خيارات البحث
النتائج 2241 - 2250 من 5,014
Comparison for the Adsorption of Catechol and Hydroquinone on Activated Carbon Fibre: Kinetic Analysis النص الكامل
2019
Mingzhao Shen, Meiya Zhu, Jintao Sun, Yunlong Zhang, Rong Li, Fang Niu, Shiying Li, Xiao Mi and Guoting Li
Catechol and hydroquinone are widely applied in industrial synthesis while they are typical toxic organic pollutants. Efficient adsorptive removal of catechol and hydroquinone is highly needed. In this research, activated carbon fibre (ACF) was used for the kinetic removal of the two pollutants. As catechol and hydroquinone have different pKa values, it was found that the highest uptake of catechol and hydroquinone was observed at pH 11.0 and 5.0, respectively. The adsorption kinetics for catechol and hydroquinone were compared. The removal of hydroquinone is higher than that of catechol at almost all the pH conditions. At pH 7.0, the uptake of catechol and hydroquinone on ACF were 125.8 and 200.4 mg/g, respectively. As both Elovich and pseudo-second-order kinetic models could better describe the adsorption process, the adsorption of catechol and hydroquinone onto ACF might be chemisorption. The rate determining step might be diffusive in nature for the uptake of catechol and hydroquinone. Linear pseudo-second-order kinetic model fitted the experimental data better than pseudo-first-order kinetic model. The presence of natural organic matter, humic acid, could inhibit the uptake of catechol and hydroquinone on ACF profoundly.
اظهر المزيد [+] اقل [-]Regeneration of Wind Power Waste Lubricating Oil by a Combination Use of Chitosan, Sodium Carbonate and Silica Gel النص الكامل
2019
Yanli Zhu, Youxian Zhang, Zhongyang Shi and Bo Li
Waste lubricant oil can be regenerated by flocculation and adsorption to get rid of impurities. In this work, the performance of flocculants (chitosan, sodium carbonate and sodium silicate) and sorbents (carclazyte and silica gel) were evaluated experimentally. The results showed that the combination of chitosan and sodium carbonate had beat results in removal of acid value and mechanical impurities. Silica gel contacting adsorption had the best colour removal. Thermal precipitation (80°C, 24h) was adopted as primary step before flocculation to wipe off heavier particulate matter. The best ratio of chitosan, sodium carbonate and silica gel was 1:1:1, and the best dosage of chitosan was 2% compared to oil. After the re-refining process, viscosity decreased from 186.34 (mm2/s, 40°C) to 155.21 (mm2/s, 40°C), the acid value from 0.26 (mg KOH/g) to 0.06 (mg KOH/g), mechanical impurities content from 3.62% to 1.41%, water content from 0.45% to 0.06%, and light absorbance from 4.31 to 1.17.
اظهر المزيد [+] اقل [-]Development of Hybrid Membrane from Clay/TiO2 -PVA for Batik Wastewater Treatment النص الكامل
2019
Anwar Ma’ruf, M. Agus Salim Al Fathoni, Agus Mulyadi Purnawanto and Rina Asih Kusumajati
Hybrid membranes are currently being developed to find the membrane that is having good chemical and thermal resistance. This research devotes to the development of hybrid membrane from clay/TiO2 with PVA polymer and its application for colour wastewater filtration. The results show that the optimum concentration of PVA is 5%. At this condition, the hybrid membrane has a bulk density of 2 g/cc and porosity of 23.13%. The hybrid membrane produces the coefficient rejection of 79.48%. At the higher concentration of PVA, the filtration becomes not effective because the flux of membrane is very low.
اظهر المزيد [+] اقل [-]Simultaneous Removal of Cu(II) and 1-Naphthol in Wastewater by Magnetic Nanoparticle-Graphene Oxide Composites النص الكامل
2019
Jie Luo, Donglin Zhao, Linxia Wang, Abdullah M. Asiri and Khalid A. Alamry
A graphene-based magnetic composite (Fe3O4/GO) was prepared and used for simultaneous removal of Cu(II) and 1-naphthol. The composite was characterized by SEM, TEM, XRD, FT-IR and Raman. Electron microscopy reflected that Fe3O4 spheres were dispersed on graphene layers. The pseudo-second-order kinetic and Langmuir isotherm models could best describe the sorption kinetics and isotherms. The sorption of Cu(II) and 1-naphthol increased with increasing temperature, and thermodynamic parameters calculated from temperature dependent sorption revealed that sorption of Cu(II) and 1-naphthol on Fe3O4/GO was spontaneous and endothermic. The results indicated that Fe3O4/GO can be utilized as potential adsorbents for purification of co-contaminated water systems.
