Transport dynamics of rare earth elements in weathering crust soils.

In modern industries, rare earth elements (REEs) are considered as essential metals and invaluable natural resources. Ion-adsorption deposits (IADs) are repositories of REE in the weathering crust soils, in which REEs are adsorbed on clay minerals. In the last few decades, the mining of REEs from IADs has caused substantial environmental damage owing to the overuse of leaching agents for the desorption and transport of REEs in weathering crust soils. These environmental issues have sparked extensive research interest in modeling REE transport dynamics in weathering crust soils. Nevertheless, because current models treat REE adsorption and transport independently, they do not accurately describe REE transport dynamics. Therefore, in this study, a unified workflow that synergizes adsorption and transport dynamics is proposed to predict REE transport. The adsorption of REEs on IADs was found to follow the Freundlich isotherm with the coefficient of determination exceeding 0.9826. The adsorption capacities of La3+, Sm3+, Er3+, and Y3+ reach 1.3127, 1.4423, 1.5793, and 1.1061 mg g-1 at 300 ppm, respectively. For the breakthrough curve, an advection-dispersion-adsorption-equation (ADAE) model was developed and utilized to accurately and reliably predict REE transport dynamics in soil columns. It was found the saturation time of REEs in soils is 39.22, 44.15, 50.64, and 32.17 h, respectively at 2 mL min-1 and decreased with the increase of flow velocity. The upper and lower limits of REE transport are ADAE-Freundlich and ADAE-Toth. More importantly, the model was applied to simulate REEs transport in field-scale weathering crusts over 100 years and predict REE accumulation in the highly weathered layered, which is found in natural weathering crusts. The qualitative prediction of REE transport dynamics in weathering crusts may help fundamentally lower the usage of leaching agents and mitigate concomitant the environmental impacts of mining.

Decision tool of medical endoscope maintenance service in Chinese hospitals: a conjoint analysis.

BACKGROUND: Medical devices are instruments, apparatus, appliances, software, implants, reagents, materials or other articles that are intended for use in the treatment or diagnosis of disease or injury in humans. Concerning medical endoscope devices, which enable doctors to observe and manipulate the area under examination through a puncture hole in the body cavity or organ, hospitals predominantly consider the quality and cost of maintenance services when making their selection. The effective and efficient provision of maintenance services plays a crucial role in ensuring cost-effective and high-quality management of medical devices. In this study, we have developed an innovative decision tool that analyzed key factors impacting the choice of medical devices' maintenance service. This tool assists hospitals in evaluating and selecting appropriate maintenance services for medical device, specifically endoscopy devices. Moreover, it also serves as a valuable resource for manufacturers and suppliers to enhance their after-sales service offerings. METHODS: A cross-sectional survey was undertaken in 50 Chinese hospitals, including primary and tertiary hospitals. Moreover, 56 medical staff and 65 medical engineers were recruited from 50 Chinese hospitals to participate the survey. A comprehensive set of factors were defined and investigated. Conjoint analysis and orthogonal design were used for survey design and statistical analysis. RESULTS: Factors importance and utility values of decision-making factors were analyzed at the aggregate, occupation, and medical institution levels. (1) At the aggregate level, the most critical factor is "maintenance response" and the least important one is "maintenance efficiency". (2) At the occupation level, medical staff paid more attention to "maintenance response" while medical engineers paid more attention to "maintenance quality". (3) At the medical institution level, Primary hospitals paid more attention to "maintenance price", while tertiary hospitals paid more attention to "maintenance quality". CONCLUSIONS: In general, this study provides a more scientific decision-making tool to both hospitals in choosing maintenance service for medical device such as endoscopy, and it also helps manufacturers and suppliers improve the after-sales service.

Using machine learning algorithms for predicting cognitive impairment and identifying modifiable factors among Chinese elderly people.

