The potential use of spent coffee ground (SCG) for the removal of copper has been investigated as a low‐cost adsorbent for the biosorption of heavy metals. Adsorption batch experiments were conducted to determine isotherms and kinetics. The biosorption equilibrium data were found to fit well the Freundlich model and an experimental maximum biosorption capacity of copper ions 0.214 mmol/g was achieved. The biosorption kinetics of SCG was studied at different adsorbate concentrations (0.1–1.0 mM) and stirring speeds (100–400/min). The results showed an increase in the copper ion uptake with raising the initial metal concentration and the kinetic data followed the pseudo‐second order rate expression. The effect of stirring speed was a significant factor for the external mass transfer resistance at 100/min and coefficients were estimated by the Mathews and Weber model. Biosorption of copper ions onto SCG was observed to be related mainly with the release of calcium and hydrogen ions suggesting that biosorption performance by SCG can be attributed to ion‐exchange mechanism with calcium and hydrogen ions neutralizing the carboxyl and hydroxyl groups of the biomass.
This paper presents experimental densities and viscosities of binary mixtures of biodiesel with 1-butanol, isobutyl alcohol, and 2butanol from 293.15 to 333.15 K at 0.1 MPa. Densities are from a vibrating tube densimeter while viscosities are from a capillary glass viscometer. Experimental data of density and viscosity of pure alcohols agree with data reported in the literature with an average absolute percentage deviation of 0.06% and 1.3%, respectively. Experimental kinematic viscosities of the mixtures show a minimum value in the concentration range. The Grunberg−Nissan equation successfully correlates kinematic viscosities with an average absolute percentage deviation of 0.98%.
This paper presents densities and viscosities of binary mixtures of 1pentanol + 2-pentanol, 1-pentanol + 2-methyl-1-butanol, and 2-pentanol + 2-methyl-1-butanol from (288.15 to 328.15) K over the entire concentration range at atmospheric pressure. Experimental densities and viscosities are measured using a vibrating tube densimeter and a glass capillary viscometer, respectively. The relative standard uncertainties estimated in the density and viscosity were 4.8 × 10 −4 and 0.01, respectively. Densities and viscosities of the binary mixtures are compared with the limits established by the diesel fuel standard (EN 590). The binary mixtures of 1pentanol + 2-methyl-1-butanol, and 2-pentanol + 2-methyl-1-butanol could be considered as alternative substitutes for diesel fuel. Excess molar volume values suggest that these mixtures behave as ideal solutions. Viscosity deviations are negative for all of the mixtures investigated in this study. The Redlich−Kister equation is used to represent the behavior of the excess molar volumes and viscosity deviations as a function of the composition. The Nava-Ri ́os and McAllister equations correlate the kinematic viscosity values with an average absolute percentage deviation of 0.139% and 0.203%, respectively.
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