MODELING AND ADSORPTION STUDIES OF SELECTED PHARMACEUTICALS AND FOOD DYES ONTO CHEMICALLY MODIFIED AGROWASTE BIOMASS

BANKOLE,, DEBORAH TEMITOPE (2022) MODELING AND ADSORPTION STUDIES OF SELECTED PHARMACEUTICALS AND FOOD DYES ONTO CHEMICALLY MODIFIED AGROWASTE BIOMASS. ["eprint_fieldopt_thesis_type_phd" not defined] thesis, Landmark University, Omu Aran, Kwara State.

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Abstract

The rapid increase in human population and industrialization has immensely escalated demands for clean water. Industrialization has, however, contributed to abiotic and biotic contaminations globally. Pharmaceuticals and food dyes presently belong to a class of pollutants generating public health concerns and contributing to mutagenicity. The presence of these pollutants in the water body, even at low concentration can disrupt the endocrine system, alter photosynthetic activities and inhibit the growth of some useful organisms. Adsorption using agricultural wastes is preferred to other water treatment techniques, due to its availability, low-cost, amenability, effectiveness, adaptability and simple design. In this study, the seed pods of Bilghia sapida, Delonix regia, Hibiscus sabdariffa, the empty fruit bunch of Elais guineensis and the epicarp of Raphia hookerie, were treated with orthophosphoric acid, potassium hydroxide and zinc chloride to boost their adsorptive properties. The treated adsorbents were fully characterized to understand their physicochemical and spectrophotometric properties. The acid-modified Bilghia sapida (BSP1), Delonix regia (DRP1), Hibiscus sabdariffa (HSP1), Elais guineensis (EGB1) and Raphia hookerie (RHP1) were used in the adsorption of pharmaceuticals viz chloroquine phosphate (CQP), ciprofloxacin (CPX) and ibuprofen (IBU) and food dyes viz allura red (ALR) and sunset yellow (SSY) dyes. Batch and column adsorption processes were investigated. The equilibrium adsorption data were analyzeded using seven isothermal models while the kinetic data were tested using seven kinetic models. Experimental data were further validated using Artificial Neural Network (ANN) model in MATLAB (R2016a) software. The Thomas and Yoon-Nelson models were used in the column adsorption experiment to evaluate the breakthrough curves. Desorption studies were also carried out on the spent adsorbents, using four different desorbing agents. BSP1, EGB1, HSP1 and RHP1 adsorbents were employed in the fixed-bed adsorption of CQP and ALR from simulated multicomponent systems. The activation processes generally improved the characteristics of all the prepared adsorbents. The Fourier Transform Infrared (FTIR) analysis revealed various functional groups such as -OH, -C=O, -C=C, -C-H. The Scanning Electron Microscopy (SEM) revealed pores of various shapes, sizes and depths. Activation and carbonization resulted in the dehydration and enrichment of the carbon contents. Acid-modified adsorbents were found effective on the targeted pollutants with BSP1 having the highest monolayer adsorption capacity (qmax) of 135 mg/g in the removal of IBU. The thermodynamics studies confirmed the feasibility and spontaneity of the adsorption processes. High desorption efficiencies were generally obtained for IBU with 80.52, 72.17, 67.74, 66.86 and 65.85% obtained for DRP1, BSP1, EGB1, RHP1 and HSP1 respectively, using 0.1 M NaOH as eluent. The ANN model revealed that BSP1-IBU adsorption system had the least Mean Square Error (4.43) with an R2 value of 0.9906. High removal efficiencies of 95.78 and 98.79% were obtained for the BSP1-CQP and EGB1-CQP adsorption systems respectively at 50 mg/L, while 92.91 and 98.89% were observed for RHP1-ALR and HSP1-ALR adsorption systems respectively. High adsorption efficiencies obtained for the prepared adsorbents demonstrated their potential, suitability, viability and prospect in the treatment of food and pharmaceutical industrial wastewaters.

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