Abstract
Nitrate adsorption onto the physically and chemically modified pumice was investigated as an effort for reducing groundwater pollution. The treatments were heating at temperatures of 300°C, 450°C, and 600°C for physical and soaking in acid solutions (HCl, H2SO4, and HNO3) for chemical treatments. The adsorption was performed in a batch system at room temperature (25±1°C) with the optimum condition (pH 4; 0.3 g/L of adsorbent dose; <63 µm of adsorbent diameters and 30 minutes of contact time). The results indicated that the physically and chemically modified pumice resulted in increasing removal efficiency and nitrate uptake compared to the natural pumice. The highest removal efficiency and nitrate uptake were achieved from 300°C of heating temperatures (62.04% and 155.09 mg/g) and H2SO4 for the acid solution (83.30% and 208.25 mg/g), while by using the natural pumice only reached 57.02 % and 142.55 mg/g. The SEM images of the modified pumice confirmed the change in the surface morphology of pumice including the pore structure and surface area which can be proper sites for adsorption of pollutants. This study demonstrated that physical and chemical modification could be the potential treatment to increase the removal efficiency and nitrate uptake of the natural pumice, thus can solve the problem of groundwater pollution.
Highlights
Due to its harmful effect, contamination of nitrate in groundwater has become a serious environmental problem
The physically modified pumice heated at 300°C and 450°C showed a greater number of open pores (Fig 2b and 2c). It demonstrates that heat treatment increased the pore volume and surface area of the pumice, which increased its adsorption capacity
The physical modification was conducted by heat treatment at 300°C, 450°C, and 600°C, while for chemical modification, soaking the pumice in three kinds of acid solution namely HCl, H2SO4, and HNO3 with 1 M of concentration were performed
Summary
Due to its harmful effect, contamination of nitrate in groundwater has become a serious environmental problem. The most common sources of nitrate are the discharge of raw wastewater, biodegradation of nitro-organic compounds, septic tank effluents, fertilizers, and pharmaceuticals. Nitrate is possibly the most widespread contaminant, causing a serious threat to drinking water supplies due to its high water solubility [1,2,3]. High nitrate concentrations in drinking water cause health problems, such as cancer due to the formation of nitrosamine and cyanosis among children. The US Environmental Protection Agency (EPA) and World Health Organization (WHO) set the maximum acceptable contaminant level of nitrate for drinking water to be 45 mg/L and 50 mg/L of nitrate, respectively [4].
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call