Selective Capacitive Removal of Heavy Metal Ions from Wastewater over Lewis Base Sites of S-Doped Fe–N–C Cathodes via an Electro-Adsorption Process

Author(s):  
Minlin Mao ◽  
Tingting Yan ◽  
Junjie Shen ◽  
Jianping Zhang ◽  
Dengsong Zhang
RSC Advances ◽  
2021 ◽  
Vol 11 (28) ◽  
pp. 17080-17091
Author(s):  
Xinggang Chen ◽  
Zhuang Tian ◽  
Haina Cheng ◽  
Gang Xu ◽  
Hongbo Zhou

The Cu2+ first bound to the outer mannan and finally entered the cytoplasm. During the whole adsorption process, the number of adsorption sites in the outer and middle cell walls was the largest, and then gradually decreased.


Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 315 ◽  
Author(s):  
Musa Yahaya Pudza ◽  
Zurina Zainal Abidin ◽  
Suraya Abdul Rashid ◽  
Faizah Md Yasin ◽  
A. S. M. Noor ◽  
...  

The materials and substances required for sustainable water treatment by adsorption technique, are still being researched widely by distinguished classes of researchers. Thus, the need to synthesize substances that can effectively clean up pollutants from the environment cannot be overemphasized. So far, materials in bulk forms that are rich in carbon, such as biochar and varieties of activated carbon have been used for various adsorptive purposes. The use of bulk materials for such purposes are not efficient due to minimal surface areas available for adsorption. This study explores the adsorption task at nano dimension using carbon dots (CDs) from tapioca. The properties of carbon structure and its influence on the adsorptive efficacy of carbon nanoparticles were investigated by energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HrTEM), and atomic force microscopy (AFM). The results implied carbon present in CDs are good adsorbents for effective adsorption of heavy metal ions (lead) with removal efficiency of 80.6% in aqueous environment. The adsorption process as explored by both Langmuir and Freundlich isotherms have proven favorability of the adsorption process. Langmuir form two and three have correlation coefficients R2 at 0.9922 and 0.9912, respectively. The Freundlich isotherm confirms CDs as having defined surface heterogeneity and the exponential distribution of active sites. The adsorption of lead unto CDs obeyed the second order kinetic model with coefficient of determination, R2 of 0.9668 and 0.9996 at an initial lead concentration of 20 mg/L and 100 mg/L, respectively. The findings validated the efficiency of CDs derived from tapioca as an excellent material for further utilization in the environmental fields of wastewater pollution detection and clean up, bio-imaging, and chemical sensing applications.


Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 176 ◽  
Author(s):  
Ya Gao ◽  
Hao Jiang ◽  
Xianyuan Li ◽  
Sultan Ahmed Khoso ◽  
Guoyuan Xiang ◽  
...  

In the field of water management, the separation of metal contaminants from wastewater is very important and challenging. This study systematically investigated the effect and underlying mechanism of silicate rectorite (REC) on the removal of heavy metal ions (Cr(VI) and Pb(II)) from wastewater. The adsorption and removal capacity of REC was further improved by its novel modification with ferric chloride hexahydrate. Compared to natural REC, the modified rectorite (Fe-REC) showed comparatively superior adsorption efficiency for both Cr(VI) and Pb(II) due to the chemisorption of Fe3+ on the REC surface as its oxidation state (Fe–O, Fe–OH, Fe–OOH). Adsorption on Cr(VI) attributed to the reaction between iron hydroxy complexes (FeOH2+, Fe(OH)2+ and Fe(OH)3(aq)) and Cr(VI) species (HCrO4− and CrO42−) in the aqueous solution. This reaction was perfectly consistent with the binding energy shifts in O 1s and Fe 2p species, as reflected by XPS analysis. While, the existence of –Al–OH and –Si–OH in silicate REC slurry reacted with PbOH+ colloids produced from lead ions hydrolysis to promote Pb(II) adsorption. Zeta potential after modification and removal occurred to shift positively or negatively to testify the adsorption of Fe3+ and heavy metal ions. Freundlich and Langmuir isotherms conformed adsorption process for Cr(VI) and Pb(II), respectively.


