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Adsorption of phenthoate and acetochlor from water by clays and organoclays

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Journal of Environmental Sciences 2004年第5期16卷 738-741页

作者： LIAOMin XIEXiao-mei CollegeofEnvironmentalandResourceSciences DepartmentofResourcesScienceZhejiangUniversityHangzhou310029China

Adsorption of phenthoate and acetochlor onto kaolin, montmorillonite, bentonite clays and respective organoclays prepared by the exchange of quaternary ammonium as tetradecyltrimethyl ammonium bromide(TTAB), dodecyltrimethylammonium bromide(DTAB), and cetylpyridinium chloride(CPC) were studied. The adsorption equilibrium data points were fitted to Freundlich isotherm equations. The adsorption of phenthoate and acetochlor were significantly enhanced by surfactant treatment of the clays. The amount of both pesticides adsorbed per unit mass of organoclay followed the order of TTA-kaolin clays. The removal efficiency of organomontmorillonite to treat acetochlor is in the order of CP(C 16 )-montmorillonite > TTA(C 14 )-montmorillonite > DTA(C 12 )-montmorillonite. Phenthoate is adsorbed to greater extent than acetochlor by each adsorbent, which may be due to the higher hydrophobicity of phenthoate, indicating considerable hydrophobic interaction between adsorbent/adsorbate systems.

关键词： adsorption clays organoclays phenthoate acetochlor

Constitutive model for overconsolidated clays

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Science China(Technological Sciences) 2008年第2期51卷 179-191页

作者： YAO YangPing HOU Wei ZHOU AnNan Department of Civil Engineering Beihang UniversityBeijing 100083China

Based on the relationships between the Hvorslev envelope,the current yield sur-face and the reference yield surface,a new constitutive model for overconsolidated clays is proposed. It adopts the unified hardening parameter,to which the potential failure stress ratio and the characteristic state stress ratio are introduced. The model can describe many characteristics of overconsolidated clays,including stress-strain relationships,strain hardening and softening,stress dilatancy,and stress path dependency. Compared with the Cam-clay model,the model only re-quires one additional soil parameter which is the slope of the Hvorslev envelope. Comparisons with data from triaxial drained compression tests for Fujinomori clay show that the proposed model can rationally describe overconsolidated properties. In addition,the model is also used to predict the stress-strain relationship in the isotropic consolidation condition and the stress paths in the undrained triaxial compression tests.

关键词： overconsolidated clays current yield surface reference yield surface unified hardening parameter Hvorslev envelope.

Trace elemental signatures and mineral chemistry of clays associated with the alteration halos of the Paleoproterozoic U mineralization in Bijawars of the Sonrai Basin,Central India

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Acta Geochimica 2020年第3期39卷 365-386页

作者： Surendra Kumar Jha Rashmi Sharma Jaya Prakash Shrivastava University of Delhi DelhiIndia Department of Cement Technology A.K.S.UniversitySatnaMPIndia

Paleoproterozoic Bijawars of the Sonrai basin consists of(a) Sonrai(mostly carbonate carbonaceous shale and phosphatic breccia) and(b) Solda Formations(commonly chloritic and ferruginous shale) with well-developed clay-organo-rich facies,often marked with hydrothermal *** studies revealed abundance order of kaolinite> chlorite> illite> smectite;and kaolinite> illite> chlorite in clay(0.2-2.0 μm) fractions separated from the Sonrai and Solda Formations,*** understand atomic substitutions and trace elemental concentrations,clay minerals were analyzed by fusion ICPMS and *** normalized data plots show U,Th,Rb,Ba,Pb Sr,and large-ion lithophiles enrichment,whereas,Bandai sandstone and Rohini carbonate clays show HREE enrichment with asymmetrical patterns,similar to those reported from the well-established McArthur River,Cigar Lake,and Sue UTUD of *** Rohni carbonate,chondrite-normalized REE data plots revealed M shape REE patterns,ascribed to Gd-Tb-Dy-Ho tetrad effect and anomalous Y,Zr,and Hf *** to HREE incorporation in the clay inter-layers,linear and flattened REE trends were *** REE patterns associated with the highly altered chlorite and illite represent negative Eu anomaly related to the dilational nature of the uraninite structure and is suggestive of anoxic conditions.

