Based on theoretical calculation of electronegativity of groups of flotation reagent and method of infrared adsorption spectroscopy,the collection and adsorption of α-nitroso-β- naphthol in hematite flotation have b...Based on theoretical calculation of electronegativity of groups of flotation reagent and method of infrared adsorption spectroscopy,the collection and adsorption of α-nitroso-β- naphthol in hematite flotation have been studied.The chemical adsorption seems to be predominant owing to formation of pentacyclic nitrosyl chelate compound by atoms of nitrosyl bond in α-nitroso-β-naphthol together with Fe(Ⅲ)on hematite surface.Mean- while,the nonuniform multilayer physical adsorption is also occurred.展开更多
The hydration of tricalcium aluminate （ C3A ） has a significant effect on the effectiveness of cement-based systems. In addition, the carbonation of hydration products of C3A is particularly important in respect of ...The hydration of tricalcium aluminate （ C3A ） has a significant effect on the effectiveness of cement-based systems. In addition, the carbonation of hydration products of C3A is particularly important in respect of durability performance. The present work investigates the hydration and carbonation reactions of C 3A and the changes induced by the presence of the heavy metal ions such as Zn^2＋ , Pb^2＋ , Cu^2＋ and Cr^3＋ by X-ray diffrac- tometry （ XRD ）. During hydration of C3A, gehlenite hydrate, hydrogarnet , calcium monoaluminate （ C4AHx ） and calcium carboaluminate were detected in C3A pastes except the Zn^2＋ doped paste, where hydrogarnet did not form. The examinations revealed that heavy metals coexisted with gehlenite hydrate, calcium monoaluminate （ C4AHx ） and calcium carboaluminate, inhibiting the formation of hydrogarnet. Hydrating C3A was liable to be carbonated on exposure to air and carbon dioxide, especially in the presence of heavy metals, resulting in the formation of carboaluminate and/or calcium carbonate. The presence of heavy metals in-fluenced the polymorphism of calcium carbonate, ndicating that heavy metals could co-precipitate with calcium to form a carbonate solid solution.展开更多
An increase in energy demand leads to further exploration, transportation, and utilization of petroleum, which creates severe soil contamination because of recurrent accidents and oil spills. Remediation of these cont...An increase in energy demand leads to further exploration, transportation, and utilization of petroleum, which creates severe soil contamination because of recurrent accidents and oil spills. Remediation of these contaminated soils is challenging. Among many treatment methods practiced for remediation of petroleum-contaminated soils, surfactant-enhanced soil washing has been widely practiced as a preferred treatment option, as it is a fast and environmentally accepted method. In this paper, we review research undertaken on various anionic, nonionic, cationic, biological, and mixed surfactants for the remediation of petroleum hydrocarbon-contaminated soils. Upcoming surfactants like gemini and switchable surfactants are summarized. We assess the challenges and opportunities of in-situ and ex-situ soil washing, the mechanisms of surfactant-enhanced soil washing, and the criteria to follow for surfactant selection.Furthermore, we briefly discuss the operational and environmental factors affecting soil washing efficiency and soil and surfactant properties affecting surfactant adsorption. We also describe the advantages of coupling soil washing with effluent treatment and surfactant reuse challenges and opportunities. Moreover, challenges and possible new directions for future research on surfactant-enhanced soil washing are proposed.展开更多
文摘Based on theoretical calculation of electronegativity of groups of flotation reagent and method of infrared adsorption spectroscopy,the collection and adsorption of α-nitroso-β- naphthol in hematite flotation have been studied.The chemical adsorption seems to be predominant owing to formation of pentacyclic nitrosyl chelate compound by atoms of nitrosyl bond in α-nitroso-β-naphthol together with Fe(Ⅲ)on hematite surface.Mean- while,the nonuniform multilayer physical adsorption is also occurred.
文摘The hydration of tricalcium aluminate （ C3A ） has a significant effect on the effectiveness of cement-based systems. In addition, the carbonation of hydration products of C3A is particularly important in respect of durability performance. The present work investigates the hydration and carbonation reactions of C 3A and the changes induced by the presence of the heavy metal ions such as Zn^2＋ , Pb^2＋ , Cu^2＋ and Cr^3＋ by X-ray diffrac- tometry （ XRD ）. During hydration of C3A, gehlenite hydrate, hydrogarnet , calcium monoaluminate （ C4AHx ） and calcium carboaluminate were detected in C3A pastes except the Zn^2＋ doped paste, where hydrogarnet did not form. The examinations revealed that heavy metals coexisted with gehlenite hydrate, calcium monoaluminate （ C4AHx ） and calcium carboaluminate, inhibiting the formation of hydrogarnet. Hydrating C3A was liable to be carbonated on exposure to air and carbon dioxide, especially in the presence of heavy metals, resulting in the formation of carboaluminate and/or calcium carbonate. The presence of heavy metals in-fluenced the polymorphism of calcium carbonate, ndicating that heavy metals could co-precipitate with calcium to form a carbonate solid solution.
基金The financial supports from the National Key Research and Development Program of China (Nos. 2016YFC0400501 and 2016YFC0400502)the Fundamental Research Funds for Central Universities of China (No. 2232018D3-43)the National Natural Science Foundation of China (No. 21277023)
文摘An increase in energy demand leads to further exploration, transportation, and utilization of petroleum, which creates severe soil contamination because of recurrent accidents and oil spills. Remediation of these contaminated soils is challenging. Among many treatment methods practiced for remediation of petroleum-contaminated soils, surfactant-enhanced soil washing has been widely practiced as a preferred treatment option, as it is a fast and environmentally accepted method. In this paper, we review research undertaken on various anionic, nonionic, cationic, biological, and mixed surfactants for the remediation of petroleum hydrocarbon-contaminated soils. Upcoming surfactants like gemini and switchable surfactants are summarized. We assess the challenges and opportunities of in-situ and ex-situ soil washing, the mechanisms of surfactant-enhanced soil washing, and the criteria to follow for surfactant selection.Furthermore, we briefly discuss the operational and environmental factors affecting soil washing efficiency and soil and surfactant properties affecting surfactant adsorption. We also describe the advantages of coupling soil washing with effluent treatment and surfactant reuse challenges and opportunities. Moreover, challenges and possible new directions for future research on surfactant-enhanced soil washing are proposed.
