Sunday, January 25, 2015

Adsorption of Acid Blue 25 From Solution Using Zeolite And Surfactant Modified Zeolite

Congratulations to Mr Mohd Alamgir Kabir who has completed his MSc research in my laboratory at Universiti Kebangsaan Malaysia.  Mr Kabir is a Bangladesh Geology officer who was sent to Malaysia for higher education.  He was supervised by me and Dr Krishna.  
Photo of Mr Alamgir Kabir in the Laboratory

Abstract: Natural zeolite has net negative charge on their surface. This net negative charge is the prime factor that restricts the use of zeolite for the adsorption of cationic dyes. So, zeolite was modified with cationic surfactant to increase its anionic adsorption capacity. Natural zeolite used in the present work was obtained from Indonesia. In the present study natural zeolite has been modified with cetyltrimethylammonium bromide (CTAB) to increase the positive charge on the zeolite simultaneously to remove anionic dye Acid blue 25(AB25) from waste water. The adsorption equilibrium and kinetic studies of anionic dyes were carried out .The adsorption of reactive dyes on zeolite and modified zeolite (zeolite-CTAB) was investigated by batch adsorption experiments. The effects of adsorbent dosage, pH, temperature, time and the initial dyes concentrations were investigated.The modification effect on the surface of zeolite was analyzed using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray fluorescence (XRF) and X-ray Diffraction (XRD). All the methods support the modification of zeolite by CTAB was done. The maximum removal of dye was obtained under acidic conditions; in particular at pH 2.The percentage removal of dye initially increases with increase in dye concentration and with time. After that the dye removal percentage decreases. The kinetic experimental results imply that the adsorption of AB25 onto these adsorbents nicely followed the second order kinetic model. Equilibrium isotherms were analyzed by Langmuir and Freundlich isotherms. From the concentration effect it is indicated that due to modification of zeolite with CTAB the adsorption capacity of zeolite for AB25 increases 36.84%.  The maximum adsorption capacity was found to be 43.48 mg/g for zeolite at 300C (3030 K) and 71.43 mg/g for zeolite-CTAB at 400C (3130 K). However, it follows an increase and decrease trend with increase in temperature. The adsorption of AB25 onto zeolite-CTAB better fitted using Langmuir model and onto zeolite better fitted with the Freundlich model. A decrease in AB25 adsorption on zeolite-CTAB has been observed with an increase in temperature. This decrease in AB25 adsorption on zeolite-CTAB indicates that the preferential adsorption may occur at low temperature. The negative value of enthalpy indicating the process was exothermic and the presence of possible physisorption phenomenon. The negative values of entropy both for zeolite and zeolite-CTAB indicate the decrease in randomness at the adsorbent and solution interface. The results of the present study substantiate that zeolite modified by CTAB material are promising adsorbents for the removal of the dye AB25.

Zeolite and zeolite-CTAB were produced in the laboratory during Mr Kabir's research

Adsorption test of Zeolite and zeolite-CTAB on Acid Blue 25