Preparation of activated carbon from Camellia oleifera shell and its application to adsorption of hexavalent chromium from aqueous solution: kinetics, equilibrium, and thermodynamics

2020 ◽  
Vol 198 ◽  
pp. 170-179
Author(s):  
Zhigong Zheng ◽  
Haoyue Zhao ◽  
Xuehui Lin ◽  
Jinbei Yang ◽  
Ronghui Shi
2020 ◽  
Vol 82 (11) ◽  
pp. 2592-2602
Author(s):  
Zhengji Yi ◽  
Jian Liu ◽  
Rongying Zeng ◽  
Xing Liu ◽  
Jiumei Long ◽  
...  

Abstract Camellia oleifera shell-based activated carbon (COSAC) was prepared by H3PO4 activation method and further used to remove U(VI) from the aqueous solution in a batch system. This research examined the influence of various factors affecting U(VI) removal, including contact time, pH, initial U(VI) concentration, and temperature. The results showed that the U(VI) adsorption capacity and removal efficiency reached 71.28 mg/g and 89.1% at the initial U(VI) concentration of 160 mg/L, temperature of 298 K, pH 5.5, contact time of 60 min, and COSAC dosage of 2.0 g/L. The pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations were used to identify the optimum model that can describe the U(VI) adsorption kinetics. The pseudo-second-order kinetics model performed better in characterizing the adsorption system compared with the pseudo-first-order and intraparticle diffusion models. Isotherm data were also discussed with regard to the appropriacy of Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models. The Langmuir model described the U(VI) adsorption process the best with a maximum adsorption capacity of 78.93 mg/g. Thermodynamic analysis (ΔG0 < 0, ΔH0 > 0, and ΔS0 > 0) indicated that the U(VI) adsorption process is endothermic and spontaneous. All the results imply that COSAC has a promising application in the removal or recovery of U(VI) from aqueous solutions.


2021 ◽  
Vol 12 (1) ◽  
pp. 1247-1262

This research work involved using factorial experimental design techniques to investigate the adsorption of hexavalent chromium from an aqueous solution on medlar activated carbon. A 24 full factorial experimental design was employed to determine the optimum values and degree of importance of parameters: pH, initial Cr (VI) concentration, adsorbent dose, and contact time at two levels. The optimized conditions for hexavalent chromium Cr (VI) removal were at initial pH 1.5, 5 mg.L−1Cr (VI), adsorbent dose 6 mg, and 60 min adsorption time. The results predicted a good agreement between the predicted values (R2= 0.9909), as obtained by the model, and the experimental value (R2= 0.9977). The main effects and interaction effects were analyzed using analysis of variance (ANOVA), F-test and P-values to define the most important process variables affecting Cr (VI) adsorption. The most significant variables were therefore the pH of the solution and the adsorbent dose. Therefore, the present results demonstrate that medlar activated carbon should be regarded as a low-cost alternative for removing Cr (VI) from an aqueous solution. The adsorption data were evaluated by Langmuir, Freundlich, and Dubinin-Radushkevich isotherms. The results showed that the Langmuir isotherm model best describes the equilibrium adsorption with a high correlation coefficient.


2012 ◽  
Vol 16 (6) ◽  
pp. 2179-2186 ◽  
Author(s):  
Juntao Zhang ◽  
Liangyu Gong ◽  
Kang Sun ◽  
Jianchun Jiang ◽  
Xiaogang Zhang

RSC Advances ◽  
2015 ◽  
Vol 5 (32) ◽  
pp. 25389-25397 ◽  
Author(s):  
Zhengjiang Jiang ◽  
Yunguo Liu ◽  
Guangming Zeng ◽  
Weihua Xu ◽  
Bohong Zheng ◽  
...  

Polyacrylonitrile (PAN)-based activated carbon fibers (PAC400 and PAC600) were prepared by heating Zn(NO3)2 pretreated-PAN at 400 °C and 600 °C for the removal of Cr(vi) from aqueous solution.


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