Article
Construction & Building Technology
Ahmad Nawaz, Naru Kim, Joonho Seo, S. Z. Farooq, H. K. Lee
Summary: This study investigated the hydration and phase conversion of MgO-modified calcium aluminate cement (CAC). By replacing CAC with different dosages of MgO (0, 5, 10, 15, and 20 wt%), the samples were subjected to accelerated curing at 60 degrees C after initial curing at 20 degrees C. Microstructural analysis revealed that MgO suppressed phase conversion during initial curing, hindering the formation of stable phases. However, after 28 days of accelerated curing, a phase conversion occurred, leading to a reduction in strength. Nonetheless, the addition of MgO promoted the development of hydrotalcite and maintained the structural integrity and strength after exposure.
CONSTRUCTION AND BUILDING MATERIALS
(2023)
Article
Engineering, Environmental
Azra Nawar, Majid Ali, Asif Hussain Khoja, Adeel Waqas, Mustafa Anwar, Mariam Mahmood
Summary: In this study, waste eggshells were used to synthesise structure modified CaO with organic acids for efficient CO2 capture. Among the modified sorbents, citric acid modification showed the highest CO2 uptake, making it a promising candidate for economical CO2 capture.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2021)
Article
Materials Science, Ceramics
I. C. Finhana, P. F. dos Santos, O. H. Borges, D. N. F. Muche, V. C. Pandolfelli
Summary: Calcium aluminate cement is commonly used as a binder for ceramic materials, providing suitable setting times and strength. By milling the cement in water, a stable suspension can be formed, resulting in improved performance in low-temperature thermal insulation applications.
CERAMICS INTERNATIONAL
(2023)
Article
Engineering, Chemical
Tong Luo, Shaolong Liu, Cong Luo, Xiaolei Qi, Bowen Lu, Liqi Zhang
Summary: Through the study of different types of CaO-based sorbents and organically modified sorbents, it was found that the modified sorbents synthesized by wet mixing combustion exhibit better performance and higher pore parameters. Citric acid is more effective than gluconic acid, and there is a good linear relationship between CaO conversion and specific surface area and pore volume.
CHINESE JOURNAL OF CHEMICAL ENGINEERING
(2021)
Article
Construction & Building Technology
Liang Bai, Hui Zheng, Xin Wang, Xingwen Liang, Shuai Hu
Summary: This study investigated the early water stability of Magnesium Potassium Phosphate Cement (MKPC) blended with Calcium Aluminate Cement (CAC) and Wollastonite (WS). The presence of CAC extended the setting time of MKPC macroscopically due to the stimulating effect of the admixture on the composite retarder. The synergistic effect between CAC and WS enhanced the early water stability and compressive strength of MKPC under water curing. Microscopically, CAC participated in the reaction of the MKPC system, producing crystalline and amorphous products, while WS inhibited crack development and strengthened the brittle matrix.
CONSTRUCTION AND BUILDING MATERIALS
(2023)
Article
Engineering, Environmental
Chongcong Li, Xingli Gong, Hao Zhang, Yan Zhang, Mingjun Yang, Bingbing Chen
Summary: This study sought to use organic acid-rich torrefaction condensate (TC) as a replacement for commercial acetic acid (AC) in the acidification treatment of CaO sorbent to enhance its CO2 capture performance. The modified sorbents with TC exhibited better cyclic stability compared to the AC-modified ones. The presence of carbon deposition from TC, which acted as a spacer and protective overlay to slow down the sintering of CaO particles, was believed to be the reason for the improved cyclic stability.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Environmental Sciences
Agnieszka Solinska, Tomasz Bajda
Summary: This study aimed to evaluate the sorption efficiency of unwashed cationic surfactant-modified natural zeolite for removing selected inorganic compounds from wet flue gas desulphurization wastewater. The modified zeolite showed enhanced removal efficiency for NH4+ and NO3-, while the removal efficiency for SO42- remained consistent regardless of sorbent dosage. Kinetic tests indicated that a significant portion of the inorganic compounds were removed within 2 hours, with sorption kinetics best fitting the pseudo-second order model. Adsorption mechanisms included cation exchange, anion exchange, electrostatic interactions, and precipitation of insoluble salts.
Article
Engineering, Chemical
Zhixin Li, Qinhui Wang, Mengxiang Fang, Jianmeng Cen, Zhongyang Luo
Summary: In this study, modified CaO-based adsorbents doped with high aluminum cement were prepared by hydration method and their performance in different reactors was investigated. The results showed that the adsorbent doped with 5 wt.% high aluminum cement had the best CO2 capture capability in all reactors, especially in the bubbling fluidized bed reactor. The activation energy of the modified adsorbent in different reaction stages was also determined, showing potential for efficient carbon capture technologies.
