Kinetic, isotherm and thermodynamic aspects of Cu2+ biosorption onto Rosa damascena leaf as a low-cost biosorbent: Optimization of process variables by Response Surface Methodology

Author(s):  
Mustafa A. Fawzy ◽  
Hatim M. Al-Yasi ◽  
Tarek M. Galal ◽  
Reham Z. Hamza ◽  
Esmat F. Ali ◽  
...  

Abstract In this study, the Rosa damascena leaf powder was evaluated as a biosorbent for copper removal from aqueous solutions. Optimized conditions of 4.0 g/L biosorbent dosage, pH of 5.5 and initial copper concentration of 55 mg/L obtained by Response Surface Methodology were employed for Cu2+ biosorption by R. damascena leaves and up to 88.7 % Cu2+ was removed. The biosorption data were well fitted to the pseudo-second order and Elovich kinetic models. The Langmuir and Dubinin-Radushkevich isotherm models were also best fit the experimental data showing monolayer isotherm with qmax value of 25.13 mg/g obtained at optimum conditions. Thermodynamic parameters showed the spontaneity, feasibility and exothermic nature of adsorption. Scanning electron microscopy, Energy-Dispersive X-Ray, and Fourier transform infrared spectroscopy were used to characterize the biosorbent before and after Cu2+ biosorption, revealing outstanding structural characteristics and high surface functional groups availability. In addition, immobilized R. damascena leaves adsorbed 90.7 % of copper from aqueous solution, which is greater than free biosorbent (85.3 %). It can be concluded that R. damascena might be employed as a low-cost biosorbent for removing heavy metals from aqueous solutions.

Gels ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 225
Author(s):  
Katarina Antić ◽  
Antonije Onjia ◽  
Dana Vasiljević-Radović ◽  
Zlate Veličković ◽  
Simonida Lj. Tomić

The adsorption of Ni2+ ions from water solutions by using hydrogels based on 2-hydroxyethyl acrylate (HEA) and itaconic acid (IA) was studied. Hydrogel synthesis was optimized with response surface methodology (RSM). The hydrogel with the best adsorption capacity towards Ni2+ ions was chosen for further experiments. The hydrogel was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis before and after the adsorption of Ni2+ ions. Batch equilibrium experiments were conducted to investigate the influence of solution pH, hydrogel weight, ionic strength, adsorption time, temperature and initial concentration of nickel ions on the adsorption. Time-dependent adsorption fitted the best to the pseudo-second-order kinetic model. A thermodynamic study revealed that the adsorption was an exothermic and non-spontaneous process. Five isotherm models were studied, and the best fit was obtained with the Redlich–Peterson model. Consecutive adsorption/desorption studies indicated that the HEA/IA hydrogel can be efficiently used as a sorbent for the removal of Ni2+ ions from the water solution. This study develops a potential adsorbent for the effective removal of trace nickel ions.


2021 ◽  
pp. 60-68
Author(s):  
Liqaa Samir Esmail

Textile wastewater including a large number of dyes and heavy metals can have adverse impacts on human health and surface water. In this work, biosorption Toluidine Blue from aqueous media onto natural Polypourus squamosus fungi as a low-cost biosorbent was investigated. Central Composite Design (CCD) in Response Surface Methodology (RSM) was successfully applied to optimize the biosorption condition. Medium parameters affected the biosorption of Toluidine Blue were determined to be initial pH, initial Toluidine Blue (Tb) concentration, temperature, and absorbent dosage. All experiments were carried out in a batch system using 250 mL flasks containing 100 mL of Toluidine Blue solution with a temperature-controlled magnetic stirrer. The Tb concentrations remaining in filtration solutions after biosorption were analyzed using UV-Spectro. With the obtained quadratic model, the optimal conditions for maximum biosorbed Toluidine blue were calculated to be 7, 27.5 mg/L, 35°C and 0.05 g for pH, C°, T (°C) and adsorbent dosage, respectively. Furthermore, most known isotherm models such as Langmuir and Freundlich were computed to find the best-fitted model.


2021 ◽  
Vol 11 (22) ◽  
pp. 10722
Author(s):  
Abdelkader Ouakouak ◽  
Messameh Abdelhamid ◽  
Barhoumi Thouraya ◽  
Hadj-Otmane Chahinez ◽  
Grabi Hocine ◽  
...  

This study proposed a novel and low-cost adsorbent prepared from dredging sediment (DSD) for effective removal of dye in aqueous solutions. The adsorption efficiency and behavior of the DSD adsorbent toward the crystal violet (CV), a cationic dye, were investigated via batch experiments. The results showed that DSD samples contain mainly clay minerals (illite and kaolinite) and other mineral phases. In addition, DSD is a mesoporous material (Vmesopore = 94.4%), and it exhibits a relatively high surface area (~39.1 m2/g). Adsorption experiments showed that the solution’s pH slightly affects the adsorption process, and a pH of 11 gave a maximum capacity of 27.2 mg/g. The kinetic data of CV dye adsorption is well described by the pseudo–second-order and the Avrami models. The Langmuir and Liu isotherm models provide the best fit for the adsorption equilibrium data. The monolayer adsorption capacity of Langmuir reached 183.6, 198.0, and 243.6 mg/g at 293, 308, and 323 K, respectively. It was also found that the adsorption process was spontaneous (−ΔG°), exothermic (−∆H°), and increased the randomness (+∆S°) during the adsorption operation. The primary mechanisms in CV dye adsorption were ion exchange and pore filling, whereas electrostatic attraction was a minor contribution. In addition, three steps involving intraparticle diffusion occur at the same time to control the adsorption process. The results of this study highlight the excellent efficiency of DSD material as an ecofriendly sorbent for toxic dyes from water media.


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