اظهر المزيد [+] اقل [-]Development of Crown Profile Models for Chinese Fir Using Non-linear Mixed-Effects Modelling النص الكامل
2019
Chengde Wang, Baoguo Wu, Yuling Chen and Yan Qi
Crown profile models are key components of growth and yield models and are crucial for estimating the crown volume and constructing 3D visualization of trees. We used a total of 431 trees collected from 98 pure even-aged temporary sample plots established in Fujian Province to develop crown profile models of Chinese fir (Cunninghamia lanceolata).To describe the shape of tree crowns more accurately, significance tests of the effects of different stand conditions (stand age, site index, and stand density) on crown shape were conducted with one-way analysis of variance (ANOVA). Multiple comparisons based on the ANOVA results were used to classify the crown data into three groups according to stand age: Group I (young forest), Group II (medium forest), and Group III (nearly mature and mature forest). We analysed the relationships between the crown variables and stand variables and used the reparameterization approach to develop three optimal crown profile models for different age groups. Stand variables (such as stand density) further improved the prediction efficacy of the models. Considering the correlation between repeated measurement data for the same tree crown, the non-linear mixed-effects modelling (NLME) method was used to account for autocorrelation. The determination coefficients (R2) of the above three optimal models fitted by the non-linear mixed-effects approach were 0.9214, 0.9398 and 0.9129, and their Root Mean Squared Errors (RMSEs) were 0.1246, 0.1409 and 0.1786, respectively. The determinant coefficients (R2) of the three models fitted by the nonlinear least squares (NLS) approach were 0.9015, 0.8794 and 0.8930, and their RMSEs were 0.1395, 0.2102 and 0.1878, respectively. The results indicated that the predicted accuracy was significantly increased by using non-linear mixed effects modelling compared with the NLS method.
اظهر المزيد [+] اقل [-]Environmental Pollution Caused by the Transportation Industry and Influencing Factors of Carbon Emission: A Case Study of Jiangxi Province, China النص الكامل
2019
Yating Huang
With the accelerating industrialization and urbanization in China, the energy consumption of the transportation industry in the country is increasing quickly, and its proportion to the total social energy consumption is significantly growing. The transportation industry is a main source of carbon emission in urban areas. The unreasonable structure of energy consumption, the low proportion of new-energy use, and low energy utilization influence the energy-saving and emission reduction in the transportation industry. Thus, in this work, the influencing factors of transportation-induced carbon emission were estimated to analyze the environmental pollution caused by the transportation industry further. Regression analysis was performed on the environmental pollution caused by the transportation industry and the influencing factors of carbon emission in Jiangxi Province, China. Subsequently, a random STIRPAT model was constructed, and the influencing factors of carbon emission from the transportation industry in Jiangxi Province from 2007 to 2017 were analyzed through the partial least squares (PLS) method. Regression results based on the PLS method were relatively ideal. Increases in gross domestic product per capita, population size, passenger person kilometers, rotation freight transport kilometers, and the number of car ownerships can intensify transportation-induced carbon emission. This emission is increased when transportation energy intensity declines, but can be significantly inhibited by increased energy prices. The conclusions of this study can provide references for the continuous optimization of the energy use structure in the transportation industry, saving of energy resources, reduction of greenhouse gas and pollutant emission, and acceleration of low carbonization in the transportation industry.
اظهر المزيد [+] اقل [-]Assessment of Ecological Status in Seawater Around Legon Bajak Port Development Plan, Karimunjawa, Central Java, Indonesia النص الكامل
2019
Slamet Isworo and Poerna Sri Oetari
The Legon Bajak port is a strategic port in Indonesia, because it is located in a busy and potential shipping lane. The port is adjacent to the Karimunjawa Marine National Park which is protected by the Indonesian government; therefore, this study aims to provide an overview of the ecological status of the Legon Bajak sea and the prediction of the impact of port activities on the ecological status of the Marine National Park. This research is a descriptive study by analysing seawater quality using atomic absorption spectroscopic methods, the status of biodiversity of seaweed and coral reefs with the transect method at 6 observed sample points and photos of underwater marine supporters. The results of the analysis of seawater quality indicate that it is in good condition, but when viewed from the analysis of seaweed conditions and coral cover <10%, this indicates that the ecological status is in a damaged condition and a category with a low functional value. An in-depth study is needed for the analysis of the environmental impact of the Legon Bajak port on the Karimunjawa National Marine Park Conservation Area.
