Photocatalytic degradation of C. I. Reactive Red 24 solution with K6SiW11O39SnⅡ

Environmental friendly materials, K₆SiW₁₁O₃₉Sn (SiWSn), was synthesized. SiWSn photocatalytic decomposition of C. I. Reactive Red 24 (RR24) with the UV-lamp (253.7 nm, 20 W), Xenon lamp filtered less than 390 nm light (500 W) and sun light was investigated. The results showed that RR24 solution could be effectively decolorized with the SiWSn photocatalyst. The photocatalytic degradation efficiency of RR24 with SiWSn was affected by the initial concentration of RR2 solution, the amount of SiWSn and the photolysis time. It is demonstrated that the process of photodegradation of RR24 with SiWSn is a pesudo first-order reaction, which can be described by Langmuir-Hinshelwood equation. Hydroxyl radicals and holes are both the main oxidants in the photocatalytic reaction of RR24 with SiWSn.     

The levels, sources and reactivity of volatile organic compounds in a typical urban area of Northeast China

Air concentrations of volatile organic compounds (VOCs) were continually measured at a monitoring site in Shenyang from 20 August to 16 September 2017. The average concentrations of alkanes, alkenes, aromatics and carbonyls were 28.54, 6.30, 5.59 and 9.78 ppbv, respectively. Seven sources were identified by the Positive Matrix Factorization model based on the measurement data of VOCs and CO. Vehicle exhaust contributed the most (36.15%) to the total propene-equivalent concentration of the measured VOCs, followed by combustion emission (16.92%), vegetation emission and secondary formation (14.33%), solvent usage (10.59%), petrochemical industry emission (9.89%), petrol evaporation (6.28%), and liquefied petroleum gas (LPG) usage (5.84%). Vehicle exhaust, solvent usage and combustion emission were found to be the top three VOC sources for O₃ formation potential, accounting for 34.52%, 16.55% and 11.94%, respectively. The diurnal variation of the total VOCs from each source could be well explained by their emission characteristics, e.g., the two peaks of VOC concentrations from LPG usage were in line with the cooking times for breakfast and lunch. Wind rose plots of the VOCs from each source could reveal the possible distribution of the sources around the monitoring site. The O₃ pollution episodes during the measurement period were found to be coincident with the elevation of VOCs, which was mainly due to the air parcel from the southeast direction where petrochemical industry emission was found to be dominant, suggesting that the petrochemical industry emission from the southeast was probably a significant cause of O₃ pollution in Shenyang.     

武汉市城市地貌灾害及防治对策

城市地貌灾害含自然地貌灾害与城市人类活动所导致的地貌灾害。而大城市人口密集,人类活动强度大,所发生的灾害常常表现为自然与人工共同作用所造成,而后者常常是自然灾害的诱发因素。     

Itaconic Acid Grafted Starch Hydrogels as Metal Remover: Capacity,Selectivity and Adsorption Kinetics

Hydrogels were synthesized by free radical graft copolymerization of itaconic acid (IA) onto corn starch (S-g-IA). For this purpose, potassium permanganate (KMnO₄)-sodium bisulfite (NaHSO₃) was used as redox initiation system. The formation of grafted starches was confirmed by Fourier transform infrared spectroscopy, wide angle X-ray scattering, thermogravimetric analysis and scanning electron microscopy. The effect of monomer concentration, neutralization, addition of crosslinking agent, N,N-bismetilenacrilamide (MBAm), and initiator concentration on grafting efficiency and adsorption capacity of the starch hydrogels was investigated. It was demonstrated that the introduction of carboxyl and carbonyl groups promoted starch hydration and swelling. Grafting degree increased with the decrease of monomer concentration, increase of initiator concentration, grade of neutralization and the addition of MBAm without neutralization. Remarkably the resulting materials exhibited water absorption capacities between 258 and 1878% and the ability to adsorb metal ions. It was experimentally confirmed the metal uptake, obtaining the higher adsorption capacity (q _e  = 35 mg/g) for the product prepared with the pre-oxidation and lower initiator concentration. The removal capacity order was Pb²⁺>Ni²⁺>Zn²⁺>Cd²⁺. Moreover, the experimental kinetic and the equilibrium adsorption data for Ni²⁺ and Pb²⁺ were best fitted to the pseudo-second order and Freundlich isotherm models, respectively. This work describes for the first time the preparation of metal removal hydrogels based on starch and itaconic acid using the pair redox system KMnO₄/NaHSO₃, which avoids the starch hydrolysis and allows itaconic acid grafting incorporation without the requirement of more reactive comonomers.     

