Application of algae as low cost and effective bio-adsorbent for removal of heavy metals from wastewater: a review study

ABSTRACT

These days the control of pollution caused by various industries is one of the major concerns of societies. It is necessary to provide cost-effective and efficient methods, despite the economic constraints for controlling the pollution of wastewater treatment processes. Nowadays, heavy metals are one of the most important environmental pollutants. So, removal of these metals from water and wastewater, up to a permissible amount, is necessary. Adsorption is widely used due to its flexibility in design and operation, reversibility, low cost, and desirable results. However, finding suitable and environmentally friendly adsorbents for removal of these metals increasingly seems essential. In recent years, the use of algae as a bio-adsorbent has received much attention due to its especial properties such as environmentally friendly, low cost, easy access and high adsorption capacity. This study, reviews various methods of removing heavy metals and investigates the use of algae as bio-adsorbents to remove these metals and their hazards and sources. Moreover, the equilibrium, kinetic, and thermodynamic behaviours of the heavy metal ion adsorption process using Langmuir and Freundlich adsorption models, pseudo-first and second-order kinetic models, and thermodynamic parameters including enthalpy (ΔH °), entropy (ΔS °) and Gibbs free energy changes (ΔG °) are reviewed briefly. In almost all cases, the pseudo-second-order kinetic model and Langmuir and Freundlich isotherms were better matched with the experimental data. Also, the heavy metal adsorption on the algae showed exothermic process.

GRAPHICAL ABSTRACT

KEYWORDS:

• Bio-adsorbent
• heavy metal
• bio-sorption
• wastewater treatment
• algae

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes on contributors

Abolhasan Ameri is an assistant professor of the Chemical and Petroleum Engineering at the Shiraz Branch, Islamic Azad University, Shiraz, Iran. His areas of interest and research are in the adsorption, renewable energy, heat and mass transfer, nanotechnology, enhanced oil recovery (EOR) and oil and gas reservoirs. He received his PhD in Chemical Engineering from Shiraz University in 2017.

Sajad Tamjidi is a PhD student of the Chemical and Petroleum Engineering at the Shiraz Branch, Islamic Azad University, Shiraz, Iran. His areas of interest and research are in the Adsorption, renewable energy, water and wastewater Treatment, nanotechnology, Environment and separation Technology.

Faegheh Dehghan Khalili is a PhD student of Chemical Engineering at Shiraz Branch, Islamic Azad University, Shiraz, Iran. Her areas of interest are mass transfer, nanotechnology, water treatment and enhanced oil recycling (EOR).

Arezoo Farhadi is a PhD student in Chemical Engineering Department at Shiraz Branch, Islamic Azad University, Shiraz, Iran. Her areas of interest are adsorption, petrochemical processes, nanotechnology, and water treatment.

Mohammad Amin Saati, a PhD student in chemical engineering at Shiraz Azad University. I am working in the refinery phases of Iranian South Pars. I am familiar with refining processes and have done research on heat exchangers and Biofilters.