Adsorption Ability for Toxic Chromium (VI) Ions in Aqueous Solution of Some Modified Oyster Shell Types

Abstract

In this paper, the chromium, Cr (VI), ion adsorption ability of oyster shell samples collected from two sea regions in Vietnam (Phu Yen province and Quang Ninh province) was investigated and compared. The oyster shell samples were calcined at different temperatures and denatured by using ethylenediaminetetraacetic acid (EDTA). The Cr (VI) ion adsorption ability of the prismatic (PP) and nacreous (NP) shell layers of oysters was also evaluated. The characteristics of oyster shell samples before and after treatment were determined by using analysis methods including XRD, IR, BET, UV-Vis, and FESEM. The Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models and fit statistic equations were used to study the adsorption isotherms of Cr (VI) ion adsorption by oyster shells. The Cr (VI) ions adsorption kinetic has been set up using four reaction models consisting of first-order, pseudo-first-order, second-order, and pseudo-second-order reaction models. Effects of experimental factors on the Cr (VI) ion adsorption process using oyster shells were also investigated and discussed in this work.

Application of the Biomass from the Shell of Pachyrhizus erosus in the Removal of Hexavalent Chromium from Contaminated Waters

“…4), using a Corning Pinnacle 530 model pH meter and 1 M HNO 3 to keep the pH value constant, since the capture speed is controlled by the time at which the adsorbate it is transported from the outside to the inside of the bioadsorbent particles [15]. These results are least efficient for those reported with the biomass of macromycete A. bisporus, which the removal was 100% at 21 minutes [7], for the C, sativum biomass, when the highest removal was observed within 3 hours, with 1.0 g of natural biomass, and 28°C [8], for the A. comosus biomass shell, the highest biosorption of the metal (100 mg/L) occurs within 10 hours, at pH of 1.0, 28°C with 5 g of natural biomass [9], too an optimum time of 2 and 4 hours for the removal of Chromium (VI) by Macadamia nutshell powder [10], 2 hours for the modified Oyster shell types, and chemically modified dried water hyacinth roots [11,12], an optimum time of 10 minutes using orange peel and wheat bran, for the removal of Chromium (VI) from wastetewater [16], 6 hours for Chromium (VI) removal and total Chromium biosorption from aqueous solution by Quercus crassipes acorn shell [17], 30 minutes for the decontamination of the same metal on modified chicken feather [18], and 80 and 50 minutes with orange peels and Fomitopsis pinicola [19]. On the other hand, the highest metal adsorption was observed at a pH of 1.0 with the analyzed biomass (Fig.…”

“…4), and this is probably what the dominant species (CrO 4 2and Cr 2 O 7 2of Cr ions in solution, interact more strongly with the ligands carrying positive charges [20,21], and this is like that reported for the fungal A. bisporus, C. sativum, and A. comosus biomass, which the optimum pH of removal was 1.0 [7,8 and 9], too the same pH valor using orange peel and wheat bran, Q. crassipes acorn shell, and modified chicken feather [16,17 and 18], a pH between 1.1-2.0 using different types of biosorbents (F. pinicola, a mixture of cones, peach stones, apricot stones, Juglans regia shells, orange peels, and Merino sheep wool to removal Chromium (VI) from aqueous solution [19]. But these results are different for the adsorption ability for toxic chromium (VI) ions in aqueous solution of some modified Oyster shell types, in which is reported an optimum pH of 6.0 [11], a pH of 3.0 for the chemically modified dried water hyacinth roots [12], a pH of 9.0 for calcite based biocomposites [22], and an optimum pH of 2.0 for the bioremotion with Arequipeña papaya seed (Vasconcellea pubescens) for total chromium removal [23].…”

