Pseudo-second Order Adsorption Kinetics Research Articles

Effective removal of chromium, copper, and nickel heavy metal ions from industrial electroplating wastewater by in situ oxidative adsorption using sodium hypochlorite as oxidant and sodium trititanate nanorod as adsorbent

Sodium hypochlorite and synthesized sodium trititanate nanorods (Na2Ti3O7, 186 × 1270 nm) were used as the oxidant and adsorbents for in situ oxidative adsorption treatment of actual electroplating wastewaters containing Cr(VI) (2.6‒5.2 mg∙L‒1), Cu2+ (2.7‒5.4 mg∙L‒1), and Ni2+ (0.2705‒0.541 mg∙L‒1) ions at pH of 8.8‒9.1 and 20‒60 °C. The as-synthesized sodium trititanate nanorods were characterized by XRD, HRTEM, N2 adsorption/desorption, SEM, EDX, and Zeta potential techniques. The concentrations of heavy metal ions in wastewaters were analyzed by ICP technique. After in situ oxidative adsorption treatment under the concentrations of 25 g∙L‒1 for sodium hypochlorite and 125 mg∙L‒1 for sodium trititanate nanorods at 60 °C for 5 h, the heavy metal ion concentrations could be reduced from initial value of 2.6 to final value of 1.92 mg∙L‒1 for Cr(VI), 3.6 to 0.17 mg∙L‒1 for Cu2+, and from 0.2705 to 0.097 mg∙L‒1 for Ni2+, respectively. Cr(VI), Cu2+, and Ni2+ ions could be effectively removed by the in situ oxidative adsorption method. The in situ oxidative adsorption processes of Cr(VI), Cu2+, and Ni2+ ions are satisfactorily simulated by the pseudo-second order adsorption kinetics and Langmuir adsorption isotherm, respectively. Adsorption thermodynamics analyses reveal that the oxidative adsorption processes of Cr(VI), Cu2+, and Ni2+ ions are spontaneous and endothermic. The oxidation degree of metal-contained complexes influences the values of thermodynamics functions.

Study on the mechanism of lignin non-productive adsorption on cellobiohydrolase

Enzymatic hydrolysis is important for lignocellulosic biomass conversion into fermentable sugars. However, the nonproductive adsorption of enzyme on lignin was major hinderance for the enzymatic hydrolysis efficiency. In this study, non-productive adsorption mechanism of cellulase component cellobiohydrolase (CBH) onto lignin was specific investigated. Research revealed that the adsorption behavior of CBH on eucalyptus alkali lignin (EuA) was affected by reaction conditions. As study on the adsorption kinetic, it was indicated that the adsorption cellulose binding domain (CBD) of CBH onto EuA well fitted with Langmuir adsorption model and pseudo second-order adsorption kinetics model. And the tyrosine site related to the adsorption of CBD onto lignin was proved by the fluorescence and UV spectra analysis. The results of this work provide a theoretical guidance to understanding the nonproductive adsorption mechanism and building method to reduce the adsorption of cellulase on the lignin.

Synthesis and characterization of Novel Igepal Co-520 surfactant coated Fe3O4 Nanoparticles: An evaluation of Vanadium enrichment in spice samples

In this study, novel Fe3O4 nanoparticles coated with surfactant Igepal Co-520 (polyoxyethylene (5) nonylphenylether) as adsorbent were synthesized, and total vanadium recovery was performed by magnetic solid phase extraction (MSPE) method. Fe3O4 nanoparticles coated with Igepal Co-520 were employed in the investigation of vanadium enrichment. The synthesized nanoparticles were characterized by Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray Analysis (EDX), X-Ray Diffraction Analysis (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Thermogravimetric Analysis (TGA), and total vanadium concentration was determined by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The corresponding values for the pH, adsorbent amount, and contact time were 3, 5 mg, and 120 min. Total vanadium was recovered from an aqueous solution under the optimum conditions. Langmuir and Freundlich adsorption isotherms, pseudo-first and pseudo-second order adsorption kinetics, foreign ion studies, desorption, and analytical value studies were performed. In isotherm studies, the effect on adsorption was examined by varying the vanadium concentration between 1 mg/L and 100 mg/L. The Langmuir model (R2>0.99) seems to be more compatible with vanadium adsorption than the Freundlich model (R2<0.87). Pseudo−first-order and pseudo-second-order equations were used to evaluate adsorption kinetic models. It has been observed that the pseudo-quadratic equation (R2>0.89) was more suitable for modeling than the pseudo-first-order equation (R2<0.56). The analytical performance parameters of the method were calculated as enrichment factor (EF) 114, the limit of detection (LOD) 8.3 µg/L, the limit of quantification (LOQ) 28.3 µg/L, and relative standard deviation (RSD) 1.20 %. At various molarities, the effects of acidic (HCl) and basic (NaOH) agents on the desorption of total vanadium ions adsorbed on the magnetic Fe3O4 surface were examined and compared. It was observed that the maximum recovery (100 %) was obtained using HCl as the desorption agent. The total vanadium concentration in spice samples was measured in an actual sample analysis. All the results demonstrate that the Fe3O4@Igepal Co-520 was successfully synthesized and has the potential to be a useful tool for heavy metal recovery.

