Preparation of solar-enhanced AlZnO@carbon nano-substrates for remediation of textile wastewaters

Photoactive aluminum doped ZnO(AlZnO) was synthesized by sol-gel method.After that,AlZnO photocatalyst was deposited on five carbon-based materials(CBMs) using ultrasonic route followed by solid-state mixing using ball mill.The CBMs used were poly aniline(PANI),carbon nitride(CN),carbon nanotubes(CNT),graphene(G),and carbon nanofibers(CNF).The crystal phases,elemental compositions,morphological,and optical properties of the AlZnO@CBMs composites were investigated.Experimental results revealed that two of AlZnO@CBMs composites exhibited superior bleaching efficiency(100% removal) and photocatalytic stability(three cycles) for 50 μmol/L Methylene Blue(MB) contaminated water after 60 min irradiation in visible light at pH 6.5,0.7% H_2O_2,and 5 g/L inorganic salts.Under optimum conditions,AlZnO@CBMs nanocomposites were employed for the treatment of mixed dyestuffs composed of MB,Methyl Orange(MO),Astrazone Blue FRR(BB 69),and Rhodamine B(RhB) dyes under dark,ultraviolet,visible,and direct sunlight.For mixed dyestuffs,the AlZnO@G achieved the highest dye sorption capacity(60.91 μmol dye stuffs/g) with kinetic rate 8.22 × 10~(-3) min~(-1) in 90 min via multi-layer physisorption(Freundlich isotherm) on graphene sheet.In additions,AlZnO@CN offered the highest photo-kinetic rate(K_(photo)) of～54.1 × 10~(-3) min~(-1)(93.8% after 60 min) under direct sunlight.Furthermore,the selective radical trapping experiment confirmed that the holes and oxidative superoxide radicals are crucial on dyes photodegradation pathway.Owing to their superior performance,AlZnO@G and AlZnO@CN nanocomposites can offer an effective in-situ solar-assisted adsorption/photocatalytic remediation of textile wastewater effluents.     

电助光催化处理高COD农药废水的研究

采用自制的电助光催化装置处理高浓度COD农药废水,处理后的出水水质符合《污水综合排放标准》(GB8978-1996)三级标准。     

异构环保信息资源整合及归档系统的开发与应用

随着环保信息资源的不断丰富,不同应用系统生成的各种异构数据日益增多,信息孤岛现象十分严重。异构环保信息资源整合及归档系统将分散的信息系统进行有效整合,在异构平台上实现了信息收集、流转及共享利用,全面提升了环保档案的信息化建设水平,为新时期下环保档案信息管理工作提供了一条新途径。     

The chemical exploitation of nickel phytoextraction: An environmental, ecologic and economic opportunity for New Caledonia

Herein, we explore the outlines of an innovative method based on the chemical recovery of metal-rich biomass produced in phytoextraction technologies. Taking advantage of the adaptive capacity of some New Caledonian plants to hyperaccumulate Ni²⁺ cations in their aerial parts, this technique is based on the direct use of metals derived from plants as “Lewis acid” catalysts in organic chemistry. Metallic cations contained in New Caledonian nickel hyperaccumulators are recovered through a simple cost-effective process and serve the preparation of heterogeneous catalysts used in synthetic transformations allowing access to molecules with high added-value. The design of all processes is in line with the principles of green chemistry; it is adapted to the new economic constraints; it offers a new relevant outlet for metal-rich biomass; and it represents an alternative to non-renewable mineral materials.     

Non-Fickian dispersion in a single fracture

Solute transport in fractured rocks is of major interest in many applications, from the petroleum industry to ground water management. This work focuses on the dispersion process in a transparent replica of a real single fracture. The fracture exhibits strong changes in heterogeneity, with the first half very heterogeneous and the second half fairly homogeneous. Three models have been used to interpret the tracer experiments: the classical advection-dispersion equation (ADE), the continuous time random walk (CTRW), and the stratified model. The main goals were to test these models and to study possible correlations between fitting parameters and heterogeneities. As expected, the solution derived from the ADE equation appears to be unable to model long-time tailing behavior. On the other hand, the results confirm the CTRW robustness and the coefficient beta seems well correlated to heterogeneities. Finally, the stratified model is also able to describe non-Fickian dispersion. The parameters defined by this model are correlated to the heterogeneities of the fracture.     

Heterogeneous oxidation of SO2 by O3-aged black carbon and its dithiothreitol oxidative potential

Ozone (O₃) is an important atmospheric oxidant. Black carbon (BC) particles released into the atmosphere undergo an aging process via O₃ oxidation. O₃-aged BC particles may change their uptake ability toward trace reducing gases such as SO₂ in the atmosphere, leading to different environmental and health effects. In this paper, the heterogeneous reaction process between O₃-aged BC and SO₂ was explored via in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Combined with ion chromatography (IC), DRIFTS was used to qualitatively and quantitatively analyze the sulfate product. The results showed that O₃-aged BC had stronger SO₂ oxidation ability than fresh BC, and the reactive species/sites generated on the surface had an important role in the oxidation of SO₂. Relative humidity or 254 nm UV (ultraviolet) light illumination enhanced the oxidation uptake of SO₂ on O₃-aged BC. The oxidation potentials of the BC particles were detected via dithiothreitol (DTT) assay. The DTT activity over BC was decreased in the process of SO₂ reduction, with the consumption of oxidative active sites.     

