Lead ion adsorption on functionalized sugarcane bagasse prepared by concerted oxidation and deprotonation
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RESEARCH ARTICLE
Lead ion adsorption on functionalized sugarcane bagasse prepared by concerted oxidation and deprotonation Shuo Ai 1,2
&
Yongchun Huang 1,2 & Chengdu Huang 1,2 & Wanguo Yu 1,2 & Zhijuan Mao 1,2
Received: 2 May 2020 / Accepted: 31 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Targeting the removal of Pb2+ in wastewater, sugarcane bagasse was treated with nitric acid and an alkaline solution to prepare adsorbents. On a typical adsorbent, the adsorption isotherms agreed well with the Langmuir expression, and the maximum adsorption capacity reached 200.3 mg/g. In the presence of 150 ppm Ca2+, a common cation in natural water, the Pb2+ adsorption capacity slightly declined. In contrast, Mg2+ obviously prohibited the adsorption for Pb2+. The spent adsorbent could be regenerated at least five times through elution with an EDTA solution. EDS and XPS results demonstrated that nitric acid functioned as an oxidant instead of nitrification agent in the treatment of bagasse. The adsorption process was consistent with quasi-second-order kinetics. Based on thermodynamic studies, the changes in enthalpy and Gibbs free energy were calculated to be − 33.3 and ca. − 18 kJ/mol, indicating that the adsorption process was exothermic and spontaneous. The equilibrium Pb2+ adsorption amounts were proportional to the numbers of carboxylate groups on different adsorbents. The binding energies of Pd 4f5/2 and Pd 4f7/2 XPS spectra of Pb2+ adsorbed were 0.6–0.7 eV lower than those of free Pb(NO3)2, indicating the transfer of electrons during adsorption. The conversion of hydroxymethyl groups in sugarcane bagasse into carboxylate groups, as well as the chelation between Pb2+ ions and carboxylate groups, was validated in this work, which is beneficial for the treatment of wastewater polluted by lead ions. Keywords Lead . Adsorption . Nitric acid . Bagasse . Carboxylate
Introduction Lead is a common heavy metal element and causes dehydrogenase deficiency (McIntire and Angle 1972), brain damage, kidney disease, liver damage, and blood disease (Eguchi et al. 2018). Also, lead can be transferred into plants (Pichtel et al. 2000) and can migrate worldwide (Brenda et al. 2015). Lead pollution sources include mines, smelters, production, and recycling industries of lead-acid batteries, fuels, house paint, etc. (Brenda et al. 2015; Gottesfeld and Cherry 2011; Small et al. 1995). Severe pollution resulting from lead-acid battery Responsible editor: Tito Roberto Cadaval Jr * Shuo Ai [email protected] 1
Department of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou City 545006, China
2
Guangxi Key Laboratory of Green Processing of Sugar Resources, Liuzhou City 545006, China
factories has been reported in China (Chen et al. 2009; Liu et al. 2017), USA (Pichtel et al. 2000), Eastern Europe (Rieuwerts et al. 1999), Mexico (Valdez 1997), South America (Paoliello and Capitani 2005), and so forth. According to the statistics from Gottesfeld et al. (Gottesf
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