Objectives: This study firstly aimed to explore predicting cognitive impairment at an early stage using a large population-based longitudinal survey of elderly Chinese people. The second aim was to identify reversible factors which may help slow the rate of decline in cognitive function over 3 years in the community. Methods: We included 12,280 elderly people from four waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), followed from 2002 to 2014. The Chinese version of the Mini-Mental State Examination (MMSE) was used to examine cognitive function. Six machine learning algorithms (including a neural network model) and an ensemble method were trained on data split 2/3 for training and 1/3 testing. Parameters were explored in training data using 3-fold cross-validation and models were evaluated in test data. The model performance was measured by area-under-curve (AUC), sensitivity, and specificity. In addition, due to its better interpretability, logistic regression (LR) was used to assess the association of life behavior and its change with cognitive impairment after 3 years. Results: Support vector machine and multi-layer perceptron were found to be the best performing algorithms with AUC of 0.8267 and 0.8256, respectively. Fusing the results of all six single models further improves the AUC to 0.8269. Playing more Mahjong or cards (OR = 0.49,95% CI: 0.38-0.64), doing more garden works (OR = 0.54,95% CI: 0.43-0.68), watching TV or listening to the radio more (OR = 0.67,95% CI: 0.59-0.77) were associated with decreased risk of cognitive impairment after 3 years. Conclusions: Machine learning algorithms especially the SVM, and the ensemble model can be leveraged to identify the elderly at risk of cognitive impairment. Doing more leisure activities, doing more gardening work, and engaging in more activities combined were associated with decreased risk of cognitive impairment.

Model construction of medical endoscope service evaluation system-based on the analysis of Delphi method.

BACKGROUND: Medical endoscope is widely used in clinical practice for the purpose of diagnosis and treatment, occupying around 5% of the medical device market. Evaluating the true service level of medical endoscope is essential and necessary to improve overall performance of medical diagnosis and treatment, and to maintain competitiveness of endoscope manufacturers, however, such a tool is not available in the market. This study develops an Evaluation Index System (EIS) to assess service level of medical endoscope, and to provide suggestions for improving the service level through the Delphi method. METHODS: Firstly, the possible factors influencing the service level were identified from literature review. In parallel, the Delphi expert method questionnaire was designed and 25 experts were invited to conduct three rounds of questionnaire, to evaluate and rate the possible factors. Finally, we determined the weights associated with the factors, using the analytic hierarchy process (AHP) and percentage method, and developed the service level EIS. RESULTS: The EIS consists of 3 first-level indicators, 24 s-level indicators and 68 third-level indicators. According to the weights computed using AHP, first-level indicators are ranked as post-sale (0.62), in-sale (0.25) and pre-sale (0.13). Through case verification, the medical endoscope brand Olympus had a total score of 4.17, Shanghai Aohua had a total score of 3.71, and Shanghai Chengyun had a total score of 3.28, which matches its market popularity and ranking in terms of market share. The results obtained from the EIS are consistent with the reality. CONCLUSIONS: The EIS established in this study is comprehensive, reliable and reasonable with strong practicality. The EIS can act as a tool for the endoscope users to evaluate potential products and make informed choices. It also provides a measurable basis for endoscope manufacturers and service providers to improve service quality.

Clinical and economic impact of methicillin-resistant Staphylococcus aureus: a multicentre study in China.

