Use of Different Types of Biosorbents to Remove Cr (VI) from Aqueous Solution.

Eva Pertile,Silvie Heviánková,Tomáš Dvorský,Vojtěch Václavík

doi:10.3390/life11030240

Abstract

This article summarizes the results of a research study that was focused on the possibility of removing Cr (VI) from aqueous solution, using low-cost waste biomaterial in a batch mode. A set of seven biosorbents was used: Fomitopsis pinicola, a mixture of cones, peach stones, apricot stones, Juglans regia shells, orange peels, and Merino sheep wool. Three grain fractions (fr. 1/2, fr. 0.5/1.0, and fr. 0/0.5 mm) of biosorbents were studied. The aim was to find the most suitable biosorbent that can be tested with real samples. The influence of other factors on the course of biosorption was studied as well (chemical activation of the biosorbent, pH value, rotation speed during mixing, temperature, and the influence of biosorbent concentration). The use of chemical activation and adjustment of the pH to 1.1 to 2.0 make it possible to increase their sorption capacity and, for some biosorbents, to shorten the exposure times. Two kinetic models were used for the analysis of the experimental data, to explain the mechanism of adsorption and its possible speed control steps: pseudo-first and pseudo-second-order. The pseudo-second-order kinetic model seems to be the most suitable for the description of the experimental data. The thermodynamic parameters suggest that the biosorption was endothermic and spontaneous. In the biosorption equilibrium study, the adsorption data were described by using Langmuir and Freundlich adsorption isotherms. The Langmuir model was applicable to describe the adsorption data of all biosorbents. Both models are suitable for chemically treated sheep fleece and peach stones.

Highlights

Water is priceless, from the point of view of the life of organisms and the landscape, it is too often underestimated by humans
A set of the following seven biosorbents was used to study the removal of hexavalent chromium from aqueous solution: Fomitopsis pinicola; a 1:1 mixture of Scots pine cones (Pinus sylvestris) and Norway spruce (Picea abies); peach stones (Prunus persica); apricot stones (Prunus armeniaca); walnut shells (Juglans regia); orange peels (Citrus sinensis); and raw, the so-called virgin Merino wool from young four-year-old sheep (Merino breed)
Since the aim of the whole study was to select the best biosorbent/biosorbents that would be useful for removing Cr (VI) from aqueous solution, one of the prerequisites was to keep the conditions of the individual experiments as uniform as possible

Summary

Introduction

From the point of view of the life of organisms and the landscape, it is too often underestimated by humans. The issue of heavy metals, with regard to their toxicity, persistence, and bioaccumulation capacity in the environment, still attracts a lot of attention. Their presence in industrial wastewater is often a major problem with respect to their discharge into surface water. Chromium, which is used in a number of industrial applications, can be included among these problematic metals as well Wastewater contains both hexavalent and trivalent chromium in a concentration 10–100 mg·L−1. The interesting properties of these sorbents include their high versatility, relatively good metal selectivity, and, in some cases, high sorption capacity, especially in the low range of concentrations. It should be noted that not all of these naturally available materials that have been studied so far have had a satisfactory sorption capacity in the verified concentration range

Objectives

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Results

Conclusion