Phenol removal from aqueous environments by natural & chemically modified kaolin clay

Natural, acid and base modified kaolin clays were studied for the sake of phenol and 4-chlorophenol removal from aqueous environments and their application to real ground and industrial wastewater samples. Scanning electron microscope (SEM), infrared spectroscopy (IR), X-ray diffraction (XRD), Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), and Surface area analysis were employed for characterization of the adsorbents microstructure. Operating factors such as adsorbent dose, solution pH, initial phenol concentration, and contact time were studied. The experimental data displayed that the increase of the adsorbent dose, contact time, and pH value from 2 to 7 increases the efficiency of the removal process. Optimal conditions for phenolic removal were; contact time of 300 min, primary phenol solution of 25 mg/L, pH 7 and 2.5 g/L as an appropriate adsorbent dose using crude (natural), acid modified and base modified kaolin clays. The higher phenolic removal efficiencies were obtained at 5 mg/L as 90, 97, 96.2%, respectively, for the adsorbents in the previously mentioned order. The adsorption capacity in the removal of phenol and 4-chlorophenol were 7.481 and 4.195, 8.2942 and 3.211, and 8.05185 and 18.565 mg/g, respectively, for the adsorbents in the same mentioned order. The adsorption equilibrium data were fitted and analyzed with four isotherm models, namely, Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm equations. The adsorption process of phenol on studied adsorbents was exothermic, spontaneous and thermodynamically favorable proved by the negative values of their thermodynamic parameters ΔH° and ΔG°. The correlation coefficient (R²) for all concentrations was higher than 0.94, which indicates that in the studied system, the data suitably fit the first-order kinetics. The % desorption capacity was amounted to 96%, 91.11%, and 87.06% of adsorbed phenol, respectively, for the adsorbents in the previous order using 0.1N NaOH and 10% V/V ethanol solutions as eluents at 25°C, indicating the reusability of the adsorbents. Kaolin and its modified forms can be introduced as eco-friendly and low-cost adsorbents in water remediation implementation.     

磺胺类抗生素在辽西河流沉积物中吸附行为研究

为了研究磺胺抗生素在辽西流域沉积物中的吸附行为特性。实验采用OECD Guideline批量平衡法,研究了磺胺甲恶唑在辽西流域沉积物中吸附动力学特性和热力学特性。动力学研究结果表明磺胺甲恶唑在沉积物中吸附动力学过程以容积扩散为主,并且是一个先快速后缓慢的非均相扩散过程。热力学研究表明磺胺甲恶唑在沉积物中的吸附,是一个自发进行的吸热过程,升高温度能够增加磺胺甲恶唑在沉积物中的吸附能力(Kd)。因此,磺胺甲恶唑容易在辽西河流沉积物中吸附残留,应当重视其在水-底泥环境体系中潜在的环境风险。     

过氧化苯甲酸叔丁酯热危险性实验研究

为了研究TBPB的热危险性,采用液体自燃点测试仪研究TBPB自燃点随浓度的变化规律,应用快速筛选量热仪研究不同升温速率下TBPB的热分解,同时利用差示扫描量热仪研究TBPB热流-温度变化规律。研究结果表明:当TBPB浓度为0.83 g/L时,自燃温度达到最低值125.1 ℃,浓度是影响其自燃温度的重要指标;随升温速率升高,初始分解温度逐渐升高,可见升温速率越高,TBPB分解的初始温度越高,当环境温度未达到初始分解温度时,相对较安全;TBPB最低起始反应温度为95.4 ℃,平均放热量为893.28 J/g,运用Kissinger,Ozawa 这2种方法得出E1=84 063.2 J/mol,E2=86 442.3 J/mol,指前因子为1.69×109,反应级数为0.92。其放热量较大,起始反应温度较低,热量无法及时移出时,极易发生燃烧爆炸事故。     

磷石膏还原分解反应热力学分析

磷石膏是高浓度磷肥工业排放的固体废弃物,采用HSC Chemistry 5热力学计算软件对焦炭、硫磺、氢气、一氧化碳与磷石膏还原反应进行了对比分析,探索如分解温度、平衡常数、耗能与还原介质的关系。结果表明,不论采用上述何种还原介质,CaSO4还原分解成CaS均比CaO容易进行。     

稻壳基活性炭的制备及其对亚甲基蓝吸附的研究

以稻壳为原料，采用K2CO3活化法和H3P04活化法制备了比表面积为1312m^2／g和682m^2／g的活性炭，通过扫描电子显微镜（SEM）、X-射线衍射仪（XRD）对样品进行了表征，并将孔隙发达的活性炭样品用于对亚甲基蓝的吸附，结果表明，K2CO3活化法制备的活性炭样品具有更多的微孔结构；随着亚甲基蓝溶液初始浓度的增加、活性炭吸附时间的延长，亚甲基蓝的去除率呈现逐渐降低和逐渐增大的变化规律，当pH值为6时，活性炭对亚甲基蓝的吸附效果最佳；稻壳基活性炭对亚甲基蓝的吸附等温线符合Langmuir模型，Qm最高可达476．2mg／g；热力学参数△G^0△H^0和△S^0均为负值，表明稻壳基活性炭对亚甲基蓝的吸附是一个自发的放热反应。     

