Batch Mode Studies Research Articles

Batch and fixed bed column studies for the removal of Indosol Yellow BG dye by peanut husk

Biosorption is an emerging technique for water treatment utilizing abundantly available biomaterials. The biosorption potential of peanut husk biomass was investigated in batch and continuous mode study. Batch experiments were conducted to compare the biosorption capacity of native, acetic acid treated and immobilized peanut husk biomass. Different important process parameters like pH, contact time, biosorbent dose, initial dye concentration and temperature were optimized during batch experiments. Maximum removal of Indosol Yellow BG dye was observed at pH 2 with 0.05g/50mL biosorbent dose. The biosorption process was found to be exothermic in nature. Maximum dye removal (79.7mg/g) was obtained with acetic acid treated peanut husk biomass. Different kinetic and equilibrium models were applied to the experimental data. Pseudo-second-order kinetic model and Langmuir adsorption isotherm model showed better fitness to the experimental data. Thermodynamic study was also carried out to check out the feasibility of biosorption process. Fixed bed study was carried out to optimize bed height, flow rate and initial dye concentration. Maximum dye removal in continuous mode experiments was found to be 25.9mg/g. Thomas model and Bed Depth Service Time (BDST) models were applied to the continuous mode experimental data. Characterization of biosorbent was carried out by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). FT-IR analysis showed the involvement of hydroxyl, carbonyl and carboxyl groups in the biosorption process. These findings revealed that peanut husk biomass has a high biosorption potential and it can be used for the treatment of dye containing waste water.

Preparation of banana frond activated carbon by microwave induced activation for the removal of boron and total iron from landfill leachate

The present work demonstrates the preparation of banana frond derived activated carbon (BFAC) by microwave induced KOH activation for the adsorptive removal of boron and total iron from the semi-aerobic landfill leachate. The physical and chemical properties of BFAC were evaluated by pore structural analysis, scanning electron microscopy and Fourier transform infrared spectroscopy. The effects of adsorbent dosage, contact time, solution pH and temperature on the adsorption performance were examined in a batch mode study. The experimental results manifested that the adsorptive removal of boron and total iron increased with increasing the adsorbent dosage, contact time and temperature, accomplished the adsorptive removal of boron and total iron of 93.56% and 95.14%, respectively. Equilibrium data was best confronted to the pseudo-second-order kinetic model, while the adsorptive removal of boron and total iron onto BFAC was satisfactory described by the Freundlich and Langmuir isotherm models. The findings illustrated the applicability of BFAC as an ideal on-site solution for the adsorptive treatment of boron and total iron from the contaminated landfill leachate.

Pseudomonas aeruginosa MTCC 7925: Producer of a Novel SCL-LCLPHA Co-Polymer

Pseudomonas aeruginosa MTCC 7925, a sludge isolate, was found to synthesize a novel short-chain-lengthlong- chain-length (SCL-LCL) co-polymer with 3-hydroxybutyric acid (3HB), 3-hydroxyvaleric acid (3HV), 3- hydroxyhexadecanoic acid (3HHD) and 3-hydroxyoctadecanoic acid (3HOD) as constituents. Under batch mode study, cells harvested at the stationary phase of growth depicted maximum PHAs accumulation, i.e. 24% of dry cell weight (dcw) at 48 h of incubation. The co-polymer accumulation was raised to 49% (dcw) under 2% ethanol-supplemented condition. A further, rise up to 78% (dcw) was recorded by optimizing the critical variables by Response Surface Methodology (RSM). When palm oil and its cakes were used as carbon sources, yield of 5.9 g/l was achieved, which was almost 85-fold higher against control. The thermal and mechanical properties of the polymer are comparable with polypropylene and polyethylene, thus opening new possibilities for various industrial applications. Keywords: Inexpensive carbon sources, N-deficiency, P-deficiency, PHAs, Pseudomonas aeruginosa MTCC 7925, RSM, SCL-LCL-PHA co-polymer

Preparation of activated carbon from sugarcane bagasse by microwave assisted activation for the remediation of semi-aerobic landfill leachate

This study evaluates the sugarcane bagasse derived activated carbon (SBAC) prepared by microwave heating for the adsorptive removal of ammonical nitrogen and orthophosphate from the semi-aerobic landfill leachate. The physical and chemical properties of SBAC were examined by pore structural analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The effects of adsorbent dosage, contact time and solution pH on the adsorption performance were investigated in a batch mode study at 30°C. Equilibrium data were favorably described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity for ammonical nitrogen and orthophosphate of 138.46 and 12.81mg/g, respectively, while the adsorption kinetic was best fitted to the pseudo-second-order kinetic model. The results illustrated the potential of sugarcane bagasse derived activated carbon for the adsorptive treatment of semi-aerobic landfill leachate.

