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Effects of TiO2/Bentonite on the Pyrolysis Process of Oily Sludge
2021
Feifei Wang, Huan Zhang, Mingming Du, Jinling Li, Penghui Yang, Tao Yu, Yijun Wang and Chengtun Qu
Oil sludge is one of the major industrial solid wastes from petroleum production and refining. Implementing the harmless and resource treatment of oily sludge is an urgent problem to be solved. In this paper, TiO2/bentonite was prepared by sol-gel method, which was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FT-IR), and then used in the pyrolysis process of oily sludge. The addition of TiO2/bentonite give the best quality of pyrolysis oil; maximum oil recovery was achieved when setting the pyrolysis condition at 420°C for final pyrolysis temperature, 3 h for reaction time, 10°C/min for heating rate, 100 mL/min for nitrogen flow rate and 1% for catalyst dosage. Compared with the non-catalyst, oil recovery rate can be increased from 76.06% to 84.16%, the oil content of the residue decreased from 2.23% to 1.36%. The pyrolysis recovery oil was analysed by GC-MC, and the fractions of pyrolysis oil C6-C15 were increased by 27.84%. This shows that the addition of TiO2/bentonite decreased the carbon residue, increased oil recovery and improved product quality.
Mostrar más [+] Menos [-]Performance and Mechanism of Layered Double Hydroxide to Remove Graphene Oxide in Aqueous Solution
2021
Haibo Kang, Jiahui Gu, Gang Liu, Ben li and Wei Wang
Intending to remove toxic graphene oxide (GO) from wastewater, LDH (layered double hydroxide) was employed to recover GO by adsorption method. The adsorption performance and the mechanism of LDH for GO have been systematically studied by diverse characterization technologies and methods. The relevant effects of solution pH (2-9), absorbent dosage (5-25mg) and the concentration of GO (20-160mg/L) were investigated in detail. The main driving force of GO condensation on LDH may be electrostatic interaction and hydrogen bonding, SEM, TEM, AFM, FT-IR and XRD analysis further confirmed this. XPS test shows that the adsorption process is carried out through C−O and O−C=O. We have got a high removal rate of 92% and an adsorption capacity of 1472 mg/g under an optimized conditions (pH = 3.0, equilibrium time = 6.0 h, dosage = 10mg, C0 = 160 mg/L). The analyses implied that LDH will be a very promising candidate for recovery of GO from wastewater.
Mostrar más [+] Menos [-]Accumulation and Translocation of Chromium (Cr) and Lead (Pb) in Chilli Plants (Capsicum annuum L.) Grown on Artificially Contaminated Soil
2021
F. Ahmed, A. N. M. Fakhruddin, Z. Fardous, M. A. Z. Chowdhury, M. M. Rahman and M. M. Kabir
The current study is an endeavour to measure the bioaccumulation potentials of heavy metals in different parts of chilli plants (Capsicum annuum L.) grown in artificially contaminated soil with various concentrations of Cr and Pb. The concentrations of heavy metals were estimated by Atomic Absorption Spectroscopy (AAS) technique. The mean concentration of Cr and Pb accumulated in different parts of plants in high, medium, and low levels of contamination was in the following order: roots > leaves > shoots > fruits. Cr concentration in fruits was lower than that of the WHO standard. However, fruits grown on medium contaminated soil contained 0.695 mg/kg Cr which did not follow the safe guideline by SEPA. A significant amount of Pb was traced in fruits grown in highly contaminated soil that exceeded the standard limit set by FAO/WHO. Accumulation of Pb was higher than Cr at different levels of contamination in every part of the chilli plants. The transfer factor for Cr and Pd was found in the following order, leaves > shoots > fruits> roots and leaves > shoots > roots > fruits, correspondingly at every level of contamination. The bioconcentration factors were higher in Pb than Cr. The daily intake of metals in combination with health and carcinogenic risk indexes indicated that the edible parts of chilli plants are safe to consume as recommended by SEPA/WHO/FAO. The present study can be considered a reference for assessment and monitoring of heavy metals associated with human health risks in chilli plants at different industrially contaminated sites.
Mostrar más [+] Menos [-]SEM-EDAX analysis of the Soil Samples of River Yamuna in Delhi
2021
Vivek Chopra and Jai Gopal Sharma
A total of 18 samples were collected from two different sites at different depths of Yamuna river bed in Delhi. Nine samples were collected at Site A (Palla Village) from three different locations at different depths of the river bed. A similar set of 9 samples were collected from Site B (Okhla barrage). All samples were analysed for atomic and weight percentage of elements using SEM-EDAX. The major elements found in the study were Si, O, Al and Nb. Si and O are found in a maximum amount in all the samples with a varying range of atomic percentage 25.3-89.27 and 55.09-95.78 respectively. The recorded atomic percentage of Nb was 0.32 while Al was 16.7-25.51. Site A, Palla is least affected by pollution while at Site B the presence of Al revealed contamination from pollutants. The weight percentage of the elements has also been calculated. SEM images of soil samples revealed the platy flakes, irregular and spongy structure of soil particles.
