Carboxymethyl cellulose-hydrogel embedded with modified magnetite nanoparticles and porous carbon: Effective environmental adsorbent (original) (raw)
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International Journal of Biological Macromolecules, 2020
Microcrystalline cellulose (MCC) has been utilized as an adsorbent material for the removal of Pb(II) ions from aqueous solution after treatment with 1,2,3,4-butanetetracarboxylic acid (BTCA) at elevated temperature to obtain MMCC. The resulting adsorbent was characterized for point of zero point charge (pHZPC), estimation of carboxyl content, fourier transform infrared spectroscopy (FT-IR), scan electron microscopy (SEM), and textural properties, including surface area, and subsequently utilized for the removal of Pb(II) ions from aqueous solution. The adsorption process was probed by investigating the effect of adsorbent dose, pH of solution, temperature, agitation time, and Pb(II) ion concentration. The results showed successful functionalization of MCC using BTCA, which significantly improved the binding properties of the adsorbent towards Pb(II) ions. Isothermal adsorption data was analyzed using Langmuir, Freundlich and Temkin models, evaluated via nonlinear regression analysis. The maximum adsorption capacity was found to be 1155 mg/g (at pH 5 and 30 °C) from Langmuir theory, and appears independent of surface area. The Freundlich model was found to provide the best fit and the constant n was determined to be 2.69, indicating that adsorption of Pb(II) ions onto MMCC is favorable. Kinetic modelling showed good agreement for the pseudo-second order kinetic model, supporting the theory that chemisorption is involved in the adsorption process, which is promoted by a high density of active sites. Thermodynamic analysis showed that the adsorption of Pb(II) ions onto MMCC was endothermic and nonspontaneous; hence, MMCC offers an effective method of Pb(II) ion removal from aqueous solutions, with potential for water remediation processes.
This study is on the kinetics and thermodynamics of the adsorption of Pb 2+ onto phosphate-modified and unmodified kaolinite clay obtained from Ubulu-Ukwu in Delta State of Nigeria. Increasing initial Pb 2+ concentration increased the rate of Pb 2+ adsorbed with increase in initial Pb 2+ concentration from 300 to 1000 mg/L. Increasing Pb 2+ concentration also increased the initial sorption rate h, from 1.404 to 13.11 mg g −1 min −1 for phosphate-modified kaolinite clay and 1.04-3.48 for unmodified kaolinite clay as Pb 2+ concentration. Increase in temperature was found to increase the initial sorption rate of Pb 2+ adsorption onto phosphate-modified adsorbent from 3.940 to 8.85 and 2.55 to 4.16 mg g −1 min −1 for the unmodified adsorbent. The overall sorption rate k, increased only slightly from 5.1 × 10 −2 to 9.7 × 10 −2 g mg −1 min −1 for phosphate-modified adsorbent, 3.8 × 10 −2 to 5.4 × 10 −2 g mg −1 min −1 for unmodified adsorbent. The adsorption reaction on both adsorbents was found to be chemically activated reaction and endothermic with energy of activation, E, at 500 mg/L of Pb 2+ in solution as 19 and 10.68 kJ mol −1 for phosphate-modified and unmodified adsorbents, respectively. The positive values of both H • and S • obtained suggest an endothermic reaction and in increase in randomness at the solid-liquid interface during the adsorption of Pb 2+ onto the adsorbents. G • values obtained were all negative indicating a spontaneous adsorption process. The presence of Cd 2+ decreased both initial sorption rate and the amount of Pb 2+ adsorbed on phosphate-modified and unmodified adsorbents at equilibrium. The adsorption process follows a pseudo-second-order reaction scheme.
Scientia Iranica, 2020
Heavy metal ions have been recognized as the most hazardous contaminants of water sources. In this study, a novel polymeric adsorbent based on 2-hydroxyethyl methacrylate (HEMA), acrylic acid (AA), and 1,4-butanediol dimethacrylate (BDDMA) was successfully synthesized and its efficiency in removal of selected heavy metal ions (Pb 2+ and Cd 2+) were investigated. The role of significant parameters such as pH, contact time, adsorbent dose, metal ions concentration and temperature on removing harmful metal ions were logically studied. Results showed that the amount of pH, contact time and polymer adsorbent dose had direct relation in adsorption of metal ions. While increasing metal ion concentrations have no significant effect in metal ions adsorption and that was fixed up to 15 mg/L. Adsorption isothermal process of the new polymeric adsorbent was studied by several selected models and also maximum values of adsorption capacities of the introduced adsorbent for Pb 2+ and Cd 2+ ions were characterized. Adsorption /desorption cycles of synthesized polymer adsorbent were around 15 times. According to the modeling of adsorption data, the pseudosecond-order kinetic equation could best describe the adsorption kinetics. According to the intra-particle diffusion studies adsorption of heavy metal ions might be dominated by external diffusion mechanism.