Selective Adsorption of Methylparaben by Submicrosized Molecularly Imprinted Polymer: Batch and Dynamic Flow Mode Studies

Highly selective submicrosized molecularly imprinted polymer (SMIPMP) for methylparaben (MP) was synthesized by molecular imprinting technique with a sol–gel process on silica submicroparticles. The prepared SMIPMP was characterized by FT-IR, SEM, TG, and N2 adsorption–desorption techniques. Compared with microsized methylparaben imprinted polymer (MMIPMP) adsorbent, SMIPMP adsorbent with small particle size and high specific surface area showed faster adsorption rate and stronger adsorption capacity for MP. The maximum static adsorption capacity for MP of SMIPMP was 32.68 mg g–1, and the adsorption equilibrium could be reached in 40 min. The SMIPMP adsorbent could be used at least 5 times without significant loss in adsorption capacity. Compared with submicrosized nonimprinted polymer (SNIP), SMIPMP indicated excellent recognition and binding affinity toward MP molecules, whose selectivity coefficients for MP relative to methyl salicylate (MS) and p-hydroxybenzoic acid (p-HB) were 5.664 and 6.129, respectively. The mechanism for static adsorption of MP onto SMIPMP was found to follow Freundlich, Redlich-Peterson isotherm, and pseudo-second-order model. Thomas’ model was applied in the quantitative description and parametrization of the dynamic adsorption of MP to SMIPMP and SNIP, which showed that the linear and nonlinear methods were both suitable to predict the breakthrough curves but the nonlinear method was better.

Lignite fired fly ash modified by chemical treatment for adsorption of zinc from aqueous solution

The purpose of the study described in this paper was to compare removal of Zn(II) from aqueous solutions by use of two adsorbents—alkali-modified fly ash (FAN) and alkali and dye-modified fly ash (FAN-MO). The effects of four conditions (solution pH, contact time, initial metal ion concentration, and dose of adsorbent) on removal of Zn(II) at 27 ± 5 °C were studied in batch mode. Adsorption of Zn(II) was greater at pH 4.0 for FAN (76.49 %) and at pH 5.0 for FAN-MO (24.72 %). Maximum adsorption of Zn(II) by FAN and FAN-MO was achieved after 50 min. The linear forms of the Langmuir, Freundlich, Tempkin, D–R, Harkin–Jura, and Frenkel–Halsey isotherms were used for experiments with different concentrations of the metals. Adsorption of Zn(II) ions satisfied the Langmuir isotherm model only. The adsorption capacity of both adsorbents was also investigated by column studies. Adsorption of Zn(II) ions on FAN in column studies (45.33 %) was lower than in batch mode studies. For FAN-MO, adsorption was 37.88 % in column studies, again lower than in batch mode studies. Fly ash modified by alkali had a higher adsorption capacity for Zn(II) ions than fly ash modified by alkali followed by addition of dye.

Decolorization of Reactive Blue 49 contaminated solutions by Capsicum annuum seeds: Batch and continuous mode biosorption applications

Biosorption potential of biomass obtained from Capsicum annuum seeds to remove a reactive textile dye from contaminated solutions was investigated. Reactive Blue 49 was chosen as model dye. Initial pH, biomass dosage, contact time, initial dye concentration and temperature were evaluated in batch mode studies. Up to 96.62% decolorization performance was achieved with 1.6 g L −1 of biosorbent. Rate constants of the biosorption were calculated by kinetic measurements. Process was well described with Langmuir isotherm model at the dye concentration range of 75–500 mg L −1. Maximum monolayer biosorption capacity was determined as 96.35 mg g −1. Decolorization ability of biomass in a packed bed column was investigated as a function of flow rate, biomass amount and initial dye concentration. The possible interaction between dye molecules and biosorbent surface was evaluated by SEM, EDX and FTIR analyses. Biosorption performance of the suggested biosorbent in simulated wastewater conditions was also tested. Overall, the proposed biosorbent material was successfully used for the removal of a reactive dye from contaminated solutions.

