Batch-mode System Research Articles

Metal organic framework anchored onto biowaste mediated carbon material (rGO) for remediation of chromium (VI) by the photocatalytic process

Groundwater contaminated with hexavalent chromium Cr(VI) causes serious health concerns for the ecosystem. In this study, a hybrid amino functionalized MOF@rGO nanocatalyst was produced by utilization of a biowaste mediated carbon material (reduced graphene oxide; rGO) and its surface was modified by in situ synthesis of a nanocrystalline, mixed ligand octahedral MOF containing iron metal and NH2 functional groups and the prepared composite was investigated for Cr (VI) removal. The photocatalytic degradation of Cr(VI) in aqueous solutions was carried out under UV irradiation. Using a batch mode system, the effect of numerous control variables was examined, and the process design and optimization were carried out by response surface methodology (RSM). The photocatalyst, NH2-MIL(53)-Fe@rGO, was intended to be a stable and highly effective nanocatalyst throughout the recycling tests. XRD, SEM, EDS, FTIR examinations were exploited to discover more about surface carbon embedded with MOF. 2 g/L of NH2-MIL-53(Fe)/rGO was utilized in degrading 200 mg/L of Cr(VI) in just 100 min, implying the selective efficacy of such a MOF-rGO nanocatalyst. Moreover, the Eg determinations well agreed with the predicted range of 2.7 eV, confirming its possibility to be exploited underneath visible light, via the Tauc plot. Thus, MOF anchored onto biowaste derived rGO photo-catalyst was successfully implemented in chromium degradation.

Graphitized corncob 3D Biomass‒driven anode for high performance batch and continuous modes Air‒Cathode microbial fuel cells working by domestic wastewater

Effective 3D anode was prepared by graphitization of corncob biomass at high temperature under an inert atmosphere. As an anode in the microbial fuel cells, the proposed electrode revealed very good performance in both batch and continuous modes when the process parameters were optimized. The physicochemical characterizations indicated that the surface of the prepared anode is decorated by micro porous layers array and composed of SiO2‒incorporated graphite. Moreover, investigation the electrical properties showed very good electrical conductivity dependent on the preparation temperature; 6.9, 8.6 and 8.9 S/m for the electrode prepared at 900, 1000 and 1100 °C, respectively. The performance of the proposed anode was evaluated in air‒cathode single chamber microbial fuel cell driven by domestic wastewater without using exterior microorganisms. The electrochemical measurements, for the batch mode cell, displayed high power density generation upon utilizing the corncob electrode compared to commercial anodes; 100 ± 8, 135 ± 11 and 2010 ± 85 mW/m2 from cells assembled using carbon paper, carbon cloth and corncob‒1100 °C, respectively. Moreover, addition of sodium acetate strongly enhanced the cell performance as the generated power density was increased from 475 ± 30 to 1963 ± 90 mW/m2 after addition of the salt (5 g/l), however the experimental results indicated that 5 g/l is the optimum salt concentration. In a continuous mode cell, the results concluded that the proposed 3D anode can be used fresh or after colonization of a biofilm. Interestingly, the generated power from the continuous mode cell is higher than the batch mode system due to mass transfer resistance elimination.

Application of constructed floating wetlands (CFWs) to treat textile effluent

Lab-scale constructed floating wetlands (CFWs) using Vetiveria zizanioides and Heliconia psittacorum in a batch mode system was studied to treat textile effluent. The CFW unit (size of 1.8 m x 0.6 m (LxW)) was made with palm fiber media wrapped in the fish net and tied to the PVC pipe frame. Two CFW units were each planted with V. zizanioides, and H. psittacorum, and one CFW unit was without plants as control treatment. Then all CFW units were placed in each microfiber cell with dimensions of 2 m x 0.98 m x 0.60 m (LxWxH). The performance of CFWs was examined for about 21 days with 20 and 50% textile effluent. V. zizanioides and H. psittacorum for both 20% and 50% textile effluent showed good performance in removing ammonia with removal efficiency (RE) ranging from 60 - 80%. Reasonable RE was observed for TN but not for TP and phosphate. The study suggests that both V. zizanioides and H. psittacorum could be potential plants used in the CFW system to treat textile effluent.

