Biosorption of Cadmium from Aqueous Solution by Shell Dust of the Fresh Water SnailMelanoides tuberculata

Abstract

The metal bioadsorption potential of shell dust of the freshwater snail Melanoides tuberculata (MTSD) was evaluated under laboratory conditions using cadmium as a model metal. As bioadsorbent, MTSD exhibited a biosorption capacity of 27.03 mg g ¡1 at pH 6, indicating potential to remove cadmium from aqueous solution. The adsorption data fit more to the Langmuir (R 2 D 0.998) equation than the Freundlich (R 2 D 0.761) equation at equilibrium condition. The kinetics of biosorption followed the pseudosecond-order model (R 2 D 0.999) better than the Lagergren model (R 2 D 0.676), as was evident from the regression analysis. The presence of calcium ions appears to have facilitated ion exchange with cadmium along with the binding of different functional groups, as revealed through Fourier transform infrared (FT-IR) analysis. It is apparent from these observations that MTSD can act as low-cost and efficient bioadsorbent for cadmium bioremediation from aquatic habitats. Use of the shells of M. tuberculata for metal biosorption will promote the utility of a waste material of biological origin for bioremediation of heavy metals such as cadmium.

Microstructure Analysis and Chemical and Mechanical Characterization of the Shells of Three Freshwater Snails

“…The growth and structural peculiarities of the molluscan shells, particularly the bivalve and gastropod shells, have been studied to corroborate the evolutionary processes, , physical properties, and functional roles. ,,, The elaboration of the microarchitecture, chemical composition, and mechanical properties ,,,, has been the foundation for promoting the molluscan shell as a biological material with multiple industrial, agricultural, and biomedical applications. − While it is considered as a waste originating from aquaculture or agriculture, the hydroxyapatite derived from the shells of the freshwater snails has biomedical applications. , In addition, the shells are used as biocatalysts for biodiesel production ,,,, as well as in metal bioremediation, − , thereby justifying the highly cost-effective means of recycling of waste. Thus, to qualify as a potential source for various industries, the calcium carbonate content of the shell of a snail needs to be substantially high.…”

“…While the calcium carbonate content of the shells of B. bengalensis as well as other snails − , is primarily attributed to the metal removal potential through biosorption, the efficacy may improve with the modification to a biocomposite. Thus, further exploration of the shell inclusive of the organic components is required to promote its possible use as a biocomposite.…”

“…26−29 While it is considered as a waste originating from aquaculture or agriculture, the hydroxyapatite derived from the shells of the freshwater snails has biomedical applications. 42,99 In addition, the shells are used as biocatalysts for biodiesel production 39,41,47,48,100 as well as in metal bioremediation, [31][32][33][34][35][36]38 thereby justifying the highly cost-effective means of recycling of waste. Thus, to qualify as a potential source for various industries, the calcium carbonate content of the shell of a snail needs to be substantially high.…”

“…For the experiments, the shells of the dead snails were cleared of flesh remnants, if any, while the opercula were removed and discarded. The shells used for the analysis were washed properly under running water and then sun-dried for at least 72 h. Prior to preparation of the shells for further studies, the shell weight (in mg) and shell length (in mm) were measured, − irrespective of the species, and recorded for analysis. The shell length and shell weight of the snails were as follows: B.…”

“…The multiple uses of the molluscan shell as a biological material are recognized, which are mostly linked with mussels, clams, abalones, and oysters that are of marine origin. − In contrast, the potential of the shells of freshwater snails and mussels as biological materials are yet to be significantly explored. Although they are harvested as food resource, the efficacy of the discarded shells of freshwater snails and mussels as metal biosorbents appears to be considerably higher − in terms of metal removal and availability in nature. The shells of the freshwater snail Pomacea canaliculata is used as PVC composite materials as well as for metal bioremediation .…”