scholarly journals Study on the adsorption of heavy metals by biochar modified with different modifiers under room temperature

2021 ◽  
Vol 293 ◽  
pp. 03014
Author(s):  
Jiajia Ding ◽  
Yu Tian ◽  
Tao Lu ◽  
Jiang Kang
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Room Temperature ◽  
Adsorption Mechanism ◽  
Physical Adsorption ◽  
Complexation Reaction ◽  
Waste Biomass ◽  
Adsorption Effect ◽  
Before And After

In order to obtain an environment-friendly biochar adsorption material with excellent adsorption performance, the biochar made from corn straw was modified with FeCl3, Na2S and KMnO4 as modifiers, and the adsorption effect of biochar on several heavy metal ions in water before and after modification was studied. The properties of biochar before and after modification were characterized by SEM, XRD, FTIR and BET, and the adsorption mechanism was discussed. The results showed that the three modified reagents could effectively improve the adsorption capacity of biochar for three heavy metal ions in water, and the adsorption effect was still good at room temperature. The adsorption difference is related to the specific surface area, pore structure, aromatic structure and SiO2 content of biochar. The adsorption mechanism mainly includes the complexation reaction between physical adsorption and surface functional groups. This study is beneficial to promote the resource utilization of agricultural and forestry waste biomass, and provides a certain reference basis for related research.

scholarly journals Effects of Electronegativity and Hydration Energy on the Selective Adsorption of Heavy Metal Ions by Synthetic NaX Zeolite

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4066
Author(s):  
Xianyuan Fan ◽  
Hong Liu ◽  
Emmanuella Anang ◽  
Dajun Ren
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Adsorption Capacity ◽  
Heavy Metal Ions ◽  
Binary Systems ◽  
Adsorption Mechanism ◽  
Selective Adsorption ◽  
Hydration Energy ◽  
Nax Zeolite ◽  
High Electronegativity

The adsorption capacity of synthetic NaX zeolite for Pb2+, Cd2+, Cu2+ and Zn2+ in single and multi-component systems were investigated. The effects of electronegativity and hydration energy on the selective adsorption, as well as potential selective adsorption mechanism of the NaX zeolite for Pb2+, Cd2+, Cu2+ and Zn2+ were also discussed. The maximum adsorption capacity order of the heavy metals in the single system was Pb2+ > Cd2+ > Cu2+ > Zn2+, and this could be related to their hydration energy and electronegativity. The values of the separation factors (α) and affinity constant (KEL) in different binary systems indicated that Pb2+ was preferentially adsorbed, and Zn2+ presented the lowest affinity for NaX zeolite. The selective adsorption capacities of the metals were in the order, Pb2+ > Cd2+ ≈ Cu2+ > Zn2+. The trend for the selective adsorption of NaX zeolite in ternary and quaternary systems was consistent with that in the binary systems. Pb2+ and Cu2+ reduced the stability of the Si-O-Al bonds and the double six-membered rings in the NaX framework, due to the high electronegativity of Pb2+ and Cu2+ than that of Al3+. The selective adsorption mechanism of NaX zeolite for the high electronegative metal ions could mainly result from the negatively charged O in the Si-O-Al structure of the NaX zeolite, hence heavy metal ions with high electronegativity display a strong affinity for the electron cloud of the oxygen atoms in the Si-O-Al. This study could evaluate the application and efficiency of zeolite in separating and recovering certain metal ions from industrial wastewater.

scholarly journals Metal-responsive elements act as positive modulators of human metallothionein-IIA enhancer activity.

1987 ◽  
Vol 7 (2) ◽  
pp. 606-613 ◽  
Author(s):  
M Karin ◽  
A Haslinger ◽  
A Heguy ◽  
T Dietlin ◽  
T Cooke
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Mutational Analysis ◽  
Enhancer Activity ◽  
Enhancer Element ◽  
Basal Activity ◽  
Before And After ◽  
Positive Modulator ◽  
Gc Box

The human metallothionein IIA (hMT-IIA) gene contains two enhancer elements whose activity is induced by heavy-metal ions such as Cd2+. To determine the nature of the relationship between the metal-responsive elements and the element(s) responsible for the basal activity of the enhancers, the basal-level enhancer element(s), the hMT-IIA enhancers were subjected to mutational analysis. We show that deletion of the metal-responsive elements had no effect on the basal activity of the enhancer but prevented further induction by Cd2+. On the other hand, replacement of the basal-level enhancer element with linker DNA led to inactivation of the enhancer both before and after treatment with Cd2+. Therefore, the metal-responsive elements seems to act as a positive modulator of enhancer function in the presence of heavy-metal ions. In addition to the two enhancers, the hMT-IIA promoter contained one other element, the GC box, required for its basal expression. Unlike deletion of the basal-level enhancer element, replacement of the GC box with linker DNA had no effect on the ability of the promoter to be induced by Cd2+.