JOURNAL OF THE TAIWAN INSTITUTE OF CHEMICAL ENGINEERS
(2021)
Article
Construction & Building Technology
Peiliang Shen, Jianxin Lu, Yangyang Zhang, Yi Jiang, Shipeng Zhang, Chi Sun Poon
Summary: This study developed an innovative wet carbonation process to prepare aragonite whisker-rich materials and used them as micro-fiber additions to cement. The results showed that needle-like aragonite whiskers could be rapidly synthesized under specific conditions, and a new type of micro-fiber reinforced cement was developed by mixing them with cement.
CEMENT AND CONCRETE RESEARCH
(2022)
Article
Chemistry, Physical
Zhongping Wang, Yuting Chen, Zheyu Zhu, Xiang Peng, Kai Wu, Linglin Xu
Summary: Mineral additions can affect the corrosion resistance of steel reinforcement in calcium aluminate cement concrete. Slag-modified specimens showed a decrease in corrosion resistance at 14 days, while specimens modified with limestone powder and calcium nitrate maintained good chloride-binding ability and slow decreasing trend within 90 days.
Article
Materials Science, Multidisciplinary
Qinli Zhang, Bingyi Zhang, Yan Feng, Chongchong Qi, Qiusong Chen, Chongchun Xiao
Summary: This study introduces an approach to enhance the reactivity of granulated copper slag (GCS) by modifying its mineral structure using calcium oxide (CaO) and aluminum oxide (Al2O3) in a molten state. The addition of CaO and Al2O3 in GCS improves its pozzolanic activity, leading to increased hydration heat emission rate and compressive strength of blended cement paste. XRD and SEM-EDS analysis indicates that the modified GCS consumes more calcium hydroxide (CH) and generates more calcium silicate hydrate (C-S-H) gels, forming a more compact structure with fewer pores. The leaching of heavy metals from the modified GCS is lower than the environmental standards. Therefore, the modified GCS can be used as a sustainable material to promote cleaner production for cement and concrete industries.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Construction & Building Technology
Yuelin Li, Wim Thielemans, Qiang Yuan, Jiabin Li
Summary: This study investigates the use of calcined cutter soil mixing residue (CSMR) as a partial cement replacement in polyvinyl alcohol fiber reinforced cement composites (PVA-FRCCs). Results show that calcined CSMR can enhance hydrate formation and improve the fiber-matrix interface. Tensile strength is not compromised with up to 40% cement replacement, while tensile strain capacity significantly increases.
CONSTRUCTION AND BUILDING MATERIALS
(2022)
Article
Construction & Building Technology
Keita Irisawa, Masahiro Namiki, Takumi Taniguchi, Ines Garcia-Lodeiro, Hajime Kinoshita
Summary: This study investigated the solidification and stabilization of Sr2+ and Cl- ions in calcium aluminate cement modified with sodium polyphosphate (CAP) with or without thermal treatment. Results showed that CAP had superior Sr2+ ion stabilization and improved Cl- ion stabilization after thermal treatment, indicating its potential for the cementation of aqueous radioactive waste contaminated with Sr-90.
CEMENT AND CONCRETE RESEARCH
(2022)
Article
Construction & Building Technology
Zhang Jian, Wan Xiangchen, Chen Xiaorong
Summary: The in-situ conversion of shale oil has immense resource potential and serves as a strategic alternative for China's oil and gas industry. However, the high temperatures involved in this process can negatively affect the mechanical strength of cement. This study investigates the influence of modified sodium hexametaphosphate on the hydration behavior of aluminate cement and explores its macro performance and microstructure. The results show that sodium hexametaphosphate can reduce the permeability of aluminate mudstone and that the use of micro-silica composite sodium hexametaphosphate can further decrease permeability and increase compressive strength.
CONSTRUCTION AND BUILDING MATERIALS
(2023)
Article
Environmental Sciences
Jinshan Wei, Bo Shen, Gan Ye, Xianghua Wen, Yonghui Song, Jin Wang, Xiaoguang Meng
Summary: Developed acrylic amine fiber (AAF) for adsorption removal of Selenium (Se) and arsenic (As) from water. Maximum adsorption capacities at neutral pH were found, along with effects of different organic acids and inorganic anions on the adsorption mechanism. Column filtration and regeneration results showed potential for reusing spent AAF with little decrease in adsorption capacity.
ENVIRONMENTAL POLLUTION
(2021)
Article
Energy & Fuels
Juncheng Ouyang, Dikun Hong, Liangkui Jiang, Zehua Li, Huan Liu, Guangqian Luo, Hong Yao
Article
Energy & Fuels
Yang Xu, Guangqian Luo, Mengli Zhou, Qingzhu Zhang, Zehua Li, Shibo Zhang
Summary: This study investigated the use of NFM as a cost-effective sorbent for Hg-0 removal from flue gas, showing that untreated NFM had high efficiency over a broad temperature range, while calcination process might have negative effects on its performance. The research also revealed the Hg-0 removal mechanism and demonstrated the dominance of chemisorption in the process.
