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Abstract  

The sorption of Cd(II) on Haro river sand from deionized water is reported. The sorption system obeyed according to the Freundlich and Dubinin–Radushkevich (D-R) isotherms. The Freundlich parameters 1/n = 0.67±0.05 and of A = 1.38±1.14 mmole·g-1 have been ascertained. D-R isotherm yields the values of = -0.003741±0.000321 kJ2·mole-2, X m = 0.23±0.21 mole·g-1 and of E = 11.6±0.5 kJ·mole-1. The influence of common anions and cations on the sorption was examined. Trivalent Bi enhances the sorption whereas Fe, Cr, Al and chromate ions reduce the sorption significantly. Hf(IV) and Ag(I) indicate substantial sorption (61–98%) whereas Gd(III), Re(VII) and Sc(III) show low sorption (<5%). The elements having low sorption can be separated from elements indicating higher sorption using Haro river sand column.

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Abstract  

The sorption of chromium(III) onto Haro river sand has been investigated as a function of sorptive solution composition, amounts of sorbent (10–500 mg) and sorbate (4.33·10−8–5.17·10−6 M), shaking time (I-60 minutes) and temperature (15–35°C). Maximum sorption has been achieved from 0.001 M HCI solution using 50 mg of the sand and 20 minutes shaking time. The sorption data followed Freundlich and D-R isotherms. The sorption capacity of 0.4 μmole·g−1 and of sorption energy of 9.9 kJ·mole−1 have been computed from D-R parameters. Thermodynamic parameters ΔH=84.4 kJ·mole−1, ΔS=284.5 J·mole−1·K−1 and ΔG=−3.32 kJ·mole−1 at 298 K have been evaluated. Fe(II), Al(III), citrate, borate, oxalate, tartrate and carbonate ions reduce the sorption significantly. Under similar experimental conditions Tc(VII), Re(VII), Sb(V) and Co(II) have very low sorption (<1%) and trivalent Eu and Sm have large distribution ratios. Haro river sand can be used to preconcentrate or to remove micro or submicro amounts of Cr(III) from very dilute solution and for the separation of Tc, Re and Sb from Cr, Eu and Sm.

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Abstract  

The sorption behavior of Sn(II) onto Haro river sand has been examined with respect to nature of electrolyte, agitation time, dosage of sorbent and concentration of sorbate. Maximum sorption (95.5%) has been achieved from 0.034M hydrochloric acid solution after equilibrating sorbate (2·10−5M) and sorbent (50 mg) for 120 minutes at aV/W ratio of 90 cm3·g−1. The kinetic data have been subjected to Morris-Weber and Lagergren equations. The kinetics of sorption proceeds a two stage process consisting of a relatively slow initial uptake followed by a much rapid increase in the sorption. The rate constant of intraparticle transport, Kd, comes out to be 8.75·10−8 mol·g−1·min−1/2 and the first order rate constant for sorption is 0.0416 min−1. The sorption data of Sn(II) onto Haro river sand followed Langmuir, Freundlich and Dubinin-Radushkevich (D-R) type isotherms. The Langmuir constant,Q, related to sorption capacity and,b, related to sorption energy are computed to be 10.6±1.1 μmol·g−1 and 1123±137 dm3·mol−1, respectively. The D-R isotherm yields the values ofC m=348±151 μmol·g−1 and β=−0.01044±0.0008 mol2·kJ−2 and ofE=6.9±0.3 kJ·mol−1. In all three isotherms correlation factor (γ) is ≥0.99. The influence of common anions and cations on the sorption has been investigated. Zn(II), Mg(II), oxalate, Pb(II), Mn(II) and tartrate reduce the sorption significantly whereas Fe(II) causes substantial increase in the sorption. It is essential that all ions causing a decrease in the sorption of Sn(II) must be absent from the sorptive solution otherwise low sorption yields would result.

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1 Introduction The ever-growing construction industry suffers due to paucity of the natural fine aggregate, the river sand. Extensive utilization of river sand [ 1 ] is restricted in many countries as it caused deepening of the riverbed depth [ 2

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finer nature. Nevertheless, in a detailed study [ 31 ] when granulated blast furnace slag (GFS), which has a particle size similar to river sand, is used as fine aggregate in concrete at 20%, 40% and 60%, better figures were noted in the quality of

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Pollack Periodica
Authors: Bintul Zehra, Ali Salem, Souphavanh Senesavath, Saied Kashkash, and Zoltan Orban

concrete, which occupy 70–80% of its volume. In most concrete mixes river sand acts as a fine aggregate. Nowadays due to the general shortage of river sand, it is highly important to apply substituents in concrete that are suitable for construction purposes

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Sustainability and scarcity in resources are the two major issues to be dealt within the present scenario by effective utilization of alternative materials. In this present study, an attempt has been taken to study the effect of supplementary materials such as fly ash and silica fume as a partial replacement to cement and steel slag and M-sand as a replacement to river sand on strength and durability of concrete. In this study, concrete specimens were prepared based on five different mixes by varying the percentages of these supplementary materials. Various mechanical properties like compressive strength, split tensile strength and flexural strength were performed to ascertain the mix with optimum levels of replacement of supplementary materials for cement and fine aggregate. Durability property like water absorption test was performed on the mix with optimum values of strength. Results revealed that mix with higher percentages of steel slag, optimum level of silica fume and fly ash have shown higher strength and lesser permeability in concrete.

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: 8112 (1989), river sand passing through 2.36 mm sieve, gravel passing through 20 mm sieve, SF collected from a local market and water confirming to IS 456 (2000) were used as raw materials in the study. Chemical constituents of cementitious materials

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; whiteness—80.1 %. The mortars were prepared using two types of aggregates. For the reference sample, clean washed and dried river sand was used. The properties of sand are fineness modulus—2.7 (EN 12620:2002 + A1:2008/HA:2008), and shape index—4

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] CaO 18.15 – SiO₂ 44.13 – Al₂O₃ 8.2 – MgO 2.7 – Fe 2 O₃ 7.6 – SO₃ 2.3 4 Na 2 O 2.9 – K 2 O 4.9 – TiO 2 0.3 – L.O.I 9.4 10 SiO 2 + Al 2 O 3 + Fe 2 O 3 , min. percent 74.8 Min. 70 2.5 Sand The natural river sand used as a fine aggregate was supplied

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