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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.
Show more [+] Less [-]Adsorption of U(VI) in Solution by Biochar and FeS Nanoparticles
2021
Xitong Zheng, Long Fu, Hao Deng, Keyuan Huang, Tianqi Liu, Yulin Deng, Jiaming Luo, Miao Xiang, Anjie Wang, Muqing Qiu, Li Han and Hai Wang
Uranium (U) is a common radionuclide in soil and groundwater. Uranium contamination often results from uranium mining and processing, nuclear energy power plants, nuclear weapon tests and nuclear accidents. Due to its toxicity and bioaccumulation, it was necessary to treat it effectively. Biochar and FeS nanoparticles were prepared for the treatment of U(VI) in solution. The characteristics of biochar and FeS nanoparticles were determined by Scanning Electron Microscopy, Energy Dispersive Spectrum and Fourier Transform Infrared Spectroscopy and BET adsorption method. The results showed that a large number of functional groups were present on the surface of biochar and FeS nanoparticles. The influencing factors, such as contact time, pH of the solution, initial concentration U(VI) and solution temperature, had an important influence on the adsorption capacity of U(VI) by biochar and FeS nanoparticles.
Show more [+] Less [-]The Construction of Magnetic MnFe2O4@TpPa-1 Composite Materials and the Adsorption Removal Performance of Organic Pollutants in Solution
2021
Wang, Shuai | Wang, Huifang | Hu, Luzeng | Lu, Zhipeng | Qiu, Muqing | Zhong, Xin
MnFe2O4@TpPa-1 adsorbent was developed by co-precipitation and solvothermal method, using ?-ketoenamine linked covalent organic frameworks (COFs, TpPa-1) as supporting material to alleviate the aggregation of MnFe2O4. The properties were characterized by XRD, FT-IR, SEM, TEM, VSM, pHpzc, and N2 adsorption-desorption. The experimental results showed that the pseudo-second-order and Langmuir model best described the adsorption process, suggesting that the adsorption process was chemisorption and spontaneous endothermic reaction, and the maximum adsorption capacity of Bisphenol A (BPA) was 926.65 mg.g-1. The main adsorption mechanism of BPA was hydrogen bonding and ?-? conjugation between active functional groups in the TpPa-1 skeleton and BPA. Furthermore, the magnetic MnFe2O4@TpPa-1 showed good regeneration ability, indicating that MnFe2O4@TpPa-1 could be used in water treatment.
Show more [+] Less [-]Kinetics of Adsorption of Reactive Red 120 Using Bentonite Modified by CTAB and Study the Effect of Salts
2021
Hasan Fadhil Al Rubai, Ahmed Khudhair Hassan, Muntadhar Salih Sultan and Waleed Mohammed Abood
Commercial bentonite was activated by aluminium hydroxide and then modified by cetyl trimethyl ammonium bromide (CTAB). The properties of modified bentonite were diagnosed using FTIR, X-ray diffraction and SEM. The adsorption of Reactive Red 120 (RR120) onto supported bentonite (B.A.CTAB) was investigated. The influence of various experimental parameters, such as temperature, initial concentration of dye, adsorbent dosages, initial pH and inorganic salts on RR120 removal was studied. The results showed that the optimum conditions for dye adsorption on modified bentonite are: temperature = 303k, pH = 3.5, contact time = 10 min, adsorbent dosage = 0.1 g and RR120 concentration 96 mg.L-1, it achieved a removal efficiency of 91%. The pseudo-second-order version yields a higher fit to the experimental facts than the pseudo-first-order model. The consequences revealed that Langmuir version turned into extra appropriate to explain RR120 adsorption than the Freundlich model. Also, the thermodynamic function such as ΔG°, ΔH° and ΔS° was evaluated. The consequences of various inorganic anions (which included Cl–, SO42-, CO32-, and so forth.) on the removal activity of RR 120 adsorption on modified bentonite was examined.