Catalytic selective separation of chloride ions from acidic wastewater

A new two-step technique was developed for selective separation of chloride ions from acidic aqueous solutions. The process is operated at ambient temperature and pressure, and it is powered by H2 gas and atmospheric oxygen. The Pt-Ag-AC catalyst comprises activated carbon (AC) loaded with platinum (Pt) nano size crystals and metallic silver (Ag) particles. The aeration of acidic chloride solution results in the oxidation of Ag0 to Ag+, which in turn reacts with chloride ions to form an insoluble AgCl precipitate on the catalyst. The regeneration of the Pt-AgCl-AC is performed by hydrogenation, that leads to reduction of AgCl into Ag0, followed by the release of Cl− ions. The process was studied in a batch mode system using acidic NaCl-H2SO4 solutions (500 mgCl/L, [H2SO4]0 = 0.5 M) and Pt-Ag-AC made of granular activated charcoal. The carbon was loaded with 0.5 %Pt and 3.22, 6.25 or 9.09 % of metallic silver. A maximal chloride adsorption capacity of 16.31 mgCl/g was recorded. Full (100 %) separation of Cl− ions from NaCl solutions with [Cl−]0 = 200 mg/L and [H2SO4]0 = 0.5 M was demonstrated.

Lignocellulosic bioethanol production using Neurospora intermedia in consolidated bioprocessing (CBP) system

Bioethanol production from lignocellulosic biomass is very efficient when using a consolidated bioprocessing (CBP) system. However, the optimum temperature conditions for the hydrolysis of cellulosic materials might not be the same as the optimum sugar fermentation temperature. This study investigated the effect of temperature on hydrolysis and bioethanol production from vetiver leaves (Vetiveria zizanioides L. Nash) as cellulosic material. The hydrolysis of pretreated vetiver leaves was done using a crude hydrolytic enzyme extracted from N. intermedia. Hydrolysis proceeded efficiently at 50 °C, obtaining the highest enzyme activity of 141 U/g. On the other hand, the bioethanol fermentation from vetiver leaves was performed in a CBP batch mode system which was carried out through two stages of fermentation in the same bioreactor. In the first stage, the N. intermedia was grown under micro-aerobic conditions at room temperature for 48 h. The cultivation was continued in the second stage by setting the fermentation temperature with various fermentation temperatures. The optimum temperature with the highest bioethanol concentration of 6905 mg/L was 45 °C. The kinetic parameters were also validated and obtained based on the growth model simulation.

Flow-through integration of FeOCl/graphite felt-based heterogeneous electro-Fenton and Ti4O7-based anodic oxidation for efficient contaminant degradation

Improvement to the synergistic performance of cathodic electro-Fenton (EF) and anodic oxidation (AO) has been severely restricted by the tendency for ineffective decomposition of cathode-produced H2O2 at the non-active anode and poor OH utilization. Herein, a paired heterogeneous EF-AO flow-through system, consisting of an FeOCl-deposited graphite felt (FeOCl/GF) cathode and a Ti4O7 membrane anode, was constructed for rapid degradation of oxytetracycline (OTC). The real-time spatiotemporal distribution of H2O2 was systematically investigated and results revealed that the necessity for H2O2 diffusion was eliminating in the proposed system, thus contributing a 2.66-fold increase with respect to OTC degradation kinetics compared to the conventional homogeneous EF-AO system. Meanwhile, the flow-through configuration demonstrated significantly enhanced OH utilization with a 6.65-fold increase in the OTC degradation rate constant compared to the batch mode system. In addition, the EF-AO flow-through system demonstrated a high OTC degradation rate (>80 %) over a wide pH range from 3 to 7 and with different real water matrices. This work opens new avenues for advanced treatment of refractory wastewater using electrochemical advanced oxidation processes.