Engineering MgHPO4·3H2O/Mg(OH)2 composite for boosting NH3 adsorption properties

The emission of ammonia gas (NH3) in agricultural composting not only leads to a decrease in fertilizer efficiency, but also causes environmental pollution. Here, an alkaline, insoluble composites was prepared and its adsorption performance for NH3 was explored. The results indicate that the material synthesized using a one-pot method with magnesium hydroxide (Mg(OH)2) and phosphoric acid (H3PO4) consists of a mixture of MgHPO4·3 H2O and Mg(OH)2 (M1). TEM images reveal the adhesion of the two materials together, with Raman spectroscopy indicating that MgHPO4·3 H2O is located on the outer surface of Mg(OH)2. The microenvironment formed by the adhesive construction of MgHPO4·3 H2O and Mg(OH)2 mixture not only provides sufficient magnesium salts and phosphate for the growth of struvite but also creates alkaline conditions conducive to struvite formation. The kinetic results show that the NH3 adsorption of M1 follows pseudo second-order adsorption kinetics and belongs to surface chemical reaction control. Compared with a simple mixture of MgHPO4·3 H2O and Mg(OH)2, M1 has a 4.5 fold increase in NH3 adsorption rate and a 3.15 fold increase in equilibrium adsorption capacity. Preliminary on-site tests demonstrated the potential application of the M1 adsorbent for NH3 adsorption in composting.

Kinetics of Direct Reaction of Vanadate, Chromate, and Permanganate with Graphene Nanoplatelets for Use in Water Purification.

Oxometalates of vanadium(V), chromium(VI), and manganese(VII) have negative impacts on water resources due to their toxicity. To remove them, the kinetics of 0.04 mM oxometalates in natural and synthetic water were studied using graphene nanoplatelets (GNP). The GNP were dispersible in water and formed aggregates >15 µm that could be easily separated. Within 30 min, the GNP were covered with ~0.4 mg/g vanadium and ~1.0 mg/g chromium as Cr(OH)3. The reaction of 0.04 mM permanganate with 50 mg of GNP resulted in a coverage of 10 mg/g in 5 min, while the maximum value was 300 mg/g manganese as Mn2O3/MnO. TEM showed a random metal distribution on the surfaces; no clusters or nanoparticles were detected. The rate of disappearance in aerated water followed a pseudo second-order adsorption kinetics (PSO) for V(V), a pseudo second-order reaction for Cr(VI), and a pseudo first-order reaction for Mn(VII). For Cr(VI) and Mn(VII), the rate constants were found to depend on the GNP mass. Oxygen sorption occurred with PSO kinetics as a parallel slow process upon contact of GNP with air-saturated water. For thermally regenerated GNP, the rate constant decreased for V(V) but increased for Cr(VI), while no effect was observed for Mn(VII). GNP capacity was enhanced through regeneration for V(V) and Cr(VI); no effect was observed for Mn(VII). The reactions are well-suited for use in water purification processes and the reaction products, GNP, decorated with single metal atoms, are of great interest for the construction of sensors, electronic devices, and for application in single-atom catalysis (SAC).

