改性硅胶对水溶液中Pd2+的吸附

采用氨基硫脲对硅胶进行改性并表征,探讨了改性硅胶(SG-TSC)对水溶液中Pd2+的吸附性能。实验考察了p H值、吸附剂质量、吸附时间以及Pd2+初始浓度等因素对吸附的影响,并探讨了SG-TSC对Pd2+吸附动力学及等温吸附特性。结果表明:在p H为3~6范围内,吸附效果最好。吸附平衡时间为90 min,吸附动力学符合二级速率方程,颗粒内扩散与液膜扩散共同影响着吸附过程。Langmuir等温吸附方程能较好地描述Pd2+在SG-TSC上的吸附特性,298 K时静态饱和吸附容量为0.105 mmol/g。热力学参数计算结果表明,SG-TSC吸附水溶液中的Pd2+是自发、吸热和熵值增加的过程。     

硅藻土固定化颗粒污泥对海水养殖废水除氨性能

针对实际海水养殖废水低碳高氮的特点,采用间歇式活性污泥法(SBR)和好氧活性污泥添加硅藻土载体的方式,考察硅藻土载体和活性污泥共同作用下的好氧曝气系统对海水养殖废水中氨态氮(NH+4-N)、亚硝酸态氮(NO-2-N)和化学耗氧量(COD)的去除效果,以及对污泥沉降性能和硝化细菌特征的影响。实验结果表明,常温条件下,溶解氧(DO)≥4.5mg/L,p H控制在7.0~8.0,HRT为11 h,沉降时间10 min,反应器可以处理NH+4-N浓度在50 mg/L左右的海水养殖废水,NH+4-N和COD去除率分别达到98.93%左右和76.62%以上,NO-2-N出水浓度低于0.028 mg/L。载体污泥颗粒照片和扫描电镜结果表明,添加硅藻土载体内核后,颗粒污泥的成熟期缩短,颗粒的稳固度和沉降性能提高。在系统启动成功稳定运行后,通过FISH分析表明,在氨氧化菌(AOB)与亚硝酸盐氧化菌(NOB)成为优势菌群后,AOB大约占总菌群的33.5%,并且AOB与NOB菌群数量约为1∶1.33,AOB和NOB两大类菌群之和约占总菌群的77.2%,成为系统中优势菌群。     

Impact of demographic dynamics on CO_2 emissions in Sichuan,China

Global climate change is one of the major environmental issues faced by humans.Existing evidence indicates that the anthropogenic push for a rise in the atmospheric concentration of greenhouse gases(GHGs)(particularly CO_2)has been a primary cause for global warming.Aside from economic and teclinological factors,demographic dynamics(including human consumption in a broad demographic sense)has been a major driver for CO_2 emissions.In this paper,we performed both nonlinear regression analysis(based on the STIRPAT model)and gray correlation degree analysis(based on gray system theory)on the impact of demographic dynamics on CO_2 emissions.Our results reveal that CO_2 emissions are positively correlated with population size and GDP per capita and negatively correlated with energy intensity.We also show that gray correlation degree with CO_2 emissions for five variables(i.e.,household consumption,urbanization rate,household size,population aging rate,population size)varies substantially:household consumptionurbanization ratehousehold sizepopulation aging ratepopulation size,with household consumption being the highest,and population size the lowest.To mitigate the impact of demographic dynamics on CO_2 emissions,it is of vital significance to nurture people's awareness of sustainable consumption and to adhere to current population control policies.     

臭氧联用技术深度处理腈纶废水的效果对比

将臭氧分别与超声波、H2O2、紫外光等联用,深度处理干法腈纶生产厂生化池出水,对各种联用技术的处理效果进行了研究。实验结果表明：在进水流量2 L/min、反应时间30 min、臭氧加入量3.5 g/（L?h）的条件下,当超声功率为300 W时,臭氧-超声联用技术的COD去除率为30.0%;当H2O2加入量为0.4 mL/L时,臭氧-H2O2联用技术的COD去除率为50.7%;当紫外灯功率为40 W时,臭氧-紫外光联用技术的COD去除率为49.9%;在各种联用技术中,臭氧-H2O2联用技术的运行成本最低（为7.5 元/t）,且处理后出水COD为143 mg/L,达到《<污水综合排放标准>（GB8978—1996）中石化工业COD标准值修改单》中的一级排放标准。综合考虑,臭氧-H2O2联用技术是深度处理干法腈纶废水的最优工艺。     

Mn/γ-Al2O3催化剂的制备及头孢合成废水的催化臭氧氧化法深度处理

对Mn/γ-Al₂O₃催化剂的制备条件及头孢合成废水的催化臭氧氧化法深度处理工艺条件进行了优化。实验结果表明：以Mn（NO₃）₂溶液为浸渍液,Mn/γ-Al₂O₃催化剂的最优制备条件为浸渍液浓度0.10 mol/L、浸渍时间9 h、焙烧温度400 ℃、焙烧时间2 h;在反应时间为30 min、废水pH为9.0、臭氧通量为4.6 mg/min、催化剂加入量为5 g/L的条件下,当进水COD、BOD₅、ρ（氨氮）和色度分别为220~250 mg/L,8~10 mg/L,10~12 mg/L和60~70倍时,出水COD、BOD₅、ρ（氨氮）和色度的平均去除率分别为53%,30%,33%和93%,出水水质满足GB 21904—2008《化学合成类制药工业水污染物排放标准》的要求。     

