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Tannic acid adsorption/desorption study onto/from commercial activated carbon

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Abstract

This study reports tannic acid adsorption onto commercial activated carbon (ACC) in a batch system. Adsorption process parameters namely pH, adsorbent dose (m ad), temperature (T), initial tannic acid concentration (C o), and contact time (T) were studied and optimized. Optimum pH and adsorbent dose were found to be 3.0 and 15 g/l, respectively. Equilibrium contact time was found to be 7 h. Pseudo-second-order kinetic best fits the adsorption kinetic data. Three isotherms namely Langmuir, Temkin, and Redlich and Peterson (R–P) isotherms were studied and it was found that Langmuir and R–P isotherm generally fitted the experimental equilibrium adsorption data. Endothermic nature of the adsorption of tannic acid onto ACC was concluded, and heat of adsorption was found to be as 89.55 kJ/mol. On considering the cost of ACC, regeneration studies of Tannic acid (TA) loaded ACC have been performed using solvent and thermal desorption methods.

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... Among these methods, adsorption has been extensively utilized because of its simplicity and high efficiency. Many adsorbents, such as amino-functionalized magnetic nanoadsorbent [13], chitosan [14], surfactant-modified zeolite [2], resin [3], silica [15], and activated carbon [12,16] have been utilized to remove TA from water and wastewater. Among different adsorbents, the anion ion-exchange resin is considered one of the most effective methods due to its high removal efficiency [17]. ...
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Amino-functionalized magnetic mesoporous silica (magMCM-41-NH2) was prepared and adsorption of organic pollutant tannic acid (TA) from aqueous solution on the resulting material was investigated. The adsorbent was characterized by elemental analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption, IR spectroscopy, Zeta potential measurements and vibration sample magnetometer (VSM). Characterization results showed that magMCM-41-NH2 had ordered mesoporous structure with amino group content of 4.57 wt%, BET surface area of 668 m2/g and the pore volume of 0.525 cm3/g. Batch adsorption tests indicated that magMCM-41-NH2 adsorbent exhibited high adsorption affinity towards aqueous TA with a maximum adsorption capacity of 510.2 mg/g. The Freundlich model could fit the adsorption isotherm of TA over magMCM-41-NH2 very well, implying that adsorption process is heterogeneous. TA adsorption on magMCM-41-NH2 could be well described by the pseudo-second-order kinetics. Adsorption of TA on the adsorbent was found to be strongly dependent on pH and ionic strength, suggesting that electrostatic interaction played a crucial role in TA adsorption. X-ray photoelectron spectroscopy (XPS) analysis confirmed the formation of complex compound between TA and surface amino groups of magMCM-41-NH2 upon adsorption.
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The adsorption of phenol and chlorophenols on four commercial granular activated carbons (GAC) was investigated by batch experiment to correlate with the structure of activated carbons. Physical properties including surface area, average pore diameter and micropore volume and chemical structure of the activated carbons were characterized by N2 adsorption experiment, scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, elemental analysis, X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopy. To calculate the adsorption parameters, adsorption isotherm data were fitted to the Freundlich equation. From the correlation between the characterization and the Freundlich parameters, it is concluded that the adsorption behavior of phenol and chlorophenols on activated carbons is controlled by the dispersion force between the π-electrons in activated carbons and those in phenol molecules.
Article
The use of activated carbon obtained from Euphorbia rigida for the removal of a basic textile dye, which is methylene blue, from aqueous solutions at various contact times, pHs and temperatures was investigated. The plant material was chemically modified with H2SO4. The surface area of chemically modified activated carbon was 741.2 m2 g−1. The surface characterization of both plant- and activated carbon was undertaken using FTIR spectroscopic technique. The adsorption process attains equilibrium within 60 min. The experimental data indicated that the adsorption isotherms are well described by the Langmuir equilibrium isotherm equation and the calculated adsorption capacity of activated carbon was 114.45 mg g−1 at 40° C. The adsorption kinetics of methylene blue obeys the pseudo-second-order kinetic model and also followed by the intraparticle diffusion model up to 60 min. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated to estimate the nature of adsorption. The activation energy of the system was calculated as 55.51 kJ mol−1. According to these results, prepared activated carbon could be used as a low-cost adsorbent to compare with the commercial activated carbon for the removal textile dyes from textile wastewater processes.