Methicillin-resistant Staphylococcus aureus (MRSA) has become a serious threat to global health. In China, the proportion of S. aureus isolates that were MRSA was 44.6% in 2014. The clinical and economic impact of MRSA in China remains largely uninvestigated. This study aims to compare the differences in hospital costs, length of hospital stay, and hospital mortality rate between MRSA and methicillin-susceptible S. aureus (MSSA) colonization or infection and between MRSA cases and those without an S. aureus infection. A retrospective and multicentre study was conducted in four tertiary hospitals in China between 2013 and 2015. Inpatient characteristics and hospital costs were collected from electronic medical records. We conducted propensity score matching (PSM) to eliminate selection bias by balancing the potential confounding variables between the two groups. The main indicators included hospital costs, length of hospital stay, and hospital mortality rate. A total of 1,335 inpatients with MRSA, 1,397 with MSSA, and 33,606 without an S. aureus infection were included. PSM obtained 954 and 1,313 pairs between the MRSA and MSSA groups and between the MRSA and S. aureus-free groups, respectively. After PSM, MRSA colonization or infection is associated with an increased total hospital cost ranging from $3,220 to $9,606, an excess length of hospital stay of 6 days-14 days, and an attributable hospital mortality rate of 0-3.58%. Between the MRSA and MSSA groups, MRSA colonization or infection was significantly associated with a higher total hospital cost and longer length of hospital stay among survivors but not among non-survivors; however, there were no differences in the hospital mortality rate between these two groups. Between the MRSA and the S. aureus-free groups, MRSA colonization or infection was significantly associated with an increased total hospital cost, a prolonged length of hospital stay and a higher hospital mortality rate among both survivors and non-survivors. It is critical to quantify the clinical and economic impact of MRSA to justify resource allocation for the development of strategies to improve clinical outcomes and to reduce the economic burden.

Chinese Minority Perceives the Doctor-Patient Relationship Differently: A Cultural and Economic Interpretation.

In China, doctor-patient relationships (D-P relationships) are cited frequently and attracted international attention. This study assesses whether the D-P relationship experienced by the Chinese is associated with ethnicity, hospital hierarchies, and socioeconomic factors. In a national cross-sectional survey, multi-stage random sampling was adopted to assess regional and socio-economic differences between year 2016 and year 2017. Each area surveyed consisted of about 250 randomly chosen households, and valid results were obtained from 4,173 adults aged 16-99. When provided a choice of eight types of D-P relationship, for doctors in primary care institutions, 63.8% of ethnic minorities indicated having a friend-type relationship with their physicians, with 23.3% having a trading/reciprocal relationship. Han Chinese, however, predicts the opposite relationship between doctors from different hierarchy and the types of D-P relationship. For physicians working in hospitals, this difference in relationship was more pronounced, where 52.9% of ethnic minorities indicated having a friend-type relationship with their physicians, and 30.1% indicated the presence of a trading/reciprocal relationship. For Han Chinese, however, 53.3% indicated having a reciprocal relationship with their doctor. Overall, the prevalence of friendly D-P relationships was correlated with ethnic minorities, lower levels of education, and lower incomes. Ethnic minorities are most likely to perceive their physicians as friends, while Han Chinese are more likely to perceive a trading relationship with their physicians. The primary contribution of this research is the finding that D-P relationships differ for Han Chinese and other ethnic minorities.

Older adults' choices of first-contact care and related factors in Zhejiang and Qinghai Province, China.

AIM: This study aimed to investigate older adults' choices of first-contact care when they felt ill in Zhejiang and Qinghai province, and the related potential pathways. METHODS: Data were from a cross-sectional survey in Zhejiang and Qinghai. We firstly compared older adults' choices of first-contact care in two provinces. Then, we applied structural equation modeling to explore pathways from socioeconomic status, accessibility and health status to older adults' choices of first-contact care. RESULTS: The proportion of older adults who selected primary healthcare institutions as first-contact care in Qinghai was higher than that in Zhejiang. Socioeconomic status played an important role in the Zhejiang model through direct and indirect pathways. In the Qinghai model, accessibility to primary healthcare institutions was the leading cause for choosing preferred first-contact care. CONCLUSIONS: A better understanding of complex pathways from factors to older adults' choices of first-contact care was essential, which might inform priorities for further maximizing the utilization of primary care. Geriatr Gerontol Int 2019; 19: 938-944.

Outpatient health-seeking behavior of residents in Zhejiang and Qinghai Province, China.

