Abstract
The presence of potentially toxic metals in water causes a strong impact on environment and human health. In this study, activated biochar was produced by using chemical oxidation method from wheat straw as natural adsorbent and was employed for heavy metals competitive remediation. The morphology, structure, and chemical properties of biochar before and after adsorption were characterized by FTIR, XRD, SEM and EDX mapping techniques. The competitive adsorption efficiency of adsorbent for divalent cadmium (Cd) and lead (Pb) from contaminated water was investigated by using wide range of several initial metal concentration, contact time and pH. Maximum adsorption of Cd(II) and Pb(II) was found in the pH range of 6–8. The adsorption capacity for Cd(II) and Pb(II) was 8.85 and 9.03 mg/g, respectively. Thermodynamics parameters and kinetic models were applied to adsorption data. The isotherm data followed Langmuir model, corresponding to monolayer adsorption of the two ions in the contaminated water. The kinetic data followed the pseudo 2nd order kinetics model, which authenticates the chemisorption nature. The thermodynamic study indicated that Cd adsorption is a spontaneous exothermic process while Pb adsorption is an endothermic process. Mineral precipitation, surface complexation, and cation-π interactions are the major remediation strategies for Cd(II) and Pb(II).
Highlights
Cr(V), Fe(III), Ni(II), Zn(II), Cd(II), Hg(II), and Pb(II) are the most well-known toxic heavy metal pollutants in wastewater, which need to be removed by appropriate methods before water recycling and reuse [2]
Several nominal approaches have been developed for heavy metals removal [4], including ion exchange [5], electrochemical [6], neutralization precipitation [7], membrane filtration [8], nanofiltration [9], flotation [10], and adsorption [11], of which adsorption is considered as one of the most environment-friendly and highly-efficient option [12]
S1, the pre-adsorbed adsorbed activated wheat straw biochar (AWSB) has a heterogeneous structure with large bulk and smaller cracks as AWSB hastoa pristine heterogeneous structure withcontain large bulk andpores smaller cracks assize compared to compared
Summary
Water containing heavy metals causes serious irritation to the respiratory tract, and damage the liver, kidney and human olfactory sense through prolonged contact. Cr(V), Fe(III), Ni(II), Zn(II), Cd(II), Hg(II), and Pb(II) are the most well-known toxic heavy metal pollutants in wastewater, which need to be removed by appropriate methods before water recycling and reuse [2]. Activated carbon [13], and molecular sieves [14] were widely used because of their distinctive adsorption properties, resulting from firm micro and mesoporous structures. Their high cost, complex preparation and recycling methods make it difficult to be conducted on a large-scale
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