银、钕掺杂TiO_2催化光解甲基橙的实验研究

实验用水热合成法制备出银、钕掺杂TiO2催化剂粉体,然后以高压汞灯为光源,掺杂TiO2催化剂粉体为光化降解催化剂,探究对甲基橙模拟印染废水光催化分解的效果。光解实验研究采用正交设计法,以模拟废水浓度、催化剂用量、光照时间以及pH为因素,各因素选取4个水平,对催化光解甲基橙染料的降解率进行评价。分析结果表明:银、钕掺杂TiO2催化剂对甲基橙光化降解有良好的效果,最佳实验条件为:溶液pH为5,甲基橙的初始质量浓度为2 mg/L,催化剂投加量60 mg/L和光照时间80 min。在最佳条件下,连续光照8 h后甲基橙的降解率达到92%以上。     

Polymer hydrogels with enhanced stability and heterogeneous Fenton activity in organic pollutant removal

Polymer hydrogel-based materials have been shown to act as novel Fenton catalysts for water treatment, but the rational design of hydrogel-based catalysts with good stability has been a great challenge. To increase the stability and activity of polymer-based Fenton catalysts, uniform urchin-like α-Fe_2O_3 was grown in situ in a PVA carrier matrix here. PVA molecules promoted the growth of urchin-like α-Fe_2O_3, and then the PVA hydrogel acted as a barrier and carrier to reduce agglomeration. Through coordination by hydroxyl groups,PVA had good combination with Fe ions and α-Fe_2O_3. The formation of Fe–O–C bonds between iron oxides and polymers was reported for the first time, enhancing the material stability during catalysis. Under higher PVA concentrations, the resulting composite hydrogel could generate more ˙OH due to the increase in the number of active sites because of the hairy urchin-like structure. In tetracycline degradation through a heterogeneous Fenton reaction, the resulting material had good catalytic activity from pH 2 to pH 10 with low iron leaching, good reusability and remained at a level of nearly 90%after five consecutive cycles. Density functional theory calculations were used to further prove the mechanism of structural change of the iron oxides. The HOMO and LUMO energies of the iron oxides changed from 5.428 and 4.899 eV to 5.926 and 5.310 eV,indicating that the presence of PVA could influence the charge of the iron atom. The results provide new insights into the preparation of polymer hydrogel-based heterogeneous Fenton catalysts with enhanced stability for water treatment.     

Carbon nanotubes-incorporated MIL-88B-Fe as highly efficient Fenton-like catalyst for degradation of organic pollutants

CNTs were incorporated into MIL-88B-Fe to get a new Fenton-like catalyst (C@M). Fe(II) was introduced in C@M to get a fast initiation of Fenton-like reaction. Fe(II) content in C@M was related with oxygen-containing functional groups on CNTs. C@M shows efficient catalytic degradation of pollutants over a wide pH range. Iron-based metal organic frameworks have been verified to be efficient heterogeneous Fenton catalysts due to their open pore channels and highly uniform distribution of metallic centers. In these catalysts, however, the iron element is mainly in the form of Fe(III), which results in a process required to reduce Fe(III) to Fe(II) to initiate Fenton reaction. To address this problem, carbon nanotubes (CNTs) with electron-rich oxygen-functional groups on the surface were incorporated into the metal organic frameworks (MIL-88B-Fe) to improve Fe(II) content for an enhanced Fenton-like performance. The prepared CNT@MIL-88B-Fe (C@M) showed much stronger catalytic ability toward H₂O₂ than MIL-88B-Fe. The pseudo-first-order kinetic constant for phenol degradation by C@M (0.32 min^–1) was about 7 times that of MIL-88B-Fe, and even higher than or comparable to the values of reported heterogeneous Fenton-like catalysts. Moreover, the Fenton-like system could effectively degrade various kinds of refractory organic pollutants and exhibited excellent catalytic activity over a wide pH range (4–9). XPS analysis confirmed that Fe(II) content of the catalyst gradually increased with CNT loadings. Electron spin resonance analysis showed that the signal intensity (•OH) of C@M was much higher than MIL-88B-Fe, which was consistent with the degradation efficiency of pollutants. Furthermore, the Fe(II) content of the catalyst gradually increased along with the oxygen-functional group content of CNTs. The result demonstrated that oxygen-containing functional groups of CNTs have a significant impact on the enhanced catalytic performance of C@M. This study provides a new insight to enhance Fenton reaction by using nanocarbon materials.     

大气中有机胺类物质反应机理和消除过程研究

综述大气中有机胺可能的来源、健康危害及其在大气中的均相和非均相化学转化机制,阐述有机胺的反应产物对二次有机气溶胶及其对大气气溶胶的物理和化学性质的改变,此类改变增强大气气溶胶间接气候效应(如成云结核能力等)。大气中的有机胺主要通过与大气氧化剂的反应和非均相反应过程的溶解或置换进入颗粒相,而后随着湿沉降(如云滴、雾滴、雨滴等)到达地面或海面。