UV/Fe3+/H2O2体系降解活性艳橙X-GN废水的研究

采用UV/Fe3 /H2O2体系光解活性艳橙X-GN模拟废水,考察了X-GN,Fe3 和H2O2的初始浓度、初始pH值及温度对光解的影响,探讨了X-GN的降解途径和机理.结果表明,在8W低压汞灯(λ＝254nm)照射下,UV/Fe3 /H2O2能够有效地降解X-GN,在pH=3.0,T=50 ℃,时间为120 min,Fe3 和H2O2的初始浓度分别为2.5×10-5 mol·l-1和1.5×10-4 mol·l-1时,对含200 mg·l-1 X-GN模拟废水的色度去除率和矿化率分别达到100%和90.15%.用IC和GC/MS对X-GN降解的中间产物和最终产物进行分析,推导出UV/Fe3 /H2O2体系中X-GN降解的途径和机理.     

Nutrient status and pollution levels in five areas around a manganese mine in southern China

• The soil TP level was high or extremely high in all areas. • TN, OM and available Cu were insufficient in EA, TA and RA. • All areas reached the heavily polluted level and had high ecological risk levels. • Mn and Cd were the dominant pollutants. Nutrient status and pollution levels are the main factors affecting soil restoration. The nutrient status and pollution levels in five areas, an unexplored mine area (UA), an explored mine area (EA), a tailings area (TA), a reclamation area (RA) and an agricultural area (AA), around the Pingle manganese mine in Guangxi, China, were assessed in this study. The results showed that the average total phosphorus in these five areas ranged from 1.05 to 1.57 mg/kg, corresponding to grades of extremely high and high. The average total nitrogen values were 0.19, 0.69, 0.93, 1.24 and 1.67 mg/kg in EA, TA, RA, UA and AA, corresponding to grades of very low, low, medium-low, medium-high and medium-high, respectively. The average organic matter values were 12.78, 8.92, 22.77, 21.29 and 29.11 mg/kg in EA, TA, RA, UA and AA, which corresponded to grades of medium-low, low, medium-high, medium-high and medium-high, respectively. All these results indicated that the total phosphorus was sufficient in these areas, while the total nitrogen and organic matter were insufficient in EA, TA and RA. The available concentrations of Mn and Zn corresponded to the intermediate grade, while the values for Cu corresponded to the very low grade; these might be another factor restricting ecological reclamation. Contamination and ecological risk assessments based on the single contamination index, Nemerow multi-factor index and potential ecological risk index showed that the five tested areas around the Mn mine were considered heavily polluted and presented high ecological risk. Mn and Cd were the dominant pollutants.     

Diphenylarsinic acid sorption mechanisms in soils using batch experiments and EXAFS spectroscopy

• DPAA sorption data was found to fit the Freundlich equation. • K_f was significantly positive correlated with oxalate-extractable Fe₂O₃. • Ligand exchange was the main mechanism for DPAA sorption on soils. • Bidentate binuclear and monodentate mononuclear DPAA bonds were identified. Diphenylarsinic acid (DPAA) is a phenyl arsenic compound derived from chemical warfare weapons. Macroscopic and microscopic work on DPAA sorption will provide useful information in predicting the partitioning and mobility of DPAA in the soil-water environment. Here, batch experiments and extended X-ray absorption fine structure (EXAFS) spectroscopy were used to investigate the sorption mechanisms of DPAA. The DPAA sorption data from 11 soil types was found to fit the Freundlich equation, and the sorption capacity, K_f, was significantly and positively correlated with oxalate-extractable Fe₂O₃. The K_f values of eight of the 11 untreated soils (1.51–113.04) significantly decreased upon removal of amorphous metal (hydr)oxides (0.51–13.37). When both amorphous and crystalline metal (hydr)oxides were removed from the untreated soils, the K_f values either decreased or slightly increased (0.65–3.09). Subsequent removal of soil organic matter from these amorphous and crystalline metal (hydr)oxide-depleted samples led to further decreases in K_f to 0.02–1.38, with only one exception (Sulfic Aquic-Orthic Halosols). These findings strongly suggest that ligand exchange reactions with amorphous metal (hydr)oxides contribute most to DPAA sorption on soils. EXAFS data provide further evidence that DPAA primarily formed bidentate binuclear (²C) and monodentate mononuclear (¹V) coring-sharing complexes with As-Fe distances of 3.34 and 3.66 Å, respectively, on Fe (hydr)oxides. Comparison of these results with earlier studies suggests that ²C and ¹V complexes of DPAA may be favored under low and high surface coverages, respectively, with the formation of ¹V bonds possibly conserving the sorption sites or decreasing the steric hindrance derived from phenyl substituents.     