Bio‐electrochemical denitrification by a novel proton‐exchange membrane electrodialysis system—a batch mode study

AbstractBACKGROUND: Contamination of nitrate in ground and surface water has become an ever‐increasing and serious environmental problem. Biological methods hold the promise of converting nitrate into harmless nitrogen. A novel denitrification system which combines proton‐exchange membrane electrodialysis with simultaneous bio‐electrochemical autotrophic denitrification has been developed. The proton‐exchange membrane was used to transfer current and to exclude oxygen or other oxidative chemicals generated in the anode reaction. The H2 generated by the cathode was utilized by autotrophic denitrifying microorganisms in the cathode cell to reduce nitrate. In this study, the transport of H+, a denitrification kinetics model and factors influencing the denitrification rate were explored in batch mode.RESULTS: The addition of 0.03 mol L−1 H2SO4 into the anode cell enhanced proton transport and maintained the pH of the cathode cell in an appropriate range for biological denitrification. The denitrification rate was affected by applied current and biomass. Under adequate current conditions, the kinetics of the denitrification process followed a zero‐order kinetics model; the average denitrification rate for unit biomass was calculated to be 9.36 mg NO3−‐N VSS g−1 h−1.CONCLUSIONS: Results indicate that the system is suitable for denitrification. Owing to its simple structure and operation, it has the potential for use as a system to reduce nitrate in water. Copyright © 2010 Society of Chemical Industry

Untreated clay with high adsorption capacity for effective removal of C.I. Acid Red 88 from aqueous solutions: Batch and dynamic flow mode studies

Batch and dynamic flow adsorption studies were carried out using natural clay for the removal of Acid Red 88 (AR88) dye from aqueous solutions. Adsorption conditions were examined with respect to initial pH, adsorbent amount, contact time, initial dye concentration, column i.d. and flow rate. Adsorption process was better described by the pseudo-second-order kinetic and Langmuir isotherm models. SEM and zeta potential analysis were used to characterize the adsorbent material. 98.10 ± 0.34% of dye could be removed in 15 min at pH 2.0 in the batch mode. The adsorbent exhibits very high monolayer dye binding capacity of 1133.10 mg g −1 which was comparable to or higher than those of many sorbent materials. Our results indicate that the suggested natural and low-cost adsorbent material may be useful for the effective removal of contaminating acid dyes.

Biosorption applications of modified fungal biomass for decolorization of Reactive Red 2 contaminated solutions: Batch and dynamic flow mode studies

Biosorption characteristics of a surfactant modified macro fungus were investigated for decolorization of Reactive Red 2 contaminated solutions. Better biosorption efficiency was obtained with a small amount of fungal biomass after modification process. Operating variables like pH, biomass amount, contact time, temperature, dye concentration, flow rate and column size were explored. The biosorption process followed the pseudo-second-order kinetic and Langmuir isotherm models. Thermodynamic data confirm that the biosorption process is spontaneous and endothermic in nature. Under optimized batch conditions, up to 141.53 mg dye g −1 could be removed from solution in a relatively short time. Modification process was confirmed by FTIR spectroscopy and zeta potential studies. Possible dye-biosorbent interactions were discussed. Good dynamic flow biosorption potential was observed for the suggested biosorbent in simulated wastewater. Overall, batch and continuous mode data suggest that this environmentally friendly and efficient biosorbent may be useful for the removal of reactive dyes from aqueous media.

Removal and recovery of Ni and Zn from aqueous solution using activated carbon from Hevea brasiliensis: Batch and column studies

In the present study, the adsorption behavior of Ni and Zn from aqueous systems onto activated carbon prepared from Hevea brasiliensis sawdust has been attempted via batch and column mode studies under various operating conditions. The experimental data were fitted to various isotherm models. The maximum adsorption capacity of Ni and Zn were found to be 17.21 and 22.03 mg g −1, respectively, at 30 °C according to Langmuir model. Kinetic studies showed the adsorption process followed pseudo second-order rate model. Breakthrough curves were plotted for the adsorption of metal ions using continuous-flow column operation by varying the bed height, flow rate, initial metal ion concentration and temperature. At the end, an attempt has also been made to model the data generated from column studies using the empirical relationship based on Adam–Boharts model and Thomas model. The model constants were also evaluated. This has helped in ascertaining the practical applicability of the adsorbent. The column regeneration studies were carried out for three adsorption–desorption cycles. The elutant used for the regeneration of the adsorbent was 0.1 M H 2SO 4. On the basis of the results, ACHB can be economically and effectively used as an adsorbent for the removal of metal ions from wastewaters.

