Removal of methylene blue dye from water using silver-exchanged Philippine natural zeolites
Silver-exchanged zeolites (AgZ) were synthesized via ion-exchange method and their removal of methylene blue (MB) from an aqueous solution were investigated. Natural zeolite powders were activated by heat treatment at 120°C and then immersed in silver nitrate (AgNO3) solution for several hours. The structure and chemical composition of raw zeolites and AgZ were analyzed using X-ray diffraction (XRD) and X-ray fluorescence (XRF) spectroscopy, respectively. XRD showed significant peaks corresponding to both clinoptilolite and heulandite mineral phases. Another diffraction peak at 38.07° appeared for AgZ samples after silver addition. Hence, XRF data determined the Si/Al ratio (SAR) ranging from 2.86 to 3.75 implying the hydrophilic nature of the samples. Adsorption tests were carried out by UV-Vis-NIR spectrometer to determine the adsorption efficiency of zeolite samples for MB aqueous solution. The highest removal efficiency was exhibited by 8AgZ with 39.36% due to the photocatalytic degradation of silver ancillary to the adsorption capacity of zeolites. This study demonstrated that silver-exchanged zeolite could be utilized as an efficient adsorbent for dyes.