2014 ◽  
Vol 1056 ◽  
pp. 16-19
Author(s):  
Shu Li Ding ◽  
Dan Dan Hou ◽  
Bo Hui Xu ◽  
Yu Zhuang Sun

The Bentonite from Yongnian is Ca-Bentonite, Montmorillonite Content 52%, Colloidal Value 57ml/15g, Eca2+/CEC 53.60%. the Adsorption Characteristics of Pb2+, Cu2+ and Cr3+ onto Bentonite under Conditions of Constant Temperature and Ph have been Studied. the Results Show that the Adsorption Capacities of Heavy Metal Ions onto Bentonite from Yongnian Follow the Order of Pb2+> Cu2+> Cr3+. it is Found that the Adsorption Process of Bentonite Accords with the Langmuir Isotherm Model. the Maximum Adsorption of 3 Kinds of Metal Ions onto Bentonite is in Order of Cr3+>Cu2+>Pb2+.


2020 ◽  
Vol 8 (4) ◽  
pp. 103971 ◽  
Author(s):  
Jumina ◽  
Yoga Priastomo ◽  
Hamid Rohma Setiawan ◽  
Mutmainah ◽  
Yehezkiel Steven Kurniawan ◽  
...  

2017 ◽  
Vol 68 (2) ◽  
pp. 362-368 ◽  
Author(s):  
Aleksandra Sucurovic ◽  
Jelena Trickovic ◽  
Snezana Maletic ◽  
Marijana Kragulj Isakovski ◽  
Akos Kukovecz ◽  
...  

This work studies the adsorption of heavy metal ions (Cu(II), Pb(II) and Cr(VI)) in aqueous solutions on amino-functionalized multiwalled carbon nanotubes (MWCNTs-NH2) in the ppb concentration range (50-3000 �g/l) as a function of contact time, initial concentration of heavy metal ions and the presence of four inorganic electrolyte anions (Cl-, SO42-, NO3-, PO43-). The adsorption of heavy metals from aqueous solution was studied using different kinetic models. The results showed that the adsorption process is best fitted with the pseudo-second-order model indicating that the process is controlled by chemisorptions through electrostatic attraction and chemical interaction/complexation between the metal ions and the surface functional groups of MWCNTs-NH2. The intra-particle diffusion model showed that diffusion is slow, but did not govern the rate of the overall adsorption process. The effects of Cl-, SO42-, NO3- and PO43- anions on the adsorption of Cu(II), Pb(II) and Cr(VI) are variable (improvement, reduction, no impact).


2019 ◽  
Vol 9 (1) ◽  
pp. 9-17
Author(s):  
Batseba Taihuttu ◽  
V Kayadoe ◽  
A Mariwy

Adsorption study of the adsorption of heavy metal ions from Fe (III) using sago dregs waste was carried out. adsorption was carried out in batches, with the mass of adsorbent is 1 g and the concentration of Fe (III) ion is 10 ppm. in this study variations in contact time were 60, 90, 120, 150 and 180 minutes to determine the kinetic suitable for the adsorption process of ion Fe (III) and the capacity and efficiency of sago dregs adsorption. The results showed that the adsorption of ion fe (III) using sago dregs followed pseudo second-order kinetics with R2 values that were closer to 1 that is 0,9651. adsorption of ion Fe (III) at optimum contact time of 90 minutes with adsorbent mass of 1 g obtained by adsorption capacity 0,3211 mg/g and the adsorption efficiency is 64,2%.


Author(s):  
Zeynab Karimi ◽  
Reza Khalili ◽  
Mohammad Ali Zazouli

Abstract In this study, polythiophene/Al2O3 (PTh/Al2O3) and polyaniline/Al2O3 (PAn/Al2O3) nanocomposites in the presence of poly(vinyl alcohol) (PVA) as the surfactant were synthesized via in situ chemical oxidative polymerization method in aqueous medium. The synthesized nanocomposites were characterized by Scanning electron microscopy (SEM), Fourier transform-infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Results indicated that the Al2O3 and poly(vinyl alcohol) influenced the properties of synthesized nanocomposites. The aim of this research was to investigate the sorption characteristic of polythiophene and polyaniline nanocomposites for the removal of heavy metal cations including Pb(II), Zn(II) and Cd(II) from aqueous solution. The factors that affected the adsorption equilibrium as well as the removal efficiency of the nanoadsorbents, i.e., contact time, metal ion concentration, pH and adsorption conditions were investigated in detail. From the kinetic results, it was concluded that the pseudo-second-order kinetic model was found to the best at describing the adsorption process for Pb(II), Zn(II) and Cd(II) on PTh-PVA/Al2O3 and PAn-PVA/Al2O3. In addition, thermodynamic analysis suggests the endothermic and spontaneous nature of the present adsorption process with increased entropy on PTh-PVA/Al2O3 and PAn-PVA/Al2O3. The results suggest polythiophene, polyaniline and their nanocomposites have great potential to be used as efficient absorbent for the removal of heavy metal ions from water.


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