Adsorption of copper(II) from aqueous solution by Beidellite

Beidellite was used as an adsorbent for the removal of copper ions from aqueous solutions. Batch mode studies were carried out by varying initial copper (II) concentrations (50–500 mg/l), initial pH (2.0–5.0), adsorbent particle size (0.095–0.890 mm) and temperature (293–333 K). A contact time of 60 min was required to reach equilibrium. Adsorption of the metal ion was highly pH dependent and the optimum pH for the removal was 5.0 at which the removal was maximum (25.3 mg/g). The result showed that the amount adsorbed of the metal ion increased with increasing initial copper (II) concentration and contact time. Three adsorption kinetic models, the pseudo first-order, second-order and intraparticle diffusion were applied to experimental data to predict the adsorption rate constants. A comparison of kinetic models on the overall adsorption rate showed that metal ion/adsorbent system was best described by the pseudo second-order rate model. The adsorption capacity (Qo) calculated from the Langmuir isotherm was 71.07 mg/g for at pH 5.0, 293 K for the particle size of 0.095–0.890 mm. The experimental data yielded excellent fits with Langmuir isotherm equation. Different thermodynamic parameters viz., changes in standard free energy, enthalpy and entropy were evaluated and it was found that the reaction was spontaneous and endothermic in nature.

Arsenate removal from water by a weak-base anion exchange fibrous adsorbent

A weak-base anion exchange fiber named FVA with primary amino groups for selective and rapid removal of arsenate species was prepared by means of electron irradiation induced liquid phase graft polymerization of N-vinylformamide onto polyethylene coated polypropylene fibers and by the subsequent alkaline hydrolysis of amide group on the grafted polymer chains. Two types of FVA were prepared. One was a non-woven cloth type named FVA-c for the batch-mode study, which clarified that uptake of arsenate species decreases with an increase in pH, and chloride and sulfate do not strongly interfere with uptake of arsenate species different from conventional anion exchange resins based on crosslinked polystyrene matrices. The other was a filamentary type one named FVA-f used in the column-mode study, which clarified that arsenate species were successfully removed from neutral pH arsenate solutions containing 1.0–99 mg of As/L at feed flow rates of 100–1050 h −1 in space velocity (SV). The most important findings are that the 1% breakthrough point in uptake from the arsenate solution containing 1.0 mg of As/L at the high feed flow rate of 1050 h −1 in SV was as large as 4670 bed volumes, giving the 1% breakthrough capacity of 0.298 mmol/g of FVA-f. Adsorbed arsenate was able to be quantitatively eluted with 1 M hydrochloric acid and FVA-f was simultaneously regenerated. Then, the repeated use of FVA-f was possible.

Highly sensitive phage-based biosensor for the detection of β-galactosidase

Development of real-time sensor based on the target-specific probe that make possible sensitive, rapid and selective detection and monitoring of the particular antigen molecules could be of substantial importance to the many applications. Because of its high specificity to the target molecules, excellent temperature stability, and easy production, bacterial phage might serve as a powerful biorecognition probe in biosensor applications. Here, we report extremely sensitive and specific label-free direct detection of model antigen, β-galactosidase (β-gal), based on surface plasmon resonance (SPR) spectroscopy. The β-gal specific landscape phage 1G40 has been immobilized on the gold surface of SPR SPREETA™ sensor chip through physical adsorption [V. Nanduri, A.M. Samoylova, V.Petrenko, V. Vodyanoy and A.L.Simonian, Comparison of optical and acoustic wave phage biosensors, 206th Meeting of The Electrochemical Society, Honolulu, Hawaii, October 3–8, (2004)]. Another non-specific to the β-gal phage, a wild-type phage F8-5, was used in the reference channel. The concentration-dependent binding of β-gal in both channels were assessed by monitoring the sensor optical response as a function of time under different experimental conditions, and the concentration of β-gal was computed in differential mode. Concentrations of β-gal between 10 −12 M and 10 −7 M could be readily detected, with linear part of calibration curve between 10 −9 M and 10 −6 M. When β-gal was pre-incubated with different concentrations of free 1G40 phage prior to exposure to the biosensor, concentration-dependent inhibition was observed, indicating on biosensor high specificity toward β-gal. Apart from a flow through mode used to deliver the samples to the surface for the SPR sensor, batch mode sensing was also employed to study the binding of β-gal to immobilized phage on the SPR sensor surface. Experiments using a flow through mode provided more consistent results in the full dose range and showed higher sensitivity as opposed to the batch mode studies. The mean K d and binding valences for the flow through mode studies was 1.3 ± 0.001 nM and 1.5 ± 0.03, in comparison to 26 ± 0.003 nM and 2.4 ± 0.01 for the batch mode studies. The average thickness of phage 1G40 adlayer deposited through flow through and batch mode was 3 ± 0.002 and 0.66 ± 0.001 nm, respectively.

