Abstract
Contamination of water by Pb 2 + and the threat of invasive vegetation affects the quality and quantity of water accessible to all life forms and has become a primary concern to South Africa and the world at large. This paper synthesized, characterized, and evaluated the resins from tannin-rich invasive Acacia species as an environmentally benign Pb 2 + adsorbent. The analysis of the pore volume and surface area of the resins reveals a small pore dimension of 9 × 10−3 cc/g and large surface area (2.31–8.65 m2/g), presenting suitable physical parameters for adsorption of Pb 2 + . Langmuir model offers the best correlation data at pH 6 with maximum monolayer coverage capacity of 189.30, 105.70 and 98.82 mg/g for silver, black and green wattle tannin resins in aqueous solutions, respectively. The kinetic data suitably fits into a pseudo-second-order model, with the Dubinin–Radushkevich adsorption energy (E) ≤ 7.07 KJ/mol and intra-particle diffusion model confirming an associated physisorption process within the bio-sorption system. The thermogravimetric analysis (TGA) and Fourier-transform infrared (FT-IR) data of the resins were informative of the high thermal stability and chelating functionality such as -OH and -NH2 responsible for the removal of Pb 2 + . All the resins showed good adsorption characteristics while silver wattle tannin resin has the best adsorption capacity compared to black and green wattle tannin resins. This study provides a prototype adsorbent from invasive plants for the removal of Pb 2 + in water.
Highlights
The quality of water can be affected by several anthropogenic activities [1]
The pseudo-second-order kinetic model is based on the assumption that the rate of adsorption is proportional to the square of the difference in the equilibrium concentration of Pb2+, mathematically expressed in Equation (4) [28]: dqt
The Langmuir adsorption isotherm is based on the assumption that there are fixed numbers of equal size and shaped adsorption sites and dynamic equilibrium exists between the adsorbed and the free Pb2+ on the surface of the resin
Summary
The quality of water can be affected by several anthropogenic activities [1]. In South Africa, Pb is the primary source of water pollution resulting from mining, textile, battery, leather, and electro coatings industries. Recent studies have shown that heavy metals can be removed from water and wastewater by asbestos, cysts, and coliform [10,11,12], the non‐application of these adsorbents as a primary filter efficient, low-cost remediation plant materials and natural tannin adsorbent [13,14,15]. Recent studies have shown that heavy metals can be removed from water and Binaeianwastewater et al [17] reported that fabricated tannin-based dithiocarbamate and hexagonal mesoporous by efficient, low‐cost remediation plant materials and natural tannin adsorbent [13,14,15]. . The choicefunctionality of the Acacia this study was immobilized resin adsorbent enhanced andspecies thermalinstability for the based onremediation our findings [23], which indicate barks ofAcacia this species can hyper-accumulate of water contaminated by that. On ourdue findings which indicate the stem barks of this species can hyper‐accumulate heavy metals due to the significantly large tannin content
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