A Systematic Review on Water Hyacinth (Eichhornia crassipes) as a Biosorbent of Cadmium

Water hyacinth (Eichhornia crassipes) has gained a noteworthy reputation as the worst invasive macrophyte for its alarming proliferation rates, which threaten transportation and irrigation systems and ecosystem biodiversity. Recently, researchers have focused their attention on developing novel materials that come from biomass such as water hyacinth capable of removing heavy metals in the water streams. In fact, sustainable efforts have found the plant to demonstrate efficiency as a biosorbent in sequestering toxic heavy metals such as cadmium from marine environments. Cadmium's presence in water, primarily brought about by anthropogenic sources, poses public health risks due to its toxicity. Consequently, studies on the applications of Eichhornia crassipes and the removal of cadmium have become active research areas in recent decades. This systematic review presents literature on the cadmium sorption capacity of various water hyacinth biosorbents. The effects and optimization of parameters including treatment, temperature, pH, and initial sorbate and sorbent concentration have been explored in classical and competitive models. Investigations on kinetics, equilibrium, and desorption studies have also been conducted. From the gathered literature, water hyacinth-derived biosorbents show considerable potential for industrial-scale applications, but their performance in multi-metal continuous adsorption systems and metal recovery require further evaluation. In addition, this study presented research gaps, trends, and developments that could set the tone of future works for the improvement of biosorbent materials for the removal of cadmium in the environment.