scholarly journals Immobilization of Heavy Metals in Boroaluminosilicate Geopolymers

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 214
Author(s):  
Piotr Rożek ◽  
Paulina Florek ◽  
Magdalena Król ◽  
Włodzimierz Mozgawa
Keyword(s):  
Mechanical Properties ◽  
Heavy Metals ◽  
Heavy Metal ◽  
Compressive Strength ◽  
Phase Composition ◽  
Molar Ratio ◽  
Metal Leaching ◽  
Heavy Metal Leaching ◽  
Composition Structure ◽  
Structure And Microstructure

Boroaluminosilicate geopolymers were used for the immobilization of heavy metals. Then, their mechanical properties, phase composition, structure, and microstructure were investigated. The addition of borax and boric acid did not induce the formation of any crystalline phases. Boron was incorporated into the geopolymeric network and caused the formation of N–B–A–S–H (hydrated sodium boroaluminosilicate) gel. In the range of a B/Al molar ratio of 0.015–0.075, the compressive strength slightly increased (from 16.1 to 18.7 MPa), while at a ratio of 0.150, the compressive strength decreased (to 12 MPa). Heavy metals (lead and nickel) were added as nitrate salts. The loss of the strength of the geopolymers induced by heavy metals was limited by the presence of boron. However, it caused an increase in heavy metal leaching. Despite this, heavy metals were almost entirely immobilized (with immobilization rates of >99.8% in the case of lead and >99.99% in the case of nickel). The lower immobilization rate of lead was due to the formation of macroscopic crystalline inclusions of PbO·xH2O, which was vulnerable to leaching.

Heavy Metals Leaching of Active Carbon from Sewage Sludge Modified by Chitosan for Dye Wastewater Treatment

2012 ◽  
Vol 627 ◽  
pp. 399-403
Author(s):  
Xiao Dan Fan ◽  
Xiang Kai Zhang
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Wastewater Treatment ◽  
Activated Carbon ◽  
Sewage Sludge ◽  
Contact Time ◽  
Metal Leaching ◽  
Dye Wastewater ◽  
Concentration Increase ◽  
Heavy Metal Leaching

Heavy metal leaching limits activated carbon from sewage sludge (referred as ACS) to be used for wastewater treatment. Cr and Cd leaching from ACS exceed the permitted values. The leaching content of Cr and Cd decrease much with depositing ACS with chitosan (CS),below the permitted values. This is mainly due to the bind of Cr and Cd with the much group –NH2 of CS. The effects of initial dye concentration, pH and contact time had been studied. The dye adsorbed can act as a supple complexion agent with increasing initial dye concentration, increase the affinity for Cr and Cd. For Cd, the amount leaching of CS/ACS or ACS remains content with pH.The amount leaching of Cr decreases when the pH from 1 to 5 and then increases above the pH of 6.0. The contact time has no important influence on the leaching contents of Cr or Cd.

Compressive strength and heavy metal leaching behaviour of mortars containing spent catalyst

2001 ◽  
Vol 19 (5) ◽  
pp. 456-464 ◽  
Author(s):  
Ubolluk Rattanasak ◽  
Chai Jaturapitakkul ◽  
Tippaban Sudaprasert
Keyword(s):  
Heavy Metal ◽  
Compressive Strength ◽  
Metal Leaching ◽  
Spent Catalyst ◽  
Heavy Metal Leaching ◽  
Leaching Behaviour

Experimental Study on New Technology for Solidifying/Stabilizing Papermaking Sludge

2010 ◽  
Vol 156-157 ◽  
pp. 84-89
Author(s):  
Xu Nan Ning ◽  
Shi Wen Li ◽  
Jing Yong Liu ◽  
Zuo Yi Yang ◽  
Zhu Ying
Keyword(s):  
Mechanical Properties ◽  
Heavy Metals ◽  
Heavy Metal ◽  
Compressive Strength ◽  
New Technology ◽  
Oxygen Demand ◽  
Heavy Metal Concentration ◽  
National Standards ◽  
Curing Time ◽  
Water Ratio