Study of the dichromate-catalysed hydrogen peroxide decomposition: Comparison of different batch mode reactors for the kinetics determination

This paper deals with an experimental batch mode study of a chemical homogeneous reaction: the dichromate-catalysed hydrogen peroxide decomposition. The thermodynamic properties and the kinetic parameters of the reaction are simultaneously determined using a calorimetric approach. Various batch-operating modes (adiabatic, isoperibolic, or differential thermal analysis) are compared and it is shown that the determined parameters do not depend on the operating mode. A complete kinetic law is proposed. The reaction rate constant is assumed to follow the Arrhenius rate law. The Arrhenius parameters are determined as frequency factor k 0 = 1.39 × 10 9 s −1 and activation energy E = 54.9 kJ mol −1. The measured enthalpy of reaction is Δ r H = −94 kJ mol −1. The reaction order is between 0 and 2 in hydrogen peroxide according to operating conditions and depends linearly on the initial dichromate concentration. The reaction can be managed by two parameters: on one hand the released reaction heat directly depends on the hydrogen peroxide concentration, and on the other hand, the kinetic rate can be increased in increasing the dichromate concentration.

Electrochemical pilot scale study for reduction of 2,4-DNT

An electrochemical pilot scale reactor was used to treat simulated munitions wastewater containing 100 mg/L of 2,4-dinitrotoluene (DNT). Experiments were conducted by using a glassy carbon (zero porosity) coated graphite cylinder as the cathode and a platinum wire as the anode. All experiments were conducted under dissolved oxygen concentration of less than 1.5 mg/L. Initially, simulating batch conditions were conducted to obtain the optimum operating conditions for the reactor. During this batch-mode study, the effects of various parameters such as applied current, electrolyte concentration, and type of electrolyte on the reduction of DNT were evaluated. Results obtained showed that the rates of reduction of DNT increased with an increase in current or concentration of electrolyte. Based on the results obtained from the batch simulation experiments, continuous flow experiments were conducted at three different currents. The ionic strength of the feed solution was maintained at 0.027 M. A current of 200 mA was found to provide a stable reduction of DNT at the 80% level for a period of 14 days after which reactor cleaning is necessary for removal of solids that were formed within the reactor. End products determined for the continuous flow experiments showed 100% molar balance conversion.

Electrochemical Reduction of 2,4-Dinitrotoluene in a Continuous Flow Laboratory Scale Reactor

An electrochemical laboratory scale reactor was used to treat 2,4-dinitrotoluene (DNT). Experiments were conducted by using a graphite carbon cylinder impregnated with glassy carbon (zero porosity) as the cathode and a platinum wire as the anode. All experiments were conducted under anoxic conditions. Initially, experiments simulating batch conditions were conducted to obtain the optimum operating conditions for the reactor. During this batch-mode study, the effect of various parameters such as applied current, electrolyte concentration, and type of electrolyte on the reduction of DNT were evaluated. Results showed that the rates of DNT reduction increased with an increase in current or concentration of electrolyte. Based on the results obtained from the batch simulation experiments, continuous flow experiments were conducted at three different currents and one electrolyte concentration. The ionic strength of the feed solution was maintained at 0.027 M. A current of 200 mA (current density 0.088 mA/cm²) provided a stable reduction of DNT at the 80% level for a period of 14 days after which reactor cleaning was necessary for removal of suspended solids that were formed within the reactor. End products determined for the experiments showed 80100% molar balance closure.

Removal of Cd(II) from wastewater by adsorption on “waste” [formula omitted] hydroxide

Effect of initial metal ion concentration, agitation time, temperature and pH on Cd(II) adsorption by “waste” Fe(III) Cr(III) hydroxide was investigated in batch mode studies. The equilibrium data could be described well by the Langmuir and Freundlich isotherm equations. The Lagergren rate constants of adsorption are reported. The intraparticle diffusion of Cd(II) through pores in the adsorbent was shown to be the main rate limiting step. Desorption of Cd(II) was 70% at pH 3.80. The studies showed that the “waste” Fe(III) Cr(III) hydroxide can be used as an efficient adsorbent material for Cd(II) removal from wastewater.