Adsorptive removal of Pb(II) and Zn(II) from water onto manganese oxide-coated sand: Isotherm, thermodynamic and kinetic studies

The potentiality of tea stem for the adsorption of methylene blue (MB) from aqueous phase was investigated. A series of operating factors, including the initial MB concentration, contact time, pH of solution, dose of tea stem, and ionic strength of solution, were conducted to understand the effect of adsorption of MB onto tea stem. Adsorption isotherm, kinetic models, thermodynamic investigation, and regenerability of tea stem were systematically investigated in this study. The experiment results revealed that the removal efficiency decreased with MB concentration and the equilibrium time of adsorption at different initial MB concentrations was approximately at 60 min. The appropriate dose of tea stem powder was found to be 4 g/L. The pHzpc of tea stem was evaluated and was observed to be 6.0 ± 0.2. The removal efficiency increased with pH ranging from 3.0 to 5.0 and remained constantly at the pH range of 5.0–11.0. The pH affected the adsorption because of the repellent power between H+ and dye cation. The ionic strength was found to have a negligible effect on the adsorption. The Langmuir and Temkin isotherm models were found to be the best isotherm models to elucidate the adsorption mechanism between MB and tea stem powder. The maximum adsorption capacity of 103.09 mg/g derived from the Langmuir model was much close to the experimental result. From the kinetic analysis, the pseudo-second-order model was found to be the suitable model to describe the adsorption behavior. The calculated adsorption capacities at different temperatures derived from the pseudo-second-order model ranging from 68.91 to 69.8 mg/g were well close to the experimental data. The intraparticle diffusion of MB molecules into pore structures of tea stem powder is the rate-limiting step for the adsorption process in this study. Evaluation of thermodynamic parameters including changes in enthalpy, entropy, and Gibb’s free energy indicated the adsorption mechanism between MB and tea stem powder was a spontaneous and exothermic process. The regeneration/adsorption experiments indicated that the tea stem powder efficiently remained more than 97% after five cycles using NaOH as a desorbing agent and thus be used for many times. On the basis of experimental results obtained, it is concluded that the tea stem has a considerable potential as a low-cost sorbent for removing MB from the aqueous phase.

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“…e pseudo-first-order model was established by Lagergren. e linear form of the model is expressed as follows [27]:…”

Section: Adsorption Kineticsmentioning

confidence: 99%

“…Temkin isotherm model, taking interaction between adsorbate and adsorbent into account, assumes that (i) the heat of sorption linearly decreases with the increasing of surface coverage and (ii) bonding energies are equally distributed on the adsorbent. e linearized model is given as follows [27,41,42]:…”

Section: Isotherm Modelsmentioning

confidence: 99%

Tea Stem as a Sorbent for Removal of Methylene Blue from Aqueous Phase

Lee

Wang

Huang

et al. 2019

Advances in Materials Science and Engineering

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“…However, due to being expensive, its extensive use in wastewater treatment is limited (Netzahuatl‐Muñoz, Carmen Cristiani‐Urbina, & Cristiani‐Urbina, ). Additionally, commercially available activated carbon has low affinity to adsorb Cr(VI) (Chaudhry, Khan, & Ali, ). The hydrothermal carbon spheres produced with the HTC technique usually have no relevant porosity, which impedes their potential application for the removal of heavy metals.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of hexavalent chromium onto alkali‐modified biochar derived from Lepironia articulata: A kinetic, equilibrium, and thermodynamic study

Asadullah

Kaewsichan

Tohdee

2019

Water Environment Research

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Hydrochar obtained after hydrothermal carbonization (HTC) of Lepironia articulata (LA) was modified into biochar by reacting with a specific amount of KOH in a tubular reactor under slow pyrolysis. The physical and chemical properties of the hydrochar and modified biochar were characterized. The performance of modified biochar (LABC) was investigated through batch sorption experiments. Removal (%) and the maximum adsorption capacity (q max ) of Cr(VI) onto LABC increased up to 98.9% and 28.75 mg/g relative to 63.44% and 21.90 mg/g in unmodified hydrochar (LAHC) at pH 2.0, 313 K, and 200 mg/L, respectively. The sorption kinetics uptake data were best interpreted with pseudo-second-order model, and sorption isotherm was simulated with the Langmuir adsorption model. The thermodynamic parameters confirm the adsorption process to be an endothermic, spontaneous, and increased disorder. The overall results revealed that LABC can be utilized as an environmentally friendly, inexpensive, and effective adsorbent in Cr(VI) removal. • Practitioner points• Hydrochar and modified biochar prepared from a tropical biomass (Lepironia articulata) were successfully used for the removal of Cr(VI) from aqueous solution. • Increased specific surface was obtained by applying chemical modification with alkali treatment, contributing to effectiveness as adsorbent. • Dimensionless K c was estimated from the Langmuir fits and then used to estimate thermodynamics of adsorption. • The signs of ∆H°, ∆G°, and ∆S° indicate that the adsorption of Cr(VI) onto LABC was an endothermic, spontaneous, and increased disorder.

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“…The experimental and theoretical values of q e are not in agreement with each other. Also, the smaller value of K 2 than K 2 q e 2 (initial rate constant) indicates the fast CO adsorption process during the initial period of time, and then, it was getting slower with time [47,53]. The value of regression coefficient (R 2 ) for this model is close to unity that it is applicable to explain CO adsorption by Al 2 O 3 /Pd(NO 3 ) 2 /zeolite adsorbent [46,54].…”

Section: Pseudo-second -Order Kineticmentioning

confidence: 72%

Investigation of carbon monoxide gas adsorption on the Al2O3/Pd(NO3)2/zeolite composite film

et al. 2019

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In this study, Al 2 O 3 /Pd(NO 3) 2 /zeolite composite films have been fabricated by roll coating method and characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy and field emission scanning electron microscopy. The gas adsorption was tested in an experimental setup by a continuous gas analyzer KIMO KIGAZ 210 at constant temperature and pressure (32 °C and 1.5 bar) and as a function of reaction time (s). The inlet CO gas concentration was 150 mg L −1 , and the saturation level of CO gas concentration was 5 mg L −1. The maximum adsorption capacity (q max) and maximum adsorption efficiency (%) were calculated as 111.16 mg g −1 and 97%, respectively. Pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were investigated to kinetic study of CO adsorption on Al 2 O 3 /Pd(NO 3) 2 /zeolite adsorbents. Results indicated that CO adsorption follows the pseudo-second-order model well according to regression coefficient value (R 2 = 0.98), and the value of pseudo-second-order rate constant of adsorption was obtained as 2 × 10 −5 g mg −1 s −1. According to the intra-particle diffusion model, adsorption is affected by only one process. So, adsorption of CO by Al 2 O 3 /Pd(NO 3) 2 /zeolite adsorbent indicated an effective adsorption by obtained results.

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Adsorptive removal of Pb(II) and Zn(II) from water onto manganese oxide-coated sand: Isotherm, thermodynamic and kinetic studies

Cited by 83 publications

References 64 publications

Tea Stem as a Sorbent for Removal of Methylene Blue from Aqueous Phase

Tea Stem as a Sorbent for Removal of Methylene Blue from Aqueous Phase

Adsorption of hexavalent chromium onto alkali‐modified biochar derived from Lepironia articulata: A kinetic, equilibrium, and thermodynamic study

Investigation of carbon monoxide gas adsorption on the Al2O3/Pd(NO3)2/zeolite composite film

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