For better harmlessly treatment of papermaking sludge, a new technology for solidifying and stabling of sludge was studied. Papermaking sludge was solidified and stabilized by the solidifying agents including cement, powder fly ash (PFA) and cinder. The mechanical properties of solidified sludge block were evaluated by compressive strength, chemical oxygen demand (COD) and heavy metals concentration in the leachate from the solidified block were tested as well. When the solidifying agents has the following composition (cement 0.12kg/kg, PFA 0.02kg/kg and cinder 0.10kg/kg respectively), and the curing time was 6ds, the compressive strength of the solidified sludge blocks reached 360kPa. The results showed that cement and cinder were all positive in the compressed strength of sludge block. If they were mixed with PFA together, they could enhanced the solidification of organic and heavy metals in the sludge. Under this conditions, the COD in leachate from the solidified block was 115.7 mg/L, and the heavy metal concentration had reached the related national standards, after 6ds of curing time, water ratio of the solidified block kept from 35% to 40%, which met the prescribed standards of landfill.

scholarly journals The Evaluation of the Heavy Metal Leaching Behavior of MSWI-FA Added Alkali-Activated Materials Bricks by Using Different Leaching Test Methods

2019 ◽  
Vol 16 (7) ◽  
pp. 1151 ◽  
Author(s):  
Peng Xu ◽  
Qingliang Zhao ◽  
Wei Qiu ◽  
Yan Xue
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Fly Ash ◽  
Metal Leaching ◽  
Alkali Activation ◽  
Leaching Tests ◽  
Leaching Behavior ◽  
Heavy Metal Leaching ◽  
Environmental Compatibility ◽  
Alkali Activated

Alkali-activated materials (AAMs) not only have the potential to replace cement applications in architecture and civil engineering, but also have an excellent effect on the stabilization solidification of hazardous industrial wastes. This study used two types of municipal solid waste incineration fly ash (MSWI-FA)—grate firing fly ash (GFFA) and fluidized bed fly ash (FBFA)—as AAMs brick raw materials. It is discovered from this study that AAMs bricks with different weight ratios of GFFA and FBFA can both meet the required standard of GB21144-2007 (Solid concrete brick). From the results obtained from the four leaching tests, the equilibrium pH of the leachate varies, resulting in significant differences in the leaching of heavy metals in Raw GFFA, Raw FBFA, and AAMs bricks with GFFA and FBFA. The AAMs brick with the addition of GFFA and FBFA has an alkali activation system to encapsulate heavy metals. By comparing the results obtained from the CEN/TS 14429 leaching behavior test and the four batch leaching tests, it was found that the most influential factors for the heavy metal leaching concentration are whether the heavy metal has been solidified/stabilized in the samples. GFFA and FBFA tend to have consistent characteristics after being activated by alkali to form AAMs bricks. This can be confirmed by the acid neutralization ability concentrated on a specific pH range. The results obtained from CEN/TS14429 verified that the AAMs bricks with the addition of GFFA and FBFA have excellent environmental compatibility and that it provides a comprehensive evaluation on the environmental compatibility of the test materials and products. This demonstrated that the MSWI-FA is suitable for used as alkali-activated materials and its products have the potential to be commercially used in the future.

Heavy Metal Leaching Behavior of Glasses Containing EAF Dust

2005 ◽  
Vol 486-487 ◽  
pp. 382-386 ◽  
Author(s):  
Hee Tai Eun ◽  
Seung Gu Kang ◽  
Yoo Taek Kim ◽  
Gi Kang Lee ◽  
Jung Hwan Kim
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Silicate Glass ◽  
Structural Changes ◽  
Chemical Durability ◽  
Metal Leaching ◽  
Lead Silicate ◽  
Heavy Metal Leaching ◽  
Eaf Dust ◽  
Ft Ir

Stabilizing characteristics of heavy metals in the silicate glass (SD) and lead silicate glass(PD) containing Electric Arc Furnace(EAF) dust was studied by the toxic characterization leaching procedure(TCLP) test. Dependence of the amount of EAF dust upon structural changes of SD and PD glasses and TCLP results was also investigated by FT-IR spectroscopy. In the TCLP test, the concentration of heavy metals leached from a glass increased with the amount of EAF dust added. The SD series specimens showed heavy metal leaching lower than the PD series specimens, but the Pb leaching from the PD series specimens was the highest owing to the high Pb content in the PD glass composition. The value R(oxygen/network former ion ratio) was used to compare the leaching characteristics of glasses, and the SD had a higer R than PD series specimens to show a better chemical durability. Adding the EAF dust to the SD mother glass decreased the Si-O-Si symmetry and increased the non-bridging oxygen, which weakened the structure and decreased the chemical durability of glasses. It is concluded that SD is more effective in stabilizing the heavy metals of EAF dust than PD series glass.

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.

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