Adsorption behavior of trace elements of 90Sr on MnO2–ZrO2 loaded with polyacrylonitrile polymer from aqueous solutions

A MnO2–ZrO2-polyacrylonitrile (MnO2–ZrO2-PAN) composite ion exchanger was produced and its properties were examined by Fourier-transformed infrared spectroscopy, scanning electron microscopy, The BET (Brunauer, Emmett and Teller) surface area, X-Ray diffraction analysis and thermogravimetric analysis. The adsorption of Strontium (Sr) from solutions by MnO2–ZrO2-PAN composite was studied thru batch experiments. The distribution Coefficient of Sr (II) on the composite sorbent was investigated against pH, interaction time, and primary concentration ion. To study the kinetics of adsorption, Pseudo-first-order and Pseudo second-order adsorption kinetics were studied and the results revealed that adsorption kinetics better fit to the pseudo-second-order model. Three iso-temperature models, Langmuir, Freundlich, and Temkin were applied to fit the experimental results. Among those models, Langmuir revealed the most suitable one with minimum deviation. The created composite exhibited strong compatibility to the elimination of Y (III), Ni (II), Pb (II), and Co (II) from radioactive waste streams. On the other, it is evident from the data that the quantifiable extraction of Sr (II) ions from Zr (IV), Mo (VI), and La (III) is feasible. MnO2–ZrO2 Loaded with (PAN) Polymer was figured out to have high ion exchange capacity and thermal stability and selectivity for strontium.

Synthesis of Chemically Modified Acid-Functionalized Multiwall Carbon Nanotubes with Benzimidazole for Removal of Lead and Cadmium Ions from Wastewater.

In this work, acid-functionalized multiwalled carbon (MWCNTs-CO2H) nanotube was successfully functionalized with a heterocyclic scaffold, namely benzimidazole, to give novel functionalized multiwalled carbon nanotubes (BI@MWCNTs). Then, FTIR, XRD, TEM, EDX, Raman spectroscopy, DLS, and BET analyses were used to characterize the synthesized BI@MWCNTs. The effectiveness of the adsorption of two heavy metal ions, Cd2+ and Pb2+, in single metal and mixed metal solutions on the prepared material was investigated. Influencing parameters for the adsorption method, for example duration, pH, starting metal concentration, and BI@MWCNT dosage, were examined for both metal ions. Moreover, adsorption equilibrium isotherms fit with the Langmuir and Freundlich models perfectly, while the intra-particle diffusion models provide pseudo-second order adsorption kinetics. The adsorption of Cd2+ and Pb2+ ions onto BI@MWCNTs revealed an endothermic and a spontaneous method with great affinity as a result of the negative values of Gibbs free energy (ΔG) and the positive values of enthalpy (ΔH) and entropy (ΔS). Both Pb2+ and Cd2+ ions were completely eliminated from aqueous solution (100 and 98%, respectively) using the prepared material. Additionally, BI@MWCNTs have a high adsorption capacity and were regenerated in a simple way and reused for six cycles, which make them a cost-effective and efficient absorbent for the removal of such heavy metal ions from wastewater.

Magnetically derived fabrication of aligned porous poly(sulfonated polystyrene-co.-chitosan) monolith as a high efficient adsorbent for metal ions separation

Designing and tuning towards the porous structure of adsorbents is of great importance for promoting the adsorptive performance. Herein, a magnetic-induced copolymerization method is applied to generate an aligned porous structure in the aligned porous poly(SPS-co.-CTS) monolith. Typically, the aligned macropores primarily derives from the equilibrium of the magnetic dipolar force to the thermodynamic Brown force by tuning the applied magnetostatic field intensity to 25 mT. Due to the aligned macroporous structure, the monolith features with low back pressure, low mass transfer resistance and high adsorptive capacity. The hydrophilicity of the monolith surface is further improved by capping chitosan activated by amino onto its porous surface via the Hinsber reaction. Detail analyses are performed by a series of physical characterizations, by which exhibit the aligned macropores centering at 5.18 μm, specific surface reaching 54 m2 g−1 and large porosity. Finally, batch adsorption experiments confirm that the adorptive behaviors to Cu2+ ions and Co2+ ions submit to the Langmuir model and Pseudo-second order adsorption kinetics. Most intriguing, the film mass transfer ([kLa]f) has been stabilized due to the aligned macropores, thus facilitating the porous diffusion ([kLa]d) and improving the chromatographic performance of the monolith. All results demonstrate that the aligned porous poly(SPS-co.-CTS) monolith promises broad applications in the field of wastewater remediation.

Preparation of the Carbonized Zif-8@PAN Nanofiber Membrane for Cadmium Ion Adsorption.

