Applications on agricultural and forest waste adsorbents for the removal of lead (II) from contaminated waters   总被引：1，自引：1，他引：0  

Cafer Saka  ?mer ?ahin  Mehmet Ma?uk Kü?ük 《International Journal of Environmental Science and Technology》2012,9(2):379-394

At present, there is growing interest in using low cost, commercially available materials for the adsorption of heavy metals. The major advantages of adsorption technologies are its effectiveness in reducing the concentration of heavy metal ions to very low levels and the use of inexpensive adsorbent materials. In this review, agricultural and forest waste adsorbents were used to remove Pb²⁺ ions in wastewater treatment, and their technical feasibilities were reviewed in studies mainly from 2000 to 2010. They all were compared with each other by metal binding capacities, metal removal performances, sorbent dose, optimum pH, temperature, initial concentration and contact time. Although commercial activated carbon is widely used in wastewater treatment applications, it has high costs. The use of agricultural by-products as adsorbent material to purify heavy metal contaminated water has become increasingly popular through the past decade because they are less expensive, biodegradable, abundant and efficient. Instead of activated carbon, this study was focused on the inexpensive materials such as agricultural and forest waste. It was shown that these alternative adsorbents had sufficient binding capacity to remove Pb²⁺ ions from wastewater.  相似文献   

K-Ar dating,whole-rock and Sr-Nd isotope geochemistry of calc-alkaline volcanic rocks around the Gümüşhane area: implications for post-collisional volcanism in the Eastern Pontides,Northeast Turkey     

Zafer Aslan  Mehmet Arslan  İrfan Temizel  Abdullah Kaygusuz 《Mineralogy and Petrology》2014,108(2):245-267

Volcanic rocks from the Gümü?hane area in the southern part of the Eastern Pontides (NE Turkey) consist mainly of andesitic lava flows associated with tuffs, and rare basaltic dykes. The K-Ar whole-rock dating of these rocks range from 37.62?±?3.33 Ma (Middle Eocene) to 30.02?±?2.84 Ma (Early Oligocene) for the andesitic lava flows, but are 15.80?±?1.71 Ma (Middle Miocene) for the basaltic dykes. Petrochemically, the volcanic rocks are dominantly medium-K calc-alkaline in composition and show enrichment of large ion lithophile elements, as well as depletion of high field strength elements, thus revealing that volcanic rocks evolved from a parental magmas derived from an enriched mantle source. Chondrite-normalized rare-earth element patterns of the volcanic rocks are concave upwards with low- to-medium enrichment (La_CN/Lu_CN?=?3.39 to 12.56), thereby revealing clinopyroxene- and hornblende-dominated fractionations for andesitic-basaltic rocks and tuffs, respectively. The volcanic rocks have low initial ⁸⁷Sr/⁸⁶Sr ratios (0.70464 to 0.70494) and εNd_(i) values (+1.11 to +3.08), with Nd-model ages (T_DM) of 0.68 to 1.02 Ga, suggesting an enriched lithospheric mantle source of Proterozoic age. Trace element and isotopic data, as well as the modelling results, show that fractional crystallization and minor assimilation played an important role in the evolution of the volcanic rocks studied. The Eocene to Miocene volcanism in the region has resulted from lithospheric delamination and the associated convective thinning of the mantle, which led to the partial melting of the subduction-metasomatized lithospheric mantle.  相似文献   

3D analysis of kinematic behavior of granular materials in triaxial testing using DEM with flexible membrane boundary   总被引：2，自引：2，他引：0  

Mehmet B. Cil  Khalid A. Alshibli 《Acta Geotechnica》2014,9(2):287-298

This paper describes the constitutive behavior and particle-scale kinematics of granular materials in three-dimensional (3D) axisymmetric triaxial testing using discrete element method (DEM). PFC3D code was used to run the DEM simulations using a flexible membrane boundary model consisting of spherical particles linked through flexible contact bonds. The overall deformation behavior of the specimen was then compared with the specimen with rigid boundary and experimental measurements. Computed tomography was used to track the evolution of particle translation and rotation within a laboratory triaxial specimen in 3D. The DEM model of the flexible membrane specimen successfully predicted the stress–strain behavior when compared with laboratory experiment results at different confining pressures. The DEM results showed that the rigid specimen applies a uniform deformation and leads to non-uniformities in the confining stress along the particle-boundary interface in the lateral direction. In contrast, the flexible specimen better replicates the uniformly applied confining stress of a laboratory triaxial experiment. The 3D DEM simulations of the specimen with flexible membrane overpredicted particle translation and rotation in all directions when compared to a laboratory triaxial specimen. The difference between the particle translation and rotation distributions of DEM specimens with rigid and flexible membrane is almost negligible. The DEM specimen with flexible membrane produces a better prediction of the macroscopic stress–strain behavior and deformation characteristics of granular materials in 3D DEM simulations when compared to a specimen with rigid membrane. Comparing macroscale response and particle-scale kinematics between triaxial simulation results of rigid versus flexible membrane demonstrated the significant influence of boundary effects on the constitutive behavior of granular materials.  相似文献   

Deciphering factors controlling trace element distribution in the soils of Karaduvar industrial-agricultural area (Mersin,SE Turkey)   总被引：1，自引：0，他引：1  

Cüneyt Güler  Musa Alpaslan  Mehmet Ali Kurt  Abidin Temel 《Environmental Earth Sciences》2010,60(1):203-218

In this study, 30 topsoil samples were collected from Karaduvar area (Mersin, SE Turkey) where at present various industrial and agricultural activities are occurring. Using a five-step ultrasound-assisted sequential extraction (UASE) procedure, trace elements in soil samples were partitioned into the following: (1) soluble-exchangeable; (2) bound to carbonates; (3) bound to Fe- and Mn-oxides; (4) bound to organic matter and sulfide compounds, and (5) residual fraction. Concentrations of 11 trace elements in the extracts were determined using ICP-MS. Total concentrations ranged between (in mg kg⁻¹) 3.35 and 7.26 for As; 1.18 and 3.96 for Cd; 10.76 and 20.26 for Co; 37.99 and 63.48 for Cr; 18.55 and 243.1 for Cu; 338.7 and 565.6 for Mn; 4.42 and 6.44 for Mo; 148 and 279.3 for Ni; 10.12 and 73.71 for Pb; 17.93 and 36.55 for V, and 25.46 and 331.7 for Zn. Factor analysis was applied to dataset in order to discriminate between natural and anthropogenic pollution sources and factors controlling the spatial distribution of trace elements in the area. Results suggest that distributions of Co, Cr, Mn, and Ni are mainly controlled by lithological factors, whereas, distributions of Cu, Pb, and Zn can be attributed to agricultural activities such as pesticide/herbicide use and fertilizer application, as well as irrigation with petroleum hydrocarbon-contaminated groundwater. Highest concentrations of Cd and Mo are generally observed around the diesel-fired thermal power plant and ATAŞ refinery. Highest concentrations of As and V are generally observed at the NW sector of the area; however, no definitive source can be designated for both of these elements.  相似文献