Catalytic selective recovery of silver from dilute aqueous solutions and e-waste leachates

The two-step catalytic process is proposed for the recovery of silver ions from aqueous solutions. First, the Ag+-containing solution is enriched with hydrogen gas and recirculated through the Pt-loaded activated carbon (Pt/AC). The Ag+ ions are reduced into the metal particles at ambient temperature and H2 gauge pressure of 1 atmosphere. Next, the Ag particles precipitated on the Pt/AC are oxidized by air to form the pure Ag+ concentrate and to regenerate the catalyst. The process was studied using pure AgNO3 solutions at varied pH values (0.0, 1.5 and 3.9) in a batch mode system that was operated with Pt/AC particles loaded with 0.1–1.0% of Pt metal. The complete removal of Ag+ ions was achieved within<2 h of hydrogenation of 1-liter AgNO3 solutions with an initial concentrations of 100–1000 mgAg/L. The hydrogenation rate was not influenced by the pH value. Increasing the Pt load in the Pt/AC media above 0.25% did not result in an increase in the Ag+ hydrogenation rate. Next, the process was applied for the separation of Ag+ ions from H2SO4 leachates of Ag2O-Zn batteries. Finally, it was shown that due to a large difference in standard reduction potentials the silver and the copper ions can be “kinetically” separated within the hydrogenation and the oxygenation steps of the process.

Adsorption of Cr(VI) from aqueous solution using mesoporous metal-organic framework-5 functionalized with the amino acids: Characterization, optimization, linear and nonlinear kinetic models

In the past decades, an extensive effort has been devoted to remove Hexavalent chromium H(Cr (VI)) from industrial effluents, owning to its great health concerns to humans and the environment. Recently, Metal organic framework (MOFs) adsorbents draws more attention of researchers to remove contaminants from aqueous environments in the recent years. In the present study, solvothermal method was employed to fabricate MOF-5 that was examined for Cr (VI) adsorption from water matrices. XRD, FESEM, EDS, FTIR and BET analyses were utilized to characterize MOF-5. The influence of some independent parameters on MOF-5 performance in Cr (VI) adsorption was explored in a batch mode system. It was found that the uptake rate of Cr (VI) is significantly affected by initial pH of solution; the maximum adsorption rate is favored by acidic pH. Also, the adsorption efficiency shows a direct relationship with contact time and adsorbent dose, and an indirect relation with initial Cr (VI) concentration. The adoption process was modeled and optimized successfully by two approach of response surface methodology and artificial neutral network approaches; both models indicated an accuracy of predictions by determining error distribution and statistical significance and a good fit to experimental data. The experimental data showed a superior agreement with linear and nonlinear Langmuir isotherm, as compared with the other isotherm models, and pseudo-second-order kinetic better described Cr (VI) adsorption data by MOF-5, compared to the other kinetic models. The maximum absorption capacity was 78.12 mg/g. Thermodynamic studies revealed that adsorption is spontaneous and endothermic process. The findings claimed the great reusability and high stability of MOF-5; adsorption efficiency decreased only by 92.4% after ten recycles. The interfering anions affected negatively on the adsorption efficiency in the order of phosphate > sulfate > chloride > nitrate. The present study provides valuable and good information for Cr (VI) adsorption on MOF-5 in water matrices.

Adsorptive Removal of Cd, Cu, Ni and Mn from Environmental Samples Using Fe3O4-Zro2@APS Nanocomposite: Kinetic and Equilibrium Isotherm Studies.

In this study, Fe3O4-ZrO2 functionalized with 3-aminopropyltriethoxysilane (Fe3O4-ZrO2@APS) nanocomposite was investigated as a nanoadsorbent for the removal of Cd(II), Cu(II), Mn (II) and Ni(II) ions from aqueous solution and real samples in batch mode systems. The prepared magnetic nanomaterials were characterized using X-ray powder diffraction (XRD), scanning electron microscopy/energy dispersion x-ray (SEM/EDX) Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Factors (such as adsorbent dose and sample pH) affecting the adsorption behavior of the removal process were studied using the response surface methodology. Under optimized condition, equilibrium data obtained were fitted into the Langmuir and Freundlich isotherms and the data fitted well with Langmuir isotherms. Langmuir adsorption capacities (mg/g) were found to be 113, 111, 128, and 123 mg/g for Cd, Cu, Ni and Mn, respectively. In addition, the adsorption kinetics was analyzed using five kinetic models, pseudo-first order, pseudo-second order, intraparticle diffusion and Boyd models. The adsorbent was successfully applied for removal of Cd(II), Cu(II), Mn (II) and Ni(II) ions in wastewater samples.

