Adsorption of Cationic Dyes on Dacryodes edulis Seeds Activated Carbon Modified Using Phosphoric Acid and Sodium Chlorid
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Adsorption of Cationic Dyes on Dacryodes edulis Seeds Activated Carbon Modified Using Phosphoric Acid and Sodium Chloride Chinenye Adaobi Igwegbe 1 & Okechukwu Dominic Onukwuli 1 & Joshua O. Ighalo 1,2 Patrick Ugochukwu Okoye 3
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Received: 7 July 2020 / Accepted: 16 September 2020/ # Springer Nature Switzerland AG 2020
Abstract
The aim of this study was to investigate the adsorption of Congo red (CR) and Vat yellow 4 (VY4) cationic dyes from aqueous media using adsorbents developed from Dacryodes edulis (African pear) seeds (DES) activated using phosphoric acid (H3PO4) and sodium chloride (NaCl). The adsorbents were characterised using X-ray Fluorescence (XRF), Fourier Transforms Infrared Spectrophotometry (FTIR) and Scanning Electron Microscopy (SEM). Maximum uptake of CR and VY4 was observed at an initial pH of 2. H3PO4 activated Dacryodes edulis carbon (ADES) performed better than the NaCl activated Dacryodes edulis carbon (SDES) which implied that the H3PO4 increased the porosity and surface area of DES compared to NaCl use. Maximum dye removal of 99.59%, 96.88%, 99.70% and 98.99% were obtained for the VY4/ADES, VY4/SDES, CR/ADES and CR/SDES, respectively. The Langmuir-Freundlich isotherm showed best fitting when using ADES as adsorbent and the Freundlich isotherm when using SDES. The pseudo-second-order kinetic model was found to best correlate with the experimental data and the adsorption process was controlled by film diffusion. Thermodynamics revealed that adsorption was favourable, spontaneous, and endothermic. Keywords Activation . Adsorption . Congo red . Dacryodes edulis . Vat yellow
* Chinenye Adaobi Igwegbe [email protected] * Joshua O. Ighalo [email protected]
1
Department of Chemical Engineering, Nnamdi Azikiwe University, Awka, Nigeria
2
Department of Chemical Engineering, University of Ilorin, Ilorin, Nigeria
3
Institutio de Energias Renovables, Universidad Nacional Autónoma de México, Mexico City, Mexico
Igwegbe C.A. et al.
1 Introduction The production of activated carbon from wastes has positive economic and environmental implications (Weng and Pan 2007). It converts unwanted, low-value waste materials to more useful and valuable materials. Activated carbon is the most commonly utilised adsorbent for colour removal (Mezohegyi et al. 2012). It is also used for the purification and removal of toxic organics and heavy metal ions (Jeirani et al. 2017). The cost of the activated carbon produced from wastes is lesser when compared to the cost of commercial activated carbon (Dias et al. 2007). Agricultural wastes are renewable, available in large amounts, and are less expensive when compared to other precursors used for adsorbent development. Some of the activated carbon used for the treatment of dye polluted effluents have been prepared from wastes such as sawdust (Salazar-Rabago et al. 2017; Un and Ates 2019), orange peels (Lam et al. 2017; Nascimento et al. 2014), African pear seeds (Igwegbe et al. 2015), almond shells (Hevira et al. 2020), rice husk (Umembamalu et al. 202
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