Organic light-emitting diodes based on a cohost electron transporting composite

The efficiency of green organic electroluminescent devices have been improved by cohosting the electron dominant complex, 4,7-diphenyl-1,10- phenanthroline into the traditional electron transporting layer of tris (8-hydroxyquinoline) aluminum. In this cohost strategy, we demonstrate that the luminous efficiency is enhanced by >20% while the driving voltage can be reduced by ∼30% in a uniformly mixed composition as compared to the traditional device configuration. The corresponding device lifetime under atmospheric condition is extended by a factor of ∼1.8, attributed to the reduction of the accumulated positive charges near the electron-hole recombination regime. Results indicate that the knowledge of bulk conductivity engineering of organic n-type transporters is essential in enhancing organic light-emitting devices. © 2006 American Institute of Physics.published_or_final_versio

A laboratory study using maple leaves as a biosorbent for lead removal from aqueous solutions

This study tested the ability of maple leaf powder (MLP) to reduce the level of Pb(II) ions in aqueous solutions. As a biosorbent, MLP has a larger specific surface area (10.94 m2/g) and contains Pb(II) binding functional groups. The highest Pb(II) removals were achieved at pH of 6.2, particle size of less than 75 μm, dose of 0.5 g, initial concentration of 10 mg/l and equilibrium time of >15 minutes. Thermodynamic results indicated that the Pb(II) adsorption process was spontaneous and exothermic. MLP biosorbent could be reused for five cycles after successfully recovery by 0.1N H2SO4. Both adsorption and desorption data fit well with Langmuir and Sips isotherm models (R2 ≈ 0.961-1.00). The Pb(II) adsorption and desorption capacities (qm) of MLP were up to 50.27 mg/g and 40.06 mg/g, respectively, for a 1 g dose at room temperature. Kinetics processes were rate controlling step and showed good fitness with the pseudo-second order and intraparticle diffusion models. Results suggest that multiple mechanisms (chelating bond, physisorption and chemisorption) are involved to adsorb the Pb(II) ions on to MLP. Higher Pb(II) removal revealed the practical applicability of MLP in water and wastewater treatment systems. © IWA Publishing 2014

A review towards finding a simplified approach for modelling the kinetics of the soluble microbial products (SMP) in an integrated mathematical model of membrane bioreactor (MBR)

Soluble microbial products (SMPs) tend to accumulate in the membrane bioreactor (MBR) systems as a consequence of high membrane rejection and apparently low biodegradability within the wastewater treatment system. The extension of the activated sludge models (ASMs) with SMPs, therefore, has received crucial importance in recent days, particularly considering their potential use as indicators of the membrane fouling propensity. This paper presents a critical review of the formation and degradation kinetics of SMP subdivisions that have so far been used for the mathematical modelling of MBR. The paper identified a simplified approach to incorporate the kinetics of the SMP formation and degradation in the general mathematical models of MBR. It suggested that the inclusion of only four additional linear differential equations in the ASM1-SMP integrated mathematical model could simulate well the effluent quality and membrane fouling prediction. The model would also serve as a useful tool in optimizing operation conditions for better treatability and fouling control. © 2013 Elsevier Ltd

Improving the efficiency of organic light emitting devices by using co-host electron transport layer

By engineering a new cohosting system of tris(8-hydroxyquinoline) and 4,7-diphenyl-1,10-phenanthroline in the electron transport layer, the current efficiency of the organic light emitting diode is improved by 34% to 4.3 cd/A as compared to the device with a single host of Alq 3 as the electron transport layer. The maximum luminance is over 16,000 cd/m 2 at the bias of 22 V and the current of 475 mA/cm 2, which is ∼ 73% higher than the single host Alq 3 device without optimizing the layer thickness. The reasons for the improvement will be investigated. The results strongly indicate that the knowledge of bulk conductivity engineering of organic n-type transporters shows practical significance in OLED applications. © 2005 Elsevier B.V. All rights reserved.postprin

Feasibility of iron loaded 'okara' for biosorption of phosphorous in aqueous solutions

This study investigated the feasibility of using soybean milk by-products (okara) as a sustainable biosorbent for phosphate removal in water and wastewater. The results show that raw okara could hardly decontaminate phosphate from aqueous solutions. Hence, in this work, okara was modified by being cationized using FeCl3 0.25M (namely iron loaded okara, ILO) to enhance the phosphorus adsorption capacity. The phosphate sorption onto ILO was well achieved under the conditions of pH 3, initial phosphorous concentration of 25mg/L, biosorbent dose of 20mg/L and contact time of 7h. Based on Langmuir model, the maximum adsorption capacity of phosphate by ILO was 4.785mg/g. The effects of interfering anions were in the order of CO32->SO42->NO3 It was also observed that Fe(III) was detached during operation. This problem can hinder the sustainable usability of ILO. Thus, further research would be necessary for improving the modification method. © 2013 Elsevier Ltd

Microbial community characteristics during simultaneous nitrification-denitrification process: effect of COD/TP ratio

