scholarly journals Green Transforming Metallurgical Residue into Alkali-Activated Silicomanganese Slag-Based Cementitious Material as Photocatalyst

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1773 ◽  
Author(s):  
Yao Zhang ◽  
Pan He ◽  
Hao Chen ◽  
Li Liu
Keyword(s):  
Photocatalytic Degradation ◽  
Separation Efficiency ◽  
Low Cost ◽  
Critical Role ◽  
Metallurgical Industry ◽  
Cementitious Material ◽  
Cementitious Composite ◽  
Silicomanganese Slag ◽  
Electron Transfers ◽  
Alkali Activated

Silicomanganese slag is a solid waste in metallurgical industry and can be transformed into an alkali-activated silicomanganese slag-based cementitious-material (ASSC) for the first time. The ASSC shows quite low electro-conductivity and can be raised dramatically by incorporated carbon black (CB) in the matrix of ASSC to create an electro-conductive alkali-activated silicomanganese slag-based cementitious-composite (EASSC), served as a low cost and environmentally-friendly photocatalyst for the removal of dye pollutant in the paper. The interrelationships of mechanical, optical, electroconductive, microstructural, and photocatalytic properties are evaluated. The network of CB plays a critical role in the electron transfers. The electrical conductivity of EASSC doped 4.5% CB drastically increases by 594.2 times compared to that of ASSC. The FESEM, XRD, and XPS results indicated that the EASSC with mean grain size about 50 nm is composed of amorphous calcium silicate hydrate (CSH), alabandite (α-MnS) and CB. The UV–vis DRS and PL exhibit that the absorption edges of electro-conductive alkali-activated silicomanganese slag-based cementitious-composite EASSC samples are gradually blue-shifted and the photoluminescence intensities progressively decrease with increasing CB content. The activities of photocatalytic degradation of basic violet 5BN dye are positive correlated to the electro-conductivities. The separation efficiency of photo-generated electron-hole pairs is enhanced due to the electron transfers from α-MnS to the network of CB. The photocatalytic degradation of dye pollutant belongs to the second order kinetics via a reaction mechanism of superoxide radical (•O2−) intermediate.

scholarly journals Preparation of ternary ZnO/Ag/cellulose and its enhanced photocatalytic degradation property on phenol and benzene in VOCs

2019 ◽  
Vol 17 (1) ◽  
pp. 779-787 ◽  
Author(s):  
Xiao-Hang Zou ◽  
Si-Wei Zhao ◽  
Ji-Guo Zhang ◽  
Hui-Liang Sun ◽  
Qing-Jiang Pan ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Separation Efficiency ◽  
Uv Light ◽  
Low Cost ◽  
Visible Region ◽  
X Ray Diffraction ◽  
Ternary Composite ◽  
Photogenerated Electrons ◽  
Excellent Photocatalytic Activity ◽  
Diffraction Patterns

AbstractThe ZnO/Ag/cellulose composite (ZAC) with excellent photocatalytic activity of degrading benzene and phenol in VOCs has been successfully synthesized. EDS, TEM, XPS and UV-vis analyses show that the ZAC is a ternary composite. It is composed of Ag, ZnO and cellulose, where the cellulose works as the substrate to anchor the other two components. The X-ray diffraction patterns find well-crystallized ZnO nanoparticles. Multiple PL peaks in the visible region measured for ZAC, imply rich defects on ZnO. It is observed that Ag nanoparticles are mainly attached on ZnO in the composite, which would raise the separation efficiency of photogenerated electrons and holes. Photocatalytic degradation shows that ZAC is able to decompose almost 100% phenol and 19% benzene in VOCs under UV light irradiation (6 W) which is almost no harm to human body. Due to the renewable cellulose, our ternary composite ZAC imparts low-cost, easily recycled and flexible merits, which might be applied in the indoor VOCs treatment.

scholarly journals Compressive Strength Characteristics of Cemented Tailings Backfill with Alkali-Activated Slag

2018 ◽  
Vol 8 (9) ◽  
pp. 1537 ◽  
Author(s):  
Gaili Xue ◽  
Erol Yilmaz ◽  
Weidong Song ◽  
Shuai Cao
Keyword(s):  
Compressive Strength ◽  
Mine Tailings ◽  
Low Cost ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Solid Wastes ◽  
Fine Grained ◽  
Activated Slag ◽  
The Relationship ◽  
Alkali Activated

With the use of glauberite mineral (GM) and sodium hydroxide (SH) alkaline catalysts to stimulate slag powder’s internal cementation activity and incorporate the two fine-grained solid wastes, such as quicklime (Q) and desulfurized ash (DA), a new cementitious material suitable for mine tailings was developed to replace traditional ordinary Portland cement (OPC) for reducing cement-related costs. A series of uniaxial compressive strength (UCS) tests were carried out on cemented tailings backfill (CTB) samples containing different activators. The results showed that (1) the highest UCS values of 14-day and 28-day cured CTB samples were 1.259 MPa and 2.429 MPa, respectively, and the effect of different activator types was in the order of SH > GM > DA > Q and SH > GM > Q > DA; (2) the relationship between UCS and activator dosages followed the function y = ax3 − bx2 + cx − d. Compared with the OPC 32.5 R cemented samples, the minimum strength growth factor was 1.45, and the maximum reached 2.03; (3) the optimal proportion of DA slag formula was 4.5% or 5.0% Q, 19% DA, 2.5% GM, and 0.7% SH. The aforesaid new cementitious materials met the mine’s UCS requirements with a relatively low cost (17.04–17.20 €/ton) and solved the stacking problem of solid wastes on the surface well. Ultimately, this study provides a useful reference for the development of mineral binders.