关键词： Bijawars Sonrai basin clays REE patterns Uranium mineralization

Optimized functional linked neural network for predicting diaphragm wall deflection induced by braced excavations in clays

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Geoscience Frontiers 2022年第2期13卷 34-51页

作者： Chengyu Xie Hoang Nguyen Yosoon Choi Danial Jahed Armaghani School of Environment and Resources Xiang tan UniversityXiangtan 411105China Department of Surface Mining Mining FacultyHanoi University of Mining and GeologyDuc ThangBac Tu LiemHanoiViet Nam Innovations for Sustainable and Responsible Mining(ISRM)Group Hanoi University of Mining and GeologyDuc ThangBac Tu LiemHanoiViet Nam Department of Energy Resources Engineering Pukyong National UniversityBusan 48513Republic of Korea Department of Urban Planning Engineering Networks and SystemsInstitute of Architecture and ConstructionSouth Ural State University76Lenin ProspectChelyabinsk 454080Russia

Deep excavation during the construction of underground systems can cause movement on the ground,especially in soft clay *** high levels,excessive ground movements can lead to severe damage to adjacent *** this study,finite element analyses(FEM)and the hardening small strain(HSS)model were performed to investigate the deflection of the diaphragm wall in the soft clay layer induced by braced *** geometric and mechanical properties of the wall were investigated to study the deflection behavior of the wall in soft ***,1090 hypothetical cases were surveyed and simulated based on the HSS model and FEM to evaluate the wall deflection *** results were then used to develop an intelligent model for predicting wall deflection using the functional linked neural network(FLNN)with different functional expansions and activation *** the FLNN is a novel approach to predict wall deflection;however,in order to improve the accuracy of the FLNN model in predicting wall deflection,three swarm-based optimization algorithms,such as artificial bee colony(ABC),Harris’s hawk’s optimization(HHO),and hunger games search(HGS),were hybridized to the FLNN model to generate three novel intelligent models,namely ABC-FLNN,HHO-FLNN,*** results of the hybrid models were then compared with the basic FLNN and MLP *** revealed that FLNN is a good solution for predicting wall deflection,and the application of different functional expansions and activation functions has a significant effect on the outcome predictions of the wall *** is remarkably interesting that the performance of the FLNN model was better than the MLP model with a mean absolute error(MAE)of 19.971,root-mean-squared error(RMSE)of 24.574,and determination coefficient(R^(2))of ***,the performance of the MLP model only obtained an MAE of 20.321,RMSE of 27.091,and R^(2)of ***,the results also indicated that the proposed

关键词： Diaphragm wall deflection Braced excavation Finite element analysis clays Meta-heuristic algorithms Functional linked neural network

Combined Bearing Capacity of Spudcans on a Double Layer Deposit of Strong-Over-Weak clays

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Journal of Ocean University of China 2019年第1期18卷 133-143页

作者： YIN Qilin DONG Sheng College of Engineering Ocean University of China

An extreme sea storm process can lead to a jack-up rig under the combined loading condition of vertical load(V), horizontal load(H), and moment(M) to have stability problems. This paper presents the analysis of combined bearing capacities of a circular spudcan on layered clays with a strong layer overlying a comparatively weaker layer. Numerical models combined with displacement-based load tests, swipe tests, and constant ratio displacement probe tests are adopted to calculate the uniaxial bearing capacities, failure envelopes in combined V-H, V-M planes, and failure envelopes in a combined V-H-M load space, respectively. A parametric study on the effects of vertical load level V, the layer strength ratio s_(u,t)/s_(u,b), and the hard layer thickness t_1 on the bearing capacities is then performed. Results show that the vertical load level is a key factor that influences the values of H and M and the size of the H-M failure envelope. The existence of the underlying weak clay decreases the bearing capacities in all directions, and the vertical capacity Vult is affected more than the horizontal(H_(ult)) and moment(M_(ult)) capacities based on a single uniform deposit. The influence of the underlying weak clay on H-M failure envelope is mainly shown where H and M are coupled in the same direction. In contrast, little difference is observed when H and M are coupled in opposite directions.

