Biosorption of hexavalent chromium and molybdenum ions using extremophilic cyanobacterial mats: efficiency, isothermal, and kinetic studies

Abstract

Two extremophilic cyanobacterial–bacterial consortiums naturally grow in extreme habitats of high temperature and hypersaline were used to remediate hexavalent chromium and molybdenum ions. Extremophilic cyanobacterial–bacterial biomasses were collected from Zeiton and Aghormi Lakes in the Western Desert, Egypt, and were applied as novel and promising natural adsorbents for hexavalent chromium and molybdenum. Some physical characterizations of biosorbent surfaces were described using scanning electron microscope, energy-dispersive X-ray spectroscopy, Fourier transformation infrared spectroscopy, and surface area measure. The maximum removal efficiencies of both biosorbents were 15.62–22.72 mg/g for Cr(VI) and 42.15–46.29 mg/g for Mo(VI) at optimum conditions of pH 5, adsorbent biomass of 2.5–3.0 g/L, and 150 min contact time. Langmuir and Freundlich adsorption models were better fit for Cr(VI), whereas Langmuir model was better fit than the Freundlich model for Mo(VI) biosorption. The kinetic results revealed that the adsorption reaction obeyed the pseudo-second-order model confirming a chemisorption interaction between microbial films and the adsorbed metals. Zeiton biomass exhibited a relatively higher affinity for removing Cr(VI) than Aghormi biomass but a lower affinity for Mo(VI) removal. The results showed that these extremophiles are novel and promising candidates for toxic metal remediation.

NOVELTY STATEMENT

Even though many researchers worked on the field of metal bioremediation, most use single organism or extracted biogenic materials for heavy metals removal. The novelty of this study is the application of a consortium of cyanobacteria and bacteria from extreme habitats (hyper-salinity, high temperature, harsh weather conditions, high intensity of light and UV light) in the field of environmental safety. This specialized microbial film composed of a diverse group of adapted organisms that co-operate between each other making them more effective bio-remediating agent. This study examined the effectiveness of these consortia as metals bioremediator and cover the gap of research results from the scarce application of novel, cheap and eco-friendly extremophiles in toxic metals removal

Keywords:

• Biosorption
• chromium
• extreme habitat
• extremophilic mats
• molybdenum

Disclosure statement

The authors declare that they have no conflict of interests.

Informed consent

This manuscript did not involve human or animal participants; therefore, informed consent was not collected.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This this research work was funded by the Deputyship for Research & Innovation, Ministry of Education in Saudi Arabia through the project number RI-44-0613.