Adsorption of Indigo Carmen Dye by Using Corn Leaves as Natural Adsorbent Material

&#x0D; In this paper, the ability of using corn leaves as low-cost natural biowaste adsorbent material for the removal of Indigo Carmen (IC) dye was studied. Batch mode system was used to study several parameters such as, contact time (4 days), concentration of dye (10-50) ppm, adsorbent dosage (0.05-0.25) gram, pH (2-12) and temperature (30-60) oC. The corn leaf was characterized by Fourier-transform infrared spectroscopy device before and after the adsorption process of the IC dye and scanning electron microscope device was used to find the morphology of the adsorbent material. The experimental data was imputing with several isotherms where it fits with Freundlich (R2 = 0.9937) and followed pseudo second order kinetic. The highest removal percent was equal to 91% of the dye which makes the corn leaves a suitable efficient material for the removal of IC dye from aqueous solutions.

Dye degradation and kinetics of online Electro-Fenton system with thermally activated carbon fiber cathodes

Abstract In this study, the effect of the gas type (N2 or CO2) and activation time (0−10 h) on the thermal activation of carbon fiber (CF) electrodes being used as the working electrodes was tested in an Electro-Fenton (EF) system with Pt anodes; this was aimed at achieving the total organic carbon (TOC) removal for the Acid Orange 7 (AO7) dye. An EF experimental system was established to perform online analyses that were different from the majority of those in the literature. Furthermore, to test the effectiveness of the EF process parameters, the cathodic potential (0.5–2.5 V) and Fe2+ concentration (0.2−1 mM) were investigated. The initial solution dye concentration (0.1 mM), pH (3), and electrolyte concentration (50 mM) were held constant in this study. In an undivided glass reactor, dry air was supplied (16 L/h) to the system in batch mode, and a 600-ml dye solution was added. The optimum dye and TOC removal efficiencies at 0.8 V with 0.3 mM of Fe2+ by using CF activated at 900 °C under N2 for 5 h were 92.9 % at 15 min and 84.0 % at 120 min. In contrast, a kinetic analysis was performed using data from an online analysis system. Accordingly, the kinetic study of the degradation reaction was evaluated in two stages, namely, for the first 3.2 min and for the subsequnet time frame. In addition, the CF electrode was found to be a promising electrode for electro-oxidation systems, with augmentaions in the electroactive surface area and crystallite size by 46.64 % and 17.15 %, respectively.

Cell-Free Protein Synthesis of Small Intrinsically Disordered Proteins for NMR Spectroscopy.

Cell-free protein synthesis (CFPS) is an established method to produce recombinant proteins and has been used in a wide variety of applications. The use of CFPS has almost from the onset been favorably linked to the production of isotopically labelled proteins for NMR spectroscopy as the resulting labelling of the produced protein is defined by the chosen amino acids during reaction setup. Here we describe how to set up production and isotopic labelling of small intrinsically disordered proteins (IDPs) for NMR spectroscopy applications using an E. coli-based CFPS system in batch mode.

Green Preparation of Hyphaene thebaica Fiber Grafted Acrylic Acid for Adsorption of Pb (II) ions from Aqueous Solution

In this study, a green chemistry approached was employed in the preparation of Hyphaene thebaica fiber grafted polyacrylic acid via microwave assisted method using potassium persulfate as chemical initiator. The optimum percentage grafting 92% was achieved under 5g concentration of acrylic acid, 0.2g concentration of potassium persulfate (KPS) and 2 minutes 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.