BACKGROUND: The eastern and western regions of China are different in many ways such as socioeconomic characteristics and health resource distribution. This study aimed to explore the outpatient health-seeking behavior and compare the influencing factors of residents in Zhejiang and Qinghai Province, which represent the situation in eastern and western China. Thus, this research will provide evidence for health resource allocation and health reform. METHODS: A cross-sectional study was conducted on a sample selected from 1600 households in Zhejiang and Qinghai province between 2016 to 2017 by the multi-stage stratified cluster random sampling method. Among the 4231 residents aged 15 years or older in the sample, 566 who reported ill-health were selected for data analysis. Two-week outpatient visits and choice of health institutions were used to measure residents' outpatient health-seeking behavior and assessed using Chi-square tests. The binary logistic regression was adopted to demonstrate the association between explanatory variables and outpatient visits. RESULTS: The study revealed that out of the people who reported ill-health, 58 individuals (50.97%) in Zhejiang and 106 (41.41%) in Qinghai went to health institutions to seek medical help (p < 0.05). The difference of residents' choice of health institution between Zhejiang and Qinghai was not statistically significant (p > 0.05). Among these respondents, Self-report severity was the common and significant factor related to their outpatient visits and it had a greater impact on outpatient visits in Zhejiang (4.18, CI 2.23-7.83, p < 0.05). Other factors such as chronic disease, knowledge of medicine and doctors and distance to the nearest health institution were significant influencing factors in Zhejiang, while in Qinghai it was occupation. CONCLUSIONS: The outpatient health-seeking behavior and its influencing factors among residents in Zhejiang and Qinghai province were different. The findings suggest the importance of having discrepant health policies in the two provinces. It's necessary to improve health literacy of residents in both provinces, strengthen the accessibility of health services in remote areas of Zhejiang and pay more attention to people with low socioeconomic status in Qinghai.

Social Determinants of Health-Related Quality of Life among Residents in Zhejiang and Qinghai, China.

Social determinants are closely related to health and play a significant role in shaping the quality of life of a population. This study aimed to explore the differences in HRQoL (health-related quality of life) scores of residents in the eastern province of Zhejiang and the western province of Qinghai and probe factors affecting the HRQoL among the two populations. A sample of 4210 residents from a cross-sectional survey was included in the analysis. The EQ-5D-3L instrument was used to measure the HRQoL of residents. A Chi-square test and a t-test were used to examine the differences between different variables and analysis of variance (ANOVA) with interaction effects was used to analyze factors associated with the HRQoL between the two provinces. Residents' EQ-5D index score (EQ VAS score) was 0.963 (82.71) and 0.962 (81.51), respectively, in Zhejiang and Qinghai. Generally, residents in Qinghai displayed significantly worse HRQoL scores than those in Zhejiang. The differences between the two regions lay on mobility, pain/discomfort, and anxiety/depressions. In both regions, an increased education level and being employed were most strongly associated with a positive HRQoL; increased age and presence of chronic diseases were most strongly associated with a negative HRQoL. When formulating health policies, the significant health disparities between western and eastern provinces must be given greater consideration. The health of vulnerable groups should be particularly focused on to improve the observed health disparities.

Kinetics and mechanisms of the interaction between the calcite (10.4) surface and Cu2+-bearing solutions.