The zeolitic imidazolate framework (ZIF−8)@polyacrylonitrile (PAN) nanofiber membrane was prepared and carbonized for heavy metal cadmium ion (Cd2+) adsorption in aqueous medium. Zinc oxide (ZnO) was first sputtered onto the surface of the PAN electrospun nanofiber membrane to provide a metal ion source. Then, the ZIF−8@PAN nanofiber membrane was prepared via in situ solvothermal reaction and carbonized in a tube furnace at 900 °C under a N2 atmosphere to enhance adsorption performance. The synthesized ZIF−8 particles with polyhedral structure were uniformly immobilized on the surface of the PAN electrospun nanofiber membrane. After being heated at 900 °C, the polygonal ZIF−8 shrank, and the carbonized ZIF−8@PAN nanofiber membrane was obtained. Compared with the nanofiber membrane without being carbonized, the adsorption capacity of the carbonized ZIF−8@PAN nanofiber membrane reached 102 mg L−1, and its Cd2+ adsorption efficiency could be more than 90% under the adsorption temperature of 35 °C and solution of pH = 7.5 conditions. According to the adsorption thermodynamics analysis, the Cd2+ adsorption process of the carbonized ZIF−8@PAN nanofiber membrane was spontaneous. The whole Cd2+ adsorption process was more suitably described by the pseudo second-order adsorption kinetics model, indicating that there exists a chemical adsorption mechanism besides physical adsorption.

Superhigh Adsorption of Cadmium(II) Ions onto Surface Modified Nano Zerovalent Iron Composite (CNS-nZVI): Characterization, Adsorption Kinetics and Isotherm Studies

The efficiency of surface modified nanoscale zerovalent iron (nZVI) composite by cashew nut shell (CNS) was tested for the removal of cadmium ions from the aqueous solutions. 2 g/l CNS-nZVI was efficient for 98% removal. The adsorption capacity was 35.58 mg/g. The Freundlich isotherm (R2 = 0.9769) and the pseudo-second order adsorption kinetics data fitted well. This proved CNS-nZVI has a high removal efficiency for Cd(II) from aqueous solutions.

Reply to “Comment on ‘Erroneous Application of Pseudo-Second Order Adsorption Kinetics Model: Ignored Assumptions and Spurious Correlations’”

ADVERTISEMENT RETURN TO ISSUEPREVCorrespondenceNEXTReply to “Comment on ‘Erroneous Application of Pseudo-Second Order Adsorption Kinetics Model: Ignored Assumptions and Spurious Correlations’”Ye XiaoYe XiaoDepartment of Chemical & Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Dr NW, Calgary, Alberta T2N 1N4, CanadaMore by Ye Xiaohttps://orcid.org/0000-0003-4235-2154, Jalel AzaiezJalel AzaiezDepartment of Chemical & Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Dr NW, Calgary, Alberta T2N 1N4, CanadaMore by Jalel Azaiez, and Josephine M. Hill*Josephine M. HillDepartment of Chemical & Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Dr NW, Calgary, Alberta T2N 1N4, Canada*Tel.: +1 403 210 9488. Fax: 1 403 284 4852. Email: [email protected]More by Josephine M. Hillhttps://orcid.org/0000-0003-2708-565XCite this: Ind. Eng. Chem. Res. 2021, 60, 24, 8960–8961Publication Date (Web):June 15, 2021Publication History Published online15 June 2021Published inissue 23 June 2021https://doi.org/10.1021/acs.iecr.1c02080Copyright © 2021 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views346Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (472 KB) Get e-AlertsSUBJECTS:Liquids,Kinetic modeling,Adsorption,Order,Adsorption kinetics Get e-Alerts

Utilization of agro-industrial waste for biosurfactant production under submerged fermentation and its synergistic application in biosorption of Pb2+

The biosurfactant production process was optimized using raw orange peel extract (ST reduction = 33.04 dyne cm−1; biosurfactant yield = ~3.7 g L−1) and the extracted metabolite was characterized in terms of its nature, and class/family. To the best of our knowledge, a first report utilizing biowaste as a sole carbon substrate for simultaneous biosurfactant production and Pb2+ removal under submerged fermentation by Bacillus haynesii strain E1. The results depicted the extracted biosurfactant to be of lipopeptide nature belonging to surfactin family having 50 mg L−1 of CMC. The crude biosurfactant was found to be tensioactive at temperature 70 °C, 6% salt concentration, and varying pH range. The biosurfactant-producing bacterium effectively remediated Pb2+ (high MIC = 2200 mg L−1) with a maximum adsorption capacity of 196.08 mg g−1. The biosorption mechanism followed Langmuir (R2 = 0.9724) and Pseudo second-order adsorption kinetics (R2 = 0.9996; 200 mg L−1).