Heterogenous impacts of components in urban energy metabolism: evidences from gravity model

Environment, Development and Sustainability - The undergoing rapid urbanization is bringing dramatic economic development and social improvement for cities, but also a series of problems associated...     

Nitrous oxide emissions from a maize field during two consecutive growing seasons in the North China Plain

Nitrous oxide (N₂O) emissions from a maize field in the North China Plain (Wangdu County, Hebei Province, China) were investigated using static chambers during two consecutive maize growing seasons in the 2008 and 2009. The N₂O pulse emissions occurred with duration of about 10 days after basal and additional fertilizer applications in the both years. The average N₂O fluxes from the CK (control plot, without crop, fertilization and irrigation), NP (chemical N fertilizer), SN (wheat straw returning plus chemical N fertilizer), OM- 1/2N (chicken manure plus half chemical N fertilizer) and OMN (chicken manure plus chemical N fertilizer) plots in 2008 were 8.51, 72.1, 76.6, 101, 107 ng N/(m²·sec), respectively, and in 2009 were 33.7, 30.0 and 35.0 ng N/(m²·sec) from CK, NP and SN plots, respectively. The emission factors of the applied fertilizer as N₂O-N (EFs) were 3.8% (2008) and 1.1% (2009) for the NP plot, 3.2% (2008) and 1.2% (2009) for the SN plot, and 2.8% and 2.2% in 2008 for the OM-1/2N and OMN plots, respectively. Hydromorphic properties of the investigated soil (with gley) are in favor of denitrification. The large differences of the soil temperature and water-filled pore space (WFPS) between the two maize seasons were suspected to be responsible for the significant yearly variations. Compared with the treatments of NP and SN, chicken manure coupled with compound fertilizer application significantly reduced fertilizer loss rate as N₂O-N.     

中国石化HSE管理系统的现场实施方案探讨

阐述了中国石化HSE管理系统的实施策略、实施流程,总结出一套适合中国石化直属企业的业务管理系统现场实施方案。     

我国民用机场建设运营的突出环境保护问题及解决对策

本文从我国民用机场的工程特点和环境影响分析入手,探究解决民用机场环境影响的对策措施,进而识别出民用机场建设运营的突出环境保护问题,重点探讨机场建设运营突出环境保护问题的解决对策措施,并提出我国民用机场建设运营在环境保护方面还存在哪些亟待解决的问题。     

The Tourism Carrying Capacity of Underwater Trails in Isabel Island National Park, Mexico

The popularity of ecotourism in the marine protected areas of Mexico has increased over the last 10 years; in particular there is a large development of a SCUBA diving industry in the Mexican Pacific including Isabel Island. Given the risks associated with human activity in the marine environments around this island, we propose two ecotourism management strategies: (1) the creation and use of underwater trails, and (2) the estimation of the specific tourism carrying capacity (TCC) for each trail. Six underwater trails were selected in sites that presented elements of biological, geological, and scenic interest, using information obtained during field observations. The methodology used to estimate the TCC was based upon the physical and biological conditions of each site, the infrastructure and equipment available, and the characteristics of the service providers and the administrators of the park. Correction factors of the TCC included elements of the quality of the visit and the threat and vulnerability of the marine environment of each trail (e.g., divers’ expertise, size and distance between groups of divers, accessibility, wind, coral coverage). The TCC values ranged between 1,252 and 1,642 dives/year/trail, with a total of 8,597 dives/year for all six trails. Although these numbers are higher than the actual number of recreational visitors to the island (~1,000 dives per year), there is a need for adequate preventive management if the diving sites are to maintain their esthetic appeal and biological characteristics. Such management might be initially directed toward using only the sites and the TCC proposed here.     

Cd2+ adsorption on alkaline-pretreated diatomaceous earth: equilibrium and thermodynamic studies

Naturally occurring diatomaceous earth was modified by alkaline pretreatment, and its effectiveness for Cd²⁺ removal from contaminated water was investigated. Batch experiments were carried out to determine Cd²⁺ adsorption capacity and the efficiency of the sorption process under different experimental conditions. Experimental data showed good fitting to Langmuir and Freundlich isotherms models. The Cd²⁺ maximum adsorption capacity was 0.058 mmol g⁻¹ for raw diatomite and increased to 0.195 mmol g⁻¹ for alkaline-pretreated diatomite with efficiency higher than 96% (diatomite dose 2.5 g L⁻¹, pH 6). Adsorption of Cd²⁺ to alkaline-pretreated diatomite increased as the temperature increased. Thermodynamic parameters were calculated to evaluate the feasibility of the adsorption process at different temperatures. The adsorption process was spontaneous and endothermic. The interaction between Cd²⁺ ions and diatomite surface was weak enough to be considered as physical sorption, confirmed by the low value of activation energy.