WASTE TYRES DERIVED-CHARS FOR WASTEWATER DYES ADSORPTION

Abstract

In response to escalating concerns over wastewater dye contamination, this thesis investigates the promising path of biochar-based adsorption for dye removal, with a specific focus on char derived from tyre waste through pyrolysis. Tyre waste, a significant environmental challenge, serves as both a pollutant and a resource. The first part of the investigation examined the impact of temperature, holding time, heating rate, and particle size on the characteristics of chars derived from waste tyre pyrolysis. The findings highlight that temperature and holding time emerge as pivotal factors influencing char yields and surface areas, with a notable increase in pore size observed with elevated pyrolysis temperatures. Conversely, heating rate and particle size do not significantly affect char yields; however, they can influence the textural attributes of the resulting chars. This phenomenon is attributed to the temperature gradient experienced by raw materials during pyrolysis, causing variations in char structure due to the level of shrinkage. In selecting experimental parameters for pyrolysis, considerations encompassed all these factors. For waste tyre pyrolysis, the temperature and particle size were set at 723 K and 1000–2000 μm, respectively, aiming to maximize char surface area. Optimal conditions involve a lower heating rate (e.g., 5 K/min) paired with a longer holding time (e.g., 2 h) to ensure thorough volatile removal during pyrolysis. The second part of this paper’s investigation focused on the adsorption isotherm study of the mechanisms of Malachite Green (MG) and Acid Yellow 117 onto waste tyre derived-char across varying temperatures (450°C, 550°C, 650°C, and 750°C). The study employs three prominent isotherm models (Langmuir, Sips, and Redlich–Peterson) to understand the intricate interplay of factors influencing these adsorption processes. The findings reveal a pronounced temperature dependency in Malachite Green and Acid Yellow 117 adsorption, with higher temperatures correlating to increased adsorption capacities. At 450°C, the Langmuir model consistently underestimates adsorption capacity Qe, while the Sips and RP models offer superior fits. The trends persist at 550°C and 650°C, emphasizing the need to consider diverse factors shaping adsorption. Notably, at 750°C, challenges emerge across all models, underscoring the necessity for further exploration at elevated temperatures. The temperature-dependent behavior of adsorption models are analyzed, revealing crucial insights for optimizing biochar-based adsorption systems. This comprehensive investigation into biochar's performance offers valuable insights for researcher, shedding light on the material's capacity to repurpose tyre waste for environmental benefit. The paper advocates further research to address existing gaps, enhance adsorption processes under diverse conditions, and contribute to the broader understanding of sustainable wastewater treatment.

Date of Award	2024
Original language	American English
Awarding Institution	HBKU College of Science and Engineering