The effect of graphene presence in flame retarded epoxy resin matrix on the mechanical and flammability properties of glass fiber-reinforced composites

The effect of adding graphene in epoxy containing either an additive (MP) or reactive-type (DOPO) flame retardant on the thermal, mechanical and flammability properties of glass fiber-reinforced epoxy composites was investigated using thermal analysis; flexural, impact, tensile tests; cone calorimetry and UL-94 techniques. The addition of MP or DOPO to epoxy had a thermal destabilization effect below 400 °C, but led to higher char yield at higher temperatures. The inclusion of 10 wt% flame retardants slightly decreased the mechanical behavior, which was attributed to the poor interfacial interactions in case of MP or the decreased cross-linking density in case of DOPO flame retarded resin. The additional graphene presence increased flexural and impact properties, but slightly decreased tensile performance. Adding graphene further decreased the PHRR, THR and burning rate due to its good barrier effect. The improved fire retardancy was mainly attributed to the reduced release of the combustible gas products.     

截留分子质量和材质对浸没式超滤膜过滤性能的影响

针对截留分子质量和材质对浸没式超滤膜处理微污染地表水过滤性能的影响问题,研究了两者对膜去除水中颗粒物和有机污染物的特性及其对膜污染的影响。结果表明,随着膜截留分子质量的减小,超滤膜对浊度和各有机物指标的去除率逐渐升高,但超滤膜对溶解性有机物的去除率较低;不同材质的超滤膜对有机物的去除率存在差异。不同截留分子质量和材质的超滤膜过滤原水时的污染程度不同,截留分子质量较小的超滤膜污染程度较轻,但容易引起不可逆膜污染;聚砜(PS)膜抗污染的能力要强于聚偏氟乙烯(PVDF)和聚氯乙烯(PVC)膜,在实际应用中应根据不同水质特点合理选择超滤膜的截留分子质量和材质。     

Feasibility assessment of introducing distributed energy resources in urban areas of China

In this study, based on the consideration of achieving a low-carbon city, a distributed energy system is promoted by integrating combined heat and power (CHP) plant, biomass energy and photovoltaic technology, for the urban areas in China. An analytical model has been developed for estimating an economically efficient installation and operation pattern for the distributed energy system. As an illustrative example, a numerical study is conducted of feasible distributed energy system for a model area in Shanghai, while considering five scenarios with different technology combinations. According to the simulation results, although enjoying reasonable environmental merits, it is hard to diffuse the distributed generation technologies, especially some renewable ones, in the model area from the economic point of view. Currently, the most feasible technology is the natural gas CHP system, which has a cost reduction ratio of only 0.7%. In addition, the sensitivity analyses illustrate that the introduction of electricity buy-back and the reduction of biogas price can promote the adoption of some renewable technologies to some extent.     

Magnetic gamma-Fe(2)O(3) nanoparticles coated with poly-l-cysteine for chelation of As(III), Cu(II), Cd(II), Ni(II), Pb(II) and Zn(II)

An anaerobic attached-growth bioreactor (AAGBR) of 3.52 L was operated for 510 days to treat sulfide-laden organic wastewater where nitrate and nitrite were introduced as electron acceptors. When the influent sulfide was kept at 200mg S(2-)-S/L and organic carbon was increased from 20 to 33.6 mg C/L, and the hydraulic retention time decreased from 41.4 to 2.67 h, the removal rates of sulfide and organic carbon reached 99.9% and 91.8% at the loading rates of 1800 mg S(2-)-S/(Ld) and 302.4 mg C/(Ld), respectively. Simultaneously, the introduced electron acceptors of nitrate and nitrite were, respectively, removed by 99.9% and 99.9% at the loading rates of 472.5 mg NO(3)(-)-N/(Ld) and 180 mg NO(2)(-)-N/(Ld). Inside the AAGBR, both autotrophic and heterotrophic denitrification processes were noted to take place. When the influent organic carbon was increased from 20 to 33.6 mg C/L, the nitrate and nitrite consumed for heterotrophic denitrification accounted for 27.3% and 48.5%, respectively. This simultaneous autotrophic and heterotrophic desulfurization-denitrification process has provided a demonstration of the possibility to eliminate sulfide and organic carbon with the presence of nitrate and nitrite.     

Microwave enhanced Fenton-like process for the treatment of high concentration pharmaceutical wastewater

This paper explored a novel process for wastewater treatment, i.e. microwave enhanced Fenton-like process. This novel process was introduced to treat high concentration pharmaceutical wastewater with initial COD loading of 49,912.5 mg L⁻¹. Operating parameters were investigated and the optimal condition included as follows: microwave power was 300 W, radiation time was 6 min, initial pH was 4.42, H₂O₂ dosage was 1300 mg L⁻¹ and Fe₂(SO₄)₃ dosage was 4900 mg L⁻¹, respectively. Within the present experimental condition used, the COD removal and UV₂₅₄ removal reached to 57.53% and 55.06%, respectively, and BOD₅/COD was enhanced from 0.165 to 0.470. The variation of molecular weight distribution indicated that both macromolecular substances and micromolecular substances were eliminated quite well. The structure of flocs revealed that one ferric hydrated ion seemed to connect with another ferric hydrated ion and/or organic compound molecule to form large-scale particles by means of van der waals force and/or hydrogen bond. Subsequently, these particles aggregated to form flocs and settled down. Comparing with traditional Fenton-like reaction and conventional heating assisted Fenton-like reaction, microwave enhanced Fenton-like process displayed superior treatment efficiency. Microwave was in favor of improving the degradation efficiency, the settling quality of sludge, as well as reducing the yield of sludge and enhancing the biodegradability of effluent. Microwave enhanced Fenton-like process is believed to be a promising treatment technology for high concentration and biorefractory wastewater.     

