H. Lobato-Aguilar, W. Herrera-Kao, S. Duarte‐Aranda, F. J. Aguilar-Pérez, Andrés I. Oliva-Arias, V. Rejón-Moo, J. M. Baas-López, J. Uribe-Calderon, J. M. Cervantes‐Uc
This study examined the incorporation of benzalkonium chloride into palygorskite and montmorillonite, assessing their potential as drug carriers. The aim was to evaluate the use of both clay minerals as viable options for antibacterial drug delivery. Various amounts (0.5, 1.0 and 2.0 times the cation-exchange capacity) of benzalkonium chloride were incorporated into both clay minerals, and the resulting materials were characterized using Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and elemental analysis using both CHNS-O elemental analysis and energy-dispersive X-ray spectroscopy. The Fourier-transform infrared spectroscopy and elemental analysis results indicate that benzalkonium chloride was incorporated successfully into the clay minerals. The X-ray diffraction traces of organo-montmorillonite indicate that the d-value increased as benzalkonium chloride content increased, confirming the intercalation of benzalkonium chloride within the montmorillonite interlayer space. By contrast, this behaviour was not observed for palygorskite. For the benzalkonium chloride-release studies, an initial burst release was found within the first 5 h, followed by a sustained release of benzalkonium chloride during the remaining testing time (24 h). Drug-release profiles were similar for modified palygorskite or montmorillonite during the testing time (24 h). Both clay minerals modified with benzalkonium chloride are promising materials for use as antibacterial fillers for several applications, including in the dental care industry.
{"title":"Characterization and drug release of benzalkonium chloride-loaded organo-palygorskite or organo-montmorillonite","authors":"H. Lobato-Aguilar, W. Herrera-Kao, S. Duarte‐Aranda, F. J. Aguilar-Pérez, Andrés I. Oliva-Arias, V. Rejón-Moo, J. M. Baas-López, J. Uribe-Calderon, J. M. Cervantes‐Uc","doi":"10.1180/clm.2023.16","DOIUrl":"https://doi.org/10.1180/clm.2023.16","url":null,"abstract":"\u0000 This study examined the incorporation of benzalkonium chloride into palygorskite and montmorillonite, assessing their potential as drug carriers. The aim was to evaluate the use of both clay minerals as viable options for antibacterial drug delivery. Various amounts (0.5, 1.0 and 2.0 times the cation-exchange capacity) of benzalkonium chloride were incorporated into both clay minerals, and the resulting materials were characterized using Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and elemental analysis using both CHNS-O elemental analysis and energy-dispersive X-ray spectroscopy. The Fourier-transform infrared spectroscopy and elemental analysis results indicate that benzalkonium chloride was incorporated successfully into the clay minerals. The X-ray diffraction traces of organo-montmorillonite indicate that the d-value increased as benzalkonium chloride content increased, confirming the intercalation of benzalkonium chloride within the montmorillonite interlayer space. By contrast, this behaviour was not observed for palygorskite. For the benzalkonium chloride-release studies, an initial burst release was found within the first 5 h, followed by a sustained release of benzalkonium chloride during the remaining testing time (24 h). Drug-release profiles were similar for modified palygorskite or montmorillonite during the testing time (24 h). Both clay minerals modified with benzalkonium chloride are promising materials for use as antibacterial fillers for several applications, including in the dental care industry.","PeriodicalId":10311,"journal":{"name":"Clay Minerals","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47300471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daiane L. Silva, Nayara Balaba, Dienifer F. L. Horsth, S. Jaerger, F. Anaissi
We obtained natural red soil (RS), rich in iron, from the region of Palotina in the state of Paraná, Brazil. The RS sample was purified by suspension in water and sieved to remove plant particulates. It was then treated thermally at 800°C to remove organic volatiles; this sample was called RS800. The samples were characterized using X-ray diffraction, X-ray fluorescence, infrared and electronic spectroscopy, ζ-potential analysis and scanning electron microscopy. Colorimetric studies were performed according to the CIEL*a*b* system. Tests have shown that RS800 has the ability to remove methylene blue (MB) dye from wastewater. Thus, it was used as an adsorbent at various temperatures (25, 35, 45°C). According to the Langmuir model, the maximum adsorption capacity (qmax) was 23.256 mg g–1 (25°C). Unexpectedly, increasing temperature reduced qmax to 21.659 mg g–1 at 35°C and to 21.186 mg g–1 at 45°C. Therefore, RS800 must be used at room temperature (25°C), making its application in large-scale wastewater treatment feasible. After using RS800 as an adsorbent, the solids were filtered, dried, pulverized, and used as hybrid pigments in commercial white paints. Pigmented paints were used to paint a plaster specimen and colorimetric measurement was performed. These paints were tested for colour stability in acidic and alkaline environments. The results indicate that RS800 is efficient in the treatment of water contaminated with cationic dyes and can be reused as a hybrid pigment.