Article
Core/shell type nanoparticles with an average diameter of 11 nm were synthesized by coating Fe3O4 core in an alkyl alcohol (octanol) with amorphous silica shell. The synthesized nanoparticles were calcined under various conditions to produce different types of core/shell particles. The particles were characterized by using various experimental techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and vibration sample magnetometer (VSM). The results suggest that the composition of the three samples (uncalcined, calcined at 200–600 °C for 5 h and 15 h) are Ox-Fe3O4@SiO2, Fe3O4/Fe@SiO2 and γ-Fe2O3/Fe@SiO2, respectively. The saturation magnetization of the particles calcined for 5 h was found to be higher than those of the other particles. It is noted that the formation of metal iron inside the particles during calcination is responsible for the enhanced magnetic property.
Article
Biological treatment of simulated tannic acid (TA)-containing wastewater by activated sludge was investigated to find the optimal biodegradation conditions and investigate the aerobic biodegradation kinetics. Activated sludge was acclimatized to simulated wastewater with TA concentration up to 950 mg/l over a period of 27 days. Batch experiments on TA biodegradation under different pH, temperature, aeration conditions and with different initial substrate concentrations were conducted. The initial biomass concentration was kept at 2000 mg/l. By comparing the degradation rates under different conditions, the optimal ranges of pH, temperature and DO for TA biodegradation in the activated sludge system were determined: pH ≈ 7, temperature = 20–35 °C, DO > 1.0 mg/l. A biodegradation kinetic model that takes into consideration substrate inhibition and endogenous decay was established, and its kinetic parameters were determined. The estimated values of μmax, Ks, Ki, kd and Y were 0.208 h−1, 226 mg/l, 522 mg/l, 0.0092 h−1 and 0.594, respectively.
Article
The sorption of two dyes, namely, Basic Blue 69 and Acid Blue 25 onto peat has been studied in terms of pseudo-second order and first order mechanisms for chemical sorption as well as an intraparticle diffusion mechanism process. The batch sorption process, based on the assumption of a pseudo-second order mechanism, has been developed to predict the rate constant of sorption. the equilibrium capacity and initial sorption rate with the effect of agitation, initial dye concentration and temperature. An activation energy of sorption has also been evaluated with the pseudo-second order rate constants. A comparison of the equilibrium sorption capacity evaluated has been made from pseudo-second order model and Langmuir isotherm.
Article
A literature review of the use of sorbents and biosorbents to treat polluted aqueous effluents containing dyes/organics or metal ions has been conducted. Over 70 systems have been reported since 1984 and over 43 of these reported the mechanism as being a pseudo-first order kinetic mechanism. Three sorption kinetic models are presented in this paper and have been used to test 11 of the literature systems previously reported as first order kinetics and one system previously reported as a second order process. In all 12 systems, the highest correlation coefficients were obtained for the pseudo-second order kinetic model.
Article
Activated carbon fibers (ACFs) were used for the adsorption of phenol, 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), 4-nitrophenol (4-NP) and 2,4-dinitrophenol (DNP) from aqueous solutions, and the adsorption capacities followed the order of TCP > DNP ≈ DCP > 4-NP > 4-CP > 2-CP > phenol. Adsorption isotherms at different temperatures were determined and modeled with Langmuir, Freundlich and Redlich–Peterson equations. Thermodynamic parameters were calculated and correlated with the adsorption behaviors. The effects of solution pH on the adsorption were also studied. The adsorption mechanism was discussed based on the experimental results, and the π–π interactions, solvent effects, hydrophobic interactions and molecular dimensions were considered to be important in the adsorption. Kinetic studies showed rapid adsorption kinetics of the phenols, due to the open pore structure of the ACFs. The kinetics was fitted with the pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Steric effects on adsorption kinetics were observed for TCP, 4-NP and DNP, but serious impact on the ultimate uptake was only found for DNP. The relationship between the steric effects and the molecular dimension was also proposed.
