Environmental Engineering

Permanent URI for this collection

http://etd.aau.edu.et/handle/12345678/129

Browse

Browsing Environmental Engineering by Subject "Adsorption isotherm"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Chromium Removal from Tannery Wastewater using Calcinated Eggshells as an Adsorbent: A Case study of Ethiopian Tannery Share Company, Ethiopia.
    (Addis Ababa University, 2019-07) Berihu, Gebrecherkos; Berhanu, Assefa (PhD)
    Discharge of untreated chromium containing tannery wastewater into the environment poses a serious environmental and health problem. Finding an environmentally safe and cost effective method which is efficient enough to meet the regulatory standards of industrial wastewater discharge presents unique challenges. There is need for environmentally friendly and cost effective methods for their removal. The present study investigated the adsorptive removal of chromium ions from Ethiopian tannery share company site using thermally modified chicken eggshells because it is high removal capacity, low cost and easy accessibility. Characterization of the adsorbent such as proximate analysis, surface charge, Fourier transform infrared radiation spectroscopy, surface area and X- ray diffraction was done prior to bio sorption process. Thermally modified eggshell was assessed in batch mode adsorption experiment for percentage chromium removal and milligrams per gram chromium uptake as a function of contact time, pH, and dose of the adsorbent and initial concentration. The effect of factors such as one factor effect and interaction effects were investigated by central composite design (CCD). The maximum percent removal was obtained 99.505 % at optimum pH =7, adsorbent dose=1g/100ml, contact time 120min and 80mg/L of initial chromium ion concentration. Sorption kinetics of chromium adsorption by Thermally modified eggshell was predicted reliably using a pseudo-first order, pseudo-second order and intra particle diffusion model. The kinetic adsorption data well fitted to pseudo-second order. Equilibrium uptakes were evaluated using Langmuir, Freundlich and Temkin adsorption isotherm models. The equilibrium data well fitted into Langmuir isotherm. The study demonstrated the efficacy of Thermally modified chicken eggshells and presents it as a viable low-cost adsorbent for bioremediation.
  • No Thumbnail Available
    Item
    Reactive Azo Dye Removal from Aqueous Solution Using Orange Peel As Bio-Adsorbent
    (Addis Ababa University, 2015-07) Jemal, Nuriya; Jabasingh, Anuradha(Perofessor)
    Presence of dyes in the aquatic systems has become a serious environmental problem. Concerning the environmental awareness and the economical point of view, the use of low-cost and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing textile dyes from wastewater. This study explores the feasibility of using orange peel, an agricultural waste, for removal of synthetic dye from aqueous solution. The adsorption characteristics of RR- DEXF dye onto powdered orange peel (POP) as a bio adsorbent that has been previously physically treated was investigated. Batch adsorption experiments were carried out for the adsorption of the dye molecule from aqueous solution onto the POPA at constant room temperature 27oC and agitation speed 200rpm. Variation effect of different parameters like solution pH, adsorbent dose, contact time and the initial concentration of the dye were studied. U V. spectrophotometer technique was used for the measurement of concentration of dye before and after adsorption. Experimental results revealed that optimal adsorption took place at an acidic solution pH. The effective solution pH, adsorbent dose and contact time on the dye removal efficiency of the adsorbent were found to be 3, 0.2g/100mL and 80min, respectively for the adsorption studies. At these experimental conditions the dye removal efficiency of 90% was achieved. The experimental results have been fitted well by the Langmuir isotherm model with the higher correlation coefficients of R2 Keywords: RR-DEXF dye; Powdered orange peel adsorbent (POPA); UV. Spectrophotometer; Adsorption isotherm; Kinetics models; effluents. = 0.995. Thus, indicating to the applicability of monolayer coverage of the dye on the surface of the adsorbent and it was found to be 3.03 mg/g. Adsorption kinetics was determined using pseudo first order and pseudo second order models and it was found that the adsorption process follows pseudo second order model. Generally the results indicate that POP may be used as a low cost adsorbent, alternative for treatment of effluents containing reactive red dye in water.