Microalgal Biosorption of Heavy Metals: A Bibliometric Review

Abstract

With their non-biodegradable and highly toxic forms, continual presence of heavy metals such as cadmium, lead, mercury, and chromium, raises an ever-present environmental problem in the world. The high cost and environmental cost of the traditional forms of treatment has sparked an explosion of interest in biological alternatives. Microalgal biosorption has been gaining momentum in the recent years as an attractive and eco-friendly method for treating heavy metal. A thorough bibliographic review is performed, assessing the advancement of microalgal biosorption in controlling heavy metals over the past two decades. Using bibliometric resources, we examine the trend in the number of publications, the most cited researchers, institutions, and countries, and evaluate the interplay of different keywords and collaborative structures. The interest among scholars has since 2010 been reflected in research articles on the topic. Cadmium is a metal of choice for research in bio adsorption, as Chlorella, Scenedesmus and Spirulina are preferred candidates for such studies. Importance of cell wall functional groups, extracellular polymeric substances and environmental parameters in enhancing biosorption efficiency has been highlighted by critical mechanistic research findings. Although early laboratory results are encouraging, limitations in terms of biomass recovery, scalability, and economics restrict such applications on a large scale in practical situations. By reflecting on the advance and development of the discipline, this paper outlines major research themes at the cutting-edge, and highlights key research gaps in dire need of attention. Many of the top aims for future research efforts include the improvement of genetic engineering, the introduction of hybrid treatment systems, and lifecycle analyses all with the goal to increase contributions to environmental biotechnology from microalgae. This review is of great benefit to the researchers, environmental engineers and policy makers seeking to develop sustainable plans to counter heavy metal pollution.