Photocatalytic Treatment of RDX Wastewater with Nano-Sized Titanium Dioxide (5 pp)

Background, Aim and Scope The polynitramines, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), are important military explosives and regulated toxic hazardous compounds. Production, testing and use of the compounds has resulted in numerous acres of contaminated soils and groundwater near many munitions facilities. Economical and efficient methods for treatment of wastewater and cleanup of soils or groundwater containing RDX and HMX are needed. This study focuses on the photocatalytic treatment of RDX wastewater with nano-sized titanium dioxide (nano-TiO2) under simulated sunlight, whose intensity and wavelength are similar to that of the real sunlight in Xi'an at noon. The objective is to determine the potential for RDX destruction with nano-TiO2 in aqueous solution. Materials and Methods: An activated carbon fiber (ACF) cloth-loaded with nano-TiO2 was put into the RDX containing solution, and the concentration of RDX was measured (by HPLC–UV) at regular time intervals under simulated sunlight. Results: The RDX degradation percentage of the photocatalytic process is higher than that of Fenton oxidation before 80 min, equivalent after 80 min, and it reaches 95% or above after 120 min. The nano-TiO2 catalyst can be used repeatedly. Discussion: The photocatalytic degradation kinetics of RDX under simulated sunlight can be described by a first-order reaction kinetics equation. The possible degradation mechanism of RDX was presented and the degradation performance was compared with that of biological method. Conclusions: It was demonstrated that the degradation of RDX wastewater is very effective with nano-TiO2 as the photocatalytic catalyst under simulated sunlight. The efficiency of the nano-TiO2 catalyst for RDX degradation under simulated sunlight is nearly identical to that of Fenton oxidation. Recommendations and Perspectives: To date, a number of catalysts show poor absorption and utilization of sunlight, and still need ultraviolet light irradiation during wastewater degradation. The nano-TiO2 used in the described experiments features very good degradation of RDX under simulated sunlight, and the manufacturing costs are rather low (around 10 Euro/m2). Moreover, the degradation efficiency is higher compared to that of the biological method. This method exhibits great potential for practical applications owing to its easiness and low cost. If it can be applied extensively, the efficiency of wastewater treatment will be enhanced greatly.     

137Cs budget during the period of 1960s in a small drainage basin on the Loess Plateau of China

A sediment profile with a thickness of 28.12 m in a failed reservoir in a small catchment of the Yuntaishan Gully in the Loess Plateau of China consisted of 44 flood couplets deposited during the period from 1960 to 1970 with total volume of 2.36 x 10(6)m(3). Specific sediment yields for a flood event varied from 300 t km(-2) to 14,400 t km(-2) and annual sediment yields varied from 2500 t km(-2) in 1966 to 40,000 t km(-2) in 1964 with a mean value of 12,700 t km(-2)a(-1) for the period. Average annual (137)Cs concentrations of the sediments increased from 0.92 Bq kg(-1) in 1960 to 4.82 Bq kg(-1) in 1963, then decreased to 1.53 Bq kg(-1) in 1970. The total (137)Cs activity in the reservoir sediments was 9.22 x 10(9) Bq, which accounted for 31.9% of the total (137)Cs fallout precipitation of 2.89 x 10(10) Bq within the catchment during the period. The proportion of the (137)Cs loss from the catchment to the (137)Cs fallout precipitation within the catchment in a year varied between 8.01% and 66.8%, and it was 20.9% for the peak (137)Cs deposition year of 1963 and 52.0% in 1964. By analysis of the (137)Cs budget in the catchment for the (137)Cs peak precipitation period from 1962 to 1964, the (137)Cs surface enrichment coefficient Gamma should be much less than 0.23. And for calculation of soil losses on the cultivated land in the inter-gully area by using the Mass Balance Model II, the value of Gamma should be 0.05-0.1.     

Influence of NOx on the activity of Pd/θ-Al2O3 catalyst for methane oxidation: Alleviation of transient deactivation

Alumina supported Pd catalyst（Pd/Al₂O₃） is active for complete oxidation of methane, while often suffers transient deactivation during the cold down process. Herein, heating and cooling cycle tests between 200 and 900 °C and isothermal experiments at 650 °C were conducted to investigate the influence of NO_x on transient deactivation of Pd/θ-Al₂O₃ catalyst during the methane oxidation. It was found that the co-fed of NO alleviated transient d...     

Review Study on Main Models of Market Integration

With the endless strengthening of the economic globalization trend, the world market gradually steps into a new turn of the market integration period. Market integration in China is always the key study field of academic communities, but it is developed late, whatever content system or methodology shall be greatly improved as expected. This paper aims at summarizing and reviewing the study on the content system and main demonstrations of market integration in order to provide theoretical guide and methodological basis for related studies.     

工业含氨污染处理技术的经济价值分析

揭示了氨污染处理的成本效益，提出氨作为废物与资源的临界点浓度与氨的经济价值模型，并探讨了不同形态及介质中氨污染处理技术的成本差异.结果表明，在废水中氨氮浓度接近于10%时，通过资源化利用基本能够达到净现值为0，即收支平衡.相同进水浓度时，氨氮在碱性条件下单位处理成本最低，为0.19~0.41元/kg NH₃，在离子态、重金属及有机物络合形态下，会分别增加2、8及13倍左右的单位处理成本.在气态介质中，氨的处理成本约为-0.5~6元/kg NH₃，但实际工艺中加热浓缩等过程会进一步增加成本.含氨污染在实际工艺中多为气态、液态以及与其他杂质共存状态，存在污染的跨介质转移风险.今后应进行全过程统筹，实现含氨污染处理经济成本最小化的同时，降低环境风险.     

Future private car stock in China: current growth pattern and effects of car sales restriction

Mitigation and Adaptation Strategies for Global Change - Car stock projection is essential to evaluating the energy and environmental impacts of private cars in China. Since the private car...     

黑龙江省大豆加工业污染调研及分析

黑龙江省是中国的大豆之乡，在中国大豆生产中起着举足轻重的作用。近年来，大豆加工业迅猛发展，但与此同时产生的废水处理问题也不容忽视。本文通过实地调研和现状分析，指出目前大豆加工企业废水处理共有问题，并提出相应的对策和措施，为中国大豆加工业污水处理提供基础和借鉴。     

中国重大自然灾害监测与评估信息系统的建设与应用

中国在１９９１～１９９５年期间，应用遥感（ＲＳ）和地理信息系统（ＧＩＳ）技术建立了重大自然灾害监测与评估信息系统，它包括洪水、林火、干旱、雪灾、地震、沙漠化和松毛虫灾害等七种自然灾害。整个研究和应用工作主要包括下述几部分：·建立灾害历史数据库和灾害背景数据库；·研究重大自然灾害的区划和危害程度分区；·建立单灾种的监测与评估系统（在微机或工作站系统上）；·对突然发生的自然灾害（如洪水、林火、地震等）建立应急反应系统；·应用这些技术和系统对１９９１年以来发生的洪水、干旱、林火等进行监测与评估，为主管部门防灾救灾提供辅助决策依据。本文是在集体研究成果的基础上加以概括，并提出一些个人的看法。