REDUCTION OF TOTAL ORGANIC CARBON AND BIOCHEMICAL OXYGEN DEMAND USING MODIFIED AND UNMODIFIED Hibiscus sabdiriffa AND Hibiscus esculentus STALKS: KINETIC AND ISOTHERM STUDY

Abstract

Treatment of dye effluent could become a great move towards environmental protection and sustainability. Hence, this research was aimed at studying the use of Hibiscus esculentus and Hibiscus sabdiriffa Stalks for the reduction of Total Organic Carbon (TOC) and Biochemical Oxygen Demand (BOD). Hibiscus esculentus and Hibiscus sabdiriffa stalks were collected, modified with Cetyltrimethylammonium Bromide and characterised by various techniques: High Resolution Scanning Electron Microscopy (HRSEM), Electron Dispersive Spectrometer (EDS), and Fourier Transform Infra Ray (FTIR). The adsorption studies of Hibiscus esculentus and Hibiscus sabdiriffa unmodified and modified for TOC and BOD reduction in wastewater collected from a dyeing pit at Kofar Mata Dye site in Kano, Nigeria were evaluated at different contact times, and dosage of adsorbents. The HRSEM results revealed surface morphology for unmodified Hibiscus sabdiriffa and Hibiscus esculentus were without defined pores, ridges, and defects, whereas for modified Hibiscus sabdiriffa and Hibiscus esculentus were textural and morphological changes. EDS studies showed evidence of the increment in carbon into the matrix of the modified Hibiscus sabdiriffa and Hibiscus esculentus activated carbon: 99.39 % and 98.21 % resp. Reduction of TOC from the wastewater increased with time and attained equilibrium at average of 94.35 % for modified Hibiscus sabdiriffa and Hibiscus esculentus activated carbon respectively and average of 80.10 % for unmodified Hibiscus sabdiriffa and Hibiscus esculentus respectively. Reduction of BOD from the wastewater, equilibrium was attained at average of 90.10 %, for modified Hibiscus sabdiriffa and Hibiscus esculentus activated carbon respectively and 85.10 % for unmodified Hibiscus sabdiriffa and Hibiscus esculentus activated carbon respectively. Isotherms data evaluated revealed Langmuir isotherm best fitted the equilibrium data. The kinetic data for all the adsorption experiments fitted to the pseudo- second–order model. Surfactant modified Hibiscus sabdiriffa and Hibiscus esculentus had good performance on TOC and BOD reduction of the textile wastewater than unmodified Hibiscus sabdiriffa and Hibiscus esculentus stalks.