Decomposition kinetics of dimethyl methylphospate(chemical agent simulant) by supercritical water oxidation

Supercritical water oxidation （SCWO） has been drawing much attention due to effectively destroy a large variety of high-risk wastes resulting from munitions demilitarization and complex industrial chemical. An important design consideration in the development of supercritical water oxidation is the information of decomposition rate. In this paper, the decomposition rate of dimethyl methylphosphonate（DMMP）, which is similar to the nerve agent VX and GB（Sarin） in its structure, was investigated under SCWO conditions. The experiments were performed in an isothermal tubular reactor with a H2O2 as an oxidant. The reaction temperatures were ranged from 398 to 633℃ at a fixed pressure of 24 MPa. The conversion of DMMP was monitored by analyzing total organic carbon （TOC） on the liquid effluent samples. It is found that the oxidative decomposition of DMMP proceeded rapidly and a high TOC decomposition up to 99.99% was obtained within 11 s at 555℃. On the basis of data derived from experiments, a global kinetic equation for the decomposition of DMMP was developed. The model predictions agreed well with the experimental data.     

以一种黏土矿物材料为非均相类芬顿催化剂对甲基橙的降解

为实现以甲基橙为代表的偶氮类染料的高效降解,采用一种黏土矿物材料——Quantum Energy? Radiating Material（下称QE）为催化剂,系统分析了其在非均相类芬顿反应中的催化剂协同静态吸附作用,并考察了不同因素对甲基橙去除效果的影响,同时基于降解过程中Fe2+和总Fe析出量（以ρ计）、·OH等的变化过程,探讨了QE降解甲基橙的作用机制.结果表明,QE对甲基橙具有良好的吸附作用,同时,其作为非均相类芬顿催化剂对甲基橙的降解受到pH、温度、c（H₂O₂）、催化剂投加量等因素的影响.优化后的降解条件:初始ρ（甲基橙）为50 mg/L、QE投加量为5 g/L、c（H₂O₂）为100 mmol/L、pH为2、温度为60℃,在该条件下反应40 min后,甲基橙的去除率可达到99%.以叔丁醇作为·OH淬灭剂,随着c（叔丁醇）的增高,反应体系中甲基橙的去除率随之下降,说明·OH在该体系甲基橙降解中起重要作用;对在反应过程中Fe2+和总Fe析出量的监测数据表明,体系中QE对甲基橙的降解为均相芬顿反应、非均相芬顿反应和吸附作用协同作用的结果.研究显示,以QE为催化剂,通过吸附协同催化氧化作用可以有效处理含甲基橙的染料废水.      

Urea hydrolysis and recovery of nitrogen and phosphorous as MAP from stale human urine

Laboratory-scale tests for magnesium ammonium phosphate(MAP)precipitation following urea hydrolysis of human urine were conducted using orthogonal experiment design.The effects of initial pH,temperature and the volumetric ratios of stale urine to fresh urine,on urea hydrolysis in urine were studied to determine the final hydrolysis time to recover most nitrogen from separated human urine by MAP.With a volumetric ratio of stale to fresh urine>10% and at temperature≥20℃,urea hydrolysis could be completed i...     

Effects of low temperature on aluminum(III) hydrolysis: Theoretical and experimental studies

In this study, the effects of low temperature on aluminum(III) (Al) hydrolysis were examined both theoretically and experimentally by constructing a solubility diagram for amorphous aluminum hydroxide (Al(OH)3(am)) and a distribution diagram of hydrolyzed Al species. First, thermodynamic data of Al species at 4 degrees C were calculated from that at 25 degrees C. A well confirmed polymeric Al species, AlO4Al12(OH)24(7+)(Al13), was involved in building the diagrams and, correspondingly, the non-linear simultaneous equations with 13 degrees were resolved. Secondly, polarized Zeeman atomic absorption spectrophotometry (AAS), 27Al nuclear magnetic resonance (NMR) spectroscopy, and ferron-based spectrophotometry were applied for constructing the practical diagrams. The results show that a decrease of temperature from 25 to 4 degrees C caused the Al(OH)3(am) boundary on the solubility diagram to shift toward the alkaline side by about 1.0 pH unit and the minimum solubility of Al(OH)3(am) to reduce by 1.0 log unit. The distribution diagram indicates that the monomeric Al, Al13, and solid-phase Al(OH)3 were alternately the predominant species with the increase of pH value during Al hydrolysis. At 25 degrees C, Al13 was the dominant species in a pH range of 4.0 to 4.5, whereas at 4 degrees C, All3 was the leading species in a pH range spaced from 4.5 to 6.3. The predominant species changed from the monomeric Al to the solid-phase Al(OH)3 over the range of 1.8 pH units at 4 degrees C in comparison with the range of 0.5 pH unit at 25 degrees C.     

