Biosorption, Metals

Abstract

Biosorption is a property of certain types of inactive, dead, microbial biomass to bind certain chemical components and thus also to concentrate heavy metals from even very dilute aqueous solutions. Certain types of biomass exhibit this property, acting just as chemical substances, as ion exchangers of biological origin. It is particularly the cell wall structure of certain algae, fungi and bacteria which was found responsible for this phenomenon. Some biomass types, serving as a basis for metal biosorption processes, can accumulate in excess of 25% of their dry weight in deposited heavy metals such as Pb, Cd, U, Cu, Zn, even Cr and others. Research on biosorption is revealing that it is sometimes a complex phenomenon where the metallic species could be deposited in the solid biosorbent through different sorption processes of ion exchange, complexation, chelation, microprecipitation, etc. A whole new family of suitably “formulated” biosorbents can be used in the process of metal removal and detoxification of industrial metal‐bearing effluents. The sorption packed‐column configuration is the most effective mode of application for the purpose. Recovery of the deposited metals from saturated biosorbent can be accomplished because they can often be easily released from the biosorbent in a concentrated wash solution which also regenerates the biosorbent for subsequent multiple reuse. This and extremely low cost of biosorbents makes the process highly economical and competitive particularly for environmental applications in detoxifying industrial metal‐bearing effluents.

Removal of Copper(II) from Aqueous Solutions by Biosorption-Flotation

“…Although precipitation may contribute to the overall removal of the metal (Naja et al 2010), it was reported that the suitable pH range for Cu(II) biosorption is 1-6, because within this range, the only stable existing species are represented by hydrated copper ions [Cu(H 2 O) 4 ] 2+ (Naja et al 2010;Peng et al 2010;Zhang et al 2010b). At higher pH values, Cu(II) ions start to precipitate resulting hydroxides (Cu(OH) + and 10, Cu(OH) 4 2− at pH≥12), and the precipitation is complete around pH 12.…”

“…Moreover, because of their high mobility, heavy metal ions are being concentrated and accumulated throughout the food chain (Naja et al 2010;Naja and Volesky 2009;Chojnacka 2009;Kotrba et al 2011). Consequently, controlling heavy metal discharges and removing the toxic heavy metals from aqueous solutions have become a challenge for the field of research and development (Volesky 2001).…”

Aporte de la biorremediación para solucionar problemas de contaminación y su relación con el desarrollo sostenible

“…Dos procesos biotecnológicos principales están disponibles para la eliminación de compuestos orgánicos volátiles de los gases (34) . Se evidencia que la biorremediación ha venido desempeñando un papel importante en el mantenimiento de un ambiente limpio, el cual se ampliará sustancialmente a medida que esta biotecnología se desarrolle e implemente para el tratamiento de todo tipo de efluentes, residuos y emisiones industriales (32,35,34) .…”

“…Sin embargo, a pesar de que la biorremediación es a menudo considerada como un tratamiento efectivo económico y amigable del ambiente (35,33) , enfrenta un nuevo reto: convencer a las compañías y a los organismos oficiales de su alto potencial, por cuanto se ha venido convirtiendo en una verdadera industria para sanear el ambiente de las afectaciones generadas por las actividades humanas (26) .…”

Cleanup of industrial effluents containing heavy metals: a new opportunity of valorising the biomass produced by brewing industry

“…Nevertheless, some practical difficul-ties have been observed, which compromise, strongly, the feasi-bility of the desorption process: (a) the deterioration of the yeast cells particularly when concentrated acids or prolonged exposure times were used; (b) the reduction of metal uptake through the successive biosorption/desorption cycles; and (c) the lower metal concentration capacity (Strandberg et al 1981;Ferraz et al 2004;Kordialik-Bogacka 2011). The last point is particularly important as the accumulation/desorption cycle should concentrate on metals, at least, ∼100 times from the initial concentration present in the wastewaters (Naja et al 2010).…”