Calcite dissolution, occurring in rocks, soils and sediments, is essential to indicate element cycles and local environments in the lithosphere, biosphere, hydrosphere and atmosphere. Calcite dissolution strongly depends on metal ions in aqueous solutions. Previous studies showed that aquatic Cu2+, a typical bio-toxic metal ion, can alter the calcite dissolution behavior. However, wide concentration ranges of Cu2+ coexisting with ubiquitous anions in local environments, such as waterways in the oxidation zones of copper deposits and soils near metal processing industry, was overlooked. When a considerable amount of aquatic Cu2+ ions are released into the environment, they migrate, diffuse, and hence become an environmental pollutant. Therefore, we focused on the interaction between calcite dissolution and wide concentration ranges of Cu2+-bearing solutions with different types of anions (SO42-, Cl- and NO3-). Comprehensive approaches including in situ atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and density functional theory (DFT) calculations were employed to investigate kinetics and mechanisms of the interaction between the calcite (10.4) surface and Cu2+-bearing solutions. Results demonstrated that both anion types and Cu2+ concentrations dramatically affect calcite dissolution. The morphology of etch pits generated in CuSO4 solutions can be fan-shaped but changed to tear-shaped in Cu(NO3)2 or CuCl2 solutions. Calcite dissolution kinetics is inhibited at cCu2+ ≤ 0.1 mM, caused by the coverage of active sites on calcite surfaces. As the Cu2+ concentration increases (1 mM ≤ cCu2+ ≤ 10 mM), calcite dissolution kinetics is enhanced due to the coupling effect of Cu2+-incorporated surface structure and solution chemistry. These results revealed the interactive mechanism between calcite dissolution and the migration of toxic Cu2+ in waterways, provided a practical consideration in dealing with the local environment.

Cognitive ageing trajectories and mortality of Chinese oldest-old.

OBJECTIVE: This study aims to identify distinctive cognitive trajectories jointly with mortality probabilities and to explore factors related to the particular trajectories of cognitive ageing in China. METHOD: 6842 individuals aged 80 years and above from 7 waves of the Chinese Longitudinal Healthy Longevity Survey were assessed with the Mini-Mental State Examination for up to 16 years. A group-based trajectory model was used to jointly estimate cognitive ageing and mortality trajectories; and to explore the factors related to membership of the trajectory groups. RESULTS: A four-group model best fit the data. For all groups, the cognitive function declined with age according to different rates. Group 4, 3, 2, and 1 showed slow (prevalence 52.8%), moderate (31.1%), progressive (12.6%) and rapid (3.5%) cognitive decline, respectively. Mortality probability trajectories followed a hierarchy in consistence with cognitive trajectories approximately. Females, illiteracy, and those born in rural areas were less likely to belong to the most favorable trajectory group. CONCLUSIONS: The heterogeneity of cognitive ageing was identified among Chinese oldest-old. Childhood socioeconomic status, especially education, was associated with the rate of cognitive decline.

Potential gains in health-adjusted life expectancy from reducing four main non-communicable diseases among Chinese elderly.

BACKGROUND: To estimate the potential gains in health-adjusted life expectancy (HALE) after hypothetical elimination of four non-communicable diseases (NCDs) among Chinese elderly from 1990 to 2016, including cardiovascular diseases (CVD), cancers, chronic respiratory diseases (CRD) and diabetes mellitus (DM). METHODS: Based on data from Global Burden of Disease 2016, we generated life table by gender using Sullivan method to calculate HALE. Disease-deleted method was used to calculate cause-elimination HALE, after hypothetical elimination of specific diseases. RESULTS: From 1990 to 2016, HALE increased for all age groups. After hypothetic eliminating the four main NCDs, potential gain in HALE by CVD, DM and cancers increased while by CRD decreased from 1990 to 2016 for both genders. Among four main NCDs, potential gain in HALE after eliminating CVD was largest and increased most for both genders. Although elimination of DM led to the smallest gain in HALE, the increasing speed of gain in HALE by DM was faster than that by CVD and cancers from 1990 to 2016. CONCLUSIONS: This study highlights the potential gains in HALE of NCDs among Chinese elderly from 1990 to 2016. HALE of Chinese elderly could further increase from the reduction of NCDs. Control measures and targeted prevention should be carried out.

A comparative study of catastrophic health expenditure in Zhejiang and Qinghai province, China.

