Eco-Efficient Biosorbent Based on Leucaena leucocephala Residues for the Simultaneous Removal of Pb(II) and Cd(II) Ions from Water System: Sorption and Mechanism.

C A Cimá-Mukul,Joel Vargas,Youness Abdellaoui,Jesús Alberto Barrón-Zambrano,Mohamed Abatal,Arlette A Santiago

doi:10.1155/2019/2814047

Abstract

Leucaena leucocephala is a potential source of polyphenols widely available in southern Mexico. This work highlights the extraction of polyphenols from Leucaena leucocephala leaves waste (LLEPs) and the evaluation of their efficiency to remove the single and multicomponent Pb(II) and Cd(II) metal ions from aqueous solutions. Batch test conditions were carried out to examine the effects of contact time, initial metal ion concentration, and adsorbent dosage on the biosorption process. The surface textures and the composition of the LLEP biosorbent was characterized using pH of point of zero charge (pHPZC), attenuated total reflectance Fourier transform infrared (ATR-FTIR), and matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry, respectively. Further analysis using ATR-FTIR after adsorption contact of biosorbent was also investigated. The highest Langmuir saturation monolayer adsorption capacity, qm, for the removal of Pb(II) by LLEPs was obtained as 25.51 and 21.55 mg/g in mono- and bimetal solutions, respectively. The pseudo-second-order model provided the best fit for the kinetic data obtained for the removal of Pb(II), Cd(II), and their mixture, and the k2 values depend on the adsorbent mass. This implied that the chemisorption process might be the mechanism of the solute ions-LLEPs interaction in this study. Furthermore, nearly 100% removal of lead and cadmium individually and 95% of their mixture was found using 0.9 g of LLEPs.

Highlights

Biosorption has emerged as a potential and promising solution to remove toxic heavy metals from water and wastewater, and is considered as an alternative process to the conventional methods such as those based on ion exchange, precipitation, membranes, and electrochemistry processes widely applied in industrial effluents treatments which are very costly and have many limitations [1, 2]
Leaf residues of Leucaena leucocephala tree were collected from the campus area of the Autonomous University of Ciudad Del Carmen identified by our botanist Dr Enrique Lopez, washed with deionized water, dried at 70°C, and stored in glass bottles to be used for the polyphenols’ extraction
Point of Zero Charge. e pH of the point of zero charge of leucocephala-extracted polyphenols (LLEPs) has been described as following: 0.10 g of each adsorbent with 50 mL of 0.01 M NaCl adjusted to different initial pH values. e suspensions were allowed to equilibrate for 24 h under agitation, decanted, and the final pH values of each remaining solution were measured using the pH meter ermo Scientific (ORION 3-Star pH Benchtop)

Summary

Introduction

Biosorption has emerged as a potential and promising solution to remove toxic heavy metals from water and wastewater, and is considered as an alternative process to the conventional methods such as those based on ion exchange, precipitation, membranes, and electrochemistry processes widely applied in industrial effluents treatments which are very costly and have many limitations [1, 2]. Algae-, fungi-, agricultural-, and forestry-based materials have proved to be eco-efficient and environmentally friendly sorbent for heavy metals [3, 4]. E use of polyphenols as biosorbents has been widely studied in water and wastewater treatment to remove heavy metals due to the large availability of these compounds in plant material that can be extracted from agricultural waste using a green solvent. Phlomis lanata, Ilex paraguariensis, and Origanum vulgare demonstrated a high total phenol content with more than 15.0 mg gallic acid equivalent (GAE)/g dried sample, whereas Geranium purpureum, Matricaria chamomilla, and Lavandula vera showed a content less than 7 mg GAE/g dried sample [16, 17]

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Methods

Results