فهرست مطالب

Energy & Environment - Volume:5 Issue:3, 2014
  • Volume:5 Issue:3, 2014
  • تاریخ انتشار: 1393/06/28
  • تعداد عناوین: 12
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  • H. Khorasanizadeh, A. Aghaei, H. Ehteram, R. Dehghani Yazdeli, N. Hataminasar Page 224
    The efficiency of the flat solar surfaces, such as thermal collectors and photovoltaic (PV) panels, depends on the received beam and diffuse radiation components and the angle of the beam incidence. In this study, based on the long term measured data tilt angle optimization of the flat solar surfaces in the city of Ilam, Iran, for the daily, monthly, seasonal and annual fixed adjustments have been performed. Study of characteristics of solar radiation showed that Ilam has 220 days in the year with horizontal global radiation in the range of 15-35 MJ/m2 and 182 sunny or very sunny days having daily clearness index higher than 0.6. The optimum tilt for the fixed daily adjustment throughout the year varies between zero and 61° and the optimum tilt for the fixed monthly adjustment varies between 0° in June and July up to 60.1° in December. The optimum tilt for the fixed annual adjustment is 26°, which is close to latitude of Ilam 33.38°). Furthermore, the optimum tilt for the fixed seasonal adjustment in winter and autumn are 12.3 and 20° higher than the latitude of Ilam, respectively; whereas in spring and summer they are 30.3 and 21.1° less than the latitude, respectively.
    Keywords: Solar radiation Optimum tilt angle Flat solar surfaces Collectors Ilam
  • P. Rejani, Asha Radhakrishnan, B. Beena Page 233
    ZnO nano rod was prepared by microwave assisted method. The crystal structure of the nano powders were confirmed by X-Ray diffraction analysis and the mean particle size was estimated by the Scherrer’s formula. The surface morphology of the nano particles were analyzed by SEM and TEM. The absorption spectrum of the material in the UV-Vis range was recorded. The prepared ZnO rod was used as a photocatalyst in presence of UV light against Malachite Green dye. The ZnO nanoparticle was found to be an efficient low cost photocatalyst which degraded Malachite Green dye in presence of UV light in a relatively short period of time.
    Keywords: Nanoparticles Zinc oxide rod Malachite Green dye Photocatalytic activity
  • Armin Farzampour, Farzin Salmasi, Behnam Mansuri Page 240
    Seepage in embankment dams is one of the important factors in stability and dam’s maintenance. Core in earth dam is essential for waterproofing and controlling of seepage. Therefore, selection of proper materials and sizes for core of earth dam are very important. Thick clay core is proper for waterproofing but because of low shear strength of the clay, it would be dangerous for dam’s stability. The optimal core would be the core which has proper waterproofing, stability safety factor and also with economic condition. In this study, the aim is to determine the optimum size for clay core of Alavian dam near Maragheh city in steady state seepage condition. For this purposes, Geo-Studio pack is used for numerical simulation. In addition, simulation of seepage and slope stability for the built maps of the dam, 11 more models of the dam with different size of cores were tested to find the optimum core thickness. From these models, data required for objective function and constraints using regression techniques for seepage, hydraulic gradient and stability safety factor were provided. Results showed that optimized volume of the core is 35% smaller than the present core.
    Keywords: Earth dam Optimization Clay core Excel solver Geo, Studio
  • A.A. Ismailova, A.K. Zhamangara, Park S. Ya, A.I. Abakumov, A.A. Adamov, R.M. Muratov Page 247
    The information-analytical system (IAS) "Monitoring of aquatic ecosystems" was developed for the analysis of ecological lakes condition in Kazakhstan. It consists of a database on hydrochemical and hydrobiological characteristics for lakes Burabai and Ulken Shabakty in Shchuchinsk Borovoye resort area of the Republic of Kazakhstan, as well as a set of statistical data processing methods. Qualitative analysis of data was made on the lakes. Data on biogenic substances for the years 2007-2013 were analyzed based on statistics. Dynamic characteristics and seasonal features of changes were identified in the concentrations of biogens. There is an absence of significant relationships between the concentrations of various biogenic substances in lakes and between lakes. Nitrogen substances were compared. The phosphorus compounds have a large stability that can contribute to a more stable life of phytoplankton species which are related to phosphorus.