BACKGROUND: China has made great achievements in health insurance coverage and healthcare financing; however, the rate of catastrophic health expenditure (CHE) was 13.0% in China in 2008, which is higher than that in some other countries. There remain some differences in life-style, national customs, medical conditions, and health consciousness in different provinces in China. This study aimed to compare the rates of households with CHE, further to explore the different performance of factors influencing CHE between Zhejiang and Qinghai province, China. METHODS: Data were derived from the household surveys conducted in Zhejiang and Qinghai. Sampling on multi-stage stratified cluster random method was adopted. Household with CHE occurs when the out-of-pocket payment for health care equals to or exceeds 40% of a household's income. Univariate and multivariate logistic regression analyses were used to identify the performance of factors of CHE. RESULTS: A total of 1598 households were included in this study, including 995 in Zhejiang and 603 in Qinghai. The average rates of CHE in Zhejiang and Qinghai were 9.6 and 30.5%, respectively. We found that economic status of households and households headed by an employed person are the protective factors for CHE; and number of members with chronic diseases and number of inpatients in household are the risk factors for CHE in the two provinces. Besides, poor/low-insured households in Zhejiang; and households having outpatients and households headed by a minority person in Qinghai are more likely to experience the risk of CHE. CONCLUSIONS: This study highlights the importance of improving economic development, expanding employment, and adjusting policies to make greater efforts to protect chronic diseases patients, outpatients, and inpatients, further to reduce the risk of CHE. The Chinese government should pay more attention to the actual conditions in different provinces, further to make policy decisions according to the local knowledge.

Measurement and analysis of equity in health: a case study conducted in Zhejiang Province, China.

BACKGROUND: Equity is the core of primary care. The issue of equity in health has become urgent, and China has attached increasing attention to it. With rapid economic development and great changes in medical insurance policy, the pattern of equity in health has changed tremendously. The reform of healthcare in Zhejiang Province is at the forefront in China, and studies on Zhejiang Province are of great significance to the entire country. This paper aimed to measure health equity from the perspectives of health needs and health-seeking behavior and to provide suggestions for the next policy formulations, with respect to timeliness. METHODS: The investigator's household survey was conducted in August 2016. A sample of 1000 households, which included2807 individuals in Zhejiang, China, was obtained with the multi-stage stratified cluster sampling method. Descriptive analysis and chi-square tests were adopted in the analysis. The value of the concentration index was used to measure the equity. RESULTS: This study found that the poor have more urgent health needs and poorer health situations than the rich. Through studies on health-seeking behavior, the utilization of outpatient services was almost equitable, while the utilization of hospitalization showed a pro-rich inequity (i.e., the rich use more services). Individuals with employer-based medical insurance used more outpatient services than those with rural and urban medical insurance. More people in the poorer income groups did not use inpatient services due to financial difficulties. CONCLUSIONS: Absolute medical prices and medical insurance may explain the equity in the utilization of outpatient services and the inequity in the utilization of hospitalization. In view of the pro-rich inequity of hospitalization, more financial protection should be provided for the poor.

Preparation and characterization of zwitterionic surfactant-modified montmorillonites.

A series of zwitterionic surfactant-modified montmorillonites (ZSMMs) were synthesized using montmorillonite and three zwitterionic surfactants with different alkyl chain lengths at different concentrations [0.2-4.0 cation exchange capacity (CEC)]. These ZSMMs were characterized by X-ray diffraction (XRD), thermo-gravimetric analysis and differential thermo-gravimetric (TG/DTG) analyses. The zwitterionic surfactant could be intercalated into the interlayer spaces of montmorillonites and causing interlayer space-swelling. From XRD measurements, the amount of the surfactants loaded and the basal spacing increased with surfactant concentration and alkyl chain length. One endothermic DTG peak occurred at ~390 °C, which was assigned to the decomposition of the zwitterionic surfactant on the organo-montmorillonites from 0.2 to 0.6 CEC. When the surfactant loading was increased, a new endothermic peak appeared at ~340 °C. From the microstructures of these ZSMMs, the mechanism of zwitterionic surfactant adsorption was proposed. At relatively low loadings of the zwitterionic surfactant, most of surfactants enter the spacing by an ion-exchange mechanism and are adsorbed onto the interlayer cation sites. When the concentration of the zwitterionic surfactant exceeds the CEC of montmorillonite, the surfactant molecules then adhere to the surface-adsorbed surfactant. Some surfactants enter the interlayers, whereas the others are attached to the clay surface. When the concentration of surfactant increases further beyond 2.0 CEC, the surfactants may occupy the inter-particle space within the house-of-cards aggregate structure.