{"title":"Characterization of calcined red soil applied in the removal of methylene blue dye from wastewater to produce a hybrid pigment","authors":"Daiane L. Silva, Nayara Balaba, Dienifer F. L. Horsth, S. Jaerger, F. Anaissi","doi":"10.1180/clm.2023.13","DOIUrl":"https://doi.org/10.1180/clm.2023.13","url":null,"abstract":"\u0000 We obtained natural red soil (RS), rich in iron, from the region of Palotina in the state of Paraná, Brazil. The RS sample was purified by suspension in water and sieved to remove plant particulates. It was then treated thermally at 800°C to remove organic volatiles; this sample was called RS800. The samples were characterized using X-ray diffraction, X-ray fluorescence, infrared and electronic spectroscopy, ζ-potential analysis and scanning electron microscopy. Colorimetric studies were performed according to the CIEL*a*b* system. Tests have shown that RS800 has the ability to remove methylene blue (MB) dye from wastewater. Thus, it was used as an adsorbent at various temperatures (25, 35, 45°C). According to the Langmuir model, the maximum adsorption capacity (qmax) was 23.256 mg g–1 (25°C). Unexpectedly, increasing temperature reduced qmax to 21.659 mg g–1 at 35°C and to 21.186 mg g–1 at 45°C. Therefore, RS800 must be used at room temperature (25°C), making its application in large-scale wastewater treatment feasible. After using RS800 as an adsorbent, the solids were filtered, dried, pulverized, and used as hybrid pigments in commercial white paints. Pigmented paints were used to paint a plaster specimen and colorimetric measurement was performed. These paints were tested for colour stability in acidic and alkaline environments. The results indicate that RS800 is efficient in the treatment of water contaminated with cationic dyes and can be reused as a hybrid pigment.","PeriodicalId":10311,"journal":{"name":"Clay Minerals","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41632963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Iron removal from kaolin by oxalic acid using a novel pre-agitating and high-pressure washing technique","authors":"Bijan Taheri","doi":"10.1180/clm.2023.11","DOIUrl":"https://doi.org/10.1180/clm.2023.11","url":null,"abstract":"","PeriodicalId":10311,"journal":{"name":"Clay Minerals","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49032981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The development and application of Fe-rich palygorskite clay has been restricted significantly by its red colour and low grade. Moreover, the nano-structured properties of palygorskite and the relatively large Fe content of Fe-rich palygorskite clay have received insufficient attention. The present study involved the synthesis of Ni-based catalysts via a coprecipitation method using Fe-rich palygorskite clay as the support. The catalysts were then evaluated for their performance for catalytic steam reforming of toluene (CSRT). The experimental findings revealed that the Fe in Fe-rich palygorskite clay interacted strongly with Ni and formed Fe-Ni alloys. The catalyst with a Ni/Fe mass ratio of 14 (Ni14/FePal) calcined in air at 600°C exhibited superior performance for CSRT under the reaction temperature 700°C and S/C molar ratio of 1.0. According to the kinetics study, Ni14/FePal exhibited the lowest apparent activation energy (33.99 kJ mol−1) among the catalysts, which further confirmed the superior catalytic activity in CSRT. The characterizations of the catalysts used demonstrated that the excellent stability and resistance to coke formation of Ni14/FePal were attributable to the presence of a sufficient amount of highly dispersed Fe-Ni alloys on its surface.
