Optimization of Reactive Black 5 Dye Removal onto Kaolin Filter Cake Activated Carbon Using Response Surface Methodology

Background: Industrialization consumes a significant amount of water, and the textile sector rapidly expands globally using vast quantities of water. Textile products undergo various procedures such as bleaching, dyeing, printing, and stiffening. Dyeing factories are the major polluters in this industry, generating waste that contains unused organic compounds and colours. Dyes can pose a risk to environmental components and public health, potentially causing harm to vital human organs. Even in small amounts, reactive black 5 dye (RB5) can block light in water, reducing photosynthesis and affecting aquatic plant growth, possibly leading to eutrophication. Prolonged exposure to RB5 has been linked to serious health issues, including skin rashes, cancer, kidney and respiratory failures, and other severe conditions. Objectives: The current study aims to establish the effectiveness of using a new, affordable, and environmentally friendly adsorbent, namely kaolin filter cake (KFC), for the removal of reactive black 5 dye from textile wastewater. Methods: The prepared kaolin filter cake (KFC) activated carbon was characterized using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), point of zero charge (pHpzc), and Brunauer–Emmett–Teller (BET) surface area. The effectiveness of KFC's decolorization was assessed by adsorption tests that looked at batch process variables, such as pH, adsorbent dosage, contact time, and beginning dye concentration. Response Surface Methodology (RSM) was employed to optimize the RB5 removal. Results: The adsorption data closely fit the Langmuir isotherm model, indicating a maximum adsorption capacity of 60.24 mg·g-1. Kinetic studies revealed that the adsorption process followed a pseudo-second-order model. Remarkably, KFC demonstrated excellent regeneration potential, retaining 60.52% of its adsorption capacity after five cycles. Conclusion: KFC is a highly promising adsorbent with significant potential for sustainable, cost-effective, environmentally friendly, and efficient applications in textile wastewater treatment.