Green carbon-based adsorbents for water treatment in Sub-Saharan Africa

Abstract As underlined by the United Nations Sustainable Development Goals (UN SDGs), providing safe and clean potable water remains a significant concern in developing regions of the world, especially Sub-Saharan Africa. Extensive research has been done on this subject in Africa. The concept of sustainable chemistry towards solving another pressing issue in Africa – waste management – led to the decision to investigate green carbon-based materials for water purification on the continent. The conversion of “waste to wealth” is a practical means of achieving proper waste management at a reasonable cost. Low-cost adsorbents such as biochar, activated carbons, graphene and carbon composites, with high surface area, porosity and efficiency have been generated from agricultural waste and biomass, carbon-rich geological materials, carbonaceous polymeric materials, and hydrocarbons/petroleum by-products, using simple thermal and/or green chemical reaction protocols. Several drawbacks have hindered the development and utilization of adsorbents for the treatment of polluted water, including chemical fouling, loss of activity, poor reusability, difficulty associated with sorbent regeneration, production of secondary pollutants, toxicities caused by exposure to sorbent residues, and inability to deal with heavily polluted water. However, the use of adsorbents is still widely acclaimed as an efficient and cleaner method among other existing water treatment options such as extraction, chemical oxidation, bioremediation, and photocatalytic degradation. This paper outlines the research carried out by Sub-Saharan African scientists to proffer solutions to water pollution using green carbon-based adsorbents and discusses the breakthroughs, challenges, and future prospects.