One-step synthesis of high surface-area honeycomb graphene clusters for highly efficient capacitive deionization

Capacitive deionization (CDI) can realize ion adsorption efficiently by forming electrochemical double layers on electrode surfaces. This potential-driven adsorption process requires electrode materials possessing a large surface area as well as a rapid and easy electrolyte-diffusion pathway. In this respect, we designed and synthesized a novel honeycomb graphene cluster (HGC) based on one-step exothermic reaction between liquid lithium and carbon monoxide gas. The obtained HGC electrode, as both cathode and anode in a CDI cell, exhibited excellent desalination performance. Its electrosorption capacity reached 14.08 mg/g in a batch-mode system with continuously recycled 28 ml of 5 mM NaCl solution. This high-level desalination ability can be attributed to the effective utilization of HGC materials: its large surface area of up to 1962 m2/g can provide abundant sites for ions adsorption, and three-dimensional mesoporous frameworks can facilitate ion transport. Thus, HGC electrodes can achieve electrosorption capacity of twice that of activated-carbon electrodes, indicating promising applications in the CDI field.

New operational mode of an electrochemical reactor and its application to the degradation of levofloxacin

The flow-by electrochemical reactor is generally used in batch mode with extended process time in order to achieve high efficiency in the removal of organic contaminant from aqueous solution. Moreover, the batch mode system is inappropriate for the treatment of wastewater in high volume or as a continuous stream. This paper presents a new operational mode for the electrochemical reactor in which the electrolyte passes over the electrodes just once at a reduced flow rate and with high hydraulic retention time. The concentration of hydrogen peroxide generated in the reactor running in the single-pass flow mode attained 10.2mgL−1cm−2 in acid medium, a value similar to that obtained previously with the same type of reactor operating in batch mode. In the single-pass mode, the electrochemical reactor showed high rates of removal of the antibiotic levofloxacin (initial 50mgL−1) and organic load (initial 130mgL−1) up to 99 and 86%, respectively, when operated under electro- or photo-Fenton degradation conditions (acid medium with Fe2+ ions; absence or presence of UV irradiation). Degradation of levofloxacin generated high levels of nitrate (up to 4.5mgL−1) and various by-products that could be identified by liquid chromatography-mass spectrometry.

Alginate graft polyacrylonitrile beads for the removal of lead from aqueous solutions

Grafting of polyacrylonitrile with sodium alginate was carried out in aqueous medium using benzoyl peroxide (BPO) as initiator. The grafting conditions such as monomer, initiator concentration, reaction time and temperature were optimized. The graft copolymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, solid-state 13C-nuclear magnetic resonance and scanning electron microscopy. Optimum percentage grafting was obtained when the concentrations of BPO, acrylonitrile and sodium alginate were 6.19 × 10−3, 7.53 × 10−1 mol L−1 and 1 % w/v, respectively. The optimum reaction temperature and reaction time were 80 °C and 4 h, respectively. The copolymer sample with optimum percentage grafting was evaluated for the removal of lead ions from aqueous solutions in batch mode systems. Langmuir and Freundlich isotherm models were applied to describe the adsorption process. The adsorption data fitted into Langmuir model better than Freundlich model with maximum adsorption capacity of 454 mg g−1 (2.20 mmol g−1) while the kinetic data correlated well to pseudo-second-order kinetic model. The adsorbent could be regenerated using HNO3 as elution solvent, and reused repeatedly without significant loss of its metal adsorption capacity.

Influence of Co-substrates for the Methane Production Rate Kinetics in Anaerobic Fermentation of Pig Slurry

