Title : Removal of toxic phenol from wastewater using solid waste adsorbents
Abstract:
This research aims for the adsorptive removal of phenol from wastewater by solid adsorbents generated from biological wastes viz. guava tree bark, rice husk, neem leaves, activated carbon from coconut coir, and industrial wastes viz. rice husk ash, red mud, clarified sludge from basic oxygen furnace, activated alumina. The adsorbents are characterized by SEM, XRD, FTIR, and BET analyzers. The experiments of phenol removal are carried out with the variation of initial phenol concentration (5-500 mg/L), initial pH (2-12), adsorbent dose (0.10-20 gm/L), temperature (25-50°C), and contact time (30-600 min). The maximum removal obtained is 97.50%. The kinetics shows that the pseudo-second-order model is best fitted for all adsorbents except red mud. The kinetic modelings show that the adsorption mechanism is supportive of film diffusion, intra-particle diffusion, and chemisorption for all adsorbents. The isotherm analysis suggests that the Freundlich isotherm model is best supportive for guava tree bark, rice husk, neem leaves, activated carbon, red mud, and activated alumina, whereas Langmuir and D-R isotherm is best supportive for rice husk ash and clarified sludge respectively. The thermodynamics shows the spontaneity, randomness, and endothermic/exothermic nature of the adsorption processes. The ANN modeling using two popular algorithms viz., Levenberg-Marquardt and Scaled Conjugate Gradient establish that the experimental and predictive data are within the allowable range. The scale-up designs are performed for their commercial applications. The regeneration and the safe disposal of used adsorbents are also studied for checking their wider industrial applicability.