Article
Most algorithms for the least-squares estimation of non-linear parameters have centered about either of two approaches. On the one hand, the model may be expanded as a Taylor series and corrections to the several parameters calculated at each iteration on the assumption of local linearity. On the other hand, various modifications of the method of steepest-descent have been used. Both methods not infrequently run aground, the Taylor series method because of divergence of the successive iterates, the steepest-descent (or gradient) methods because of agonizingly slow convergence after the first few iterations. In this paper a maximum neighborhood method is developed which, in effect, performs an optimum interpolation between the Taylor series method and the gradient method, the interpolation being based upon the maximum neighborhood in which the truncated Taylor series gives an adequate representation of the nonlinear model. The results are extended to the problem of solving a set of nonlinear algebraic e
Article
Surfactant-modified zeolites (SMZs) with various loadings of cetylpyridinium bromide (CPB) were used as adsorbents to remove tannic acid (TA) from aqueous solution. The TA adsorption efficiencies for natural zeolite and various SMZs were compared. SMZ presented higher TA adsorption efficiency than natural zeolite, and SMZ with higher loading amount of CPB exhibited higher TA adsorption efficiency. The adsorption of TA onto SMZ as a function of contact time, initial adsorbate concentration, temperature, ionic strength, coexisting Cu(II) and solution pH was investigated. The adsorbents before and after adsorption were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FT-IR) spectroscopy. The adsorption kinetics of TA onto SMZ with CPB bilayer coverage (SMZ-CBC) followed a pseudo-second-order model. The equilibrium adsorption data of TA onto SMZ-CBC were well represented by Langmuir, Redlich-Peterson and Sips isotherm models. The calculated thermodynamic parameters indicated that TA adsorption onto SMZ-CBC was spontaneous and exothermic. The TA adsorption capacity for SMZ-CBC slightly decreased with increasing ionic strength but significantly increased with increasing Cu(II) concentration. The TA adsorption capacity for SMZ-CBC was relatively high at solution pH 4.0-7.0, and decreased with an increase in solution pH from 7.0 to 8.5. The mechanisms controlling TA adsorption onto SMZ-CBC at solution pH 5.5 include electrostatic attraction, hydrogen bonding and organic partitioning.
Article
Present study reports treatment of simulated dairy wastewater (SDW) by inorganic coagulants such as poly aluminum chloride (PAC), ferrous sulphate (FeSO(4)) and potash alum (KAl(SO(4))(2)·12H(2)O). Batch coagulation experiments were conducted to evaluate the influence of initial pH (pH(i): 5-10) and coagulant dosage (m: 100-5000 mg/L) on chemical oxygen demand (COD) removal from SDW. Residual COD and system pH were observed as function of time. Optimum pH(i) (pH(i,op)) was found to be 8.0 for all the three coagulants. Optimum m (m(op)) was found to be 300, 800 and 500 mg/L for PAC, FeSO(4) and KAl(SO(4))(2)·12H(2)O, respectively, giving 69.2, 66.5 and 63.8% COD removal efficiency in 30 min. Heating values of the sludge generated by the coagulants PAC, FeSO(4) and KAl(SO(4))(2)·12H(2)O were found to be 20.7, 29.6 and 17.3 MJ/kg, respectively.
Article
Present study reports treatment of synthetic dairy wastewater (SDW) in terms of chemical oxygen demand (COD) removal by means of adsorption onto activated carbon-commercial grade (ACC) and bagasse fly ash (BFA). Optimum conditions for SDW treatment were found to be: initial pH approximately 4.8, adsorbent dose of 20g/l for ACC and 10g/l for BFA and contact time approximately 8h. Pseudo-second-order kinetic model was found to fit the kinetic data and Redlich-Peterson isotherm model was generally found to best represent the equilibrium data for SDW treatment by ACC and BFA. The change in entropy and enthalpy for SDW adsorption onto ACC and BFA were estimated as 125.85kJ/molK and 91.53kJ/mol; and 25.71kJ/molK and 17.26kJ/mol, respectively. The negative values of change in Gibbs free energy indicate the feasibility and spontaneous nature of the adsorptive treatment.
Article
In this paper, a new polymeric adsorbent WJN-09 for adsorbing and removing tannic and gallic acids from water was prepared, and its adsorption capacities for these two natural organic acids were tested by using the commercial resins XAD-7, XAD-4 and NDA-7 as references. The adsorption capacities of WJN-09 for tannic and gallic acids were higher than those of XAD-4, XAD-7 and NDA-7 at 303 K, which may be attributed to its amino function groups, pore structure and Zeta potential. The adsorption enthalpy changes DeltaH exhibited that the adsorption of tannic acid by WJN-09 was a chemical and endothermic process. Furthermore, batch kinetic studies indicated that the tannic acid adsorbed to WJN-09 could be fitted well by both pseudo-first-order and pseudo-second-order adsorption equations, but the intra-particle diffusion played a dominant role in the adsorption of gallic acid. Changes of resin's Zeta potential and acids' average molecular size were observed when Cu(II) was added in solutions, which could explain the significant increase in WJN-09's adsorption capacity for tannic and gallic acids in the presence of Cu(II).
