Absorption of Cu(II) and Zn(II) from Aqueous Solutions onto Biochars Derived from Apple Tree Branches

Abstract

<jats:p>The aim of this study was to investigate the adsorption of Cu(II) and Zn(II) onto apple tree branches biochar (BC) produced at 300, 400, 500 and 600 °C (BC300, BC400, BC500, and BC600), respectively. The effect of adsorbent dosage, pH value, contact time, initial concentration of Cu(II) or Zn(II), and temperature on the adsorption process were investigated. The result showed that 5 g BC·L−1 was the optimal dosage to remove Cu(II) and Zn(II) from wastewater and the maximum adsorption efficiency was achieved at a pH of 5.0 for all the BCs when the initial concentration of Cu(II) and Zn(II) were 64 and 65 mg L−1, respectively. Adsorption kinetics and isotherm experiments showed that the pseudo-second order equation and the Langmuir isotherm could best describe the adsorption process, indicating that the adsorption of Cu(II) and Zn(II) onto BCs were monolayer processes and chemisorption was the rate limiting step. The values of ΔG0 for the absorption of Cu(II) and Zn(II) on all BCs were negative, while the values of ΔH0 were positive, suggesting that the absorption was a spontaneous endothermic process. The mechanisms of BC adsorption of metal ions adsorption include surface precipitation, ion exchange, and minor contribution by cation-π interaction. BC500 had highest Cu(II) and Zn(II) adsorption capacity under various conditions (except at pH 2.0). The maximum adsorption capacities of Cu(II) and Zn(II) on BC500 were 11.41 and 10.22 mg·g−1, respectively. Therefore, BC derived from apple tree branches produced at 500 °C can be used as an adsorbent to remove Cu(II) and Zn(II) from wastewater.</jats:p>

The enhancement of black liquor treatment by applying a natural flocculant and converting its sludge to a high‐benefit product

“…The first heat carbonization process of BLS‐CA 1 occured at 575 °C for 3 h while the BLS‐CA 2 first heat carbonization process occured at 450 °C for only 1 h. It is very clear that increasing temperature and time influence the surface properties, including the micropore surface area. In agreement with previous works, which evaluate how temperature and time effect the surface area as well as pore size until the adsorption ability of the carbon material, the increasing of temperature and time might allow the containing volatile matter to decrease significantly. This proves that the pore formation and kinds are getting better .…”

“…In agreement with previous works, which evaluate how temperature and time effect the surface area as well as pore size until the adsorption ability of the carbon material, the increasing of temperature and time might allow the containing volatile matter to decrease significantly. This proves that the pore formation and kinds are getting better . Component analysis of BLS‐CA 1 as the best carbonaceous adsorbent from this work is shown in Table as the result of SEM‐edx measurement.…”

Characterization Techniques as Supporting Tools for the Interpretation of Biochar Adsorption Efficiency in Water Treatment: A Critical Review

“…Pseudo-first order and pseudo-second order models are the most frequently computed models. However, there are some less common works that thoroughly investigate the adsorption performances of BCs through the Elovich model [ 103 ] (predicting the mass and surface diffusion and the activation/deactivation energy of the system) or through the intraparticle diffusion and Boyd models [ 104 , 105 ] (which determine the effect of internal and external diffusion on the adsorption mechanism).…”

Magnetic Steel Slag Biochar for Ammonium Nitrogen Removal from Aqueous Solution

“…This might be attributed to smaller surface area and pore size at MSSB than at PB (Table 2) or to the considerable amount of metal oxides derived from BOF slag at MSSB (Table 1). Biochars can carry a lot of negative charges on the surface [15] and some metal oxides of BOF slag such as MgO and CaO can be dissolved in aqueous solution, which could form cations around MSSB [37,38]. Consequently, the metal cations seemed to compete with NH 4 -N for the adsorption sites of MSSB, resulting in a decrease in the capacity of adsorbent material for NH 4 -N [39].…”

“…Biochar is solid biomass such as wood, crop residues, or agricultural waste that is pyrolyzed under oxygen-free conditions [10,11]. It has been used as a soil amendment [12], carbon sequestration agent [13], and adsorbent for the removal of organic and inorganic compounds (e.g., NH 4 -N, Cu, Zn, and Pb) in aquatic environments [14][15][16][17][18][19]. However, biochar in the form of fine powder is difficult to separate from aqueous solution after adsorbing pollutants [10,20].…”