Highly efficient removal of lead and cadmium during wastewater irrigation using a polyethylenimine-grafted gelatin sponge

Abstract

Wastewater irrigation is a very important resource for heavy metal pollution in soil and then accumulation in vegetable crops. In this study, a polyethylenimine (PEI)-grafted gelatin sponge was prepared to effectively adsorb heavy metals during wastewater irrigation. Based on the strong water adsorption ability, wastewater remained in the PEI-grafted gelatin sponge for a sufficient time for the heavy metals to interact with the sorbents. The binding capacities of Pb(II) ions and Cd(II) ions on the PEI-grafted gelatin sponge were 66 mg g −1 and 65 mg g −1 , which were much more than those on the gelatin sponge (9.75 mg g −1 and 9.35 mg g −1 ). Subsequently, the PEI-grafted gelatin sponge was spread on the surface of soil planted with garlic and then sprayed with synthetic wastewater. The concentrations of cadmium and lead in the garlic leaves were 1.59 mg kg −1 and 5.69 mg kg −1 , respectively, which were much lower than those (15.78 mg kg −1 and 27.98 mg kg −1 ) without the gelatin sponge, and the removal efficiencies were 89.9% and 79.7%. The PEI-grafting gelatin sponge could effectively remove heavy metals during wastewater irrigation, which improved the soil environment and reduced human exposure to heavy metals.Water shortages in the world have led to the reuse of municipal wastewater for irrigation. In many developing countries, wastewater irrigation is a very important way in agricultural production, however, it would increase human exposure to the pollutants. Amin et al. found that vegetables grown in the Mardan District of Pakistan were highly polluted by heavy metals due to the irrigation of untreated wastewater, which would lead to serious health risks for local people 1 . Jiang et al. reported that agricultural soil was potentially at risk of heavy metal accumulation from irrigation water, which was higher than those from atmospheric deposition and fertilizer 2 . Thus, decrease the contaminants in wastewater system was an important way to avoid their entrance into agricultural soil and then food chain.Various technologies were proposed to decrease the heavy metal concentration in wastewater, such as ion exchange, adsorption, chemical precipitation and membrane separation [3][4][5][6][7] . Among them, adsorption was considered as a flexible, convenient and low cost technology. After simple desorption, the adsorbents are regenerated for multiple uses and it still has a high efficiency 4,8 . Therefore, it was a preferred process for wastewater pollution control. However, developing a specific sorbent with high adsorption capacity is an interesting yet still challenging task. Currently, carbon materials (such as carbon foam, carbon nanotubes, graphene and activated carbon) 9-11 , nanosized metal oxides (such as ferric oxides, manganese oxides and zinc oxides) 4 , chitosan composites 12-13 and low-cost adsorbents (such as zeolites and weathered coal) [14][15][16] are all considered in the literatures to be promising choices for the heavy metal pollution control. Unfortunately, it is impossible to recover t...

Kinetic Study of Garlic and Ginger Particles in Adsorption of Heavy Metals in Aqueous Solution

“…This is further demonstrated by the R-squared values (Table 5). Similar observation on the comparison of First and Second Order Pseudo Kinetics had been reported in earlier studies (Li et al, 2016;Sharma et al, 2016;Azizi et al, 2017 andKulkarni et al, 2017).…”

“…Again, from Figures 23 and 24, the linear relationship for chromium ion were more close to the origin, indicating that chromium ion diffused more into the particles than cadmium and lead ions. This was also observed by other studies for adsorption of heavy metal in aqueous solution (Ademiluyi and Ujile, 2013;Li et al, 2016 andKulkarni et al, 2017). Tables 4, 5 and 6.…”

Enhanced removal of hexavalent chromium from aqueous media using a highly stable and magnetically separable rosin-biochar-coated TiO2@C nanocomposite

“…Heavy metal ions (HMIs) in surface and ground water, soil and sediments are posing severe threats to environmental and human health. [1][2][3][4][5][6][7][8] Among these heavy metal ions (HMIs), chromium (Cr) is a highly toxic metal according to the United States Environmental Protection Agency (USEPA). 9 The extensive use of chromium (Cr) in different industries such as electroplatingoperations, tanning (leather), metal nishing, textiles, 10 steel and metal alloy production, brass industry, cement industry, photographic components, and corrosive paint industry has resulted in its release into the ecosystem at concentrations that exceed environmental safety levels.…”

Rapid removal of Pb(II) from aqueous solution using branched polyethylenimine enhanced magnetic carboxymethyl chitosan optimized with response surface methodology

“…These functional groups can improve the hydrophilic property of CMC and provide enough adsorption sites for increasing adsorption capacity 22 . Polyethylenimine (PEI) which is composed of plenty of amine groups on the macromolecular chains has been reported to have strong adsorption ability for heavy metals 23 , 24 . However, because of the water soluble nature of PEI, it has to be immobilized on matrix to ensure the maneuverability when used as adsorbent 25 .…”