关键词： combined bearing capacity circular spudcan layered clays vertical load level strength ratio hard layer thickness

An improved damaging model for structured clays

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Journal of Central South University 2008年第S2期15卷 76-80页

作者：姜岩雷华阳郑刚徐舜华 Department of Civil Engineering Tianjin University

An improved damaging model formulated within the framework of bounding surface for structured clays was proposed. The model was intended to describe the effects of structure degradation due to geotechnical loading. The predictive capability of the model was compared with those of triaxial compression test on Tianjin soft clays. The results show that, by incorporating a new damage function into the model, the reduction of elastic bulk and shear modulus with elastic deformations and the reduction of plastic bulk modulus and shear modulus with plastic deformations are able to be appreciable. Before the axial strain reaches 15%, the axial strain computed from the model is smaller than that from the test under the drained condition. Under the undrained condition, after the axial strain reaches 1%, the axial strain increases quickly because of the complete loss of structure and stiffness; and the result computed from the model is nearly equal to that from the model without the incorporation of the damage function due to less plastic strain under undrained condition test.

关键词： structured clays constitutive relation soil structure bounding surface damage function

THE STEPWISE EXCHANGE ACTION AND STERIC HINDRANCE EFFECT OF ORGANIC PHENOLS ON clays IN SEAWATER

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Chinese Journal of Oceanology and Limnology 1994年第1期12卷 61-70页

作者：杨桂朋张正斌 1. Ocean University of Qingdao 266003 Qingdao

The exchange action of six types of organic phenols on clay surfaces in seawater is systematically studied in this work. The following significant conclusions are drawn from the experiments. (1) The interaction of organic phenols with montmorillonite, illite and kaolinite in seawater is monovalent anion exchage.(2) Their isotherms of stepwise exchage on clay surfaces belong to the Langmuir type or stepwise type.(3) The discovery of the"steric hindrance effects of stepwise exchange of organic phenols on clays surfaces", and revelation of an exchange mechanisrn diffeient from that in references are the greatest achieverments in this work.

关键词： organic phenols clays exchange isothenns stepwise exchange steric hindrance effect

A modified creep index and its application to viscoplastic modelling of soft clays

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2014年第4期15卷 272-281页

作者： Qi-yin ZHU Ze-xiang WU Yan-ling LI Chang-jie XU Jian-hua WANG Xiao-he XIA Department of Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China School of Civil Engineering and Architecture East China Jiaotong University Nanchang 330013 China Research Center of Coastal and Urban Geotechnical Engineering Zhejiang University Hangzhou 310058 China

Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index Cae with increasing soil density. Based on all selected and conducted experimental results, a modified creep index Cae＊ defined in double logarithmic plane lge-lgt, was plotted for various clays, from which Cae＊ can be assumed as a constant for different soil densities. Then, the modified creep index was applied to a newly developed elastic viscoplastic model. In this way, the modified creep index Ca＊ can naturally take into account the nonlinear Cae revealing the influence of soil density in the soil assemblies without additional parameters. Finally, the enhanced model was incorporated into the finite element code ABAQUS and used to simulate a consolidation test and a test embankment. The improvement of simulations by the modified creep index was highlighted by comparing simulations using the conventional creep index Cae.

关键词： clays Creep Consolidation test Embankment Finite element method Viscoplasticity

Adsorption Behavior of Acid-Leached clays in Bleaching of Oil

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American Journal of Analytical Chemistry 2015年第6期6卷 495-512页

作者： I. Z. Mukasa-Tebandeke P. J. M. Ssebuwufu S. A. Nyanzi G. W. Nyakairu M. Ntale F. Lugolobi Schumann Andreas Department of Chemistry Makerere University Kampala Uganda Department of Earth Sciences Wesleyan University Middletown USA Department of Geology Makerere University Kampala Uganda

The available data have shown that acid-leached clays had sites for adsorption of impurities in oils. Data obtained on residual impurities in cotton and sunflower-seed oils bleached with the same clay materials produced linear Langmuir and Freundlich isotherms. The increase in constant, k with increase in both temperature of thermal activation and concentration of acid used to leach the clay, suggests that bleaching efficiency increased. The value of n decreased with increase in temperature of activation and concentration of acid used to leach the clay suggesting that bleaching capacity increased. The mineral compositions of the clays influenced their surface, structural and bleaching properties.

关键词： Adsorption Isotherms Bleaching Acid Activation clays