磷石膏水热法合成硫酸钙晶须

以磷石膏为原料,二水合硫酸钙、硫酸镁、甘油为添加剂,采用水热法合成硫酸钙晶须,考察了料浆含量、反应温度、反应时间、体系pH等因素对晶须的直径和长径比的影响;并采用SEM技术观察硫酸钙晶须的形貌。实验结果表明,当磷石膏含量2.5%（w）、反应温度130 ℃、反应时间4 h、体系pH 4时,制备得到的硫酸钙晶须长径比为56.24,平均直径为0.17 μm。SEM表征结果显示,硫酸钙晶须形貌规整、分散均匀、直径较小,达百纳米级。     

Heavy metal pollution in vegetables grown in the vicinity of a multi-metal mining area in Gejiu,China: total concentrations,speciation analysis,and health risk

A field survey was conducted to investigate the present situation and health risk of arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) in soils and vegetables in a multi-metal mining area, Gejiu, China. Furthermore, three vegetables (water spinach, potato, and summer squash) containing high metal concentrations were selected to further analyze metal speciation. The results showed that the average concentrations of five metals in soil exceeded the limiting values, and their bioavailable concentrations were significantly positively correlated to the total ones. Heavy metals in the edible parts of vegetables also exceeded the corresponding standards. The leaves of pakchoi, peppermint, and coriander had a strong metal-accumulative ability and they were not suitable for planting. Except the residue forms, the main forms of metals in the edible parts of three selected vegetables were ethanol-, NaCl-, and HAc-extractable fractions for As, Pb, and Cd, respectively; however, Cu was mainly presented as NaCl-extractable and Zn as HAc-extractable fractions. A high proportion of ethanol-extractable As showed that As bioactivity and toxic effects were the highest. Although the total and bioavailable Cd were high in soil, its speciation in vegetables was mainly presented as HAc-extractable fraction, which has a relatively low bioactivity. Lead and arsenic were imposing a serious threat on the local residents via vegetable consumption.     

Catalytic hydrolysis of urea from wastewater using different aluminas by a fixed bed reactor

In order to find an effective method for treating urea wastewater, the experiments on the hydrolysis of urea in wastewater were conducted in a fixed bed reactor with different aluminas (α-Al₂O₃, γ-Al₂O₃, and η-Al₂O₃) as catalysts respectively in contrast with inert ceramic particle. The results indicate that the three alumina catalysts show obvious catalytic activity for urea hydrolysis at 125 °C. The order of activity is η-Al₂O₃?>?γ-Al₂O₃?>?α-Al₂O₃, and the activity difference increases with increasing temperature. According to the characterization results, surface acidity has little impact on the activity of catalyst. However, it was found that surface basicity of alumina catalyst plays an important role in catalytic hydrolysis of urea, and the activity of catalyst may be also influenced by the basic strength. With η-Al₂O₃ as catalyst, the urea concentration in wastewater is reduced to 4.96 mg/L at a temperature of 165 °C. Moreover, the η-Al₂O₃ shows a good stability for urea hydrolysis. The hydrolysis of urea over η-Al₂O₃ catalyst can evidently reduce the reaction temperature and is promising to replace industrial thermal hydrolysis process.     

Behavior and mechanism of arsenate adsorption on activated natural siderite: evidences from FTIR and XANES analysis

Activated natural siderite (ANS) was used to investigate its characteristics and mechanisms of As(V) adsorption from aqueous solution. Batch tests were carried out to determine effects of contact time, initial As(V) concentration, temperature, pH, background electrolyte, and coexisting anions on As(V) adsorption. Arsenic(V) adsorption on ANS well-fitted pseudo-second-order kinetics. ANS showed a high-adsorption capacity of 2.19 mg/g estimated from Langmuir isotherm at 25 °C. Thermodynamic studies indicated that As(V) adsorption on ANS was spontaneous, favorable, and endothermic. ANS adsorbed As(V) efficiently in a relatively wide pH range between 2.0 and 10.0, although the removal efficiency was slightly higher in acidic conditions than that in basic conditions. Effects of background electrolyte and coexisting anions were not significant within the concentration ranges observed in high As groundwater. Results of XRD and Fe K-edge XANES analysis suggested ANS acted as an Fe(II)/(III) hybrid system, which was quite effective in adsorbing As from aqueous solution. There was no As redox transformation during adsorption, although Fe(II) oxidation occurred in the system. Two infrared bands at 787 and 872 cm^?1 after As(V) adsorption suggested that As(V) should be predominantly adsorbed on ANS via inner-sphere bidendate binuclear surface complexes.     

渗滤液耦合矿化垃圾制备甲烷氧化菌菌液

利用甲烷氧化菌菌液增加材料中甲烷氧化菌的数量,可以得到高甲烷氧化率的填埋场甲烷生物氧化覆盖材料。研究发现,渗滤液原水和渗滤液处理尾水均能促进甲烷氧化菌的生长,可利用渗滤液耦合矿化垃圾混合培养制备甲烷氧化菌菌液用于填埋场甲烷减排。填埋龄长的渗滤液原水有着较好的培养效果,得到的菌液在4 d内最高甲烷氧化速率达到2.68 mL/h,超过甲烷氧化菌培养液(nitrate minimal salt medium,NMS)的实验结果。渗滤液中总氮、无机碳、总有机碳和Ni元素的含量对甲烷氧化菌的培养过程影响较大,适用于甲烷氧化培养的渗滤液应满足:总氮1 400 mg/L,总有机碳55 mg/L,Ni元素0.4 mg/L,总磷含量较高。