scholarly journals Combined Influence of Low-Grade Metakaolins and Natural Zeolite on Compressive Strength and Heavy Metal Adsorption of Geopolymers

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 486
Author(s):  
Alcina Johnson Sudagar ◽  
Slávka Andrejkovičová ◽  
Fernando Rocha ◽  
Carla Patinha ◽  
Maria R. Soares ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Compressive Strength ◽  
Natural Zeolite ◽  
Metal Adsorption ◽  
Low Grade ◽  
Heavy Metal Adsorption ◽  
Adsorption Model ◽  
X Ray ◽  
Adsorption Capacities

Metakaolins (MKs) prepared from low-grade kaolins located in the Alvarães (A) and Barqueiros (B) regions of Portugal were used as the aluminosilicate source to compare their effect on the compressive strength and heavy metal adsorption of geopolymers. Natural zeolite, an inexpensive, efficient adsorbent, was used as an additive in formulations to enhance geopolymers’ adsorption capacities and reduce MK utilization’s environmental footprint. Geopolymers were synthesized with the replacement of MK by zeolite up to 75 wt.% (A25, B25—25% MK 75% zeolite; A50, B50—50% MK 50% zeolite; A75, B75—75% MK 25% zeolite; A100, B100—100% MK). The molar ratios of SiO2/Al2O3 and Na2O/Al2O3 were kept at 1 to reduce the sodium silicate and sodium hydroxide environmental impact. Geopolymers’ crystallography was identified using X-ray diffraction analysis. The surface morphology was observed by scanning electron microscopy to understand the effect of zeolite incorporation. Chemical analysis using X-ray fluorescence spectroscopy and energy dispersive X-ray spectroscopy yielded information about the geopolymers’ Si/Al ratio. Compressive strength values of geopolymers obtained after 1, 14, and 28 days of curing indicate high strengths of geopolymers with 100% MK (A100—15.4 MPa; B100—32.46 MPa). Therefore, zeolite did not aid in the improvement of the compressive strength of both MK-based geopolymers. The heavy metal (Cd2+, Cr3+, Cu2+, Pb2+, and Zn2+) adsorption tests exhibit relatively higher adsorption capacities of Barqueiros MK-based geopolymers for all the heavy metals except Cd2+. Moreover, zeolite positively influenced divalent cations’ adsorption on the geopolymers produced from Barqueiros MK as B75 exhibits the highest adsorption capacities, but such an influence is not observed for Alvarães MK-based geopolymers. The general trend of adsorption of the heavy metals of both MK-based geopolymers is Pb2+ > Cd2+ > Cu2+ > Zn2+ > Cr3+ when fitted by the Langmuir isotherm adsorption model. The MK and zeolite characteristics influence geopolymers’ structure, strength, and adsorption capacities.

Study on the adsorption of bacteria in ceramsite and their synergetic effect on adsorption of heavy metals

2013 ◽  
Vol 69 (2) ◽  
pp. 407-413 ◽  
Author(s):  
Shan Qiu ◽  
Fang Ma ◽  
Xu Huang ◽  
Shanwen Xu
Keyword(s):  
Electron Microscopy ◽  
Heavy Metals ◽  
Heavy Metal ◽  
Scanning Electron Microscopy ◽  
Adsorption Capacity ◽  
Synergetic Effect ◽  
Covalent Bond ◽  
Metal Adsorption ◽  
Heavy Metal Adsorption ◽  
Scanning Electron

In this paper, heavy metal adsorption by ceramsite with or without Bacillus subtilis (B. subtilis) immobilization was studied, and the synergetic effect of ceramsite and bacteria was discussed in detail. To investigate the roles of the micro-pore structure of ceramsite and bacteria in removing heavy metals, the amount of bacteria immobilized on the ceramsite was determined and the effect of pH was evaluated. It was found that the immobilization of B. subtilis on the ceramsite was attributed to the electrostatic attraction and covalent bond. The scanning electron microscopy results revealed that, with the presence of ceramsite, there was the conglutination of B. subtilis cells due to the cell outer membrane dissolving. In addition, the B. subtilis immobilized ceramsite showed a different adsorption capacity for different heavy metals, with the adsorption capacity ranking of La3+ > Cu2+ > Mg2+ > Na+.

Coupled removal of organic compounds and heavy metals by titanate/carbon nanotube composites

2008 ◽  
Vol 58 (10) ◽  
pp. 1985-1992 ◽  
Author(s):  
Ruey-An Doong ◽  
Li-Fen Chiang
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Organic Compounds ◽  
Heavy Metal Adsorption ◽  
Hydrothermal Conditions ◽  
Surface Areas ◽  
Aspect Ratios ◽  
Adsorption Capacities ◽  
Nanotube Composites ◽  
Carbon Nanotube Composites