Show more [+] Less [-]Effect of Pyrolysis Temperature on Adsorption Characteristics of Biochar Derived from Corn Straw
2021
Jing Dai, Ruolin Xu, Wangying Li, Yulin Li, Yang Yang, Yang Xiao, Huan Mao, Muqing Qiu, Hai Wang, Ningcan Yang and Li Han
With the growth of population and the rapid development of industry, a large amount of wastewater containing heavy metals has been produced. How to treat wastewater containing heavy metals effectively is an important problem. In this study, biochar derived from corn straw is prepared at different carbonization temperatures by oxygen-limited carbonization, and finally, biochar derived from the corn straw at different temperatures is obtained. Then, the adsorption characteristics of ionic heavy metal copper in aqueous solution were studied by biochar prepared at different temperatures. Adsorption kinetics of copper in aqueous solution by biochar from corn straw is discussed in detail. Experimental results show that the adsorption capacity of Cu2+ ions in solution by biochar prepared at different temperatures is significantly different. The prepared biochar derived from corn straw is a fragmentary and porous structure. A lot of functional groups appear on the prepared biochar. The pseudo second order kinetic equation can better describe the entire adsorption of Cu2+ ions in solution by biochar prepared under different temperatures. The adsorption process of Cu2+ ions by biochar is controlled by liquid diffusion and intraparticle diffusion.
Show more [+] Less [-]Novel Approaches Towards Sustainable Management of an Agricultural Residue - The Rice Husk
2021
A. Geethakarthi
Recent developments in the reuse of agricultural residues/resources have led to environmental sustainability and cleaner technology emphasizing the utilisation of natural resources. Novel approaches to sustainable and energy conservations inter-relates the scientific and practical applications employed in engineering solutions. The increasing importance of biomass had led to an acute need for mitigating global sustainable problems. In the third world economics, Rice Husk (RH) collected from rice milling industry is considered as one of the abundant and invaluable agro-based residues. A focus on industrial food production and its sustainability is due to the generation of huge quantity of RH. The improper handling and disposal management of RH has resulted in environmental and population health risk, due to its large space occupancy and leaching. The effective utilization and study of rice husk in various industrial applications such as construction industry, energy production, water purification and soil stabilization have shown acceptable results. This review discusses the current research works focussing on the suitability of RH and its ash over a wide field of applications. Silica being the dominant content in RH and Rice Husk Ash (RHA) has attracted interest among the researchers to develop it into high strength composite materials, porous nanomaterials, a precursor of renewable energy and soil stabilising biochars. Replacement of fine aggregates with RHA has improved the strength and durability of the concrete. The RHA is also developed into an adsorbent and coagulant in water purification. The binding between the ions present in impure water and highly reactive silica bond enhances the removal efficiencies of metal ions in water treatments. Very few researches are carried out using RH compared with the pyrolyzed RHA as an alternative. This paper highlights the various field of RH applications and suggests composting of RH with nitrogen-rich garden waste to obtain an enriched soil stabilizing product with high nutrient and organic value. This approach would restore RH in its the place of generation, thereby improving the economic value of the agricultural mass and sustainable way of living.
Show more [+] Less [-]The Physicochemical Characteristic of Activated Carbon Based on Sludge and Preparation Method
2021
H. Lu, F. Luo, Q. Zhang, J. Li and L. Cai
To understand the features and best preparation of sludge activated carbon (SAC), and the pore structure, component, adsorption characteristics, and the yield rate of SAC, many tests have been carried out. The study illustrated that the pore structure was mostly mesopore and amorphous pore such as the ink bottle hole. In terms of different preparations to obtain SAC, the yield of SAC in sample No.1 achieved 88.09%. Using the preparation of ZnCl2 as an activator, the iodine adsorption value was significantly higher than other preparations. However, the content of quartz in sample No.1 achieved a maximum of 52.51%. Charcoal was detected in all samples except sample nos 9-12. The adsorption capacity of Cu(II) and Cd(II) reached a maximum of 600.02 mg.kg-1 and 383.2 mg.kg-1. The results showed an optimum preparation condition, which was by using the ZnCl2 as an activator, 2:1 as the impregnated ratio, 40% concentration in activator and at 400?C reaction temperature could create rich pore structure and charcoal inside.
Show more [+] Less [-]Removal of Various Contaminants by Highly Porous Activated Carbon Sorbent Derived from Agricultural Waste Produced in Malaysia - A Review
2021
N.Z. Zabi, W.N. Wan Ibrahim, N.S. Mohammad Hanapi and N. Mat Hadzir
This paper aims to review recent studies in preparing activated carbons from different types of agricultural wastes in Malaysia and how it can help Malaysia manage agricultural waste. It can be seen that most biomasses can be used as precursors to produce activated carbon for a wide range of pollutants and this adsorbent can be modified to optimally function depending on the types of pollutants. Under optimum dosages, modification through chemical activation using acidic, basic, or drying agents has significant effects on the selectivity of the analyte adsorption. The acidic activating agent causes the activated carbon to have negatively charged acid groups which enable it to adsorb cationic adsorbate while the basic activating agent causes the adsorbent to have a positive surface charge and enable it to adsorb anionic adsorbate.
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