{"title":"High catalytic performance of Fe-rich palygorskite clay-supported Ni catalysts for steam reforming of toluene","authors":"Minghao Ji, Xuehua Zou, Haibo Liu, Yinsheng Zhang, Shiwei Dong, Chen Xu, Qiao-qin Xie, Dong Chen, Chengzhu Zhu, Tianhu Chen","doi":"10.1180/clm.2023.12","DOIUrl":"https://doi.org/10.1180/clm.2023.12","url":null,"abstract":"Abstract The development and application of Fe-rich palygorskite clay has been restricted significantly by its red colour and low grade. Moreover, the nano-structured properties of palygorskite and the relatively large Fe content of Fe-rich palygorskite clay have received insufficient attention. The present study involved the synthesis of Ni-based catalysts via a coprecipitation method using Fe-rich palygorskite clay as the support. The catalysts were then evaluated for their performance for catalytic steam reforming of toluene (CSRT). The experimental findings revealed that the Fe in Fe-rich palygorskite clay interacted strongly with Ni and formed Fe-Ni alloys. The catalyst with a Ni/Fe mass ratio of 14 (Ni14/FePal) calcined in air at 600°C exhibited superior performance for CSRT under the reaction temperature 700°C and S/C molar ratio of 1.0. According to the kinetics study, Ni14/FePal exhibited the lowest apparent activation energy (33.99 kJ mol−1) among the catalysts, which further confirmed the superior catalytic activity in CSRT. The characterizations of the catalysts used demonstrated that the excellent stability and resistance to coke formation of Ni14/FePal were attributable to the presence of a sufficient amount of highly dispersed Fe-Ni alloys on its surface.","PeriodicalId":10311,"journal":{"name":"Clay Minerals","volume":"58 1","pages":"67 - 81"},"PeriodicalIF":1.5,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43073548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this study, aluminium fluoride trihydrate (AlF3⋅3H2O) was used to inhibit the sintering of calcined coal-series kaolin (CCSK). In addition, the oil absorption properties of CCSK were studied. The particle-size distribution, specific surface area and porosity of the samples were investigated as a function of calcination temperature and the addition of AlF3⋅3H2O. Moreover, the ability of AlF3⋅3H2O to improve the oil absorption of CCSK was explored. The morphology, structure and phase composition of the specimens were investigated using scanning electron microscopy and X-ray diffraction. The phase transition during heating of the samples was studied using thermogravimetric analysis. The preparation with 10 wt.% AlF3⋅3H2O had the optimal sintering inhibition effect on CCSK at 1000°C. The release of SiF4 gas during heating and the formation of mullite whiskers on the particle surface caused by AlF3⋅3H2O moderated the formation of molten-phase liquid bridges between particles and inhibited sintering of the raw material powder. Furthermore, the formation of submicron mullite whiskers on the surface of the CCSK particles enhanced the oil-absorption properties of the sample significantly.
