Single and Competitive Adsorption Behaviors of Cu2+, Pb2+ and Zn2+ on the Biochar and Magnetic Biochar of Pomelo Peel in Aqueous Solution

Abstract

As an environment-friendly material, biochar has been used to remove heavy metals from wastewater, and the development of cost-effective biochar has been an emerging trend. However, limited studies consider the competitive adsorption of co-existing metals and the separation efficiency of absorbent and solution after adsorption. In this study, pomelo peel was used to prepare biochar (BC) and magnetic biochar (MBC) at different temperatures. Then, the physicochemical properties of the biochars were characterized and the adsorption characteristics of Cu2+, Pb2+, and Zn2+ on the biochars in single, binary, and ternary metal systems were investigated. The results showed that both pyrolysis temperature and magnetization could affect the adsorption capacity of biochar. The adsorption kinetic and thermodynamic processes could be well described by the pseudo-second-order kinetic model and Langmuir model. The adsorption isotherm types of Pb2+ and Zn2+ changed in the binary metal condition. The competitive adsorption order of three heavy metal ions in ternary metal adsorption was Pb2+ > Cu2+ > Zn2+. The MBC of 500 °C showed a good adsorption capacity to Pb2+ in the co-existing environment, and the maximum adsorption capacity was 48.74 mmol g−1. This study also provided technical support for the utilization of pomelo peel and the engineering application of biochar.

Zr-Based Metal–Organic Framework Nanocrystals for Water Remediation

“…However, Pb­(II) cations are hydrated in water and thus have a total diameter of 8.02 Å with their hydration shell, which might have hindered their diffusion into the UiO-66­(COOH) 2 porous structure . This could mean that most of the adsorption took place on the outer surface of the MOFs and not inside the porous structure, which marginalizes the effect of the surface area and pore volume of the MOFs and the ionic diameter of the pollutant . This could be especially true given the small particle size of the UiO-66­(COOH) 2 samples, as could be seen in the SEM images in Figure S7, which increases the level of the external surface area of the adsorbent relative to the internal one.…”

“…58 This could mean that most of the adsorption took place on the outer surface of the MOFs and not inside the porous structure, which marginalizes the effect of the surface area and pore volume of the MOFs and the ionic diameter of the pollutant. 59 This could be especially true given the small particle size of the UiO-66(COOH) 2 samples, as could be seen in the SEM images in Figure S7, which increases the level of the external surface area of the adsorbent relative to the internal one. Another possible scenario is the dehydration of Pb(II) ions, which could allow their diffusion in the UiO-66(COOH) 2 porous structure; in fact, the lower the hydration energy of a certain ion, the higher the possibility of it losing all, or part of, its hydration shell, increasing its adsorption.…”

Removal of Copper(II) from Aqueous Environment Using Silk Sericin-Derived Carbon

“…The thermodynamic fitting curve is shown in Figure 4 b, and the thermodynamic parameters are reported in Table 2 . According to Table 2 , the negative ΔG value increased with increasing temperature, showing that the adsorption process was more favorable at higher temperatures and implying that the adsorption process was chemisorption [ 9 ]. In addition, the positive ΔH value indicated that adsorption was endothermic.…”

“…Relevant studies show that Cu(II) accumulation limits the growth and development of plants and causes a reduction in the fecundity of aquatic life [ 5 , 6 ]. Moreover, an enrichment of trace copper(II) in organisms can be achieved through the food web, leading to excessive intake of copper by people, which can evoke diarrhea, hepatic and renal dysfunctions, and severe mental and neurological illnesses [ 5 , 7 , 8 , 9 ]. Numerous approaches and techniques, including adsorption [ 10 ], membrane separation [ 11 ], electrocoagulation [ 12 ], chemical precipitation [ 13 ], and microbial treatment [ 14 ], have been used to remove copper ions from water.…”

Activated Biocarbons Obtained from Plant Biomass as Adsorbents of Heavy Metal Ions

“…Bio-oil, biochar and pyrolytic gas are useful products formed during this process [ 1 ]. In this way, we can reduce the storage or incineration of such waste as fruit stones, nut shells, sawdust, corn cobs, sunflower husks, straw or herbal herbs [ 2 , 3 , 4 ].…”