Article
Engineering, Environmental
Yang Xu, Guangqian Luo, Qingzhu Zhang, Wei Cui, Zehua Li, Shibo Zhang
Summary: Novel waste-derived sorbents synthesized through one-step co-pyrolysis of wood and PVC have shown good stability in Hg and halogens removal, with Fe doping further enhancing the stability. Kinetic analysis revealed different rate-limiting steps before and after Fe doping, and water-washing pretreatment can remove loosely-bonded halogens while retaining essential halogens for Hg removal.
JOURNAL OF HAZARDOUS MATERIALS
(2021)
Article
Engineering, Environmental
Xiaoyu Li, Juan Chen, Yi Xiao, Shouyan Chen, Chunmei Lu, Guangqian Luo, Hong Yao
Summary: Combining quantum chemistry, kinetic simulations, and DTF experiments, the research revealed the transformation behavior of chromium under oxy-coal combustion in the presence of steam and HCl. It was found that HCl promoted the oxidation of chromium to hexavalent CrO2Cl2, while the coexistence of HCl and steam divided the transition of chromium into two stages, ultimately leading to the formation of CrO2Cl2 as the predominant species. The introduction of HCl into the combustion atmosphere induced more chromium release, and the presence of steam reinforced the effect of HCl on chromium transformation.
JOURNAL OF HAZARDOUS MATERIALS
(2021)
Article
Energy & Fuels
Yang Xu, Guangqian Luo, Qingzhu Zhang, Zehua Li, Shibo Zhang, Wei Cui
Summary: Sulfurized chars derived from wood and scrap tire pyrolysis were developed as cost-effective sorbents for capturing elemental mercury (Hg-0) from flue gas. The synergistic effect between wood and tire during co-pyrolysis enhanced the Hg-0 capture capability of the sulfurized chars. Chemisorption dominated the Hg-0 removal process, with organic sulfur/elemental sulfur serving as active components for Hg-0 oxidization into HgS.
Article
Chemistry, Multidisciplinary
Zehua Li, Renjie Zou, Yang Xu, Liang Cao, Guangqian Luo, Hong Yao
Summary: The study utilized a self-designed micro fluidized bed reactor and an online char particle sampling system to investigate the kinetics of coal char combustion and gasification. It was found that the reactivity of sampled char in oxy-fuel combustion followed a specific trend with sampling time, while the gasification reactivity increased gradually with sampling time.
Article
Energy & Fuels
Zehua Li, Renjie Zou, Yang Xu, Guangqian Luo, Hong Yao
Summary: This study reported a novel microfluidized bed reactor combined with a solid char particle online sampling system to investigate the effect of CO2/H2O on semi-char properties and reactivity. The results showed that the activation energy of the semi-char increases during oxy-steam combustion, and the reactivity of the semi-char is higher than that of the original coal char in the early combustion stage, with H2O having a greater influence on semi-char reactivity compared to CO2.
Article
Engineering, Environmental
Mengli Zhou, Yang Xu, Guangqian Luo, Qingzhu Zhang, Lin Du, Xiaowei Cui, Zehua Li
Summary: Phosphorus-doped biochars (PBCs) derived from one-step pyrolysis of H3PO4-laden biomass showed improved mercury removal efficiency and surface area. The chemisorption mechanism involving electron transfer was responsible for the enhanced Hg-0 oxidation.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Thermodynamics
Zehua Li, Renjie Zou, Yang Xu, Yuan Fang, Guangqian Luo, Hong Yao
Summary: In this study, coal chars with different cooling rates were prepared and characterized, showing that carbon structure tends to be graphitized during cooling and in-situ char has the lowest carbon graphitization. The reactivity of chars decreases with cooling rate, with in-situ char having the highest carbon defects and most active surface area.
COMBUSTION AND FLAME
(2022)
Article
Materials Science, Multidisciplinary
Ruihuan Cheng, Xingchen Shen, Stefan Klotz, Zezhu Zeng, Zehua Li, Alexandre Ivanov, Yu Xiao, Li-Dong Zhao, Frank Weber, Yue Chen
Summary: In this study, the high-pressure lattice dynamics of PbTe were investigated using molecular dynamics simulations. The results show that the transverse-optical mode and the frequency of the transverse-acoustic phonon exhibit non-monotonic pressure dependence under high pressure. The theoretical predictions were compared with experimental data, and the phonon transport mechanisms were revealed by calculating the pressure-dependent lattice thermal conductivity.
Article
Materials Science, Multidisciplinary
Zehua Li, Shasha Li, John-Paul Castellan, Rolf Heid, Yu Xiao, Li-Dong Zhao, Yue Chen, Frank Weber
Summary: This study investigates the soft transverse optic phonon mode in SnTe compared to PbTe using inelastic neutron scattering and ab initio lattice dynamical calculations. The calculations predict that the soft mode in SnTe has a strongly asymmetric spectral weight distribution similar to PbTe, contrary to previous reports. Experimentally, the overall width of the phonon peaks in the neutron scattering spectra is found to be comparable in SnTe and PbTe.