Strain rate dependent mechanical properties of new albany reference shale

Drilling, mining and blasting of rock-like materials, in situ fracturing, rock fragmentation size and permeability extension are strongly affected by strain rates of loading. For low strain rates, fragment sizes are large, and cracks propagate further. For high strain rates, fragment sizes are small and cracks are localized. The purpose of the present investigation is to determine the effects of strain rate on the initial (linear) value of Young's modulus and on Poisson's ratio for different grades of New Albany oil shale, a reference oil shale designated by the U.S. Department of Energy. Material anisotropy is considered. Cylindrical specimens cored in a particular orientation of the oil shale formation are tested in compression, and the rate effects are investigated. An efficient data acquisition/reduction system is developed, interfacing with an Instron closed-loop hydraulic testing machine. Strain gauge instrumentation is used to measure lateral and longitudinal strains. Strain rates of about 10⁻⁵–10⁰/sec are studied.     

Assessing spatial and temporal variations in regional sustainability in mainland China from 2004 to 2014

Clean Technologies and Environmental Policy - Sustainable development in China is under increasing pressure from rapid population growth and economic activities in recent decades. Despite the...     

Effect of orifice shapes on the detonation transmission in 2H2–O2 mixture

In this study, the effect of orifice geometries on the detonation propagation is considered systematically in stoichiometric 2H₂–O₂ mixture. Three various orifice shapes with the same blockage ratio (BR = 0.889) are used firstly, i.e., round, square and triangular. Eight PCB pressure transducers are employed to obtain the average velocity through two adjacent signals while the smoked foil technique is used to record the detonation cellular pattern. The experimental results indicate that three different propagation modes can be observed: (1) when the initial pressure (P₀) is smaller than the critical value (P_c), the steady detonation wave cannot be produced before the orifice plate, afterwards, the mechanism of deflagration to detonation transition (DDT) is seen; (2) near the critical pressure, a steady detonation wave is formed prior to the obstacle, but the failure of detonation is seen after its propagation through the orifice plate due to the diffraction effect and the mass and momentum loss from the wall, and then the phenomenon of detonation re-initiation is observed due to the reflection from the wall; (3) at the initial pressure larger than the critical value, the steady detonation wave can propagate through the orifice plate without decay. Moreover, although the effect of orifice shapes on the critical pressure can be nearly ignored, the re-ignition position is different among three various orifice geometries. For the cases of round and square orifices, the ignition position is produced near the center of the wall. However, the detonation wave is re-ignited from the corner in the case of triangular orifice. Finally, the critical condition of detonation propagation can be quantified as D_H/λ > 1. But the critical values of D_H/λ are not uniform among three different orifice geometries. For the cases of round, square and triangular orifices, the critical values of D_H/λ are 8.94, 5.88 and 3.84, respectively.     

膜生物反应器与预处理联用净化微污染引黄水库水

为考察膜粉末活性炭生物反应器(PAC-MBR)处理微污染原水的效能,向其中加入混凝剂(聚合氯化铝和三氯化铁)以及与混凝-沉淀、混凝-气浮联用,研究4种组合工艺对引黄水库水的除污染效能和膜污染状况,并与水厂常规工艺及超滤工艺进行比较.结果表明:各种组合工艺均可将出水浑浊度和颗粒数控制在0.02 NTU和50 mL-1以下,去除率分别达98%和95%以上;4种组合工艺出水UV254平均为0.043～0.045 cm-1,去除率分别为(18.28±9.35)%、(16.76±6.14)%、(3.23±1.26)%和(6.38±2.26)%;出水CODMn平均值在1.85～1.94 mg/L,去除率分别为(34.22±7.49)%、(33.20±6.99)%、(22.20±8.91)%和(41.72±14.25)%.各工艺对颗粒物质和有机物的去除效能均优于常规工艺,而同常规工艺+超滤膜出水基本相同.各工艺对氨氮的去除率在95%以上,且不存在亚硝酸盐氮积累的现象.在膜污染控制方面,混凝-沉淀以及混凝-气浮的效果较优,随后是三氯化铁,而投加聚合氯化铝的效果最差.     

浮石催化水中臭氧分解研究

为考察浮石表面化学性质对水中臭氧分解的影响,测定了浮石催化水中臭氧分解的速率常数并探讨催化臭氧分解的途径．结果表明:浮石促进水中臭氧一级分解速率常数提高了37.4％;利用叔丁醇捕获生成的羟基自由基,催化臭氧分解速率常数降低了45.2％,浮石催化臭氧分解生成了羟基自由基;浮石表面羟基密度与催化臭氧分解率成正相关;随着溶液初始pH值增大,单独臭氧分解和浮石催化臭氧分解率均增加;由浮石pH_pzc决定的表面电荷状态与催化臭氧分解效果有关,表面接近电中性时对催化臭氧分解有利．水中臭氧分解主要发生在浮石表面,浮石表面的金属氧化物可能是催化水中臭氧分解的活性物质．