Removal of Cr(VI) and Cu(II) ions from aqueous solution by rice husk ash—column studies
TL;DR: In this paper, the technical feasibility of rice husk ash for adsorptive removal of Cr(VI) and Cu(II) is examined in packed bed from aqueous solutions.
Abstract: In this present study, the technical feasibility of rice husk ash for adsorptive removal of Cr(VI) and Cu(II) is examined in packed bed from aqueous solutions. The effects of different operating parameters such as height of the packed bed column (5–15 cm), flow rate of aqueous metal ion solution (10–30 ml min−1), and initial metal ion concentration (10–30 mg L−1) were studied. Capacity of the bed to absorb metal ions was found to increase with an increase in bed height, decrease in flow rate, and metal ion concentration. Adams–Bohart, Yoon–Nelson, and Thomas models were applied to the experimental data for the prediction of breakthrough point and also to determine the model parameters to characterize the column. The Yoon–Nelson model and Thomas model were applicable for Cr(VI) removal, and for Cu(II), Thomas model was suited.
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TL;DR: In this paper, the effect of various mineral additives on the mechanical, durability and microstructure properties of concrete and geopolymer mixtures was summarized and the results advocate that mixtures with desired properties can be designed for ambient temperature curing condition with minerals additives which may further promote them as an environmentally friendly construction material.
125 citations
TL;DR: In this paper, a scale-up design for Cr(VI) removal using walnut shell as an adsorbent and its economic feasibility are done to find out its applicability in real life.
90 citations
TL;DR: These adsorbents have an excellent potential and are useful for water treatment particularly small- and medium-sized industries of third world countries, as breakthrough time and exhaustion time are longer in comparison to peanut shell.
Abstract: Cr(VI) is a toxic water pollutant, which causes cancer and mutation in living organisms. Adsorption has become the most preferred method for removal of Cr(VI) due to its high efficiency and low cost. Peanut and almond shells were used as adsorbents in downflow fixed bed continuous column operation for Cr(VI) removal. The experiments were carried out to scrutinise the adsorptive capacity of the peanut shells and almond shells, as well as to find out the effect of various operating parameters such as column bed depth (5–10 cm), influent flow rate (10–22 ml min−1) and influent Cr(VI) concentration (10–20 mg L−1) on the Cr(VI) removal. The fixed bed column operation for Cr(VI) adsorption the equilibrium was illustrated by Langmuir isotherm. Different well-known mathematical models were applied to the experimental data to identify the best-fitted model to explain the bed dynamics. Prediction of the bed dynamics by Yan et al. model was found to be satisfactory. Applicability of artificial neural network (ANN) modelling is also reported. An ANN modelling of multilayer perceptron with gradient descent and Levenberg-Marquardt algorithms have also been tried to predict the percentage removal of Cr(VI). This study indicates that these adsorbents have an excellent potential and are useful for water treatment particularly small- and medium-sized industries of third world countries. Almond shell represents better adsorptive capacity as breakthrough time and exhaustion time are longer in comparison to peanut shell.
41 citations
Cites background from "Removal of Cr(VI) and Cu(II) ions f..."
...Higher incoming flow rate gives the lower removal efficiency (Han et al. 2009b; Chen et al. 2012; Sarkar and Das 2015) Effect of influent concentration of Cr(VI) The effects of influent concentration of Cr(VI) on the breakthrough curves for peanut and almond shell are shown in Fig....
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...…transfer coefficient or diffusion coefficient and hence the breakthrough curves became sharper which indicates that the adsorption process controlled by the smaller mass transfer zone and also intra-particle diffusion (Uddin et al. 2009, Baral et al. 2009; Chen et al. 2011, Sarkar and Das 2015)....
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...The intake of Cr(VI) increased with the increase of bed depth due to an increase in contact time for Cr(VI) adsorption as well as adsorbent surface area increased (Suksabye et al. 2008; Sarkar and Das 2015)....
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...Higher incoming flow rate gives the lower removal efficiency (Han et al. 2009b; Chen et al. 2012; Sarkar and Das 2015) Effect of influent concentration of Cr(VI)...
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TL;DR: In this article, a study was performed in fixed bed downflow columns at multiple flow rates, bed depths, and influent concentrations for Cr(VI) elimination using the above green adsorbents.
39 citations
TL;DR: In this article , the performance and applicability of several adsorptive materials for hexavalent chromium (Cr(VI) removal from aqueous media are discussed, along with a detailed analysis of the mechanisms involved.
38 citations
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352 citations
TL;DR: The present study deals with the adsorption of Pb(II) from aqueous solution on rice husk ash, a by-product generally obtained from rice mill, and the suitability of the process in waste water treatment operation.
326 citations
TL;DR: The present paper will develop mathematical descriptions of single solute chromatography for the two simplest reasonable mechanisms of adsorption considered as a kinetic process for the multiple solute problem.
Abstract: The theory of chromatography has been discussed by several wi’iter~.l-~ For the most part, the problem has been treated from the point of view of instantaneous equilibrium between solution and adsorbent. Walters has, however, given a kinetic treatment of the problem for the case of ion exchange between solution and solid. The complete solution of this latter problem has been given by the present writer.1° The present paper, after a review of pertinent parts of the equilibrium theory, will develop mathematical descriptions of single solute chromatography for the two simplest reasonable mechanisms of adsorption considered as a kinetic process. The results of some experiments in which rate data were obtained are reported, and are discussed from the point of view of the kinetic theory. The multiple solute problem is mentioned.
289 citations
TL;DR: A systematic evaluation of six different natural adsorbents for the removal of Cr(VI) from aqueous solutions in batch process indicated that the adsorption processes were endothermic and chemical in nature.
215 citations
TL;DR: The results suggested that chaff as adsorbent to removal heavy metal ions from solution prove efficient, and the rate of biosorption process is speedy.
195 citations