© 2015, Springer-Verlag Berlin Heidelberg. To evaluate the impact of chemical oxygen demand (COD)/total phosphorus (TP) ratio on microbial community characteristics during low-oxygen simultaneous nitrification and denitrification process, three anaerobic-aeration (low-oxygen) sequencing batch reactors, namely R1, R2, and R3, were performed under three different COD/TP ratios of 91.6, 40.8, and 27.6. The community structures of each reactor were analyzed via molecular biological technique. The results showed that the composition of ammonia-oxidizing bacteria (AOB) was affected, indicated by Shannon indexes of the samples from R1, R2, and R3. Nitrosomonas was identified to be the dominant AOB in all SBRs. Moreover, the copy numbers of nitrifiers were more than those of denitrifiers, and the phosphorus-accumulating organisms to glycogen-accumulating organisms ratio increased with the decrease of COD/TP ratio

Nitrous oxide generation in denitrifying phosphorus removal process: Main causes and control measures

Despite the many benefits of denitrifying phosphorus removal process, the significant generation of nitrous oxide (N2O), a potent greenhouse gas, remains a problem for this innovative and promising process. To better understand and more effectively control N2O generation in denitrifying phosphorus removal process, batch experiments were carried out to investigate the main causes of N2O generation, based on which the control measures were subsequently proposed. The results showed that N2O generation accounted for 0.41 % of the total nitrogen removal in denitrifying phosphorus removal process, whereas, in contrast, almost no N2O was generated in conventional denitrification process. It was further demonstrated that the weak competition of N2O reductase for electrons and the high nitrite accumulation were the two main causes for N2O generation, evidenced by N2O production and reduction rates under different conditions. Accordingly, the reduction of N2O generation was successfully achieved via two control measures: (1) the use of continuous nitrate addition reducing N2O generation by around 91.4 % and (2) the use of propionate as the carbon source reducing N2O generation by around 69.8 %. © 2013 Springer-Verlag Berlin Heidelberg

Effect of phosphorus load on nutrients removal and N<inf>2</inf>O emission during low-oxygen simultaneous nitrification and denitrification process

Three laboratory scale anaerobic-aerobic (low-oxygen) SBRs (R1, R2 and R3) were conducted at different influent phosphorus concentration to evaluate the impacts of phosphorus load on nutrients removal and nitrous oxide (N2O) emission during low-oxygen simultaneous nitrification and denitrification (SND) process. The results showed that TP and TN removals were enhanced simultaneously with the increase in phosphorus load. It was mainly caused by the enrichment of polyphosphate accumulating organisms (PAOs) under high phosphorus load and low COD/P ratio (<50), which could use nitrate/nitrite as electron acceptors to take up the phosphorus. N2O emission was reduced with increasing phosphorus load. N2O-N emission amount per cycle of R3 was 24.1% lower than that of R1. It was due to the decrease of N2O yield by heterotrophic denitrification. When the phosphorus load increased from R1 to R3, heterotrophic denitrification (D) ranged from 42.6% to 36.6% of the N2O yield. © 2013 Elsevier Ltd

N<inf>2</inf>O reduction during municipal wastewater treatment using a two-sludge SBR system acclimatized with propionate

A two-sludge denitrifying phosphorus removal process (A2N-SBR), acclimatized with propionate, was proposed as an efficient method for nitrous oxide (N2O) reduction during municipal wastewater treatment. Compared with the conventional nitrification-denitrification process (AO-SBR) operated in parallel, the A2N-SBR not only significantly improved total nitrogen and soluble phosphorus removal efficiencies by around 32.3% and 23.5%, respectively, but also greatly reduced N2O generation by around 31.5%. Moreover, like the anoxic stage of AO-SBR, nearly zero N2O (merely 0.054% of the removed nitrogen) was generated during the anoxic stage of A2N-SBR. The substantial N2O reduction achieved in the proposed A2N-SBR can be reasonably explained by: (i) the use of independent nitrification reactor resulting in higher activity of nitrifying bacteria and no occurrence of heterotrophic denitrification in aerobic stage, and (ii) the use of propionate as carbon source decreasing nitrite accumulation in anoxic stage. © 2013 Elsevier B.V

Phosphorus elimination from aqueous solution using 'zirconium loaded okara' as a biosorbent

This work deals with the capture of phosphorus from aqueous solutions by biosorption onto zirconium loaded okara (ZLO). The batch-mode experiments were conducted to examine the effect of pH, biosorbent dose, initial phosphorus concentration, contact time, and temperature on the process. It was found that, the adsorption was most favored in the pH range of 2-6. The optimal doses for the adsorption, at initial phosphorus concentrations of 5, 10, 25, 50mg/L were 2, 3, 7, 10g/L, respectively. The maximum adsorption capacity of ZLO was approximately 44.13mg PO4/g at 298K. The phosphate removal was rapid, reaching 95% in 30min. Freundlich model best fitted the equilibrium data, while Pseudo-second order model satisfactorily described the kinetic results. Thermodynamic analysis revealed feasible, spontaneous, and endothermic nature of the process. The research would be beneficial for developing a promising, eco-friendly phosphorus biosorbent from a plentiful AWB - okara. © 2014 Elsevier Ltd