Potentials of agricultural wastes as the ultimate alternative adsorbent for cadmium removal from wastewater. A review

• Main Authors: Muhajir Mussa Kwikima, Said Mateso, Yonas Chebude
• Format: Article
• Language: English
• Published: Elsevier 2021-09-01
• Series: Scientific African
• Subjects: Biosorption; Agricultural wastes based biosorbents; Cadmium; Removal efficiency
• Online Access: http://www.sciencedirect.com/science/article/pii/S2468227621002386

The removal/recovery of cadmium from wastewaters by conventional technologies is proving expensive due to the non-renewability of the materials used and the high costs of both operation and materials. Biosorption using agricultural wastes is emerging as a method that offers economical alternate biological materials to save the purpose. Functional groups like carboxyl, hydroxyl, sulphydryl, and amido present in these Agricultural waste-based biosorbents (AWB) make it possible for them to attach Cd2+ from waters. This review article discusses the potential use of different AWBs for the removal of cadmium in terms of their adsorption efficiencies, variable influencing factors, and pre-treatment methods. The literature studies consulted signpost that AWBs have equal and even greater adsorption capabilities in some cases compared to conventional adsorbents. Initial concentration, pH, ionic strength, co-ions, biosorbent dosage, temperature, and particle size of AWBs significantly determine the biosorption potential for Cd2+ removal. Furthermore, physical and chemical pre-treatments of AWBs bring remarkable improvement in Cd2+ uptake capacity, but some chemical additives have been found to have negative impacts on aquatic life. Nevertheless, there are some gaps observed, which require further study, such as (i) searching for pre-treatment chemicals with maximum adsorption potential enhancement with minimal impact on aquatic lives, (ii) developing the most cost-effective modification methods, and (iii) assessing AWBs under real wastewater systems. The study moreover recommends that the extensive use of AWBs should not jeopardize food security.