On the adsorption behavior of a fluorochemical onto carbonate rock with the application of wettability alteration to a gas wetting condition

In this study, some new aspects of adsorption of a fluorochemical onto carbonate rocks as a wettability alteration agent to a gas wetting condition with the potential application for reduction of condensate blockage in gas condensate reservoirs are presented. To achieve this, kinetics, equilibrium, and thermodynamic of the adsorption process besides contact angle, imbibition, and characterization tests are investigated. Results of adsorption experiments revealed that kinetics behavior of the utilized fluorochemical–calcite system obeyed the pseudo-second order kinetics model. There was no change in adsorption after about 20 h. Also, the intraparticle diffusion mechanism was not the only rate controlling mechanism of the process. For equilibrium condition, Freundlich isotherm, which supports multilayer adsorption of nanofluid onto calcite surface, matched well with the obtained data. Obtained enthalpy and of 15.8 kJ/mol and entropy of 127.9 kJ/mol from thermodynamic analysis showed the endothermic nature of the adsorption process and the tendency of the fluorochemical to be adsorbed onto calcite rock surface, respectively. Analysis of static contact angle measurement of water, crude oil, and n-decane on the treated calcite rock samples at different concentrationss and aging times resulted in two new mathematical expressions for concentration-dependent, which is based on Freundlich isotherm, and aging time-dependent, which is based on pseudo-second order adsorption kinetics, of wettability alterations. The parameters of proposed models matched well with the obtained experimental data and were evaluated for different fluid-rock systems. Results showed that the major part of wettability alteration occurs at <5 h. After the treatment, water, crude oil, and n-decane contact angles were increased from 65o, 0o, and 0o to 138o, 93o and 73o. Comparing spontaneous imbibition results before and after treatment of carbonate plugs confirmed reliable gas-wetting condition, and showed 77% PV and 81% PV reduction in imbibed water and n-decane, respectively. When coupled with an imbibition model, reduction of liquid permeability by a factor of 79% and 72%, respectively, was observed. Characterization of treated and untreated surfaces were performed through SEM, EDX, FTIR, XRD, and AFM tests. EDX revealed the presence of 9.5 wt% of fluorine on the treated surface. SEM and AFM disclosed that mean roughness of polished surface increased from 29 nm to 417 nm due to adsorption of spherical nanoparticles. Results of this study may provide a deeper understanding of adsorption of fluorochemical onto carbonate rocks as a potential wettability alteration agent to gas wetting condition in gas condensate reservoirs.

Optimization of the use of mother liquor in the synthesis of HKUST-1 and their performance for removal of chromium (VI) in aqueous solutions

In this study, copper-benzene tricarboxylic (Cu-BTC), or better known as HKUST-1, was successfully synthesized using the solvothermal method in a solvent mixture of water, ethanol and N,N-Dimethylformamide (DMF). The mother liquor from the first synthesis was reused as a solvent for the subsequent HKUST-1 synthesis for up to four repetitions, cutting back the use of fresh solvent as much as 37 %. The fifth material obtained showed similar thermal stability and specific surface area to that of the first one, even though the surface morphology turned from an octahedral shape in the first material to an irregular shape in the fifth material. The results of the adsorption study on Cr(VI) in aqueous media showed that the first and the fifth materials had adsorption capacities of 91 mg/g and 100 mg/g respectively. Both adsorbents followed a pseudo-second order adsorption kinetics with a Langmuir isothermal adsorption model.