    Keywords: Statistical analysis Hydrobiology Hydrochemistry Classification of lakes Mathematical modeling
  • Syafalni, Roslina Mohd Rusli Page 259
    Leachate pollutants adsorption using potassium hydroxide (KOH) and Surfactant Modified Bentonite (SMB) have been used as a new method for leachate treatment. KOH was used for removing the heavy metal elements and natural bentonite (NB) and SMB as adsorbents to adsorb ammoniacal nitrogen, nitrate and phosphate. The suitable conditions for adsorbents are obtained using the percentage removal of colour, iron, COD, ammoniacal-nitrogen, nitrate and phosphate. The results obtained at optimum conditions for dosage and pH for NB was 233.3 g/L at pH 9. By comparison, for SMB they were 166.7 g/L at pH 8. For the contact time, using slow mixing and rapid mixing, SMB is better than NB. From the SEM-EDX analysis of weight percentage, after the NB and SMB treatments the elements of nitrogen, phosphorus and potassium for NB increased by 1.04, 1.32 and 5.13%; respectively; also for SMB 1.30, 2.25 and 6.81% respectively. It is clear that SMB gives better adsorption than NB and can be used for future application as a slow release fertiliser for plants.
    Keywords: Leachate Natural bentonite Surfactant modified bentonite Adsorption Fertiliser
  • Mohammad Javad Jafari, Leila Omidi, Mansour Rezazadeh Azari, Mohammad Reza Massoudi Nejad, Mahshid Namdari Page 270
  • A.S. Kovo, S.C. Olu, E.S. Gwatana Page 277
    The adsorption capacity of Neem Leaves powder (NLP) used as a low-cost adsorbent for the removal of Chromium (VI) from aqueous solutions was investigated. During the adsorption process, batch technique was used. The effects of initial metal ion concentration, adsorbent dose, temperature, pH and agitation/contact time on adsorption rate at constant solution pH of 6.4, under a constant temperature of 30°C were studied.The results were analyzed using three adsorption isotherm models; Freundlich, Langmuir and Temkin. Evaluating the correlation coefficients showed that Langmuir isotherm described the data more appropriately than the other isotherms. The adsorption capacity (qm) from Langmuir isotherm for Chromium (VI) was found to be 125.83mg g 1. The effectiveness of Neem Leave Powder (NLP) in the adsorption of the heavy metal (Chromium VI) from aqueous solution, kinetic studies showed that a pseudo second order model was more suitable than the pseudo first order model. It was concluded that Neem Leave Powder (NLP) can be used as an effective adsorbent for the removal of Chromium (VI) from aqueous solutions. The adsorption process was observed to be exothermic. The negative value of Gibb free energy indicates feasibility and spontaneity of the system while the negative values of the entropy and enthalpy indicate randomness and the exothermic nature of adsorption, respectively.
    Keywords: Neem leave Adsorption isotherm Adsorption kinetics Chromium (IV) Thermodynamic properties
  • Nur Zulaikha Yusof, Mohd Azraai Kassim, Razali Ismail, Abdull Rahim Mohd Yusoff Page 287
    In the present study, eight locally available low cost adsorbents (raw and heat treated) have been screening for its capability to remove As(III). The shale sedimentary rock (SSR) was selected as a good adsorbent based on high As(III) removal. The activation of adsorbent was carried out by heat (250 - 550°C) and acid treatment (0.1 - 1 M H2SO4) in order to chose the best treatment method for A (III) removal. Sorption experiments were conducted to examine the effect of initial As(III) concentration, contact time and initial pH on As(III) removal by SSR. Results show that, only by heating the adsorbent at 500°C for h, 0.2 g of SSR adsorbent capable to reduce the residual As(III) concentration below than maximum concentration limit (10μg/L) for initial concentration from 100 to 700 μg/L and optimum pH ranges between 3 to 9 after 24 h of contact time. The adsorption data fits well with Langmuir isotherm and yielded Langmuir monolayer capacity of 0.987 mg As(III)/g of SSR at pH 7. The SSR adsorbent has been successfully used for the removal of arsenic from seven real groundwater samples containing arsenic in the range of 20.2 to 697.34 μg/L with 86.73 to 97.86% removal efficiency.