The objective of this study was to fabricate 1-dimensional (1-D) nanocomposite materials with high aspect ratios and specific surface areas for the coupled degradation of refractory organic compounds and heavy metals. The 1-D nanomaterials were composed of various ratios of carbon nanotubes (CNT) and titanate nanotubes (TNT) (CNT/TNT). Alkaline hydrothermal method was used to fabricate TNT under various hydrothermal conditions. The morphology changed from nanoparticles/nanosheets, nanotubes, nanowires and then to nanoribbon as the hydrothermal temperatures increased from 60 to 230°C. In addition, the CNT/TNT nanomaterials have a good capability toward heavy metal adsorption. The Langmuirian maximum adsorption capacities of nanomaterials were in the range 83–124 mg/g for Cu2 +  and 192–588 mg/g for Pb2 + , which is superior to that of CNT. The removal efficiency of Cu2 +  by CNT/TNT decreased when 40 mg/L MX5B was due to the complexation of MX5B with Cu2 + . Results obtained in this study clearly show the 1-D CNT/TNT nanomaterials are a promising nano-adsorbent for coupled removal of organic as well as heavy metal ions in solution.

scholarly journals Heavy Metal Adsorption and Release on Polystyrene Particles at Various Salinities

2021 ◽  
Vol 8 ◽  
Author(s):  
Beta Susanto Barus ◽  
Kai Chen ◽  
Minggang Cai ◽  
Rongmao Li ◽  
Huorong Chen ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Adsorption Capacity ◽  
Release Rate ◽  
Heavy Metal Concentration ◽  
Aquatic Environments ◽  
Particle Sizes ◽  
Heavy Metal Adsorption ◽  
Heavy Metal Concentrations ◽  
Adsorption Capacities

Microplastics (MPs) and heavy metals are two major types of pollutants that interact with each other, but they are poorly understood. Polystyrene (PS) is one type of MPs that is often detected in aquatic environments. In this study, we examined the adsorption capacity and release rate of heavy metals with respect to different particle sizes of PS, heavy metals, initial heavy metal concentrations, and salinities. Virgin (new) PS with diameters of 20, 50, 130, and 250 μm was used in this study, and four heavy metals (lead, cadmium, copper, and zinc) were used. The results showed that larger PS particle sizes adsorbed more heavy metals even though it took longer to achieve equilibrium adsorption. An increase in heavy metal concentration caused the adsorption capacity (μg g–1) of PS particles to also increase, but the adsorption rate (%) decreased. Increased salinity of the heavy metal solution resulted in a slower adsorption time and a lower adsorption capacity and release rate from the surface of PS particles. Different heavy metals also had different adsorption capacities. Pb was consistently more highly adsorbed by MPs, followed by Cu, Zn, and Cd. Larger PS sizes released heavy metals faster than smaller PS sizes, and the amounts of heavy metals released were higher. The heavy metal with the highest release rate was Cd, followed by Pb, Cu, and Zn. Finally, our findings highlight the interactions between PS and heavy metals and strongly support that PS particles can act as vectors for heavy metals in aquatic systems.

scholarly journals Overview of Leachability of Heavy Metals Using Solidification/Stabilization Method Incorporated with Agricultural Wastes

2015 ◽  
Vol 773-774 ◽  
pp. 1148-1152
Author(s):  
Ali Benlamoudi ◽  
Aeslina Abdul Kadir ◽  
S. Ahmad Tajudin
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Treatment Temperature ◽  
Agricultural Wastes ◽  
Metal Adsorption ◽  
Particle Sizes ◽  
Heavy Metal Adsorption ◽  
Great Capacity ◽  
Pre Treatment ◽  
Almost All

The solidification/stabilization (S/S) is one of the effective methods that are used for the heavy metals treatment. It was known that one of the main issues of this method is that the heavy metal is stayed inside the matrices, not destroyed nor adsorbed, which may cause serious problems for the environment once the matrices would be crashed. Agricultural wastes have shown a great capacity to the heavy metal adsorption from solid and liquid wastes. This paper reviews the incorporation of the agricultural wastes as heavy metals’ adsorbents inside the matrices of the S/S method. In addition, changes in particle sizes, pre-treatment, temperature and other factors have also been discussed towards the heavy metal adsorption. Nevertheless, research regarding the incorporation of the agricultural wastes into the S/S method is very minimal, and almost all the previous researches were only focusing comprehensively on the leaching characteristics of the method.

scholarly journals 3D printed composites from heat extruded polycaprolactone/sodium alginate filaments and their heavy metal adsorption properties

2020 ◽  
Vol 4 (8) ◽  
pp. 2472-2483
Author(s):  
Ioannis L. Liakos ◽  
Alessio Mondini ◽  
Emanuela Del Dottore ◽  
Carlo Filippeschi ◽  
Francesca Pignatelli ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Sodium Alginate ◽  
Copper Sulphate ◽  
Adsorption Properties ◽  
Metal Adsorption ◽  
Heavy Metal Adsorption ◽  
3D Printed

Polycaprolactone/sodium alginate composite filaments and their resulted 3D printed structures were able to adsorb heavy metals from aquatic copper sulphate solutions.

Regeneration of chitosan-based adsorbents used in heavy metal adsorption: A review

2019 ◽  
Vol 224 ◽  
pp. 373-387 ◽  
Author(s):  
Mohammadtaghi Vakili ◽  
Shubo Deng ◽  
Giovanni Cagnetta ◽  
Wei Wang ◽  
Pingping Meng ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Metal Adsorption ◽  
Heavy Metal Adsorption
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