Nitrogen and fluorine co-doped 3-dimensional reduced graphene oxide architectures as high-performance electrode material for capacitive deionization of copper ions

• Nitrogen and fluorine doped 3-D reduced graphene oxide (rGO) through hydrothermal route was prepared. • High capacitive deionization of Cu 2+ ions by 3D-NFrGO when applied in capacitive electrode material. • Chemisorption and ion diffusion onto electrode govern the Cu 2+ ion removal. • Heteroatoms doping, good surface area and pore structure result in high specific capacitance. Heavy metal ions pose a threat to human life as their consumption can be hazardous. In this regard, unprecedented interests towards the development of technology for water purification have been witnessed. The present work is yet another novel attempt to develop a promising nanomaterial for the removal of Cu(II) from aqueous media using fast and facile capacitive deionization (CDI) method. Nitrogen- and fluorine- co-doped 3-dimensional reduced graphene oxide (3D NFrGO) architectures were developed via a hydrothermal route at 180 °C for 12 – 24 h and then applied as CDI electrode for Cu(II) removal. The fabrication of NFrGO at 180 °C for 16 h shows excellent 3D structures with high specific surface area of 182.7 m 2 g −1 and bimodal pore size distribution at 2.1 and 5.6 nm, which can facilitate rapid ions/electrons transport inside the interconnected mesoporous channels. In addition, the doping of heteroatoms can not only increase the conductivity, but also create the vacancy defect of NFrGO, resulting in accelerated electrochemical performance. The specific capacitance of 245.6 F g −1 was also achieved, demonstrating the high capacitive features of the as-obtained material. Moreover, a high percent removal of 95% and specific electrosorption capacity of 52.4 mg g −1 at 100 mg L -1 Cu(II) was obtained. Electrosorption results can be well-described by the pseudo second-order adsorption kinetics and the intraparticle diffusion model, which signify that chemisorption and ion diffusion into electrode pores govern Cu(II) removal. Results obtained in this study have demonstrated that N, F-co-doped 3D rGO can be a promising CDI material for efficient removal of heavy metal ions as well as for water purification.

Synthesis of a new thiophenol-thiophene polymer for the removal of mercury from wastewater and liquid hydrocarbons

This work reports the synthesis of a novel thiophenol-thiophene polymer (termed KFUPM-Hg) and its suitability as an adsorbent for mercury removal from wastewater and liquid hydrocarbons. KFUPM-Hg was synthesized through a Friedel-Crafts polycondensation reaction of thiophenol and thiophene in the presence of p-formaldehyde as a linker. The crosslinked polymer structure was characterized using solid-state 13C-nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR). Thermogravimetric analysis was performed to assess the polymer thermal stability, which indicated that the polymer is thermally stable to over 300 °C. A series of batch adsorption studies were used to investigate the effects of different parameters (pH, temperature, concentration, and time) on the mercury removal from aqueous solution as well as from a model liquid hydrocarbon media (decane/toluene mixture). The batch adsorption studies in aqueous media showed near quantitative removal of inorganic mercury (II) at 100 ppm using the thiophenol-thiophene polymer adsorbent. Furthermore, the thiophenol-thiophene polymer demonstrated excellent removal capabilities of methylmercury in a decane/toluene hydrocarbon mixture. Mercury adsorption onto KFUPM-Hg is an exothermic reversible physical process and follows pseudo-second order adsorption kinetics. Remarkably, these removal capabilities were achieved using polymers that directly incorporated thiophenol and thiophene groups during synthesis without the use of thiol-ene post-synthesis modifications.

A Novel Phenolic Foam-Derived Magnetic Carbon Foam Treated as Adsorbent for Rhodamine B: Characterization and Adsorption Kinetics

In recent decades, dye wastewaters produced by dye-manufacturing and dye-consuming industries have become a growing water pollution problem. Herein, a novel phenolic foam-derived magnetic carbon foam is synthesized by in-situ pyrolysis of iron acetylacetonate (Fe(acac)3) containing phenolic resin and its corresponding application as an adsorbent for the removal of Rhodamine B from effluent is investigated. The characterization of the as-prepared adsorbent is carried out by SEM, EDS, XRD, XPS, VSM, FT-IR, Raman, and BET. The magnetic carbon foam is observed to consist of a CFe15.1/C matrix modified with α-Fe/Fe3C/Fe2O3 composites, possessing a 3D porous architecture formed by inter-connected cells with diameters of 50–200 μm and narrow ligaments with thicknesses of ~20 μm. Experimental tests demonstrate that the equilibrium of adsorption behavior of Rhodamine B onto the obtained adsorbent can be reached within 40 min and the corresponding maximum adsorption capacity is 258.03 mg/g. The effects of contact time and adsorbent dosage on the adsorption performance are investigated. Besides, four models are introduced to fit the experimental data to evaluate the adsorption kinetics. The overall rate constant is determined by the chemisorption process, according to the pseudo-second order adsorption kinetics mechanism. Besides, the pH effect on RhB adsorption onto magnetic carbon foam is investigated, with the pH values varying from 3 to 10. The above results prove the application prospect of magnetic carbon foam prepared in this work in dye wastewater treatment.

