Removal of Mercury Ions from Simulated Wastewater Using Scapes of <i>Allium sativum</i> L. as Low-Cost Bio- Adsorbent

Mankind has witnessed various environmental issues with the onset of industrialization. Several industries, like paint, electroplating, leather, textiles, petroleum refining, dyes and pigments, etc., holds significant amounts of metals and heavy metals in their wastewater. Consequently, disturbance in ecosystems is quite visible in the form of water pollution. Conventional metals and heavy metal removal methods, such as reverse osmosis, chemical precipitation, ion exchange, electrodialysis, chemical oxidation, membrane separation, and so on, are energy intensive, expensive, and produce toxic by-products as secondary pollutants. Among the conventional methods, adsorption has been found to be cost-effective with high efficacy for removing heavy metals from wastewater. In the present study, finely powdered garlic scapes have been used as bio-adsorbents for mercury removal from simulated wastewater. Characterization of prepared bio-adsorbent was carried out by XRD, ATR-FTIR and FE-SEM, EDX. For the optimization of various parameters, batch studies were carried out using AAS (Atomic Adsorption Spectroscopy) by varying contact time, adsorbent dose, temperature and pH. Optimum results were obtained at 10 pH when the adsorbent dose was 50 mg for 45 minutes of contact time at 100ºC. The adsorption efficiency of the prepared biosorbent at optimum conditions was found to be 45–77%. Investigational data were best fitted into a pseudo-second order kinetic model (r2=0.99993). Therefore, the prepared adsorbent has the potential to remove mercury ions from simulated wastewater and can be explored further at a pilot scale.