Mostrar más [+] Menos [-]Physiological Response of Juvenile Schizothorax prenanti under Supersaturated Stress
2021
Quan Yuan, Kefeng Li, Ruifeng Liang, Yuanming Wang, Jingjie Feng, Qianfeng Ji and Yaodan Zhang
Supersaturated water can adversely affect many species of fish and can sometimes lead to death. In the present study, we established an experimental platform on the downstream section of the Dagangshan Hydropower Station on the Dadu River. During flood discharge at the Dagangshan Hydropower Station, the river water supersaturation concentration at the experimental site was monitored, and a unique fish in the river section was selected for a cage experiment. Juvenile fish die under the 110% gas supersaturation conditions in the river, accompanied by symptoms of bubble disease. After the end of flood discharge, the remaining experimental fish were placed in clean water for approximately 180 days, and all the fish died. Exposing the experimental fish to a 127% concentration test tank in the laboratory revealed that the onset of death, semi-lethal time and total death time were 6.7 hours, 12 hours, 31.5 hours, respectively. The test fish that were exposed to supersaturated water for 6 hours were placed in clean water and tested every hour, and the change was minimal. Six-hour exposure may cause irreversible damage to the experimental fish.
Mostrar más [+] Menos [-]Fish Community Structure and Ecological Health Assessment of the Shuaishui River Basin, China
2021
Y. X. Fang, G. J. Liu and R. J. Liu
The Shuaishui River originates from the southern mountainous area of Anhui Province and is an important water source for local residents. The ecological environment of this basin has been seriously damaged because of the effects of human disturbance. In August 2016, a field study of five units of the Shuaishui River Basin was conducted to understand the fish community structure and assess the ecological health status. A total of 43 fish species were collected from the entire river basin, and they belonged to 4 Orders, 10 Families, and 31 Genera. The maximum number of species belonged to the family Cyprinidae, and the main trophic guild was omnivorous fish. Among the five units, species number was the highest in unit 2 (27 species) and the lowest in unit 3 (12 species). The dominant species in the five units were mainly typical mountain-stream fish, such as Zacco platypus, Acrossocheilus fasciatus, and Vanmanenia stenosoma. In some areas, Varicorhinus barbatulus or Rhinogobius cliffordpopei also showed great dominance because of the impacts of the local habitat conditions. Redundancy analysis showed that altitude, water velocity, stream order, and water surface width were the main factors that influenced the distribution and species composition of the fish. Eigenvalues of the first two axes were 0.183 and 0.082 and explained 40.9% and 18.3% of the species-environment relationship variables, respectively. The ecological health of the five units and the entire basin was assessed based on the arithmetic mean of three indicators, namely, number of classification units, Shannon-Wiener index, and Berger-Parker dominance index. The results indicated that the ecological health status was relatively poor in unit 3, general in units 1 and 5, and good in units of 2 and 4. The status of the entire basin was general. To the best of our knowledge, this is the first comprehensive assessment of the ecological health of the Shuaishui River Basin, and it has great significance for the ecological management and protection of this basin.
Mostrar más [+] Menos [-]Electronic Waste Recycling Mode and Control Measures in China Based on PEST and SWOT
2021
Linsheng Wang and Wei Yang
The service life of electronic (e-) products is decreasing gradually due to the continuous improvement of manufacturing technologies and increasing prices and performance of these products, thereby accelerating the growth of e-waste. Only a small proportion of e-waste is disposed of according to standards in China. Due to a contradiction between high output and low disposal, environmental pollution and resource waste caused by e-waste intensify daily. To further analyze the e-waste recycling mode from a macroscopic level and thereby propose specific control measures, we first reviewed studies on e-waste recycling modes and control measures in foreign developed countries. Second, the e-waste recycling mode in China was analysed through political, economic, social and technological (PEST) and strengths, weaknesses, opportunities and threats (SWOT) models in combination with practical situations in China. Finally, e-waste control measures were proposed from various perspectives. Results show that the ambiguous definition of responsibilities for different e-waste disposal subjects in China has led to serious environmental pollution. This pollution, the extensive waste of natural resources, and frequent occurrence of social crises are three consequences of environmental pollution caused by e-waste in China. All four factors in the PEST model have laid the foundation to accelerate e-waste recycling in the country. Environmental pollution caused by e-waste can be relieved by perfecting relevant laws and regulations for e-waste recycling and disposal; establishing and perfecting the punitive system for e-waste recycling corporate responsibility; strengthening technological support, promotion, and education on e-waste recycling; and increasing the market supervision efforts and manufacturers’ consciousness of responsibility. Research conclusions can provide important references to analyze e-waste status, achievements, challenges, and existing problems in disposal as well as their causes. These factors can also propose countermeasures and suggestions in e-waste disposal in accordance with practical situations in China based on insights into the experiences of foreign countries with a typical level of development.