The influence of co-substrates on kinetics of methane production in anaerobic fermentation of pig slurry was studied by performing a series of laboratory experiments using food waste and biowaste as co-substrates. Experiments were performed in the laboratory reactors of «Hohenheim» biogas testing system in batch mode at the temperature of 37ºC. Given 40 g of fresh pig slurry was fed to each digester and mixed with co-substrates in the ration of 55:45% by organic dry matter content. Methane production rate was used to evaluate co-digestion of pig slurry. Research results showed that co-substrates gave significant effect to methane production kinetics. The kinetic parameters of methane production i.e. potential yield of methane (P), maximum methane yield rate (Rm) and duration of lag-phase (λ) were analyzed using modified Gompertz equation. Technical time to produce 95% of potential methane yield was investigated and efficient period of anaerobic digestion was calculated. The potential production of methane was reached in lag-phase duration (λ) of 10-13 days. Maximal methane production rate was reduced 2-3 times in co-digestion than in mono-digestion of pig slurry. The potential yield of methane (P) was 0.420 Nm3(kg оDM)-1, 0.246 Nm3(kg оDM)-1 and 0.198 Nm3(kg оDM)-1 in mono-digestion and co-digestion of pig slurry with food waste and biowaste, respectively.

Removal of cadmium from aqueous solution using low molecular weight chitosan derivative

A 23 factorial design was used to examine the sorption of Cd2+ onto cross-linked low molecular weight chitosan pyruvic acid derivative. Three factors and two levels of solution pH (A) (6.0 or 10.0), temperature (B) (45 or 70°C) and Cd(II) concentration (C) (1 or 3mg/L) were considered. Batch mode system was employed with 0.05g of the sorbent and 25mL of Cd(II) solution. The efficiency of cadmium removal during an exposition time of 4h was then evaluated. The factors and their interaction effect on the cadmium removal efficiency followed the order: Cd(II) concentration>solution pH>interaction between solution pH and Cd(II) concentration>interaction between solution pH, temperature and Cd(II) concentration. Langmuir isotherm model was the best isotherm model. The Pseudo second order fitted well the kinetic data. The thermodynamic studies revealed the nature of the cadmium sorption.

Synthesis of Multiwalled Carbon Nanotubes‐Titania Nanomaterial for Desulfurization of Model Fuel

This work reported on the development of novel nanomaterials of multiwalled carbon nanotubes doped with titania (CNT/TiO2) for the adsorptive desulfurization of model fuel oils. Various analytical techniques such as field emission scanning electron microscope (FESEM), energy dispersive X‐ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) were used for the characterization of the nanomaterials. The initial results indicated the effectiveness of the prepared CNT/TiO2 nanomaterials in removing sulfur compounds from model fuel oil. The adsorption of DBT, BT, and thiophene from model fuel onto the derived sorbents was performed using batch mode system. These CNT/TiO2 nanomaterials initially afforded approximately 45% removal of DBT, 55% BT, and more than 65% thiophene compounds from model fuels. The CNT/TiO2 nanomaterials provided an excellent activity towards interaction with organosulfur compounds. More experiments are underway to optimize the parameters for the adsorptive desulfurization processes. We believe that these nanomaterials as adsorbents will find useful applications in petroleum industry because of their operational simplicity, high efficiency, and high capacity.

Adsorption of methylene blue on strongly basic anion exchange resin (Zerolit DMF): kinetic, isotherm, and thermodynamic studies

This work explored the adsorption potential of Zerolit DM-F (ZDMF) resin for methylene blue (MB) removal form aqueous system in batch mode. Both linear and non-linear models have been applied to kinetic and isotherm data. Practical feasibility of ZDMF was testified by performing breakthrough, desorption, and regeneration studies. Results showed optimum adsorption (24.75 mg/g) at pH 10. Contact time studies showed equilibration time ranged between 30 and 90 min for various MB concentrations (Co—25–200 mg/L). Kinetic modeling studies showed applicability of pseudo-first-order model at various MB concentrations while, isotherm studies showed applicability of Freundlich model at various temperatures. Thermodynamics studies showed endothermic and spontaneous process. The breakthrough studies showed that 550 mL of MB solution (Co—50 mg/L) which was prepared separately in deionized water and tap water matrix could be passed through the columns without detecting MB traces. The breakthrough and exhaustive capacities in deionized water and tap water matrix were found to be 27.5 and 45 mg/g, respectively. Desorption studies showed optimum MB recovery (86%) with 5M HCl solution while, regeneration studies revealed 10.20 and 16.28% loss in adsorption and desorption after five consecutive cycles, respectively.