Recent Advances on Chemically Functionalized Cellulose-Based Materials for Arsenic Removal in Wastewater: A Review

Abstract

Clean water is very important for the good health of society. In South Africa, it is estimated that people need 20 to 50 litres of safe water daily for basic hygiene, drinking, and cooking. In recent times, water bodies have harboured harmful pollutants, including oil, heavy metal ions, and dyes. As a result, this has become a major global concern. Societies with limited clean water are often forced to utilise contaminated water or buy filtered water, which might be a problem for poor residents. The health consequences that are related to contaminated water include Guinea worm disease, dysentery, cholera, etc. The side effects associated with the utilisation of unclean water are gastrointestinal diseases such as cramps, vomiting, and diarrhoea. The wastewater disposed of by chemical industries contains toxic elements such as arsenic. Wastewater that is released directly without treatment causes serious damage to the environment. Chronic arsenic poisoning can lead to keratinisation of the skin and even cancer. Cellulose biomass materials have the potential to become the greatest bio-based materials used in wastewater treatment applications. There are two major reasons that validate this statement: firstly, cellulose is a low-cost material that is abundant in nature, and, secondly, cellulose is an environmentally friendly material. However, these are not the only reasons that validate cellulose as a good candidate for wastewater treatment applications. Cellulose has a unique structure a large surface area, good mechanical properties and is degradable, renewable, and biocompatible. Cellulose also has an abundance of hydroxyl groups on its surface. These hydroxyl functional groups allow cellulose to be chemically modified in various ways, which results in the fabrication of nanocomposites with tunable characteristics. Since arsenic pollution has become a serious global concern, this review uniquely provides a broad discussion of the work that has been accomplished recently on the fabrication of functionalised cellulose-based materials designed specifically for the removal of arsenic heavy metal species from wastewater treatment facilities. Furthermore, the functionalised cellulose materials’ arsenic adsorption capacities are also discussed. These adsorption capacities can reach up to a maximum of 350 mg/g, depending on the system used. Factors such as pH and temperature are discussed in relation to the adsorption of arsenic in wastewater. The removal of As(V) was found to be effective in the pH range of 3.0–8.8, with a removal efficiency of 95%. Moreover, the removal efficiency of As(III) was reported to be effective in the pH range of 6–9. However, the effective pH range also depends on the system used. The selective extraction of cellulose from various sources is also discussed in order to verify the percentage of cellulose in each source. Future work should be focused on how the chemical modification of cellulose affects the toxicity, efficiency, selectivity, and mechanical stability of cellulose materials. The use of cheaper and environmentally friendly chemicals during cellulose functionalisation should be considered.