اظهر المزيد [+] اقل [-]Application of Single Factor and Multi-Factor Pollution Indices Assessment for Human-Impacted River Basins: Water Quality Classification and Pollution Indicators النص الكامل
2019
Gebrehiwet Reta, Xiaohua Dong, Zhonghua Li, Huijuan Bo, Dan Yu, Hao Wan and Bob Su
Anthropogenic activities are most likely to alter the natural composition of waters. Extensive phosphate mining in Huangbaihe River Basin (HRB), China, has resulted in the reduction of the self-purification capacity of freshwater reservoirs in the basin. Based on a three-year (2014-2016) water quality monitored data and the application of three pollution index assessment (PIA) methods: Single Factor Pollution Index (SFPI), Nemerow’ Pollution Index (NPI), and Water Quality Index (WQI), the main objective of this study was to determine the water quality standards of surface water in the river basin. Research findings indicated that a holistic approach, a combination of a single factor and multi factor pollution indexes (MFPIs) method was able to distinguish pollutant characteristics and used to classify water quality of the river system. Comparison of the results showed that the SFPI classification is more conservative and highly influenced by the worst evaluated index. On the other hand, the MFPIs: the NPI and the WQI methods classified the water quality into a more reasonable grade because they integrate the effects of different impacting factors. The most impaired pollutants affected the water quality classification were total phosphorus (TP) and total nitrogen (TN). Application of the PIA result for the water quality management purpose in the basin showed that there is a direct causal relationship between the TP concentration and water quality of reservoir water; low water quality reservoirs were correlated with high TP. On the other hand, the reservoir water quality did not show any significant dependence on TN. A linear regression equation was proposed to determine WQI of reservoirs’ water using measured TP. The equation may be used to characterize the pollution level of reservoir water for prioritizing water quality management measures in HRB.
اظهر المزيد [+] اقل [-]Some Studies on the Removal of Chromium from Aqueous Solutions by an Adsorbent Obtained from Terminalia chebula النص الكامل
2019
Monangi Murali, R. Srinivasa Rao and Priya Darshini Pradhan
Several methods of treatment have been suggested for the removal of chromium from raw water, which include chemical precipitation, reverse osmosis, ion exchange, foam formation, etc. The main disadvantages of the above processes are that they produce a large amount of sludge and there are no possibilities of metal recovery as they are very costly. The use of plants and other plant materials for the removal of the heavy metals has already been reported in the literature as the non-conventional adsorbents. In the present work, an attempt has been made to check the suitability of Terminalia chebula powder for removing chromium from raw water by adsorption and for suggesting an environmental friendly as well as economically feasible solution to overcome the problems due to the presence of toxic pollutants like chromium in drinking water. Batch experiments were conducted using aqueous solution of chromium to determine the chromium removal. Terminalia chebula powder (commonly known as karakkaya locally) has been collected locally and used as an adsorbent for all the batch experiments. Variation of chromium removal with dosage of adsorbent and initial pollution concentration is studied.
اظهر المزيد [+] اقل [-]Variations of Environmental Isotopes in Precipitation and Surface Water in Plain Area Influenced by Summer Monsoon: A Case Study in Jinjiang River Basin, Chengdu, China النص الكامل
2019
Chengcheng Xia, Jie Mei, Wen Liu, Jing Zhou and Guodong Liu
Monsoon is a typical wind system, which influences a quarter of continental area on the earth and is closely bound up with the life of one half of the earth’s population. Therefore, it is important to explore the information on monsoon activities. In the present study, samples of precipitation and surface water collected in the summer of 2018 were analysed to reveal the variation of stable isotopes influenced by summer monsoon and its relationship with the sources of water vapour. The temporal variation of stable isotopes in precipitation is great during the monsoon period, which is primarily the result of the varying proportions of water vapour from continental and oceanic sources. The heavy isotopes in precipitation grew gradually as the proportion of ocean-source water vapour increased from May to August. The meteorological parameters of temperature and precipitation amount are not the main factors that influence the isotopic composition in precipitation, for the determination coefficient (R2 value) is low. The isotopic characteristics of river water are similar to those of precipitation, indicating that the rivers are mainly recharged by precipitation. The temporal-spatial variations of isotopes surface water are complex for the joint influence of the distribution of isotopes in precipitation, isotopic compositions of the river source, rainfall amount and evaporation, which can be considered as the indirect effects of monsoon activities.
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