scholarly journals Wastewater Treatment Using Alkali-Activated-Based Sorbents Produced from Blast Furnace Slag

2021 ◽  
Vol 11 (7) ◽  
pp. 2985
Author(s):  
Saverio Latorrata ◽  
Riccardo Balzarotti ◽  
Maria Isabella Adami ◽  
Bianca Marino ◽  
Silvia Mostoni ◽  
...  
Keyword(s):  
Low Cost ◽  
Steel Production ◽  
Metallurgical Industry ◽  
High Alumina ◽  
Ambient Conditions ◽  
Good Opportunity ◽  
Metal Capture ◽  
Mine Effluent ◽  
Alkaline Component ◽  
Alkali Activated

Currently, slags from secondary steel production, foundries, and blast furnaces represent a major environmental problem since they end up mainly in landfills, and their valorization would bring undeniable advantages both to environment and economy. Moreover, the removal of heavy metal ions from mines wastewater is one of the challenges of the last decades, and adsorption has been proposed as one of the most promising techniques for this purpose. In this context, the use of alkali-activated slags as sorbent can be a good opportunity to develop low cost, environmentally friendly, and sustainable materials. Accordingly, wastewater decontamination by adsorption over a porous monolithic bed made of alkali-activated hydraulic binders is proposed. Alkali-activated materials were prepared using slags from the metallurgical industry and reacted with an alkaline component (high alumina calcium aluminate cement, CAC 80) at ambient conditions. The obtained monolithic foams were tested to evaluate the uptake efficiency towards metal capture. Solutions containing Cu(II), Fe(III), Ni(II), Mn(II), and simulating the metal concentrations of a real mine effluent were tested, both in single- and multi-ion solutions. Promising capture efficiency, values of 80–100% and of 98–100% in the case of the single ion and of the multi-ion solutions were obtained, respectively.

Geopolymer, green alkali activated cementitious material: Synthesis, applications and challenges

2019 ◽  
Vol 224 ◽  
pp. 930-949 ◽  
Author(s):  
Yanguang Wu ◽  
Bowen Lu ◽  
Tao Bai ◽  
Hao Wang ◽  
Feipeng Du ◽  
...  
Keyword(s):  
Cementitious Material ◽  
Material Synthesis ◽  
Alkali Activated

scholarly journals Preparation and photocatalytic performance of metallic Nb0.9Ta0.1S2/2D-C3N4 composite

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Hanxiang Chen ◽  
Jianjian Yi ◽  
Zhao Mo ◽  
Yanhua Song ◽  
Wenshu Yang ◽  
...  
Keyword(s):  
Separation Efficiency ◽  
Low Cost ◽  
Metal Sulfide ◽  
Electron Hole ◽  
Practical Applications ◽  
Energy And Environment ◽  
Photocatalytic Application ◽  
Light Utilization ◽  
Ternary Metal ◽  
Key Issues

Abstract Photocatalysis technology has potential application in the field of energy and environment. How to expand visible light utilization and promote the separation efficiency of the carriers are the key issues for the high active photocatalysts preparation and future practical applications. In this work, a ternary metal sulfide Nb0.9Ta0.1S2 was prepared and used as an electron collector in the photocatalytic application. As a result, the generated electrons are quickly transferred to the surface of the composite to participate in the reaction. It was demonstrated that the photocatalytic activity of 2D-C3N4 was enhanced after the modification of Nb0.9Ta0.1S2. The Nb0.9Ta0.1S2/2D-C3N4 composite material was synthesized by solvothermal method. The composition of 5% Nb0.9Ta0.1S2/2D-C3N4 showed the highest H2 evolution rate of 1961.6 μmolg−1h−1, which was 6.6 times that of 2D-C3N4. The 15% Nb0.9Ta0.1S2/2D-C3N4 exhibited the best activity in Rhodamine B degradation rate of 97% in 2 h, which is 50% higher than that of 2D-C3N4. Nb0.9Ta0.1S2/2D-C3N4 can be used as electron trap to promote the effective separation of electron–hole pairs. This work provides benchmarks in exploring low-cost and efficient cocatalyst.

scholarly journals Hydrogen production from water electrolysis: role of catalysts

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Shan Wang ◽  
Aolin Lu ◽  
Chuan-Jian Zhong
Keyword(s):  
Hydrogen Production ◽  
Water Splitting ◽  
Noble Metal ◽  
Active Sites ◽  
Current Knowledge ◽  
Low Cost ◽  
Critical Role ◽  
Water Electrolysis ◽  
Efficient Production ◽  
Production Of Hydrogen

AbstractAs a promising substitute for fossil fuels, hydrogen has emerged as a clean and renewable energy. A key challenge is the efficient production of hydrogen to meet the commercial-scale demand of hydrogen. Water splitting electrolysis is a promising pathway to achieve the efficient hydrogen production in terms of energy conversion and storage in which catalysis or electrocatalysis plays a critical role. The development of active, stable, and low-cost catalysts or electrocatalysts is an essential prerequisite for achieving the desired electrocatalytic hydrogen production from water splitting for practical use, which constitutes the central focus of this review. It will start with an introduction of the water splitting performance evaluation of various electrocatalysts in terms of activity, stability, and efficiency. This will be followed by outlining current knowledge on the two half-cell reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in terms of reaction mechanisms in alkaline and acidic media. Recent advances in the design and preparation of nanostructured noble-metal and non-noble metal-based electrocatalysts will be discussed. New strategies and insights in exploring the synergistic structure, morphology, composition, and active sites of the nanostructured electrocatalysts for increasing the electrocatalytic activity and stability in HER and OER will be highlighted. Finally, future challenges and perspectives in the design of active and robust electrocatalysts for HER and OER towards efficient production of hydrogen from water splitting electrolysis will also be outlined.

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