{"title":"Sintering inhibition and oil-absorption properties of calcined coal-series kaolin","authors":"Jiaquan Li, Zhiwei Huang, Qian Wang, Fengnian Zhang, Yang Miao, Feng Gao","doi":"10.1180/clm.2023.10","DOIUrl":"https://doi.org/10.1180/clm.2023.10","url":null,"abstract":"Abstract In this study, aluminium fluoride trihydrate (AlF3⋅3H2O) was used to inhibit the sintering of calcined coal-series kaolin (CCSK). In addition, the oil absorption properties of CCSK were studied. The particle-size distribution, specific surface area and porosity of the samples were investigated as a function of calcination temperature and the addition of AlF3⋅3H2O. Moreover, the ability of AlF3⋅3H2O to improve the oil absorption of CCSK was explored. The morphology, structure and phase composition of the specimens were investigated using scanning electron microscopy and X-ray diffraction. The phase transition during heating of the samples was studied using thermogravimetric analysis. The preparation with 10 wt.% AlF3⋅3H2O had the optimal sintering inhibition effect on CCSK at 1000°C. The release of SiF4 gas during heating and the formation of mullite whiskers on the particle surface caused by AlF3⋅3H2O moderated the formation of molten-phase liquid bridges between particles and inhibited sintering of the raw material powder. Furthermore, the formation of submicron mullite whiskers on the surface of the CCSK particles enhanced the oil-absorption properties of the sample significantly.","PeriodicalId":10311,"journal":{"name":"Clay Minerals","volume":"58 1","pages":"57 - 66"},"PeriodicalIF":1.5,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49022676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Nandi, Alexandre Zaccaron, F. Raupp-Pereira, S. Arcaro, A. Bernardin, O. Montedo
Abstract Fast drying (~60 min) is useful for optimizing production processes by increasing productivity and reducing costs and environmental impacts, especially in red ceramic industries in Brazil. However, suitable clays are necessary and, currently, studies focused on the plastic behaviour of clays with compositions suitable for extrusion, especially for fast drying, are scarce. Therefore, in this study, three different clays from the same mineral deposit were studied for producing clay-based structural products via fast drying. The clays were characterized according to their chemical, mineralogical and thermal properties, particle size, cation-exchange capacity, specific surface area and open pore volume distribution. Ten formulations were developed using a simplex-centroid mixture design of experiments and their plasticity index (PI) values were determined. The response surfaces of the formulations were evaluated according to their PI, while the formation characteristics were determined according to their extrusion workability factor values. Formulations F5 (50.0 wt.% yellow clay and 50.0 wt.% green clay) and F8 (66.6 wt.% yellow clay, 16.7 wt.% grey clay and 16.7 wt.% green clay; PI = 15.5–16.6%) displayed optimal extrusion properties, followed by formulations F7 (33.3 wt.% yellow clay, 33.3 wt.% grey clay and 33.3 wt.% green clay) and F10 (16.7 wt.% yellow clay, 16.7 wt.% grey clay and 66.6 wt.% green clay; PI = 13.8–14.2%), which are within acceptable extrusion index values. Thus, the chosen formulations have significant potential for use in the manufacture of fast-drying red ceramics.
{"title":"Plastic behaviour of clay materials for the manufacture of fast-drying red ceramics","authors":"V. Nandi, Alexandre Zaccaron, F. Raupp-Pereira, S. Arcaro, A. Bernardin, O. Montedo","doi":"10.1180/clm.2023.9","DOIUrl":"https://doi.org/10.1180/clm.2023.9","url":null,"abstract":"Abstract Fast drying (~60 min) is useful for optimizing production processes by increasing productivity and reducing costs and environmental impacts, especially in red ceramic industries in Brazil. However, suitable clays are necessary and, currently, studies focused on the plastic behaviour of clays with compositions suitable for extrusion, especially for fast drying, are scarce. Therefore, in this study, three different clays from the same mineral deposit were studied for producing clay-based structural products via fast drying. The clays were characterized according to their chemical, mineralogical and thermal properties, particle size, cation-exchange capacity, specific surface area and open pore volume distribution. Ten formulations were developed using a simplex-centroid mixture design of experiments and their plasticity index (PI) values were determined. The response surfaces of the formulations were evaluated according to their PI, while the formation characteristics were determined according to their extrusion workability factor values. Formulations F5 (50.0 wt.