Electrochemically Modified Adsorbents for Treatment of Aqueous Arsenic: Pore Diffusion in Modified Biomass vs. Biochar

2021 ◽  
pp. 130061
Author(s):  
Khaled Zoroufchi Benis ◽  
Jafar Soltan ◽  
Kerry N. McPhedran
2001 ◽  
Vol 234 (2) ◽  
pp. 328-336 ◽  
Author(s):  
C.W. Cheung ◽  
C.K. Chan ◽  
J.F. Porter ◽  
G. McKay

2015 ◽  
Vol 5 (1) ◽  
pp. 45
Author(s):  
Tchuifon Tchuifon Donald Raoul ◽  
Nche George Ndifor-Angwafor ◽  
Ngakou Sadeu Christian ◽  
Kamgaing Théophile ◽  
Ngomo Horace Manga ◽  
...  

<p>The present study is based on the adsorption of cadmium (II) ions on rice husk and egussi peeling, unmodified and modified with nitric acid in aqueous solution, using batch technique. It was carried out as a function of contact time, dosage, pH and initial concentration. The equilibrium time was achieved within 25 minutes for unmodified rice husk (Glu NT) and 20 minutes for unmodified egussi peeling (Cuc NT) with an adsorbed quantity of 13.18 mg/g. In the case of modified materials, we obtained 15 minutes for modified rice husk (Glu HNO3) and 10 minutes for modified egussi peeling (Cuc HNO3) with an adsorbed quantity of 18.77 mg/g. The maximum biosorption occurred at pH 5.5 for all biosorbents. The adsorbent mass for maximum adsorption was 0.4 g giving an adsorption capacity of 62.02 % for unmodified adsorbents. In the case of modified adsorbents, the minimal mass at which maximum adsorption occurred was 0.4 g giving an adsorption capacity of 98.33 % and 0.6 g giving an adsorption capacity of 98.33 % for modified rice husk and egussi peeling respectively. The adsorbent/adsorbate equilibrium was well described by the pseudo-second order kinetic model and by Langmuir’s and Freundlich adsorption model. This models showed that the adsorption of cadmium (II) is a chemisorption process.</p>


2020 ◽  
Vol 82 (10) ◽  
pp. 2159-2167
Author(s):  
Ru-yi Zhou ◽  
Jun-xia Yu ◽  
Ru-an Chi

Abstract Double functional groups modified bagasse (DFMBs), a series of new zwitterionic groups of carboxyl and amine modified adsorbents, were prepared through grafting tetraethylenepentamine (TEPA) onto the pyromellitic dianhydride (PMDA) modified bagasse using the DCC/DMAP method. DFMBs' ability to simultaneously remove basic magenta (BM, cationic dye) and Congo red (CR, anionic dye) from aqueous solution in single and binary dye systems was investigated. FTIR spectra and Zeta potential analysis results showed that PMDA and TEPA were successfully grafted onto the surface of bagasse, and the ratio of the amount of carboxyl groups and amine groups was controlled by the addition of a dosage of TEPA. Adsorption results showed that adsorption capacities of DFMBs for BM decreased while that for CR increased with the increase of the amount of TEPA in both single and binary dye systems, and BM or CR was absorbed on the modified biosorbents was mainly through electrostatic attraction and hydrogen bond. The adsorption for BM and CR could reach equilibrium within 300 min, both processes were fitted well by the pseudo-second-order kinetic model. The cationic and anionic dyes removal experiment in the binary system showed that DMFBs could be chosen as adsorbents to treat wastewater containing different ratios of cationic and anionic dyes.


2017 ◽  
Vol 18 (2) ◽  
pp. 460-472 ◽  
Author(s):  
E. Shokri ◽  
R. Yegani ◽  
B. Pourabbas ◽  
B. Ghofrani

Abstract In this work, montmorillonite (Mt) was modified by environmentally friendly arginine (Arg) and lysine (Lys) amino acids with di-cationic groups for arsenic removal from contaminated water. The modified Mts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential and thermal analysis. The adsorption of As(V) onto modified Mts as a function of initial As(V) concentration, contact time and solution pH was investigated. The removal efficiency was increased with increasing the As(V) concentration and contact time; however, it was decreased with increasing solution pH. The maximum As(V) adsorption capacities of Mt-Arg and Mt-Lys were 11.5 and 11 mg/g, respectively, which were five times larger than pristine Mt. The high adsorption capacity makes them promising candidates for arsenic removal from contaminated water. The regeneration studies were carried out up to 10 cycles for both modified Mts. The obtained results confirmed that the modified adsorbents could also be effectively used for As(V) removal from water for multiple adsorption – desorption cycles.


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