Mostrar más [+] Menos [-]Phytochemical Evaluation, FT-IR and GC-MS Analysis of Leaf Extracts of Pergularia daemia
2021
M. Maheshwari and P. Vijayarengan
Pergularia daemia is traditionally used to treat various ailments like anthelmintic, antipyretic and expectorant and to treat infantile diarrhoea, malarial intermittent fever, asthma, mental disorder, toothache and cold. In the present study leaf extracts of P. daemia was subjected to qualitative phytochemicals, GC-MS and FT-IR analysis. The quantitative analysis of the leaves showed the presence of flavonoids, steroids, alkaloids, terpenoids, saponins, phenols, carbohydrates, amino acids, tannins and cardiac glycosides. The GC-MS study of methanol extract revealed 16 compounds. Some major compounds identified are 9-Octadecenoic Acid (E), Cis- Vaccenic Acid, N-Hexadecanoic Acid, 1- Dimethyl (Butyl), Silyl Oxy Butane along with other minor constituents. FT-IR analysis revealed the presence of 12 functional groups such as amines, alkanes, carbon dioxide and alkynes. The results suggested that P. daemia contains significant photo components and can be used as a source for many pharmacological studies and a curative for various ailments.
Mostrar más [+] Menos [-]Effect of Chlorpyrifos 50% + Cypermethrin 5% EC on Eisenia fetida Exposed in Coco Peat and Sphagnum Peat
2021
A. Rajini and K. Revathy
Toxicity effect of Chlorpyrifos 50% + Cypermethrin 5% EC to terrestrial invertebrate Eisenia fetida in two different sphagnum peat substituted soil was assessed. Artificial soil substrate for earthworm toxicity test comprises of 70% sand, 20% clay and 10% sphagnum peat. In this study, coco peat was used as an alternative substitute for sphagnum peat. The LC50 was 83.7 mg/kg for coco peat and 76.3 mg/kg for sphagnum peat soil. No significant difference was observed in mortality and biomass between the two soil substrates, but a significant difference was observed in the reproduction. Based on the observations, it is concluded that coco peat can also be used as an alternative to sphagnum peat in toxicity studies.
Mostrar más [+] Menos [-]Study on the Effects of Sewage Irrigation on Soil
2021
Xiuli Li and Xu Wu
The long-term use of sewage to irrigate farmland will increase the content of heavy metals in the soil and cause soil pollution. Heavy metal pollution in soils will restrict the sustainable development of local agriculture and will have a negative impact on the ecological environment. In this paper, the irrigation areas using domestic sewage, mixed sewage and industrial sewage as an irrigation water source for many years have been selected as the research objects, and the content of the heavy metals lead (Pb), copper (Cu), zinc (Zn) and cadmium (Cd) in the soil with the depth of 0-20cm, 20-50cm and 50-80cm of three kinds of sewage irrigation areas are assessed using single factor pollution index method and Nemerow comprehensive index method, and the potential ecological risks of heavy metals in the soil are assessed using Hakanson ecological risk index method. The results show that the content of heavy metals Pb, Cu, Zn and Cd in different depths of the three sewage irrigation areas does not exceed the national standard limit, and the heavy metal pollution grade in the soil belongs to the safety grade, indicating that the content of heavy metals in the soil has not reached the alert level. The potential ecological risks of heavy metals in the soil show minor ecological risks judging from single indexes, while Cd shows that the ecological risks are at a strong level. Judging from the comprehensive potential ecological risk index, the potential ecological risks of the heavy metals in the study area is minor in graded, but the heavy metals in the soil of the mixed sewage irrigation area and the industrial sewage irrigation area have a moderate grade of potential ecological risks at the depth of 50-80 cm. Therefore, although the content of the heavy metals in the soil of the three kinds of sewage irrigation areas in the study area is safe, the potential ecological risk of Cd is quite high, which should be paid attention to.
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