% yellow clay and 50.0 wt.% green clay) and F8 (66.6 wt.% yellow clay, 16.7 wt.% grey clay and 16.7 wt.% green clay; PI = 15.5–16.6%) displayed optimal extrusion properties, followed by formulations F7 (33.3 wt.% yellow clay, 33.3 wt.% grey clay and 33.3 wt.% green clay) and F10 (16.7 wt.% yellow clay, 16.7 wt.% grey clay and 66.6 wt.% green clay; PI = 13.8–14.2%), which are within acceptable extrusion index values. Thus, the chosen formulations have significant potential for use in the manufacture of fast-drying red ceramics.","PeriodicalId":10311,"journal":{"name":"Clay Minerals","volume":"58 1","pages":"26 - 37"},"PeriodicalIF":1.5,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45419100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The Clay Minerals Group (CMG), the first of the Special Interest Groups of the Mineralogical Society of the UK and Ireland, was inaugurated in January 1947. The CMG, together with its Belgian equivalent (originally the Comité Belge pour l'Etude des Argiles, later the Belgian Clay Group, now defunct), formed the world's first organizations dedicated to clay mineral research. The CMG celebrated its 75th anniversary in 2022. The Group's aims are to stimulate interest in clay mineralogy, to facilitate an exchange of information between members by providing facilities for reading and discussing papers on research on clay minerals (and allied topics) and to expedite their publication and to encourage practical applications of such research, and these have remained reassuringly the same throughout its history. A founder and active member of both the European Clay Groups Association and the Association Internationale Pour L'Etude des Argiles, the CMG has promoted clay science through the publication of the highly regarded journal Clay Minerals and a series of influential book titles, organizing international and national scientific conferences and meetings, the George Brown Lecture series, providing bursaries and grants to assist researchers and hosting the Images of Clay archive. The initial and sustained success of the CMG has been largely due to the labours of many officers and committee members, some of whom have been recognized for their science and service with awards from the Mineralogical Society of the UK and Ireland and elsewhere. By maintaining this effort, the evident, continuing demand for clay mineral research to assist with changing societal needs should ensure the relevance and health of the CMG for the foreseeable future.
{"title":"The Clay Minerals Group (CMG): 1947–2022","authors":"S. Kemp","doi":"10.1180/clm.2023.3","DOIUrl":"https://doi.org/10.1180/clm.2023.3","url":null,"abstract":"Abstract The Clay Minerals Group (CMG), the first of the Special Interest Groups of the Mineralogical Society of the UK and Ireland, was inaugurated in January 1947. The CMG, together with its Belgian equivalent (originally the Comité Belge pour l'Etude des Argiles, later the Belgian Clay Group, now defunct), formed the world's first organizations dedicated to clay mineral research. The CMG celebrated its 75th anniversary in 2022. The Group's aims are to stimulate interest in clay mineralogy, to facilitate an exchange of information between members by providing facilities for reading and discussing papers on research on clay minerals (and allied topics) and to expedite their publication and to encourage practical applications of such research, and these have remained reassuringly the same throughout its history. A founder and active member of both the European Clay Groups Association and the Association Internationale Pour L'Etude des Argiles, the CMG has promoted clay science through the publication of the highly regarded journal Clay Minerals and a series of influential book titles, organizing international and national scientific conferences and meetings, the George Brown Lecture series, providing bursaries and grants to assist researchers and hosting the Images of Clay archive. The initial and sustained success of the CMG has been largely due to the labours of many officers and committee members, some of whom have