68 research outputs found
The Adsorption of Pb, Zn, Cu, Ni, and Cd by Modified Ligand in a Single Component Aqueous Solution: Equilibrium, Kinetic, Thermodynamic, and Desorption Studies
In this investigation, an amino functionalized adsorbent was developed by grafting 4-aminobenzoic acid onto the backbone of cross-linked chitosan beads. The 3 sets of beads including chitosan (CX), glutaraldehyde cross-linked chitosan (CCX), and 4-aminobenzoic acid grafted cross-linked chitosan (FGCX) were characterized by FTIR, XRD, SEM, and TGA. The water content and amine concentration of FGCX were determined. The effect of adsorption parameters was studied and the optimum was used for further studies. Equilibrium data was obtained from the adsorption experiment carried out at different initial concentration; the data were applied in isotherm, thermodynamics, and kinetic studies. The Langmuir and Dubinin-Kaganer-Radushkevich (DKR) models were successful in describing the isotherm data for the considered metal ions while the Freundlich and Temkin model fit some of the considered metal ions. Pseudo-second-order and intraparticle model described the kinetic data quite well. Thermodynamic parameters such as Gibbâs free energy change (ÎGo), enthalpy change (ÎHo), and entropy change (ÎSo) were calculated and the results showed that the adsorption of Pb, Cu, Ni, Zn, and Cd ions onto FGCX is spontaneous and endothermic in nature. Regeneration of the spent adsorbent was efficient for the considered metal ions
Interfacial Molecular Imprinting in Nanoparticle-Stabilized Emulsions
A new interfacial nano and molecular imprinting approach is developed to prepare spherical molecularly imprinted polymers with well-controlled hierarchical structures. This method is based on Pickering emulsion polymerization using template-modified colloidal particles. The interfacial imprinting is carried out in particle-stabilized oil-in-water emulsions, where the molecular template is presented on the surface of silica nanoparticles during the polymerization of the monomer phase. After polymerization, the template-modified silica nanoparticles are removed from the new spherical particles to leave tiny indentations decorated with molecularly imprinted sites. The imprinted microspheres prepared using the new interfacial nano and molecular imprinting have very interesting features: a well-controlled hierarchical structure composed of large pores decorated with easily accessible molecular binding sites, group selectivity toward a series of chemicals having a common structural moiety (epitopes), and a hydrophilic surface that enables the MIPs to be used under aqueous conditions
Kinetics, Equilibrium, and Comparision of Multistage Batch Adsorber Design Models for Biosorbent Dose in Metal Removal from Wastewater
Kinetics of leadÂ(II) adsorption onto
increasing masses of raw and CaÂ(OH)<sub>2</sub>-treated pine cone
powder was evaluated. The first rapid stage in the adsorption profile
was found to be controlled by film and intraparticle diffusion while
the second slow stage was influenced by slow movement of leadÂ(II)
through longer diffusion paths created by particle aggregation especially
at higher dose. Slight changes in surface properties due to base activation
was observed which lead to greater contribution of the diffusion processes
to the rate-controlling step. On the basis of the Langmuir isotherm,
three multistage batch adsorber models were compared
Kinetics, Equilibrium, and Comparision of Multistage Batch Adsorber Design Models for Biosorbent Dose in Metal Removal from Wastewater
Kinetics of leadÂ(II) adsorption onto
increasing masses of raw and CaÂ(OH)<sub>2</sub>-treated pine cone
powder was evaluated. The first rapid stage in the adsorption profile
was found to be controlled by film and intraparticle diffusion while
the second slow stage was influenced by slow movement of leadÂ(II)
through longer diffusion paths created by particle aggregation especially
at higher dose. Slight changes in surface properties due to base activation
was observed which lead to greater contribution of the diffusion processes
to the rate-controlling step. On the basis of the Langmuir isotherm,
three multistage batch adsorber models were compared
Engineered Geomedia Kaolin Clay-Reduced Graphene OxideâPolymer Composite for the Remediation of Olaquindox from Water
Globally, there is an upsurge in the use of unregulated
veterinary
pharmaceuticals with enhanced release into the environment, resulting
in water pollution, which is difficult to remediate. To address this
issue, we synthesized and characterized highly hydrophobic three-dimensional
ordered engineered geomedia with multiple channels. Kaolin clay (K)
was functionalized with either graphene oxide (GO) synthesized via
Tourâs method or reduced GO in situ with covalently linked
methoxyether polyethylene glycol (GO-PEG) using a simple and easily
scalable amidation reaction. This was done to enhance the adsorption
of olaquindox, a veterinary antibiotic. The X-ray diffraction profile
confirmed the grafting of GO and GO-PEG to kaolin. Morphological analysis
revealed the architecture of thin films of GO/GO-PEG grafted on the
kaolin surface with extensive porosity. Energy-dispersive X-ray mapping,
infra-red spectra, and elemental analysis confirmed the successful
synthesis of the engineered geomedia composite of K, GO/rGO, and PEG
(KrGO-PEG). Due to multiple surface functional groups of polyamide
and amido-carbonic groups on the KrGO-PEG composite, it was suitable
for olaquindox adsorption. In batch sorption studies of 0.5XKrO-PEG,
the effect of pH (2â10) was negligible but with fast equilibrium
time (2â1440 min) at 30 min, while the kinetics and equilibrium
data suited the pseudo-second order and Langmuir models, respectively.