高温高压下C-O-H流体的研究

C O H流体是地球内部流体的主要组成部分 ,确定高温高压下它们的组成关系对于认识地球的演化、氧化还原环境以及促进包裹体的研究都具有重要的意义。高温高压实验确定了它们与石墨平衡存在一个间断温度 ,理论计算一般在此温度之上进行。当压力、温度确定时 ,再加上一个外部条件如fO2 或H/O比值 ,就可以得到它们的平衡组成。由于缺乏流体组分的高温高压热力学数据 ,目前的理论计算结果与实验值存在差别。电解质的出现和动力学因素影响着流体组分的平衡计算。加强系统研究 ,在实验中尽量采用就位分析的方法 ,获取更多更可靠的高温高压热力学数据 ,加强流体平衡影响因素的研究 ,是今后进一步的研究方向     

Preparation1 and utilization of wheat straw anionic sorbent for the removal of nitrate from aqueous solution

In order to reduce the impact of eutrophication caused by agricultural residues (i.e. excess nitrate) in aqueous solution, economic and effective anionic sorbents are required. In this article, we prepared anionic sorbent using wheat straw. Its structural characteristics and adsorption properties for nitrate removal from aqueous solution were investigated. The results indicate that the yield of the prepared anionic sorbent, the total exchange capacity, and the maximum adsorption capacity were 350%, 2.57 mEq/g, and 2.08 mmol/g, respectively. The Freundlich isotherm mode is more suitable than the Langmuir mode and the adsorption process accords with the first order reaction kinetic rate equation. When multiple anions (SO42-, H2PO4-, NO3-, and NO2-) were present, the isotherm mode of prepared anionic sorbent for nitrate was consistent with Freundlich mode; however, the capacity of nitrate adsorption was reduced by 50%. In alkaline solutions, about 90% of adsorbed nitrate ions could be desorbed from prepared anionic sorbent. The results of this study confirmed that the wheat straw anionic sorbent can be used as an excellent nitrate sorbent that removes nitrate from aqueous solutions.     

Non-equilibrium thermodynamics of ecosystems: Entropic analysis of stability and diversity

The aim of the paper is first to develop a non-equilibrium thermodynamic model of a multi-species ecosystem. The key to this is the expression of entropy-production (change of entropy) which is equivalent to a well-known expression of Liapunov function used in many problems of ecological and chemical reaction systems. On the basis of the expression of entropy-production we have made an entropic (thermodynamic) analysis of ecological stability (both global and local) including the study of interrelation between ecological diversity and stability. As illustrative examples we have discussed some basic problems of classical and generalized Lotka–Volterra systems.     

改性沸石同步深度脱氮除磷的实验研究

以氯化铝、硫酸镁为活性剂，采取高温活化，对天然沸石进行改性，并通过正交试验优化了改性工艺。以模拟二级出水为研究对象，考察了改性沸石同步去除水样中氮磷的效果及其影响因素，并对不同温度下改性沸石对磷酸盐和氨氮的吸附平衡和吸附热力学，以及脱氮除磷机理进行了探讨。结果表明，15 min后改性沸石脱氮除磷过程基本完成，其pH值范围与实际污水相符，最佳pH值为8；当投加质量浓度为0.8 g/L时，出水中氨氮浓度和总磷浓度均达到景观环境用水水质标准(GB/T 18921-2002)。改性沸石对氨氮和磷酸盐的吸附均符合Langmuir等温吸附方程。热力学参数ΔG⁰、ΔH⁰分别为正值和负值，表明该吸附是一个自发的吸热过程。     

梧桐叶活性炭对不同极性酚类物质的吸附

以梧桐枯叶为原料、磷酸为活化剂制备活性炭,研究了不同浸渍比、活化温度、活化时间对活性炭孔结构和表面化学性质的影响. 通过XRD(X射线衍射)、BET比表面积、红外图谱、XPS(X射线光电子能谱)等对梧桐叶活性炭进行表征,并对其表面零电荷点(pH_pzc)进行了测定,从热力学的角度研究了梧桐叶活性炭对水溶液中不同极性酚类物质的吸附行为. 结果表明,梧桐叶活性炭制备的最佳工艺条件为:浸渍比(质量比)为3∶1,活化温度为450℃,活化时间为2.5h. 浸渍比增大、活化温度升高和活化时间的延长,都有利于增加活性炭表面极性;活性炭的极性表面对酚类物质的吸附有重要影响,梧桐叶活性炭对苯酚、邻硝基苯酚和对硝基苯酚的吸附量分别达到79.2、93.9和95.8mg/g. 热力学研究表明,梧桐叶活性炭对不同极性酚类物质的吸附符合Frenundlich等温吸附方程,并且是一个自发的放热过程,其吸附焓变、吸附熵变、吸附自由能变均小于零.