Abstract

The purpose of this study was to fabricate a low-cost and eco-friendly adsorbent using bamboo biochar (BB), a kind of charcoal composed of high Brunauer–Emmett–Teller surface area and variety of functional groups, and chitosan as substrates for remediation of Cd(II) in Cd(II) contaminated water and characterized the functional group characteristics, surface morphology, and Cd(II) adsorption effect using the Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and energy-dispersive X-ray spectrometer (EDS). Results showed that chitosan-modified bamboo biochar (CBB) provided more active adsorption sites (such as –NH2, –COOH, –OH, and C=O) on the surface to enhance the Cd(II) removal efficiency in Cd(II) contaminated wastewater. Meanwhile, the optimal pH, contact time, and dose of CBB on the Cd(II) removal efficiency are 7, 120 min, and 600 mg, respectively. In addition, the adsorption isotherm results revealed that the possible adsorption mechanisms might include surface adsorption, electrostatic adsorption, and ion exchanges. Furthermore, the maximum adsorption capacity (Qm) values predicted from the Langmuir model were 37.74 and 93.46 mg/g for BB and CBB, respectively, also indicating a potential application of CBB in practical wastewater. Desorption and regeneration of CBB were attained simultaneously and the results showed that even after five cycles of adsorption-elution, the adsorption and desorption of CBB exhibited a slight decline and still reached at 71.70% and 65.92%. Results from this study would provide a reference to functionalized CBB for Cd(II) adsorption in contaminated water.

Highlights

  • Water pollution is one of the most severe problems on our planet

  • Preparation of bamboo biochar (BB) and chitosan-modified bamboo biochar (CBB). is study successfully fabricated a new kind of CBB using BB and chitosan as substrates for Cd(II) remediation in Cd(II) contaminated water

  • Some previous studies reported by Zhou et al [29] and Zhang et al [30] had explored the use of chitosan to modify the BB surface to fabricate chitosan-modified biochars (CMB) and chitosan-modified magnetic biochar (CMMB) to enhance their affinity to heavy metals (Cr(IV), Pb(II), Cu(II), and Cd(II)) in water

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Summary

Introduction

Water pollution is one of the most severe problems on our planet. It is a novel challenge to manage water resources sustainably under climate change and population growth in the 21st century [1, 2]. Many techniques, including ion exchange [7], membrane filtration [6], flocculation/ coagulation [8], chemical precipitation [9], photocatalysis [10], phytoremediation [11], and adsorption [12], are performed to remove heavy metals from the contaminated water and soil. Various physical and chemical techniques have been employed to lower the Cd(II) concentration to meet environmental standards, including chemical precipitation, ultrafiltration, membrane separation, electrochemical deposition, and adsorption [13]. These techniques have great limitations for heavy metals removal due to their higher cost of energy and sludge production

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