The maximum adsorption value obtained for the composite was 59.5 mg/g;
the higher the GO content, the higher the adsorption. The sorption
mechanism was majorly through hydrophobic and ÏâÏ
interactions. Regenerated/reused adsorbents after 4 cycles had the
same efficacy in remediating olaquindox from simulated/real water
Removal of cationic dye methylene blue (MB) from aqueous solution by ground raw and base modified pine cone powder
The adsorption capacity of raw and sodium hydroxide-treated pine cone powder in the removal of methylene blue (MB) from aqueous solution was investigated in a batch system. It was found that the base modified pine cone exhibits large adsorption capacity compared with raw pine cone. The extent of adsorption capacity was increased with the increase in NaOH concentration. Overall, the extent of MB dye adsorption increased with increase in initial dye concentration, contact time, and solution pH but decreased with increase in salt concentration and temperature for both the systems. Surface characteristics of pine cone and base modified pine cone were investigated using Fourier transform infrared spectrophotometer and scanning electron microscope. Equilibrium data were best described by both Langmuir isotherm and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity was found to be 129.87 mg g-1 at solution pH of 9.02 for an initial dye concentration of 10 ppm by raw pine cone. The base modified pine cone showed the higher monolayer adsorption capacity of 142.25 mg g-1 compared with raw pine cone biomass. The value of separation factor, RL, from Langmuir equation and Freundlich constant, n, both give an indication of favourable adsorption. The various kinetic models, such as pseudo-first-order model, pseudo-second-order model, intraparticle diffusion model, double-exponential model, and liquid film diffusion model, were used to describe the kinetic and mechanism of adsorption process. Overall, kinetic studies showed that the dye adsorption process followed pseudo-second-order kinetics based on other models
Two-stage batch sorber design and optimization of biosorption conditions by Taguchi methodology for the removal of acid red 25 onto magnetic biomass
Equilibrium, Kinetics, and Thermodynamics of Methylene Blue Adsorption by Pine Tree Leaves
The adsorption capacity of pine tree leaves for removal of methylene blue (MB) from aqueous solution was investigated in a batch system. The effects of the process variables, such as solution pH, contact time, initial dye concentration, amount of adsorbent, agitation speed, salt concentration, and system temperature on the adsorption process were studied. The extent of methylene blue dye adsorption increased with increase in initial dye concentration, contact time, agitation speed, temperature, and solution pH but decreased with increased in amount of adsorbent and salt concentration. Equilibrium data were best described by both Langmuir isotherm and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity of pine tree leaves biomass was 126.58 mg/g at 30°C. The value of separation factor, R L , from Langmuir equation and Freundlich constant, n, both give an indication of favorable adsorption. The intrapartical diffusion model, liquid film diffusion model, double exponential model, pseudo-first and second order model were used to describe the kinetic and mechanism of adsorption process. A single stage bath adsorber design for the MB adsorption onto pine tree leaves has been presented based on the Langmuir isotherm model equation. Thermodynamic parameters such as standard Gibbs free energy (ÎG 0), standard enthalpy (ÎH 0), and standard entropy (ÎS 0) were calculated
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