Adsorptive and Coagulative Removal of Trace Metals from Water Using Surface Modified Sawdust-Based Cellulose Nanocrystals

Abstract

The presence of toxic metals in surface and natural waters, even at trace levels, poses a great danger to humans and the ecosystem. Although the combination of adsorption and coagulation techniques has the potential to eradicate this problem, the use of inappropriate media remains a major drawback. This study reports on the application of NaNO2/NaHCO3 modified sawdust-based cellulose nanocrystals (MCNC) as both coagulant and adsorbent for the removal of Cu, Fe and Pb from aqueous solution. The surface modified coagulants, prepared by electrostatic interactions, were characterized using Fourier transform infrared, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive spectrometry (SEM/EDS). The amount of coagulated/adsorbed trace metals was then analysed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). SEM analysis revealed the patchy and distributed floccules on Fe-flocs, which was an indication of multiple mechanisms responsible for Fe removal onto MCNC. A shift in the peak position attributed to C2H192N64O16 from 2θ = 30 to 24.5° occurred in the XRD pattern of both Pb- and Cu-flocs. Different process variables, including initial metal ions concentration (10–200 mg/L), solution pH (2–10), and temperature (25–45 °C) were studied in order to investigate how they affect the reaction process. Both Cu and Pb adsorption followed the Langmuir isotherm with a maximum adsorption capacity of 111.1 and 2.82 mg/g, respectively, whereas the adsorption of Fe was suggestive of a multilayer adsorption process; however, Fe Langmuir maximum adsorption capacity was found to be 81.96 mg/g. The sequence of trace metals removal followed the order: Cu > Fe > Pb. The utilization of this product in different water matrices is an effective way to establish their robustness.

Heavy Metals Removal from Water and Wastewater

“…With the recent development of nanotechnologies, researchers have turned their attention to the uses of carbon nanotubes as adsorbent materials [72,73]. Numerous studies have been carried out regarding the use of activated carbon obtained from vegetable waste as an adsorbent material, or various natural adsorbent materials [74][75][76][77][78][79][80][81][82], or on different wastes [83,84]. They have the advantage of low costs, but also the disadvantage of developing low adsorption capacities and low selectivity.…”

“…Since the structure of the adsorbent greatly influences the adsorption process, compounds with well-ordered structures, such as layered double hydroxides and metal-organic frameworks, have also been intensively studied [93][94][95][96][97]. To obtain materials with high selectivity and improved absorbent properties, functionalized Combination of adsorption and coagulation techniques q m = 111.1 mg Cu/g q m = 2.82 mg Pb/g q m = 81.96 mg Fe/g [84] Cobalt ferrite nanoparticles Aqueous solutions containing Pb 2+ , Zn 2+ , and dyes.…”

Cellulose Nanocrystals (CNCs) and Cellulose Nanofibers (CNFs) as Adsorbents of Heavy Metal Ions

“…Oyewo et al [227] prepared CNCs from sawdust (MCNC). Te data obtained from Cu(II) and Pb(II) adsorption ftted well with the Langmuir adsorption model from the values of the R 2 , which was indicative of the chemical adsorption of Cu(II) and Pb(II) onto the MCNCs.…”

Adsorption of Nickel (Ii) Ions From Solution Using Sawdust and Modified Sawdust

“…For Zn 2+ and Ni 2+ cations, agitation rates of 120 and 100 rpm, biosorbent weights of 1.5 and 0.5 g, and adsorption times of 30 and 90 mins were obtained, respectively. The use of NaNO2/NaHCO3 modified sawdust-based cellulosic nanocrystals (MCNC) materials as an adsorbent and coagulant to remove Fe, Cu, and Pb from cationic solution has been described [16]. According to the study, lead and copper uptake followed the Langmuir isotherm model, with highest adsorption capacities of 2.82 and 111.1 mg.g -1 , respectively, and iron uptake had a maximum biosorption capability of 81.96 mg.g -1 .…”