Article
Chitosan is a well-known excellent adsorbent for a number of organics and metal ions, but its mechanical properties and specific gravity should be enhanced for practical operation. In this study, activated clay was added in chitosan slurry to prepare composite beads. The adsorption isotherms and kinetics of two organic acids (tannic acid, humic acid) and two dyes (methylene blue, reactive dye RR222) using composite beads, activated clay, and chitosan beads were compared. With composite beads as an adsorbent, all the isotherms were better fitted by the Freundlich equation. The adsorption capacities with composite beads were generally comparable to those with chitosan beads but much larger than those with activated clay. The pseudo-first-order and pseudo-second-order equations were then screened to describe the adsorption processes. It was shown that the adsorption of larger molecules such as tannic acid (MW, 1700 g mol(-1)), humic acid, and RR222 from water onto composite beads was better described by the pseudo-first-order kinetic model. The rate parameters of the intraparticle diffusion model for adsorption onto such adsorbents were also evaluated and compared to identify the adsorption mechanisms.
Article
Adsorbent (T3K618) has been prepared from Tunçbilek lignite by chemical activation with KOH. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by t-plot based on N2 adsorption isotherm. The N2 adsorption isotherm of malachite green on T3K618 is type I. The BET surface area of the adsorbent which was primarily contributed by micropores was determined 1000 m2/g. T3K618 was used to adsorb malachite green (MG) from an aqueous solution in a batch reactor. The effects of initial dye concentration, agitation time, initial pH and adsorption temperature have been studied. It was also found that the adsorption isotherm followed both Freundlich and Dubinin-Radushkevich models. However, the Freundlich gave a better fit to all adsorption isotherms than the Dubinin-Radushkevich. The kinetics of adsorption of MG has been tested using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Results show that the adsorption of MG from aqueous solution onto micropores T3K618 proceeds according to the pseudo-second-order model. The intraparticle diffusion of MG molecules within the carbon particles was identified to be the rate-limiting step. The adsorption of the MG was endothermic (DeltaH degrees = 6.55-62.37 kJ/mol) and was accompanied by an increase in entropy (DeltaS degrees = 74-223 J/mol K) and a decrease in mean value of Gibbs energy (DeltaG degrees = -6.48 to -10.32 kJ/mol) in the temperature range of 20-50 degrees C.
Article
The removal of tannin from aqueous media by cationic surfactant-modified bentonite clay was studied in a batch system. The surfactant used was hexadecyltrimethylammonium chloride. Adsorbent characterizations were investigated using X-ray diffraction, infrared spectroscopy, surface area analysis, and potentiometric titration. The effects of pH, contact time, initial solute concentration, adsorbent dose, ionic strength, and temperature on the adsorption of tannin onto modified clay were investigated. The adsorbent exhibited higher tannin removal efficiency (>99.0%) from an initial concentration of 10.0 micromol/L at pH 3.0. Adsorption capacity decreased from 90.1 to 51.8% with an increase in temperature from 10 to 40 degrees C at an initial concentration of 25.0 micromol/L. The adsorption process was found to follow pseudo-first-order kinetics. Film diffusion was found to be the rate-limiting step. Tannin adsorption was found to decrease with increase in ionic strength. The tannin equilibrium adsorption data were fitted to Langmuir and Freundlich isotherm models, the former being found to provide the best fit of the experimental data. The maximum monolayer adsorption capacity for tannin was 69.80 micromol/g at 30 degrees C. Comparison of adsorption capacity of the modified clay with reported adsorbents in the literature was also presented. Adsorbed tannin on modified clay can be recovered by treatment with 0.1 M NaOH solution. Regeneration experiments were tried for four cycles and results indicate a capacity loss of <10.0%. From the results it can be concluded that the surfactant-modified clay could be a good adsorbent for treating tannin-contaminated waters.
Article
Dynamic batch experiments were carried out for the biosorption of basic yellow dye on to the green macroalgae Caulerpa scalpelliformis. The factors affecting the sorption process such as the initial concentration of the dye and pH of the solution, the adsorbent dosage and the time of contact were studied. The sorption kinetics followed pseudo-second order kinetic model. The Caulerpa species exhibited a maximum uptake of 27 mg of dye per gram of seaweed. The Boyd's plot confirmed the external mass transfer as the rate-limiting step. The average effective diffusion coefficient was found to be 2.47 x 10(-4)cm(2)/s. Sorption equilibrium studies demonstrated that the biosorption followed Freundlich isotherm model, which implies a heterogeneous sorption phenomenon. Various thermodynamic parameters such as enthalpy of sorption DeltaH degrees , free energy change DeltaG degrees and entropy DeltaS degrees were estimated. The negative value of DeltaH degrees and negative values of DeltaG degrees show the sorption process is exothermic and spontaneous. The negative value of entropy DeltaS degrees shows the decreased randomness at the solid-liquid interface during the sorption of dyes onto green seaweed.