The stimuli-responsive properties of doxorubicin adsorbed onto bimetallic Au@Pd nanodendrites and its potential application as drug delivery platform

Bimetallic nanoparticles have continued to attract interest as drug delivery systems in cancer therapy even though their nature of interaction with small molecules is limited. Currently, many delivery systems based on monometallic nanoparticles are being fabricated for loading of drugs, thus prompting the need to explore and get more understanding of dendritic bimetallic nanostructure-drug interaction. The bimetallic gold-core palladium-dendritic shell nanoparticles (Au@PdNDs) were synthesized by hot injection method and stabilized with methoxy polyethylene glycol thiol (mPEG-SH). An anti-cancer drug, doxorubicin (DOX) was conjugated to the bimetallic nanodendrites leading to the formation of DOX/Au@PdNDs.PEG complex. We used TEM, FTIR, and zeta-potential to study the drug-nanodendrites interaction. The effect of DOX binding and release capacity with regards to pH, adsorption kinetics, solvent polarity, isotherms and temperature on Au@PdNDs.PEG were investigated. The results showed a spontaneous heterogeneous binding of DOX on the Au@PdNDs.PEG surfaces and time-dependent loading capacity of ~90% maximum adsorption within 24h. Moreover, the experimental results showed that the adsorption isotherm data fitted well with the Freundlich model and a pseudo-second order adsorption kinetics. The desorption of DOX was triggered under simulated tumor microenvironmental conditions and should open new opportunities for potential multi stimuli-responsive drug delivery applications.

Preparation and Characterization of Activated Carbon Derived from Antidesma bunius L. in Methylene Blue Removal from Wastewater

This study investigated the effect of contact time and methylene blue (MB) solution concentration on the adsorption capacity of granulated activated carbon derived from bignay (Antidesma bunius L.) seeds. The raw bignay seeds were subjected to physical activation via oven drying at 120°C and carbonization at 500°C for 30 min. The maximum adsorption capacity of both powdered and granulated activated carbon were determined. The alkyl functional groups of Bignay activated carbon (BAC) were determined using Fourier transform infrared (FTIR) analysis and the surface morphology and composition of the BAC were analyzed using scanning electron microscopy-energy dispersive x-ray (SEM-EDX). Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models were used to analyze the adsorption of isotherm BAC. But the data best fitted with the Freundlich isotherm. The mean energy of the adsorption showed that the adsorption of MB by BAC was physical adsorption implying that MB molecules were trapped in the pores of the BAC. The maximum adsorption capacity was 1.60 mg g-1. The rate of adsorption was used to determine if the process is physisorption or chemisorption using pseudo-first order and pseudo-second order adsorption kinetics. The data showed best fit for pseudo-second order ,suggesting that the reaction depends on the concentration of both reactants

A novel tri-metal composite incorporated polyacrylamide hybrid material for the removal of arsenate, chromate and fluoride from aqueous media

Abstract Excessive amounts of fluoride ions and other heavy metals in drinking water instigate a solemn threat to human health. Even though materials with specific binding ability towards these ions have been developed, it is yet a challenge to meet the practical utility of developing an efficient remedy as such. With this regard, a novel tri-metal composite incorporated polyacrylamide (TCIP) has developed. TCIP has shown a significant binding efficiency towards arsenate, chromate and fluoride ions in the presence of the other competing anions. The maximum adsorption capacities (qmax) of 43.85, 42.25 and 107.52 mg/g were achieved for arsenate, chromate and fluoride respectively at 300 K and in pH 7.00. Arsenate, chromate and fluoride adsorption is highly pH dependent. Monolayer adsorption of arsenate, chromate and fluoride ions was observed and adsorption data were found well behaved with the Langmuir adsorption isotherm. Arsenate, chromate and fluoride adsorption to TCIP has shown pseudo-second order adsorption kinetics, and no leaching of metal ions was observed from the metal composite into the aqueous medium.