1,721,004 research outputs found
Electrochemical remediation of copper(II) from an industrial effluent. Part III foam cathodes in a single pass reactor
No full textTherefore, in the present communication, the removal of copper (II) from the
same industrial wastewater, by foam electrodes in a single-pass cell, is describe
Electrochemical remediation of copper(II) from an industrial effluent. Part II: three-dimensional foam electrodes
No full textA batch recycle removal of copper ions from an industrial effluent by means of copper foam cathodes was tested. A constant current of 750 A was applied to the cell in order to perform the reduction. Copper depletion was investigated at different solution flow rates and a removal greater than 98% was obtained with a flow rate of 1000 l:h. The influence of initial metal concentration on copper deposition and current efficiency is also discusse
Influence of the hydration degree on copper removal by Spirulina platensis biomass
No full textIn the present work, hydrated biomass of Spirulina platensis has been used for copper removal from aqueous solution
Adsorption of inorganic mercury from aqueous solutions onto dry biomass of Chlorella vulgaris: kinetic and isotherm study
No full textThis study focused on kinetics and equilibrium isotherms of mercury biosorption from water using dry biomass of Chlorella vulgaris as biosorbent at pH 5.0. Biosorption tests were performed at 2.0 g/L biomass dosage varying initial Hg concentration from 11.0 to 90.6 mg/L. The Lagergren equation was found to best describe the process, with R2of 0.984 and specific rate constant of 0.029 ± 0.004 min−1. Although equilibrium data were well fitted by the Dubinin and Radushkevich isotherm (R2 = 0.870; qDR = 16.6 mg/g), important insights on phenomenological events occurring at equilibrium were concurrently provided by the Lamgmuir one (R2 = 0.826; q0 = 32.6 mg/g; KL = 0.059 L/mg). FT-IR analysis confirmed that Hg biosorption took place via physisorption. Since C. vulgaris is a fresh-water microalga that can be easily cultivated anywhere, these promising results suggest its possible use as an effective, low-cost biosorbent to treat industrial effluents contaminated by this metal
Effects of pH on chromate(VI) adsorption by Spirulina platensis biomass: batch tests and FT-IR studies
No full textRaw and methylated biomass of Spirulina platensis was employed in chromate batch adsorption tests at pH range 1-7. The acid conditions seemed to favour the removal of chromium (Cr) with a yield of 87.0 and 97.6% by using raw and methylated biomass, respectively. However, the chromate and total chromium determination, carried out in the same sample, evidenced that a fraction of the initial chromate present in solution was reduced to Cr(III). This was ascribed to the presence of reducing groups on the biomass surface, active in the acid medium. The data showed that the methylated biomass was able to operate an effective Cr(VI) removal only. In fact, the biomass treatment allowed a lowering of the amount of negative functional groups, making the biomass surface available to bind the anions. The real best efficiency of Cr(VI) removal (83.5%) was obtained by methylated biomass of S. platensis at pH about 7.0. The nature of the biomass/chromate interactions was investigated by Fourier transform infrared spectroscopy (FT-IR) analysis. The bands ascribing to the adsorbed Cr(VI) species were well evident in the spectra of the biomass after adsorption, confirming this experimental finding
Methylene blue adsorption using chabazite: Kinetics and equilibrium modelling
No full textThe adsorption of methylene blue from aqueous solution by a natural zeolite (chabazite) was studied. The effect of adsorbate concentration and pH were evaluated using raw and acid-treated chabazite. Fourier transform infrared spectroscopy analysis revealed surface modification of acid-treated chabazite, thus resulting in a decrease in adsorption capacity. The sorption kinetics and the equilibrium isotherms were evaluated. The pseudo-second-order model was found to be the most suited for kinetic results, and the Langmuir isotherm was chosen to better describe the sorption system. The results confirmed the efficacy of raw chabazite in removing almost all methylene blue fraction from the solution. The use of such a material, at low cost and easily available, can therefore represent a possible efficient way to remove dyes from effluent of many industries
A Maximum Likelihood-based Method for the Nonlinear Estimation of Equilibrium Adsorption Parameters
No full textAdsorption technologies are widely employed in many important separation processes, especially in fine chemistry and environmental control. Thus, the increasing pressure for cost reduction in the operation of industrial plants, which calls for the use of efficient design techniques based on scientifically advanced methods, has led to the development of sophisticated physical chemical models for the description of adsorption equilibrium parameters. To account for the complex phenomena that take place at the microscopic level in the adsorption process, the most recently developed models require the estimation of a number of parameters higher than the ones present in the traditional Langmuir and Freundlich models. On the other hand, the presence of an increased number of strongly correlated parameters requires the use of suitable statistical methods for the information contained in the experimental results to be utilized efficiently. In this article we present a method that generalizes previous identification procedures to complex models containing an arbitrary number of parameters. The sensitivity of the resulting estimates on error distributions assumed and theoretical models chosen is examined using both simulated and experimental data
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