Iranica Journal of Energy and Environment (IJEE)

224-232

Authors: H. Khorasanizadeh, A. Aghaei, H. Ehteram, R. Dehghani Yazdeli and N. Hataminasar

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.

240-246

Authors: Armin Farzampour, Farzin Salmasi and Behnam Mansuri

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.

259-269

Authors: Syafalni and Roslina Mohd Rusli

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.

277-286

Authors: A.S. Kovo, S.C. Olu and E.S. Gwatana

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.

295-302

Authors: Mariana Alvarez-Navarrete, Jaime Alioscha Cuervo-Parra, Jorge Ricaño-Rodríguez and Mario Ramírez-Lepe

Beta-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 ITV01 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

313-322

Authors: M.F.M. Nordin, I. Puspasari, S.M. Tasirin, W.R.W. Daud, Y. Gariépy, M.Z.M. Talib, G.S.V. Raghavan

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.