“…6B). This is like that reported for A. bisporus biomass, where at low concentrations of the metal (200 mg/L and 28oC), this biomass showed the best removal responses, adsorbing 100% at 60 minutes while with 1.0 g/L of Chromium (VI), removal was 90.3%, while, at 60oC, the biomass studied removal 100% at 90 minutes with 1 000 mg/L of the metal [7], for the removal of the same metal for C. sativum biomass, with a elimination of 100% at 4 and 24 hours, at 28°C, for 200 and 1000 mg/L, respectively [8], for the A. comosus biomass, which the highest removal was observing at 60°C, in 3 hours, when the metal is completely adsorbed, and at low metal concentrations (200 mg/L) a 28°C, was observe the best results for the elimination because the removal of the metal was 100% and 48%, at 24 hours for 200 and 1000 mg/L, respectively [9], for the chemically modified dried water hyacinth roots, with an optimum concentration reported of the metal was 10 mg/L [12], for calcite based biocomposites, in which is increase the metal concentration of 250 to 2000 mg/L decrease the removal of the metal [22], if increase the initial concentration of the metal, from 1 to 3 g, decrease the Chromium (VI) removal with modified biomass from wheat residues (T. aestivum) in wastewater [24], and it has shown that as the initial concentration of hexavalent chromium increases, decrease the biosorption capacity of the activated carbon from the coffee grounds and therefore the efficiency [27], and these results are different for the modified Oyster shell types, and Q. crassipes acorn shell, which if increase the metal concentration too increase the removal of the same metal [11,17], for the decontamination of hexavalent Chromium on modified chicken feather, the percentage removal gradually increases with increasing initial concentration of the metal from 5 to 25 mg/L [18], and using orange peel and wheat bran, the concentration of the metal does not affect the removal of Chromium (VI) under the conditions selected for the wastewater [16].…”

“…The influence of the biomass concentration on the Chromium (VI) elimination capacity is shown in Fig. 7, in which it is observed that if the biomass concentration increases, the elimination of the metal in solution increases, since with 5 grams of biomass 93.3% of the metal is removed at 2.7 hours, while with 1.0 g, 52% is removed at the same time of incubation, because there are more bioadsorption sites of it, since the amount of bioadsorbent added determines the number of binding sites available for the biosorption of heavy metals [20,21], and these results are like those reported for A. bisporus biomass, when If the amount of biomass is increased from 1 to 5 g, the removal of the metal in solution also increases, with 90.3%, with 1.0 g of biomass at 160 minutes, while with 5 g of biomass, the removal is 100 % at 100 minutes, at pH 1.0, 28oC and 100 rpm [7], for the A. comosus biomass, in which with 5 g of biomass at 10 hours, the metal is fully removed, while with 20 g of biomass, the removal is 100 % at 5 minutes, at pH 1.0, 28oC and 100 rpm [9], for the modified Oyster shell types, if increased the concentration of biomass of 1.65 mg/g to 2.92 mg/g, the removal capacity increase from 29.3% to 58.3% [11], for the chemically modified dried water hyacinth roots, with an optimum adsorbent concentration reported was 14 g/L [12], too, it was observed that quantitative removal of the hexavalent Chromium ion increases with increasing biosorbent dose and maximum removal was achieved by using 0.15 g/50 mL of chicken feather [18], if increase the initial concentration of the biomass, from 1 to 3 g, increase the Chromium (VI) removal with modified biomass from wheat residues (T. aestivum) in wastewater [24], and are different for the C. sativum biomass, if was increasing the amount of biomass, the removal of the metal in solution decreased slightly, well the removal obtained was observed between 100%-80%, with 1-5 g of natural biomass [8].…”

“…Exposure to Chromium causes several toxic effects, namely dermatitis, allergies, cancer, mutations, and teratogenic effects, which have been attributed to hexavalent Chromium ions [Cr (VI)] [4]. Chromium contamination and the impact on public health, has led man to seek alternatives to solve this problem, using traditional methods such as: reverse osmosis, electrodialysis, ultrafiltration, ion exchange and chemical precipitation [5]; but the high cost of conventional methods led to the development of technological alternatives, which, in addition to take advantage of and apply the natural processes that occur in an ecosystem to purify a polluting residue, offer the possibility of recover the resources present in it for later use, also generating an economic value that contributes to sustainability of the system, about the Chromium (VI) removal process there are many investigations in this regard [6], like the use of the biomass of Agaricus bisporus for the bioremediation of this metal in solution [7], the application of Coriandrum sativum biomass in the removal of Chromium (VI) from polluted waters [8], the biosorption of the same metal in aqueous solution by Ananas comosus biomass shell [9], their removal of their by Macadamia nutshell powder [10], their adsorption by modified Oyster shell types [11], the adsorption of Chromium (VI) from the synthetic aqueous solution using chemically modified dried water hyacinth roots [12], and for the biomass from the coffee industry [13]. For the above, the objective of this work was studying the removal capacity of Chromium (VI) by the biomass of the shell of Pachyrhizus erosus.…”