Recent progress on tobacco wastes-derived adsorbents for the remediation of aquatic pollutants: A review.

Tobacco (Nicotiana tabacum L.) is a significant crop widely planted worldwide. Its leaves have a special economical value as raw materials for the cigarette industry. During tobacco harvesting and cigarette production, a large amount of wastes that could not be used in the cigarette industry are generated such as tobacco stems, stalks, and low-grade leaves. The utilization of such agro-industrial wastes in raw or carbonaceous form as adsorbents for wastewater treatment is an economic and eco-friendly step for elimination of such waste. Tobacco waste can be directly applied as adsorbents for aquatic pollutants owing to its favorable lignocellulosic composition and functional groups enriched structure. Moreover, this waste has high volatile matters and thus can be an efficient precursor for high surface area carbonaceous adsorbents including biochar and activated carbon with high removal performance. This article is a recent and comprehensive review about the preparation of adsorbents (raw, biochar and activated carbon) from different tobacco wastes (stems, stalks, leaves, etc.) along with its characterization and regeneration. The adsorption behavior of different aquatic adsorbates on these adsorbents under specific conditions along with the isotherm, kinetic, thermodynamic, and mechanism studies is also considered. The highest uptakes for most tested pollutants were 399.0, 195.2, and 173.0 mg/g for lead, chromium, and cadmium, 517.5 mg/g for methylene blue, and 210.66 and 1.602 mg/g for phosphate and chlorpyrifos. Significant findings and future ideas for the studied adsorbate/adsorbent systems are finally given.