813 research outputs found

    Removal of mercury (II) from aqueous solution by using rice residues

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    Sorption potential of rice residues for Hg(II) removal from aqueous solution was investigated. Rice husk (RH) and rice straw (RS) were selected and treated with sodium hydroxide (NaOH). The raw and modified adsorbents were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and BET surface area measurements. The effects of pH, initial ion concentration, and agitation time on the removal process were studied in batch adsorption experiments. Two simple kinetic models, which are pseudo-first-order and pseudo-second-order, were tested to investigate the adsorption mechanisms. The kinetic data fits to pseudo second order model with correlation coefficients greater than 0.99 for all adsorbents. The equilibrium data fitted well with the Langmuir compared to Freundlich isotherm models. Alkali-treated adsorbent obtained larger surface area and RH-NaOH showed highest adsorption capacity followed by RS-Pure > RH-Pure > RS-NaOH. The maximum removal efficiency obtained by RH-NaOH and RS-Pure was 42 mg/l (80%) at pH 6.5 and with 2 days contact time (for 50 mg/l initial concentration and 25 mg adsorbents)

    Minimal model for beta relaxation in viscous liquids

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    Contrasts between beta relaxation in equilibrium viscous liquids and glasses are rationalized in terms of a double-well potential model with structure-dependent asymmetry, assuming structure is described by a single order parameter. The model is tested for tripropylene glycol where it accounts for the hysteresis of the dielectric beta loss peak frequency and magnitude during cooling and reheating through the glass transition.Comment: Phys. Rev. Lett. (in press

    Multivariate Analysis of the Morphological Traits of Female Duck, Muscovy-duck and Mule-duck

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    The objective of this study was to evaluate the characteristics of morphometrical measurements inthe female waterfowls. The animals used in this research were 90 ducks , 90 muscovy-ducks and 90mule-ducks in Bulukumba district of Brebes regency, Central Java, Indonesia. Parameters measuredwere maxilla length, neck length, body length, chest circumstance, wing length, chest length, femurlength and tibia length. The data were analyzed using the Statistical Analysis System ver. 9.1. Muscovyduckgenerally had the largest of size, followed by mule-duck and then duck. The most discriminantvariables were showed by chest length and chest circumstance. Muscovy-duck and mule-duck hadclosest genetic distance (3.974870) than both of the distance between duck and mule duck (14.10), andmuscovy-duck and duck (24.73). The smallest errorness level in grouping was showed in duck 1%followed by 2% in mule-duck and 3% in muscovy-duck

    Toxicity comparison of silver nanoparticles synthesized by physical and chemical methods to tadpole (Rana ridibunda)

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    One of the possible threats in increasing use of nanomaterials is the emergence of toxicity in humans and other animals which is discussed in nanotoxicology. In addition to toxic effects of nanomaterials themselves, different chemical precursors which are usually used in bottom-up approaches for production of nanomaterials may have secondary toxic effects in living organisms. In contrast, less use of chemicals in top-down approaches may reduce these secondary effects. To test this hypothesis, toxic effects of two types of silver nanoparticles (AgNPs) produced by physical (top-down) and chemical (bottom-up) methods were investigated and compared on the tadpole, Rana ridibunda survival. The estimated 48 h LC50 values of AgNPs produced by chemical and physical methods for tadpoles were 0.055 ± 0.004 and 0.296 ± 0.085 mg.L-1, respectively. No observed effect concentration, lowest observed effect concentration, maximum acceptable toxicant concentration and median lethal concentration of AgNPs produced by chemical method were respectively 3.42, 4.50, 4.84 and 5.38 times less than those produced by physical method. Therefore, approving the mentioned hypothesis, it was revealed that AgNPs produced by chemical method are more toxic than those generated by physical method. However, it seems totally that AgNPs regardless of the method used for their production, have toxic effects on aquatic organisms and so, inhibiting their accidental or intentional entrance into the aquatic ecosystems should be more considered

    Consolidation parameters of reconstituted peat soil: oedometer testing

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    This paper presents the consolidation parameters of reconstituted peat soils with different peat soil particle sizes. The reconstituted peat sample was used to determine the consolidation parameters since the undisturbed samples were difficult to collect. The selected sizes of soil particles passing given sieve sizes have been collected and formed the reconstituted peat samples by preloading with a given pressure. The testing involve was one-dimensional oedometer consolidation test with the load increment method (5 – 320kPa). It is important to gather the information about a soil profile, especially on consolidation properties which were important in predicting the settlement of soil. Based on the results, compression index (Cc) and swell index (Cs), the values were increased with the increasing peat particles siz

    Study on Treatment of Slaughterhouse Wastewater by Electro-coagulation Technique

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    Electro-coagulation (EC) is well known as a technique for removing suspended solids as well as oils and greases from wastewater. The aims of this research are to study the performance of the EC technique to treat a high strength wastewater from slaughterhouse in batchwise mode. The effect of various process variables such as number and electrode material, initial pH, suspended solid (SS) content, and operating time was investigated The electrolytic cell (electro-coagulator) used was a 600 ml cylinder glass reactor with working volume 400 ml and equipped by magnetic stirrer without temperature control. Cast iron (Fe) and aluminum (Al) cylinder were used as anode/cathode pair. The number of electrode was varied 1 and 2 pairs. The effective area of the electrode pair was 6.28 cm2. The DC power supply was controlled by a voltmeter and be adjusted constant at 125 A/m2 for each test runs. The initial SS concentration were varied from 1250, 2100, 3000, and 4000 mg/L by diluting wastewater. It is found that effluent temperature depends on SS and increases up to 98 °C when SS content was 4000 mg/L. One and two pairs of Fe-Al electrode will give SS removal efficiency are 97.2 and 99.6 %, respectively. However, the higher electrode number will need the shorter time to get certain removal efficiency of SS. Number of electrodes didn\u27t give the significant impact to the final pHs. With initial pH 7.05 both two pair of electrode will give the final pH relatively constant to 7.80. Further work will be conducted to optimize the CD and charge loading to avoid the excessive temperature increas
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