The adsorption of divalent heavy metal ions on (8,0) carbon nanotubes: The first-principles study

2020 ◽  
Vol 34 (32) ◽  
pp. 2050368
Author(s):  
Z. Zhu ◽  
L. An ◽  
T. Chen ◽  
X. Jia
Keyword(s):  
Carbon Nanotubes ◽  
Heavy Metal ◽  
Metal Ions ◽  
First Principles ◽  
Industrial Wastewater ◽  
Heavy Metal Ions ◽  
Density Functional ◽  
Physical Adsorption ◽  
Functional Theory ◽  
Sensing Material

In order to explore new ways to detect and remove heavy metal ions from industrial wastewater, the first-principles method based on density functional theory has been used to investigate the performance of carbon nanotubes (CNTs) in adsorbing divalent heavy metal ions which include Zn[Formula: see text], Cu[Formula: see text], Pb[Formula: see text] and Sn[Formula: see text]. Results show that the adsorption of Zn[Formula: see text] on CNTs is weak and only physical adsorption forms between them. However, for Cu[Formula: see text], Pb[Formula: see text] and Sn[Formula: see text], the final adsorption distance with CNTs is greatly decreased, and the adsorption energy and charge transfer amount with CNTs are significantly increased. In addition, the charge density of Cu[Formula: see text], Pb[Formula: see text] and Sn[Formula: see text] overlaps effectively with that of CNTs. These indicate the formation of strong chemisorption between these ions and CNTs. Therefore, CNTs could be used as a sensing material to detect and remove Cu[Formula: see text], Pb[Formula: see text] and Sn[Formula: see text] from wastewater. The research provides theoretical guidance for the application of CNTs in heavy metal ions treatment.

scholarly journals Absorbed Pb2+ and Cd2+ Ions in Water by Cross-Linked Starch Xanthate

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Kai Feng ◽  
Guohua Wen
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Adsorption Mechanism ◽  
Potato Starch ◽  
Sodium Acrylate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Concentration Of Ions ◽  
Cross Linker

A cross-linked starch xanthate was prepared by graft copolymerization of acrylamide and sodium acrylate onto starch xanthate using potassium persulfate and sodium hydrogen sulfite initiating system and N,N′-methylenebisacrylamide as a cross-linker. As this kind of cross-linked potato starch xanthate can effectively absorb heavy metal ions, it was dispersed in aqueous solutions of divalent heavy metal ions (Pb2+ and Cd2+) to investigate their absorbency by the polymer. Factors that can influence absorbency were investigated, such as the ratio of matrix to monomers, the amount of initiator and cross-linker, pH, and the concentration of metal ions. Results were reached and conclusion was drawn that the best synthetic conditions for the polymer adsorbing Pb2+ and Cd2+ were as follows: the quality ratio of matrix to monomers was 1 : 12 and 1 : 11, the amount of initiator was 2.4% and 3.2% of matrix, and the amount of cross-linker was 12 mg and 13 mg. When the initial concentration of ions was 10 mg/L, the highest quantities of adsorption of Pb2+ and Cd2+ were 47.11 mg/g and 36.55 mg/g. Adsorption mechanism was discussed by using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) test, and adsorption kinetic simulation.

Biomass based hydrogel as an adsorbent for the fast removal of heavy metal ions from aqueous solutions

2017 ◽  
Vol 5 (7) ◽  
pp. 3434-3446 ◽  
Author(s):  
Mingyue Zhang ◽  
Lihua Song ◽  
Haifeng Jiang ◽  
Shu Li ◽  
Yifei Shao ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Acrylic Acid ◽  
Aqueous Solutions ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Low Cost ◽  
Waste Biomass ◽  
One Step ◽  
Fast Removal ◽  
Poly Acrylic Acid

In order to achieve the reutilization of waste biomass soybean dregs, a low-cost hydrogel, soybean dregs–poly(acrylic acid) (SESD–PAA) was prepared through a one-step reaction.

scholarly journals Room-temperature fabrication of magnetite-boehmite sol-gel composites for heavy metal ions removal

2020 ◽  
Vol 13 (1) ◽  
pp. 1933-1944 ◽  
Author(s):  
Olga E. Shapovalova ◽  
Andrey S. Drozdov ◽  
Ekaterina A. Bryushkova ◽  
Maxim I. Morozov ◽  
Vladimir V. Vinogradov
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Room Temperature ◽  
Sol Gel ◽  
Heavy Metal Ions Removal ◽  
Metal Ions Removal
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