Adsorption and desorption properties of arsenate onto nano-sized iron-oxide-coated quartz
This study was conducted to investigate the adsorption and desorption properties of arsenate [As(V)] on nano-sized iron-oxide-coated quartz (IOCQ) through batch experiments. The coating of nano-sized iron oxide on the quartz surface was performed using the heat treatment process which aimed to utilize the adsorption properties of the nano-sized iron oxide and the filtration properties of the quartz. Environmental SEM-EDAX and BET techniques were used to analyze the surface morphology, elemental composition, surface area and the porosity of the adsorbent. SEM-EDAX analyses confirmed that arsenate was adsorbed on the IOCQ surface. BET results showed that the IOCQ adsorbent had higher pore volumes and high specific surface areas compared with the pure quartz. The study revealed that the adsorption rate of As(V) ion was very rapid and reached the equilibrium within 5 min. This study also revealed that almost 100% of As(V) removal was achieved within 5 minutes of adsorption reaction from the initial solution containing 1,000 μg-As(V)/L. The Langmuir adsorption isotherm model suitably explained the sorption characteristics of As(V) onto IOCQ. This desorption study showed that the adsorbent could be reused after reacting with mild HCl solution but the concentration of acid eluant or pH has a great impact on the coated adsorbent surface. The results indicate that the nano-sized iron oxide-coated adsorbent is potentially suitable for removal of arsenate from drinking water.
Keywords: adsorption, arsenate, desorption, nano-sized iron oxide, quartz