| 1. |
- Abd Ali, Ziad T., et al.
(författare)
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Predominant mechanisms for the removal of nickel metal ion from aqueous solution using cement kiln dust
- 2020
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Ingår i: Journal of Water Process Engineering. - : Elsevier BV. - 2214-7144. ; 33
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Tidskriftsartikel (refereegranskat)abstract
- The experimental methodology achieved in the present study signified that the adsorption and precipitation were main mechanisms occurred together in the removal of nickel from aqueous solution by sorption using cement kiln dust (CKD) byproduct as sorbent. Finding the contribution of each mechanism in the removal process and derivation an analytical model for finding the portion of precipitation were the focal points of this work. Results proved that pure precipitation was increased with the increase of CKD dosage and metal concentration where total removal (adsorption-precipitation) ranged from 45 to 100%. The SEM micrographs of the CKD sorbent before and after sorption process certified that there was crystal precipitates on the surface of the CKD. Also, these graphs in combination with FT-IR tests proved that [Ni(OH2)n]+2 (n=4-6) species were bonded with CKD and insoluble hydroxide species may be precipitated onto the CaO surfaces by co-precipitation, while K–O, Si-O and Ca-O groups enhanced the adsorption mechanism.
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| 2. |
- Faisal, Ayad A.H., et al.
(författare)
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COMSOL multiphysics 3.5a package for simulating the cadmium transport in the sand bed-bentonite low permeable barrier
- 2020
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Ingår i: Journal of King Saud University - Science. - Netherlands : Elsevier. - 1018-3647. ; 32:3, s. 1944-1952
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Tidskriftsartikel (refereegranskat)abstract
- Here, batch study for Iraqi bentonite-cadmium aqueous solution interaction was conducted with condi- tions of contact time ::; 120 min, sorbent dosage from 0.05 to 1 g per 100 mL and shaking speed from 50 to 300 rpm for initial concentration of 50 mg/L with initial pH of 3 to simulate the acetogenic phase in the sanitary landfill. The best conditions were 1 h, 0.7 g/100 mL and 250 rpm, respectively to obtain the high- est removal (90%). The sorption data were well formulated by Freundlich and Langmuir models with determination coefficient (R2) 2: 0.98 and sorption capacity of 145.3 mg/g; so, the removal process gov- erned by the physico-chemical forces. The average coefficient of the hydraulic conductivity was found equal to 1.98 x 10-10 m/s and this is suitable for low permeable barrier (LPB). Finally, the predictions of COMSOL package were presented satisfactory simulation for the cadmium concentrations within two-dimensional physical model packed with sand aquifer and Iraqi bentonite. Two configurations of LPB were evaluated for restriction of contaminant front migration and the results proved that the sur- rounding of the location required to protect it from three sides against to the flow direction can be more dependable from continuous configuration.
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| 3. |
- Shi, Changsheng, et al.
(författare)
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Managing excitons for high performance hybrid white organic light-emitting diodes by using a simple planar heterojunction interlayer
- 2018
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Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 112:2
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Tidskriftsartikel (refereegranskat)abstract
- High performance hybrid white organic light-emitting diodes (WOLEDs) were fabricated by inserting a planar heterojunction interlayer between the fluorescent and phosphorescent emitting layers (EMLs). The maximum external quantum efficiency (EQE) of 19.3%, current efficiency of 57.1 cdA(-1), and power efficiency (PE) of 66.2 mu m W-1 were achieved in the optimized device without any light extraction enhancement. At the luminance of 1000 cdm(-2), the EQE and PE remained as high as 18.9% and 60 mu m W-1, respectively, showing the reduced efficiency-roll. In order to disclose the reason for such high performance, the distribution of excitons was analyzed by using ultra-thin fluorescent and phosphorescent layers as sensors. It was found that the heterojunction interlayer can efficiently separate the singlet and triplet excitons, preventing the triplet excitons from being quenched by the fluorescent emitter. The introduction of the heterojunction interlayer between the fluorescent and phosphorescent EMLs should offer a simple and efficient route to fabricate the high performance hybrid WOLEDs. Published by AIP Publishing.
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| 4. |
- Wu, Zhongbin, et al.
(författare)
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Achieving Extreme Utilization of Excitons by an Efficient Sandwich-Type Emissive Layer Architecture for Reduced Efficiency Roll-Off and Improved Operational Stability in Organic Light-Emitting Diodes
- 2016
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:5, s. 3150-3159
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Tidskriftsartikel (refereegranskat)abstract
- It has been demonstrated that the efficiency roll-off is generally caused by the accumulation of excitons or charge carriers, which is intimately related to the emissive layer (EML) architecture in organic light-emitting diodes (OLEDs). In this article, an efficient sandwich-type EML structure with a mixed-host EML sandwiched between two single-host EMLs was designed to eliminate this accumulation, thus simultaneously achieving high efficiency, low efficiency roll-off and good operational stability in the resulting OLEDs. The devices show excellent electroluminescence performances, realizing a maximum external quantum efficiency (EQE) of 24.6% with a maximum power efficiency of 105.6 lm W-1 and a maximum current efficiency of 93.5 cd A(-1). At the high brightness of 5 000 cd m(-2), they still remain as high as 23.3%, 71.1 lm W-1, and 88.3 cd A(-1), respectively. And, the device'lifetime is up to 2000 h at initial luminance of 1000 cd m(-2), which is significantly higher than that of compared devices with conventional EML structures. The improvement mechanism is systematically studied by the dependence of the exciton distribution in EML and the exciton quenching processes. It can be seen that the utilization of the efficient sandwich-type EML broadens the recombination zone width, thus greatly reducing the exciton quenching and increasing the probability of the exciton recombination. It is believed that the design concept, provides a new avenue for us to achieve high-performance OLEDs.
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