Cellulose, 2020
An optimized method is presented to make magnetite (MG) modified cellulose membrane (Cell-MG) from 3-aminopropyltriethoxysilane and diethylenetriaminepentaacetic acid dianhydride functionalized waste cell fibers; (Cell-NH 2 and Cell-DTPA), and amino-modified diatomite. Functionalized Cell-NH 2 , Cell-DTPA fibers, and diatomite were structurally and morphologically characterized using FT-IR, Raman, and FE-SEM analysis. Amino and carboxyl group content was determined via standard volumetric methods. Response surface method was applied to rationalize the number of experiments related to Cell-MG synthesis and heavy metal ions column adsorption experiments. The effects of pH, contact time, temperature, and initial concentration of pollutants on adsorption and kinetics were studied in a batch, while initial concentration and flow rate were studied in a flow system. The calculated capacities of 88.2, 100.7, 95.8 and 78.2 mg g-1 for Ni 2? , Pb 2? , Cr(VI) and As(V) ions, respectively, were obtained from Langmuir model fitting. Intra-particle diffusion as a rate-limiting step was evaluated from pseudosecond-order and Weber-Morris model fitting. Thermodynamic parameters indicated spontaneous and low endothermic processes. The results from reusability study, wastewater purification and fixed-bed column study proved the high applicability of Cell-MG. Additionally, high removal capacity of four dyes together with density functional theory and molecular interaction fields, help in the establishment of relation between the adsorption performances and contribution of non-specific and specific interactions at adsorbate/ adsorbent interface.
Separations
Heavy metal toxicity in water is a serious problem that may have harmful effects on human health and the ecosystem. Lead [Pb(II)] and cadmium [Cd(II)] are two such heavy metal ions, present in water, whose severity is well-known and well-studied. In the current research, magnetic biochar composite (MBC) is studied as an adsorbent material for the effective removal of lead and cadmium ions from water solutions. Magnetite (Fe3O4) nanoparticles and pine-needle-derived ultrasonicated magnetic biochar were used in different weight ratios to prepare APTES (3-aminopropyl triethoxysilane)-functionalized MBC (FMBC). An average crystalline size of ~10 nm for magnetite NPs was obtained via XRD analysis. The adsorption characteristics of both Pb(II) and Cd(II) ions were investigated in a batch experiment. The FTIR spectra of raw biochar, MBC, FMBC, and metal-loaded FMBC were obtained at different stages. The decrease in the intensity of the –NH2 functional group in the FTIR spectra of the resid...
Journal of Environmental Chemical Engineering, 2017
In this study, cadmium and lead ions removal from aqueous solutions using a commercial activated carbon adsorbent (CGAC) were investigated under batch conditions. The adsorbent was observed to have a coarse surface with crevices, high resistance to attrition, high surface area and pore volume with bimodal pore size distribution which indicates that the material was mesoporous. Sorption kinetics for Cd(II) and Pb(II) ions proceeded through a two-stage kinetic profile-initial quick uptake occurring within 30 minutes followed by a gradual removal of the two metal ions until 180 minutes with optimum uptake (q e,exp) of 17.23 mgg-1 and 16.84 mgg-1 for Cd(II) and Pb(II) ions respectively. Modelling of sorption kinetics indicates that the pseudo first order (PFO) model described the sorption of Pb(II) ion better than Cd(II), while the reverse was observed with respect to the pseudo second order (PSO) model. Intraparticle diffusion modelling showed that intraparticle diffusion may not be the only mechanism that influenced the rate of ions uptake. Isotherm modelling was carried out and the results indicated that the Langmuir and Freundlich models described the uptake of Pb(II) ion better than Cd(II) ion. A comparison of the two models indicated that the Langmuir isotherm is the better isotherm for the description of Cd(II) and Pb(II) ions sorption by the adsorbent. The maximum loading capacity (q max) obtained from the Langmuir isotherm was 27.3mgg-1 and 20.3mgg-1 for Cd(II) and Pb(II) ions respectively.