    Keywords: As (III) removal Shale sedimentary rock Heat treatment Langmuir isotherm Adsorption
  • Mariana Alvarez, Navarrete, Jaime Alioscha Cuervo, Parra, Jorge RicaÑo., RodrÍ, Guez, Mario RamÍ, Rez, Lepe Page 295
    glucosidases have attracted considerable attention in recent years due to their important roles in various biotechnological processes such as hydrolysis of isoflavone glucosides, the production of fuel ethanol from agricultural residues, the release of aromatic compounds from flavorless precursors, among others. In this study, extracellular -glucosidase induced by cellulose from Penicillium commune IT 01 was purified to homogeneity by electrofocusing (IEF) and Sephadex G-100 gel filtration. The enzyme was characterized and the molecular weight was 144.2 kDa as estimated by SDS-PAGE. The isoelectric point determined by IEF was 4.73 and the enzyme was able to hydrolyze cellobiose and cellulose to glucose but not laminarine, xylan, starch, pullulan, colloidal chitin and carboxymethyl-cellulose. Optimal pH and temperature were detected at 5.0 and 50°C, respectively. Stability was observed at temperatures 30 to 50°C and pH values between 5 and 7 for 24 h. Enzyme activity was activated by K+, Cu+, Mn++, Fe++, Cu++, Ca++ ions and significantly by Co++. -glucosidase was completely inhibited by Hg++. In conclusion, the novel -glucosidase purified from P. commune shows great potential for biotechnological uses.
    Keywords: Purification Glucosidase Peniclillium Hydrolase Fungi Cellulolytic activity
  • P. Kanmani, E. Dhivya, J. Aravind, K. Kumaresan Page 303
    Pectin is a structural hetero polysaccharide, commonly obtained from the peels of citrus fruits and finds prime commercial use as a gelling agent and stabilizer in food industries. In the present study, pectin was extracted using alcohol precipitation method from the peels of orange (Citrus sinensis), sweet lime (Citrus limetta) and lemon (Citrus limon). When the extraction conditions were varied one-at-a-time, a maximum yield of 36.71% was obtained from C. limon, after which the yield was further enhanced using the Box-Behnken Design of Response Surface Methodology. Optimum conditions for the extraction process were established to be pH 3.5, temperature 65°C and time 67.5 min. The interaction effects of these variables were studied using 3-D and contour plots. A 1.5-fold increase in pectin yield was obtained as a result of this experimental design. Analysis of variance indicated the significance of the model. The pectin obtained was then subjected to qualitative and quantitative analyses and found to contain desirable methoxyl, hyaluronic acid contents and degree of esterification. Functional groups present in the pectin were investigated using FTIR spectroscopy. The overall results point towards the amenability of the extracted pectin for industrial applications.
    Keywords: Pectin Citrus limon Yield Optimization Response surface methodology FTIR
  • M.F.M. Nordin, I. Puspasari, S.M. Tasirin, W.R.W. Daud, Y. GariÉpy, M.Z.M. Talib, G.S.V. Raghavan Page 313
    Quality changes of red pitaya (Hylocereus undatus) slices dried in hot air, microwave-hot air and microwave-vacuum dryers were investigated. The quality parameters were colour, water activity, shrinkage, rehydration ratio, ascorbic acid content and visual market quality. Microwave-vacuum produced pitaya with the best quality compared to hot air and microwave-hot air. Pitaya dried in microwave vacuum had the highest rehydration ratio while the other methods presented similar rehydration ratios. Ascorbic acid in dried pitaya was also better retained when drying by microwave-vacuum. Apart from that, the drying time of pitaya dried in microwave-vacuum could be reduced by 83% compared to hot air.
    Keywords: Dragon fruit Drying kinetics Microwave convective drying Microwave vacuum drying
  • A.M. Mansouri, A.A.L. Zinatizadeh, A. Akhbari Page 323
    The kinetics of simultaneous removal of carbon, nitrogen and phosphorus from a synthetic wastewater in an innovative up-flow aerobic/anoxic sludge fixed film (UAASFF) bioreactor was investigated. The kinetic analysis was performed using the experimental data obtained in an earlier study where the UAASFF bioreactor was examined under different operating conditions by changing three independent variables, HRT, COD:N:P ratio and aeration time. In the analysis, different kinetic models (Monod, first order, second-order and Stover-Kincannon models) were evaluated. The maximum removal efficiency of COD, total nitrogen (TN) and phosphorus (TP) were obtained to be 95.42, 79 and 79.1 %, respectively. All the models examined, gave high correlation coefficients for carbon, nitrogen and phosphorus removal. Biokinetic coefficients were determined as Y= 0.417-0.496 g VSS/g COD, kd= 0.027-0.053 d, μmax =1.36 g VSS /g VSS.d, KB 37.96 g/l.d, Umax =38.46 g/l.d, 1 KB(N)=0.271-7.2 g/l.d 6, Umax(N) =0.33-5.4 g/l.d, KB (P)=0.09-0.89 g/l.d, Umax (P) 0.07-0.42 g/l.d.
    Keywords: Simultaneous nutrients removal kinetics UAASFF bioreactor Monod Grau second, order model Stover, Kincannon model