been recognized for their science and service with awards from the Mineralogical Society of the UK and Ireland and elsewhere. By maintaining this effort, the evident, continuing demand for clay mineral research to assist with changing societal needs should ensure the relevance and health of the CMG for the foreseeable future.","PeriodicalId":10311,"journal":{"name":"Clay Minerals","volume":"58 1","pages":"38 - 56"},"PeriodicalIF":1.5,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44039644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Various approaches have been used for the preparation of heterostructured materials based on clay minerals, with numerous potential applications offered by the resulting functional materials. In this study, a fibrous clay mineral (palygorskite) and a tetraethyl orthosilicate reagent were used to obtain silica–palygorskite heterostructures. The aim was to highlight the influence of two factors during the preparation process: the effect of acid activation pre-treatment of the palygorskite with HCl and the effect of varying the length of the amine chains used – dodecylamine and butylamine – on the formation and development of silica nanoparticles on the surface of the palygorskite fibres. The silica–palygorskite heterostructures were obtained after the removal of the organic templates by calcination at 500°C. The textural and structural properties of the silica–palygorskite heterostructured samples were determined using various experimental characterization techniques, such as X-ray diffraction, transmission electron microscopy, gas adsorption and Fourier-transform infrared spectroscopy. The experimental variables targeted in this study appeared to have a significant effect on the textural properties of the silica–palygorskite heterostructure obtained. The great specific surface area and the mesoporous, microporous and ultramicroporous volumes as determined using nitrogen and/or carbon dioxide gas adsorption confirm the benefit of combining the acid activation pre-treatment of the fibrous clay mineral with the use of a long-chain amine co-surfactant (dodecylamine). The resulting silica–palygorskite heterostucture has a great specific surface area (628 m2 g–1) and a well-developed total pore network (VN2 = 0.24 cm3 g–1; Vultra (CO2) = 0.18 cm3 g–1). This material will be tested for the removal of volatile organic compounds at low concentrations.
{"title":"Effects of clay activation and amine chain length on silica–palygorskite heterostructure properties","authors":"L. Boudriche, F. Bergaya, A. Boudjemaa","doi":"10.1180/clm.2023.6","DOIUrl":"https://doi.org/10.1180/clm.2023.6","url":null,"abstract":"Abstract Various approaches have been used for the preparation of heterostructured materials based on clay minerals, with numerous potential applications offered by the resulting functional materials. In this study, a fibrous clay mineral (palygorskite) and a tetraethyl orthosilicate reagent were used to obtain silica–palygorskite heterostructures. The aim was to highlight the influence of two factors during the preparation process: the effect of acid activation pre-treatment of the palygorskite with HCl and the effect of varying the length of the amine chains used – dodecylamine and butylamine – on the formation and development of silica nanoparticles on the surface of the palygorskite fibres. The silica–palygorskite heterostructures were obtained after the removal of the organic templates by calcination at 500°C. The textural and structural properties of the silica–palygorskite heterostructured samples were determined using various experimental characterization techniques, such as X-ray diffraction, transmission electron microscopy, gas adsorption and Fourier-transform infrared spectroscopy. The experimental variables targeted in this study appeared to have a significant effect on the textural properties of the silica–palygorskite heterostructure obtained. The great specific surface area and the mesoporous, microporous and ultramicroporous volumes as determined using nitrogen and/or carbon dioxide gas adsorption confirm the benefit of combining the acid activation pre-treatment of the fibrous clay mineral with the use of a long-chain amine co-surfactant (dodecylamine). The resulting silica–palygorskite heterostucture has a great specific surface area (628 m2 g–1) and a well-developed total pore network (VN2 = 0.24 cm3 g–1; Vultra (CO2) = 0.18 cm3 g–1). This material will be tested for the removal of volatile organic compounds at low concentrations.","PeriodicalId":10311,"journal":{"name":"Clay Minerals","volume":"58 1","pages":"19 - 25"},"PeriodicalIF":1.5,"publicationDate":"2023-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47916916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shoufan Cao, Jingtao Guo, Jianchao Ma, Jin Pang, Siyu Zhang, Haidong Hao, Danlei Wu, Shaobin Wang
