Advancements in adsorption and photodegradation technologies for Rhodamine B dye wastewater treatment: fundamentals, applications, and future directions

Organic dye pollutants present in wastewater pose a significant global challenge. Among pollutants, the synthetic dye Rhodamine B (RB) stands out due to its non-biodegradable nature and associated neurotoxic, carcinogenic, and respiratory irritant properties. Extensive research has been conducted on the efficacy of adsorption and photodegradation techniques for the removal of RB from wastewater. While adsorption and advanced oxidation processes (AOPs) have gained considerable attention for their effectiveness in recent years, the underlying behaviors and mechanisms of these technologies remain incompletely understood. Therefore, a comprehensive summary of recent research progress in this domain is imperative to clarify the basics and present the up-to-date achievements. This review provides an in-depth exploration of the fundamentals, advancements, and future trajectories of RB wastewater treatment technologies, mainly encompassing adsorption and photodegradation. This work starts with a general introduction outlining the sources, toxicity, and diverse applicable removal strategies. Subsequently, it thoroughly examines crucial techniques within non-photochemical, photochemical, and adsorption technologies, such as UV light-assisted AOP, catalyst-assisted AOP, ozonation, Fenton systems, electrochemical AOP, and adsorption technology. The primary objective is to furnish a broad overview of these techniques, elucidating their effectiveness, limitations, and applicability. Following this, the review encapsulates state-of-the-art computational simulations pertaining to RB adsorption and interactions with clays and other adsorbents. Lastly, it delves into column adsorption of RB dye, and elucidates various influencing factors, including bed height, feed concentration, pollutant (RB) feeding or flow rate, and column regeneration. This panoramic review aims to provide valuable insights into suitable techniques, research gaps, and the applicability of non-photochemical, photochemical, and adsorption technologies in the treatment of wastewater containing RB dye.