热重法研究模化城市生活垃圾燃烧和热解特性

利用热重技术研究了模化城市生活垃圾(model municipal solid waste，MMSW)的热解和燃烧过程的特性。结果表明，在小于300℃的温度范围内，热解和燃烧的失重曲线基本一致，不同升温速率对失重特性有影响。利用分峰拟合处理技术对MMSW热处理过程的DSC曲线进行分析，发现MMSW燃烧和热解的失重特性基本上是所含物质失重特性的叠加。对MMSW热处理过程进行动力学分析，计算结果表明反应级数在1．2～1．8之间，化学反应的平均活化能在30～50kJ／mol之间。     

壳聚糖对染料的吸附动力学研究

通过壳聚糖吸附酸性染料普拉蓝RAWL和阳离子蓝染料X-GRRL的试验，研究了壳聚糖对这两种水溶性染料吸附的动力学行为，包括吸附速率K和颗粒内有效扩散系数Di′，同时通过对吸附焓△H的试验计算，初步分析了它们的吸附机理。     

Performance, microbial community and inhibition kinetics of long-term Cu2+ stress on an air-lift nitritation reactor with self-recirculation

Biological nitrogen removal process could be affected due to the presence of heavy metals owing to their toxicity and accumulation in the sludge.In this study,the impact of Cu~(2+)shock on a long-term nitritation operation was investigated in an air-lift reactor with selfrecirculation.Both the dynamics of microbial community and inhibition kinetics under Cu~(2+) stress were ascertained.The results showed that Cu~(2+) exerted severe inhibition on nitritation performance of an air-lift reactor(ALR) at 25 mg/L.The corresponding NH_4~+-N removal efficiency decreased to below 50%,which was mainly due to the variation of microbial community structure,especially the inhibition of nitrifiers like Nitrosomonas(the relative abundance decreased from 30% to 1% after Cu~(2+)inhibition).Kinetic parameters were obtained and compared after fitting the Haldane model.The long-term Cu~(2+) stress on the ALR aggravated the ammonium affinity and the resistance to substrate self-inhibition of the nitritation sludge,but reduced the resistance to Cu~(2+) inhibition.Furthermore,Cu~(2+)acted as uncompetitive inhibitor on nitritation process.Our results provide new insights into the nitritation characteristics under long-term Cu~(2+) stress.     

Differences in nitrite-oxidizing communities and kinetics in a brackish environment after enrichment at low and high nitrite concentrations

Nitrite accumulation in shrimp ponds can pose serious adverse effects to shrimp production and the environment.This study aims to develop an effective process for the enrichment of ready-to-use nitrite-oxidizing bacteria(NOB)inocula that would be appropriate for nitrite removal in brackish shrimp ponds.To achieve this objective,the effects of nitrite concentrations on NOB communities and nitrite oxidation kinetics in a brackish environment were investigated.Moving-bed biofilm sequencing batch reactors and continuous moving-bed biofilm reactors were used for the enrichment of NOB at various nitrite concentrations,using sediment from brackish shrimp ponds as seed inoculum.The results from NOB population analysis with quantitative polymerase chain reaction(q PCR)show that only Nitrospira were detected in the sediment from the shrimp ponds.After the enrichment,both Nitrospira and Nitrobacter coexisted in the reactors controlling effluent nitrite at 0.1 and 0.5 mg-NO_2~--N/L.On the other hand,in the reactors controlling effluent nitrite at 3,20,and 100 mg-NO_2~--N/L,Nitrobacter outcompeted Nitrospira in many orders of magnitude.The half saturation coefficients(Ks)for nitrite oxidation of the enrichments at low nitrite concentrations(0.1 and 0.5 mg-NO_2~--N/L)were in the range of 0.71–0.98 mg-NO_2~--N/L.In contrast,the Ksvalues of NOB enriched at high nitrite concentrations(3,20,and 100 mg-NO_2~--N/L)were much higher(8.36–12.20 mg-NO_2~--N/L).The results suggest that the selection of nitrite concentrations for the enrichment of NOB inocula can significantly influence NOB populations and kinetics,which could affect the effectiveness of their applications in brackish shrimp ponds.     