Simultaneous and sequential adsorption of crystal violet and 2-naphthol onto montmorillonite: a microstructural and thermodynamic study.

Thermodynamic analysis of simultaneous and sequential adsorption of crystal violet (CV) and 2-naphthol adsorption on montmorillonite has been conducted, and the changes of microstructure of the clay after adsorption were investigated using X-ray diffraction (XRD). The basal spacing and structural order of CV and 2-naphthol adsorbed montmorillonites varied with different CV loadings. In principle, larger basal spacing was resulted from a higher loading of CV in montmorillonites. The excellent structural order of the resultant hybrids is achieved in samples with 0.50-0.75 CEC (cation exchange capacity) loadings of CV. The effects of temperature and ionic strength on the adsorption of CV and 2-naphthol on montmorillonite were also investigated. The Freundlich isotherm model was applied for curve-fitting of the equilibrium isotherm data. The resulting thermodynamics parameters suggested that the sorption process was a spontaneous exothermic process in the case of low CV concentrations. The negative values of Gibbs free energy in all of the adsorption processes indicated that these processes are spontaneous processes. With the increase of CV concentration, the sequential adsorption of 2-naphthol onto montmorillonite proved to be an endothermic process.

Silylation of layered double hydroxides via a calcination-rehydration route.

Silylated layered double hydroxides (LDHs) were synthesized through a surfactant-free method involving an in situ condensation of silane with the surface hydroxyl group of LDHs during its reconstruction in carbonate solution. X-ray diffraction (XRD) patterns showed the silylation reaction occurred on the external surfaces of LDHs layers. The successful silylation was evidenced by (29)Si cross-polarization magic-angle spinning nuclear magnetic resonance ((29)Si CP/MAS NMR) spectroscopy, attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy, and infrared emission spectroscopy (IES). The ribbon shaped crystallites with a "rodlike" aggregation were observed through transmission electron microscopy (TEM) images. The aggregation was explained by the T(2) and T(3) types of linkage between adjacent silane molecules as indicated in the (29)Si NMR spectrum. In addition, the silylated products show high thermal stability by maintained Si related bands even when the temperature was increased to 1000 degrees C as observed in IES spectra.

Simultaneous sorption of crystal violet and 2-naphthol to bentonite with different CECs.

This work was to examine the feasibility and efficiency to use bentonite for simultaneous removal of cationic dyes and hydrophobic organic carbons (HOCs) from water. The sorption capacities of crystal violet (CV) on two bentonites and one activated carbon were compared. Simultaneous sorption of CV and 2-naphthol on the two bentonites were tested, and the removal efficiencies of 2-naphthol by the simultaneous sorption method and by CV modified bentonite was also compared. The experimental results in this study showed that the bentonite is more effective in sorption of CV than the activated carbon. With the sorption of CV, bentonite surfaces were altered from hydrophilicity to hydrophobicity, and thus 2-naphthol could be simultaneously removed. The aromatic effect between CV and 2-naphthol was supposed to be the primary driving force for the sorption of 2-naphthol. The simultaneous sorption method was shown to be more effective in the sorption of 2-naphthol than the CV modified bentonite. Results of this work could provide novel information for the treatment of wastewater containing both cationic dyes and HOCs.