Abstract Water pollution by hexavalent chromium (Cr(VI)) is widespread and problematic. As a result, more research into economic Cr(VI) removal is needed. In this study, we created and employed an adsorption–reduction mechanism to remove Cr(VI). Magnetically reduced graphene oxide bentonite (MrGO-BT) is acid resistant and can undergo magnetic separation. The hydroxyl group of chitosan (CS) condensed with the functional groups on the surface of bentonite (BT), and the MrGO-BT sandwich has been fabricated and constructed from an Fe3O4 core layer sandwiched by reduced graphene oxide (rGO) and a BT shell, with CS acting as a crosslinker. Cr(VI) elimination by MrGO-BT was exothermic and spontaneous according to thermodynamic analyses. The adsorption kinetics and adsorption isotherms were characterized by the pseudo-second order kinetic theory and the Langmuir model, respectively. Regarding the elimination of Cr(VI), the greatest adsorption ability for Cr(VI) elimination achieved was 91.5 mg g–1. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that Cr(VI) was reduced by C–O–H on MrGO-BT to produce Cr(III) and H–C=O, and that Cr(III) chelated with amino groups or exchanged with BT after intercalation. In addition, the introduction of Cu2+ increased the positive charge of MrGO-BT and amplified the electrostatic interaction between Cr2O72− and HCrO4–, which is what caused Cr(VI) to be eliminated. Cu2+ and reduced Cr(III) combined with -NH2 on the surface of MrGO-BT to form -NH-Cr(III) or -NH-Cu2+, and Cr(VI) elimination via chelation and ion exchange was confirmed. MrGO-BT is shown to be an adsorbent with high acid resistance and good magnetic responsiveness and stability.
{"title":"Effective removal of hexavalent chromium with magnetically reduced graphene oxide bentonite","authors":"Shoufan Cao, Jingtao Guo, Jianchao Ma, Jin Pang, Siyu Zhang, Haidong Hao, Danlei Wu, Shaobin Wang","doi":"10.1180/clm.2023.4","DOIUrl":"https://doi.org/10.1180/clm.2023.4","url":null,"abstract":"Abstract Water pollution by hexavalent chromium (Cr(VI)) is widespread and problematic. As a result, more research into economic Cr(VI) removal is needed. In this study, we created and employed an adsorption–reduction mechanism to remove Cr(VI). Magnetically reduced graphene oxide bentonite (MrGO-BT) is acid resistant and can undergo magnetic separation. The hydroxyl group of chitosan (CS) condensed with the functional groups on the surface of bentonite (BT), and the MrGO-BT sandwich has been fabricated and constructed from an Fe3O4 core layer sandwiched by reduced graphene oxide (rGO) and a BT shell, with CS acting as a crosslinker. Cr(VI) elimination by MrGO-BT was exothermic and spontaneous according to thermodynamic analyses. The adsorption kinetics and adsorption isotherms were characterized by the pseudo-second order kinetic theory and the Langmuir model, respectively. Regarding the elimination of Cr(VI), the greatest adsorption ability for Cr(VI) elimination achieved was 91.5 mg g–1. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that Cr(VI) was reduced by C–O–H on MrGO-BT to produce Cr(III) and H–C=O, and that Cr(III) chelated with amino groups or exchanged with BT after intercalation. In addition, the introduction of Cu2+ increased the positive charge of MrGO-BT and amplified the electrostatic interaction between Cr2O72− and HCrO4–, which is what caused Cr(VI) to be eliminated. Cu2+ and reduced Cr(III) combined with -NH2 on the surface of MrGO-BT to form -NH-Cr(III) or -NH-Cu2+, and Cr(VI) elimination via chelation and ion exchange was confirmed. MrGO-BT is shown to be an adsorbent with high acid resistance and good magnetic responsiveness and stability.","PeriodicalId":10311,"journal":{"name":"Clay Minerals","volume":"58 1","pages":"7 - 18"},"PeriodicalIF":1.5,"publicationDate":"2023-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45737371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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