Effects of low temperature on aluminum(Ⅲ) hydrolysis:Theoretical and experimental studies

In this study,the effects of low temperature on aluminum(Ⅲ)(Al)hydrolysis were examined both theoretically and experimentally by constructing a solubility diagram for amorphous aluminum hydroxide(Al(OH)_3(am))and a distribution diagram of hydrolyzed Al species.First,thermodynamic data of Al species at 4℃were calculated from that at 25℃.A well confirmed polymeric Al species, AlO_4Al_(12)(OH)_(24)~(7+)(Al_(13)),was involved in building the diagrams and,correspondingly,the non-linear simultaneous equations ...     

河流锶元素及其同位素地球化学研究现状与问题

文章系统阐述了近30年来河流锶元素及其同位素地球化学研究方面取得的进展、现状及目前存在的问题,这些问题主要包括:河流锶同位素比值对于源岩的解释问题、河流锶元素含量及其同位素组成的全球参比值问题、不同的端元输入对河流锶元素及其同位素组成的影响以及不同制约因素及研究方法对河流锶元素及其同位素组成的影响等问题。根据目前的研究资料,笔者指出在进行河流锶元素及其同位素地球化学研究过程中应当:(1)考虑矿物岩石在风化过程中锶元素的释放特征及其同位素演化规律;(2)结合同位素地球化学及雨水化学方法对大气及人类活动输入对河流锶元素及其同位素组成的贡献进行校正;(3)开展主要流域的研究工作,尤其是不同构造、地质及气候背景条件不同流域间的对比研究,建立河流锶元素及其同位素组成区域参比值;(4)在研究方法上,应该对区域内降雨、岩石、土壤、沉积物及地下水中的锶元素及其同位素地球化学特征进行系统分析,包括不同形态的锶元素及其同位素地球化学特征的研究。     

香港及珠三角地区MODIS高分辨率气溶胶光学厚度的反演

为了有效解决地区性和城市范围内的气溶胶分布并反演陆地上气溶胶的性质,一种针对中分辨率成像光谱辐射计(MODIS)的气溶胶反演新算法应运而生.本文首先通过改良的最小反射率技术(MRT)来确定季节性的地表反射率和利用瑞利通道辐射率中解析出大气上气溶胶的反射率来估计气溶胶的反射系数.结果表明,MRT地表反射率的图像和MODIS地表反射系数的产品(MOD09)有很好的契合度.两者的相关系数高达0.9.此外,考虑到不同气溶胶的光学性质和太阳观测组合对计算辐射传输的影响,本研究还制定了全面广泛的差算表(LUT).由此产生的卫星500m分辨率的气溶胶光学厚度(AOT)和香港太阳光度计(AERONET)及MicrotopsⅡ观测资料的相关系数r分别为0.96和0.87(相伴概率值P<0.0001).该研究证明了城区高分辨率气溶胶反演的可行性,还能帮助研究气溶胶的分布和城区大气瞬态污染的影响.此外,MODIS 500m分辨率的气溶胶光学厚度图像还可用于研究跨境气溶胶,使定位珠江三角洲区域污染源变得可行.     

Mass transfer in the absorption of SO2 and NOx using aqueous euchlorine scrubbing solution

Attempts have been made to generate euchlorine gas by chlorate-chloride process and to utilize it further to clean up SO2 and NOx from the flue gas in a lab scale bubbling reactor.Preliminary experiments were carried out to determine the gas and liquid phase mass transfer coefficients and their correlation equations have been established.Simultaneous removal of SO2 and NOx from the simulated flue gas using aqueous euchlorine scrubbing solution has been investigated.Euchlorine oxidized NO into NO2 completely and the later subsequently absorbed into the scrubbing solution in the form of nitrate.SO2 removal efficiency of around 100% and NOx removal efficiency of around 72 % were achieved under optimized conditions.Mass balance has been confirmed by analyzing the sulfate, nitrate, euchlorine and chloride ion using ion chromatograph/auto-titrator and comparing it with their corresponding calculated values.     

An experimental study on the airlift pump with air jet nozzle and booster pump

The experiments for high head airlifting performance with vertical tube were examined for wastewater treatment. Comparing with the centrifugal pump and other pumps, the airlift pump has some problems and limited applications. However, an advantage of an airlift pump is in its geometrical simplicity, not having any moving parts, so it is suitable in lifting fluids including tiny pieces of metal or grit. In this study, for the purpose of high lifting head, an air jet nozzle was used. We have performed experimentally according to various characteristics of the airlift pump system such as the change of submerged depth, lifting head of liquid-air mixture (total head) and air flow rate. This work has verified through experiments that airlift pump shows lifting ability for 3 m (S_r = 0.3) in comparison with conventional height, 2 m (S_r = 0.4). Also, we suggested that the new airlift pump system with the air booster pump be used to improve the higher lifting head performance.