As(III) and As(V) remediation in an aqueous medium using a cellulosic biosorbent: kinetics, equilibrium, and thermodynam
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As(III) and As(V) remediation in an aqueous medium using a cellulosic biosorbent: kinetics, equilibrium, and thermodynamics study Moonmoon Choudhary1 · Krishna Gopal Bhattacharyya2 Received: 9 April 2020 / Accepted: 24 August 2020 © Springer Nature Switzerland AG 2020
Abstract Arsenic is an element of concern, as it is widely distributed in the environment and poses a great threat to the health of humans and other living beings. The present study investigates the uptake of arsenite (As(III)) and arsenate (As(V)) ions from aqueous solution using low-cost Polyalthia longifolia leaf powder (PLP). The low-cost adsorbent was characterized by FTIR and SEM–EDX measurements. Adsorption experiments were carried out, with contact time, pH, adsorbent amount, the concentration of As(III) and As(V) and co-existing anions (PO43− and BO33−) as the variables. Maximum adsorption of As(III) and As(V) was found at pH 7.5 and 3.0, respectively. The presence of PO43− and BO33− was found to be sufficient for the uptake of As(III) and As(V), respectively. Adsorption of both As(III) and As(V) on PLP was found to follow the pseudo-second-order kinetic model. Freundlich, Langmuir, and Temkin models of adsorption were tested for adsorption of As(III) and As(V) on PLP, and the results indicated that adsorption data closely followed the Langmuir model. The maximum adsorption capacity for As(III) and As(V) was 1.76 mg g−1 and 1.87 mg g−1, respectively, under the experimental conditions. Thermodynamic analysis showed that the process of adsorption of both As(III) and As(V) on PLP was spontaneous and exothermic with decreasing degrees of freedom. The results indicated that PLP-As(III) and PLP-As(V) interaction equilibria were efficient and therefore could be explored for practical applications. Keywords Adsorption · Polyalthia longifolia · As(III) · As(V)
1 Introduction Creating one of the largest pollution problems in the world’s history, arsenic (As) is recognized as a Class A human carcinogen by the US Environmental Protection Agency [1, 2]. The present-day scenario is that many developed and developing countries have reported arsenic contamination, with southern and southeastern Asia being the most heavily affected. The river valleys of the GangaMeghna-Brahmaputra river system in India and Bangladesh, the Indus River in Pakistan, the Red River in Vietnam, the Irrawaddy River in Myanmar, the Yellow River in China, and the Mekong River in Laos and Cambodia have been reported to have elevated concentrations of As [3].
Arsenic pollution is induced in the environment by both natural and anthropogenic sources, including weathering reactions, volcanic eruptions, biological activity, use of arsenical pesticides and fertilizers, industrial waste discharge, mining, discharge from coal-fired thermal power plants, petroleum refining, and ceramic industries [4, 5]. Arsenic is found in both organic and inorganic form in nature, but inorganic As compounds are known to be 100 times more poisonous than organic As compounds [6]. The oxidation states o
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