Adsorption behavior Study for Praziquantel from Aqueous Phase Using Activated Carbon Prepared From Coffee Husk

Abstract

Background:In recent years there has been an increased focus on pharmaceutical residues in the environment. Praziquantel has been identified at concentration ranging 7.8-15microgram/litre in wastewater, linked to its wide spread use in human and veterinary medicine. The removal of pharmaceuticals by adsorption on commonly efficient adsorbents is one of the most promising techniques because of its convenience when applied in current water treatment processes. Activated carbons are a good material for removal of pharmaceuticals, by adsorption. Objective: To evaluate adsorption behaviour of activated carbon prepared from coffee husk for Praziquantel in aqueous phase. Method and materials: Coffee husk was used to prepare the activated carbon by chemical activation using phosphoric acid. The adsorption experiments of Praziquantel onto Activated Carbon were performed using a batch method where the effect of parameters such as contact time, p H and initial Praziquantel Concentration on Praziquanteladsorption was investigated. The result was presented using Microsoft Excel Worksheet 2010.In order to identify the adsorption mechanism of Praziquantel and the main rate-controlling steps;kinetic study was tested for two models. Those models were pseudo first order and pseudo second order models. Two isotherms, namely Langmuir and Freundlich isotherms wereused to correlate experimental isotherm data. Correlation coefficient (R2 ) was calculated using Origin Pro.software both for the kinetics and isotherm studies. Result:The experiments showed that highest removal rate 99.95% for activated carbon was at pH 8.The amount of Praziquantel adsorbed by the Activated Carbon increased with increasing contact time until it reaches at equilibrium. The equilibrium time was 8hrs (qe= 199.99). As Praziquantel initial concentration in the adsorption medium increased (50-250mg/l) amount adsorbed increases. Those results were presented using Microsoft Excel. The pseudo-second order kinetic model fitted the experimental data better than the pseudo-first-order kinetic model. Data was analysed by Origin Pro. Soft ware. The data had a higher R2 (1) with pseudo second order. The Langmuir model with a higher R2 (0.9918) and better representation of the data seemed to be more applicable than the Freundlichmodel(R2 0.9818). II Conclusion and Recommendation:The adsorption characteristics were shown to be influenced by of pH , initial concentration of Praziquantel, and contact time. Though the effect of PH was minimal, the amount of Praziquantel adsorbed by the Activated Carbon increased with increasing initialPraziquantel concentration. The equilibrium time was found to be 8 hrs. The adsorption data showed good agreement with the pseudo-second-order kinetic model for different adsorbent concentration. The isotherms exhibited the Langmuir behaviour at 25◦Ctemperature, which indicates a monolayer surface binding. Since this study is lacking data on characterization of activated carbon and the adsorption complex surface, future researchers are recommended for further investigations.