Physicochemical Problems of Mineral Processing, 2022
To develop the sorption efficiency of heavy metals: Cd(II), Co(II), Zn(II) and Pb(II) ions the biochar was modified by chitosan, FeSO4 and NaBH4. The morphology, physical structure and chemical composition of the biochar based sorbents were characterized by the scanning electron miscroscopy method, N2 adsorption and desorption isotherms, X-ray diffractometry as well as the Fourier transform infrared spectroscopywith the attenuated total reflectance analyses. The research of M(II) ions sorption was carried out as a function of pH (2-6), interaction time (0-360 minutes) and temperature (293, 313, 333 K). The maximum sorption was obtained by the ChBC for Zn(II) ions-19.23 mg/g and for MBC-Pb(II)-19.11 mg/g. Different kinetic models as well as both isotherm and thermodynamic equations were used the sorption data modelling. For Cd(II), Co(II) and Zn(II) ions the nonlinear regression of the Elovich equation gave the best fit for the experimental data. On the other hand, for Pb(II) ions, the nonlinear forms of pseudo first order and pseudo second order show a better match. The value of the correlation coefficient >0.960 determined from the Freundlich isotherm model is the highest suggesting a good fit to the experimental data. The thermodynamic parameters: ∆G°, ∆H° and ∆S° were listed and indicated that the process is spontaneous and endothermic in nature. The desorption efficiency was determined with the use of nitric, hydrochloric and sulfuric acids and the largest desorption yield for Pb(II)-ChBC equal 99.5 % was gained applying HNO3.
In this study, a green chemistry approach was employed in the preparation of Hyphaene thebaica fiber grafted polyacrylic acid via microwave assisted method using potassium persulfate as the chemical initiator. The optimum percentage grafting of 92% was achieved under 5 g concentration of acrylic acid, 0.2 g concentration of potassium persulfate (KPS) and 2 minutes of reaction time. The grafted sample was characterized using the following techniques, FTIR, SEM and XRD. The prepared graft copolymer was examined for adsorption of Pb(II) ions from aqueous solution in batch mode systems. The adsorption parameters such as pH, initial metal ion concentration and contact time were also studied. The Langmuir and Freundlich isotherm models were applied to simulate the equilibrium adsorption experimental data. The Langmuir model fitted well with experimental data with maximum adsorption capacity (qmax) of 20.37 mg/g at 45 minutes. Higher regression coefficient obtained confirmed the suitability of the Langmuir isotherm model which assumed monolayer coverage on the adsorbent surface. The adsorption studies revealed the efficacy of the grafted fiber for removal of Pb(II) ions from dilute aqueous solutions.
Adsorption of Pb2+ ions from aqueous solutions by gelatin/activated carbon composite bead form
Adsorption Science & Technology, 2017
Gelatin and activated carbon materials have been combined together to obtain a gelatin/activated carbon composite bead form which is ecofriendly, nontoxic, biocompatible, and inexpensive material. In this paper, gelatin/activated carbon adsorption for Pb 2þ ions from aqueous solutions was studied experimentally under various conditions. The experimental conditions such as contact time, solution pH, and gelatin/activated carbon dosage were examined and evaluated by using batch adsorption experiments. The maximum adsorption capacity of gelatin/ activated carbon for Pb 2þ ions was obtained to be 370.37 mg g À1. This maximum capacity was comparable with that of commercial ion exchange resins and it was much higher than those of natural zeolites. The uptake process for Pb 2þ ions was found to be relatively fast with 92.15% of the adsorption completed in about 5 min in batch conditions. The adsorption capacity was also strongly solution pH dependent. Adsorption was observed at pH value as low as 2.0 and maximum adsorption was achieved at a pH of approximately 5. The results indicated that the gelatin/activated carbon was effective to be used as an adsorbent for Pb 2þ ions removal in wastewater treatment.
Clean, Soil, Air, Water
Magnetic separation technology has been extensively used in the field of environmental problems, due to solving difficulties resulted from filtration and centrifuging. In this study, powder activated carbon (PAC) was magnetized by magnetite nanoparticles (Fe3O4@C) as an adsorbent for lead ions (Pb2+) from aqueous solution. The characteristics of the modified PAC were analyzed by scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, Brunauer-Emmett-Teller surface area analysis, energy dispersive X-ray spectroscopy and vibrating sample magnetometry. Batch adsorption experiments were conducted as a function of pH, contact time, adsorbent dosage and initial Pb2+ concentration and solution temperature. The equilibrium isotherm and kinetic models were used to evaluate the fitness of the experimental data. The maximum monolayer adsorption capacity of Pb2+ was 71.42 mg/g at 50°C. It could also be shown that the sorption isotherms were well described by the Langmuir equilibrium model. The kinetic of the adsorption process was found to follow the pseudo-second-order model expression. Thermodynamic studies indicated that the adsorption process was feasible, spontaneous and endothermic. Desorption experiments exhibited that the Fe3O4@C had a good potential in regard to regeneration and reusability and is easily regenerated by HCl solution. The proposed adsorption process can be a promising technique for Pb2+ removal from aqueous solutions and to be used in full-scale and industrial applications.