煤矸石复合吸附剂对Zn~(2+)的吸附性能

采用某洗煤厂的煤矸石和天然粘土石灰石作为主要原料,添加适量的氯化铝制备吸附剂对Zn~(2+)进行吸附,运用SEM技术对吸附剂进行了表征,研究了不同因素对Zn~(2+)去除率的影响,并探讨了吸附机理。实验结果表明:当反应温度为20℃、振荡时间为70 min、废水pH为6、吸附剂投加量为0.5 g时,Zn~(2+)去除率达到96.28%。煤矸石复合吸附剂对Zn~(2+)的吸附符合准二级动力学方程,在高浓度时符合Langmuir等温吸附模型低浓度时符合Freundlich等温吸附模型,且吸附是易发生的。     

改性聚乙烯醇吸附镍离子的动力学与热力学研究

研究了自制改性聚乙烯醇对Ni~(2+)的吸附行为,在不同的吸附条件下,探讨相关因素的影响,并对实验数据进行动力学与热力学的拟合。结果表明,室温下,在溶液p H=6.0,NaNO_3的浓度为0.1 mol/L,吸附时间为60 min,液固比为250 m L/g,改性聚乙烯醇对浓度为0.1 mol/L Ni2+的吸附效果好,去除率达到98.05%;当干扰因子设定为0.1 mol/L的Ca(NO_3)_2,对Ni2+的去除率降到59.29%。改性聚乙烯醇对Ni2+的吸附动力学符合准二级动力学方程;Langmuir等温模型的拟合度较高,推测改性聚乙烯醇表面是均一的等质体,计算的最大吸附量为1.35 mmol/g,与实验结果一致;D-R等温模型的拟合度次之,在各温度下,E16 k J/mol,说明改性聚乙烯醇对Ni2+的吸附是以化学吸附为主。通过Van’t Hoff方程的拟合,计算得到的吉布斯自由能以及熵变和焓变表明该吸附过程为吸热化学反应。     

Kinetics of Solvent Blue and Reactive Yellow removal using microwave radiation in combination with nanoscale zero-valent iron

We investigated the efficiency and kinetics of the degradation of soluble dyes over the p H range 5.0–9.0 using a method employing microwave radiation in combination with nanoscale zero-valent iron(MW–n ZVI). The n ZVI particles(40–70 nm in diameter) were prepared by a liquid-phase chemical reduction method employing starch as a dispersant.Compared to the removal of Solvent Blue 36 and Reactive Yellow K-RN using only n ZVI,more rapid and efficient dye removal and total organic carbon removal were achieved using MW–n ZVI. The dye removal efficiency increased significantly with decreasing p H, but was negligibly affected by variation in the microwave power. The kinetics of dye removal by MW–n ZVI followed both an empirical equation and the pseudo first-order model, while the kinetics of dye removal using n ZVI could only be described by an empirical equation. It was also concluded that microwave heating of the dye solutions as well as acceleration of corrosion of n ZVI and consumption of Fe(II) were possible reasons behind the enhanced dye degradation.     

Toward rational design of amines for CO2 capture: Substituent effect on kinetic process for the reaction of monoethanolamine with CO2

Amines have been considered as promising candidates for post-combustion CO₂ capture. A mechanistic understanding for the chemical processes involved in the capture and release of CO₂ is important for the rational design of amines. In this study, the structural effects of amines on the kinetic competition among three typical products (carbamates, carbamic acids and bicarbonate) from amines + CO₂ were investigated, in contrast to previous thermodynamic studies to tune the reaction of amines with CO₂ based on desirable reaction enthalpy and reaction stoichiometry. We used a quantum chemical method to calculate the activation energies (E_a) for the reactions of a range of substituted monoethanolamines with CO₂ covering three pathways to the three products. The results indicate that the formation of carbamates is the most favorable, among the three considered products. In addition, we found that the E_a values for all pathways linearly correlate with pK_a of amines, and more importantly, the kinetic competition between carbamate and bicarbonate absorption pathways varies with pK_a of the amines, i.e. stronger basicity results in less difference in E_a. These results highlight the importance of the consideration of kinetic competition among different reaction pathways in amine design.     

城市生活垃圾在热解处理中的产气特性研究

通过对沈阳市皇姑区内的3个垃圾排放点进行实地采样并分类称量,得出其组分含量,得到了生活垃圾的主要物料组份.在此基础上在外加热固定床式热解试验台上,用热解实验的方法对8种城市生活垃圾中的主要物料中的典型成分进行热解试验.通过数据分析总结出不同工况下产气特性和热解气体的组分含量、热值,并建立热解气体析出模型进行产气量预测.     

SO_2浓度对双通道自动荧光过氧化氢在线监测的影响研究

为验证大气中SO2的浓度对气态H2O2自动荧光法监测的影响,设置了SO2与H2O2在自动荧光过氧化氢分析仪中的反应实验;同时,利用SO2和H2O2的反应速率公式进行了模拟计算,模拟计算结果与仪器的监测结果基本相符.证明了在大气SO2浓度较高的情况下,气态SO2对H2O2的自动荧光法测定确实会有显著影响,通过模拟计算的方法可对在线监测的H2O2浓度数据进行校正.