粉煤灰合成NaX型分子筛的表征及其对Fe~（2＋）离子的吸附研究

以高温碱熔融处理粉煤灰合成了NaX型沸石分子筛,考察了不同水热晶化温度对产物结果的影响,用粉末XRD、XRF、SEM和FT-IR等手段对产品进行了表征,结果表明,以粉煤灰为原料用水热合成法合成微孔分子筛时,在晶化温度为90℃时能得到晶形较好的NaX型分子筛。同时考察了NaX分子筛的用量、时间和pH值等因素对Fe2＋离子的吸附影响,在25 mL Fe2＋离子浓度为2×103 mg/L的溶液中,当吸附剂用量为0.2 g,吸附时间为2 h,吸附效率达到最大值（36.41%）,而随着溶液pH值的升高其吸附效率显著增大。     

溶液环境对纳米Fe2O3/水界面NOM吸附过程中疏水效应的影响

以腐殖酸和纳米Fe2O3为对象,着重研究了腐殖酸分子在纳米Fe2O3表面的吸附过程中的疏水效应,借助红外光谱和热重等分析方法研究了腐殖酸吸附前后的疏水性随溶液环境变化的规律。结果表明,当离子强度为0、0.005、0.01和0.05 mol/kg,pH从7变到12时,纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的热失重量随着pH的升高先减小后增大。当pH从7升高到10时,亲水性降低,疏水性增强;当pH从10升高到12时,亲水性增强,疏水性降低。当离子强度为0.001 mol/kg,pH从7变到12时,复合体的热失重量随着pH的升高而减小,亲水性降低,疏水性增强。当pH为定值,离子强度变化时,纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的热失重量随着离子强度的增加不断变化,曲线呈现出波动趋势,亲、疏水性在交替变化。红外光谱分析结果说明,对纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的亲疏水性起主要影响的官能团可能是亲水性的羟基—OH、羰基CO和疏水性的CH2烷烃。     

Fe3O4／Ag磁性纳米颗粒去除水中的铅离子

采用水相共沉淀法制备小尺寸磁性Fe3O4纳米颗粒,以没食子酸作为还原剂和表面修饰剂,还原Ag[（NH3）2]’制备出Fe3O4／Ag磁性纳米颗粒。研究该磁性纳米颗粒对水溶液中铅离子的吸附行为,研究结果表明,pH为7．0,吸附温度30℃时可得到最好的处理效果,铅的去除率可达99．7％以上,Fe3O4／Ag颗粒吸附行为符合二级动力学模型（R2〉0．99）。该磁性纳米颗粒经过多次再生处理后,仍具有很好的吸附效果,表明Fe3O4／Ag在水处理方面拥有良好的应用前景。     

六铝酸盐催化剂的催化还原脱硫脱硝性能

采用共沉淀法制备Cu和Fe掺杂的六铝酸盐催化剂(SrCuxFe1-xAl11O19-δ,x为0,0.2,0.4,0.5,0.6,0.8,1),通过XRD、TPR、BET等技术方法对催化剂的结构及性质进行了研究,并考察了以CO为还原剂的催化脱硝活性。结果表明,用碳酸铵作为沉淀剂在1 200℃焙烧4 h可以形成完整的六铝酸盐晶型,Cu和Fe能够取代Al3+,很好地促进六铝酸盐晶体结构的形成;SrCuxFe1-xAl11O19-δ催化剂有很好的脱硫脱硝催化活性,此类型的催化剂均使SO2、NO的转化率在空速为6 000 h-1下达到了80%和90%以上。向体系中加入氧气会对催化活性有较大影响。     

负载型氧化铁对高毒气体PH3的催化分解

采用沉积-沉淀法制备了碳纳米管(CNTs)和二氧化硅(SiO2)负载的纳米Fe2O3催化剂,将其应用于高毒气体PH3分解反应.通过XRD,TEM,XPS,BET等一系列检测手段,对制备样品的相结构、形貌、组分和比表面积进行了表征.研究结果表明,在PH3催化分解反应过程,极少量的产物P迁移至Fe2O3中,形成金属磷化物FeP作为反应的活性相.与Fe2 O3/SiO2相比,Fe2O3/CNTs显示了较高的催化性能.在440℃反应温度下,Fe2O3/CNTs对PH3分解率达到99.8％.CNTs作为催化剂载体的优秀性能可归因于CNTs良好的导电性能和活性组分在其上的高度分散.     

Ni/Fe/Al2O3·PVDF催化还原剂的表征及制备过程优化

在PVDF基体改性的基础上,采用浸渍法制备出Ni/Fe/Al₂O₃·PVDF催化还原剂。通过对一氯乙酸的脱氯效果研究,对交联液配比及交联时间、不同浓度硫酸镍浸渍时间、镍铁比等因素进行优化,实验优化结果表明,Ni/Fe/Al₂O₃·PVDF催化还原剂对一氯乙酸脱氯60 min脱氯率达到64%。经SEM表征,制备出的双金属在膜载体表面及断面分布均匀,呈球状和片状结构且双金属未发生团聚。     

Mn的氧化价态对Mn/γ-Al2O3催化剂催化臭氧氧化气相低浓度甲苯的影响

采用共沉淀法,以Al₂O₃为载体制备Mn/γ-Al₂O₃和Mn-Ce/γ-Al₂O₃催化剂,并分别在N₂气氛和O₂气氛下焙烧。采用固定床连续流动反应器,研究所制备催化剂在室温条件下催化臭氧氧化甲苯的性能。通过XRD、XPS和FTIR等手段对催化剂的结构和组成进行表征。结果表明,Mn/γ-Al₂O₃催化剂具有良好的催化臭氧氧化甲苯和催化臭氧自身分解的性能,共沉淀法制备催化剂的最佳Mn负载量为20%。O₂气氛焙烧和Ce的加入,可以有效提高催化剂的活性和寿命。原因是O₂气氛焙烧和Ce的加入可以提高Mn的氧化价态。催化剂失活的主要原因是有机副产物在催化剂表面吸附堆积,失活催化剂在550℃、空气气氛下焙烧可恢复催化性能。