（4.91 mmol/L）加入量1.2 mL、n（K₂S₂O₈）∶n（Fe²⁺）=10、反应时间7 min的条件下,RhB模拟废水（50 mL）的脱色率达到89.45%;超声与Fe²⁺-K₂S₂O₈/NaHSO₃体系对RhB的降解产生了协同效应,降解反应符合表观一级反应动力学,速率常数增强因子可达13.6。自由基猝灭实验结果表明,硫酸根自由基和羟基自由基是攻击RhB 分子的活性自由基,硫酸根自由基起主要作用。     

改进催化光度法测定水中的微量钒

采用改进催化光度法测定微量钒,即利用微量钒催化溴酸钾氧化甲基紫溶液褪色实现快速测定水中的微量钒。在50mL容量瓶中,在pH为1.6的硫酸加入量0.90mL、0.0100mol/L的溴酸钾溶液加入量4.50mL、2.5×10-4mol/L的甲基紫溶液加入量5.00mL的条件下,聚乙二醇-200作活化剂时,在92℃恒温反应12min,加钒和不加钒溶液的吸光度之差与钒质量浓度呈线性关系。该法的测定波长为580nm,检出限为5.2×10-8g/L,最大相对标准偏差为4.3%,回收率为95.8%~104.0%。该法可用于湖水、化工厂排水中微量钒的直接测定。     

Simultaneous removal of phosphorus and potassium from synthetic urine through the precipitation of magnesium potassium phosphate hexahydrate

This study investigated the simultaneous removal of P and K from synthetic urine through the precipitation of magnesium potassium phosphate hexahydrate (MPP, MgKPO₄·6H₂O) in bench-scale experiments. Results show that the removal efficiencies of P and K are mainly determined by the solution pH and the molar ratio of Mg:K:P. Co-precipitation of struvite-type compounds, i.e., magnesium ammonium phosphate hexahydrate (MAP, MgNH₄PO₄·6H₂O), magnesium sodium phosphate heptahydrate (MSP, MgNaPO₄·7H₂O), and MPP, was confirmed by analysis of the solid precipitates using a Scanning Electron Microscope/Energy Dispersive X-ray Apparatus and an X-ray Diffractometer. The co-precipitation significantly influenced the removal of K. As much ammonium as possible should be removed prior to MPP precipitation because MAP had higher tendency to form than MPP. The inevitable co-precipitation of MPP and MSP resulted in the addition of more MgCl₂·6H₂O and Na₂HPO₄·12H₂O to obtain the high removal of K. In total, the removal efficiencies of P and K were 77% and 98%, respectively, in the absence of ammonium when pH was 10 and the molar ratio of Mg:K:P was 2:1:2. The results indicate that the MPP precipitation is an efficient method for the simultaneous removal of P and K to yield multi-nutrient products.