Coir fiber as an effective biosorbent for the remediation of paraphenylenediamine dye from wastewater

Water is a vital resource for sustaining life and industrial development, yet its quality is increasingly deteriorated by the presence of emergent pollutants. Among these, para-phenylenediamine (PPD), widely used in industries such as cosmetics, textile dyeing, and hair colouring, has garnered attention due to its toxicity, persistence, and potential carcinogenic effects. In this study coir fibers are examined as cost-effective biosorbents for paraphenylenediamine dye removal from wastewater, promoting sustainable wastewater management. Coir fibers’ surface structure was examined using Scanning Electron Microscopy (SEM), x-ray diffraction for analysing crystalline structure, Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the functional groups on coir fibers. Batch sorption experiments were conducted to assess the biosorption efficiency under varying pH conditions, contact time, dye concentration, and adsorbent dosage. Langmuir isotherm showed that coir fiber has an adsorption capacity of 31.23 mg g⁻¹. Adsorption kinetics were analysed using pseudo 1st order, pseudo 2nd order models, elovich and intra particle diffusion model revealing chemisorption and diffusion playing role in adsorption process. SEM revealed an increase in surface roughness, while FTIR confirmed the presence of functional groups critical for dye adsorption. XRD indicated partial crystallinity alterations. BET isotherm studies also confirmed the adsorption on the fiber surface. This work highlights the viability of employing agricultural residues for wastewater treatment and provides insights into optimizing biosorption processes for industrial applications.