Synthetic Aqueous Solutions Research Articles

Aqueous phase phenol removal from synthetic and real steel plant effluents through a batch and Semifluidized bed column operation: Experimental and model analysis

In this present research, an attempt has been made for performance analysis of a semifluidized bed (SFBR) column operation with a low-cost biomass based-adsorbent for the removal of phenol from synthetic aqueous solution and actual steel plant effluents. The solid phase of gas-solid-liquid SFBR operation was Ca-alginate –biochar composite adsorbent beads which were prepared from low-cost agricultural solid waste-derived sugarcane bagasse biochar capture in Calcium-alginate. In batch adsorption study, the various physicochemical process parameters like temperature, initial phenol concentration, pH and adsorbent doses were identified and its effects on the phenol adsorptive removal and adsorption mechanism were studied. In a semi-fluidized bed column (SFBR) operation, the effect of adsorbents loading (bed height), initial phenol concentration, and liquid flow rate on phenol removal efficiency were studied. The 65 % bed efficiency performance of the semifluidized bed system was found with actual raw steel plant effluents and BOD, COD, TS etc. are also removed during actual steel plant effluents treatment operation. Finally, a mass transfer dynamic model has been developed and the model predicts the degree of axial dispersion of the system and the overall mass transfer coefficient of the system. Results suggested that this three-phase semifluidized bed composite bed adsorption column operation is suitable for industrial phenol bearing wastewater treatment.

An Application of Polydopamine-dip Coating as a Gentle Surface Modification Process for Cryogel Disks

The process called “polydopamine-dip coating” was successfully applied to modify the surface of poly(2-hydroxyethyl methacrylate), PHEMA, cryogel disks for the first time. This facile surface modification process fitted very well to the chemistry of cryogels since the integrity of the cryogel disks was maintained during the whole process. Polydopamine (PDA) nanocoating process was observed to be homogeneously performed through the pores and there was a net color change from white to brown after 24 h. The obtained (brownish) material (PHEMA-PDA) was characterized with respect to FTIR spectroscopy, pHpzc, and water-holding capacity analyses. The potential of this new material was studied by utilizing it as an adsorbent for the adsorption of Ni(II) from synthetic aqueous solutions. The equilibrium adsorption data were analyzed on the basis of the Langmuir, the Freundlich, and the Temkin isotherm models. In general, Ni(II) adsorption on PHEMA-PDA was evaluated as a favorable process as depicted from the studied models. The proposed approach was found to be a promising post-surface modification process for tailoring the surface of monolithic cryogels without any difficult synthesis steps and harsh chemicals.

Sorptive removal of copper(II) from water by biochar produced from a novel sustainable feedstock: wild herbs.

We have reported the removal performance from the synthetic aqueous solution of copper of a low-cost and eco-friendly biochar (WHC) produced by facile thermal pyrolysis of wild herbs (WH), a new feedstock, at 550 °C under anoxic conditions. The characteristics of WHC were determined by physicochemical techniques. It exhibited a low BET surface area, total pore volume, and mean pore size of 16.45 m2/g, 0.01 cm3/g, and, 2.34 nm respectively. Batch sorption studies were performed by examining the effects of varying pH, WHC dosage, initial Cu(II) concentrations, interaction time, and temperature to determine optimum removal conditions. In modeling of sorption, data were used the pseudo-first- and pseudo-second-order kinetics and the Langmuir and Freundlich isotherm models. The maximum Cu(II) sorption capacity of WHC was 24.21 mg/g. Thermodynamic parameters were computed for predicting the nature of WHC-Cu(II) sorption system.

Degradation of Nonylphenol ethoxylate 10 (NP10EO) in a synthetic aqueous solution using a combined treatment: Electrooxidation-gamma irradiation

Nonylphenol ethoxylate 10 (NP10EO) is a recalcitrant substance and treatments used to remove it from the environment have been unsuccessful. In this study, degradation of NP10EO was assessed by applying a combined sequenced treatment: electrooxidation (EO) process using a Boron-Doped Diamond (BDD) electron as anode and gamma irradiation. To ascertain the effectiveness of the treatment, experiments with EO, gamma irradiation, and a combined treatment (EO-gamma irradiation) were carried out. The variables were pH, current density, electrolysis time, and dosage of radiation. The best conditions found were for EO: 180 min, pH = 2.3 ± 0.5, current density of 16.66 mA cm−2, radiative: 40 kGy and 440 μL L−1 H2O2, and EO-Rad: 60 min 16.66 mA cm−2 + 40 kGy and 440 μL L−1 H2O2. These techniques are reliable because they have been conceived to be long-lasting and their performance in this application was excellent. The combined treatment reached 100% of NP10EO degradation efficiency, a result that was verified by UV/VIS spectrophotometry and COD analysis.

Size-controlled Synthesis of Zeolitic Imidazolate Framework-67 (ZIF-67) Using Electrospray in Liquid Phase

To achieve rapid intraparticle diffusion when metal-organic frameworks are used as adsorbents and/or catalysts, it is preferable to reduce their crystal size and improve their monodispersity. The simplest method for reducing the crystal size in a synthetic aqueous solution is increasing the ligand concentration. However, this produces an environmental load, because a large amount of ligand remains in the waste solution. In this study, size-controlled synthesis of the zeolitic imidazolate framework 67 (ZIF-67) was achieved by using a fine liquid droplet as the reaction field. This droplet was generated by electrospraying in the liquid phase, which improved the crystal size, morphology, and monodispersity of ZIF-67.

Effective removal of dyes from aqueous solutions using a novel antibacterial polymeric adsorbent

Here, ethylenediamine-epichlorohydrin-trichlorophenol (EET) cross-linked polymer was synthesized and characterized by Fourier Transforms Infrared spectroscopy (FTIR), thermogravimetric analysis (TGA–DSC) and scanning electron microscopy (SEM). EET exhibited substantial antibacterial activity with inhibition zones of 38 and 64 mm against E. coli and S. aureus bacteria. Therefore, it was applied to treat methyl orange (MO) and rhodamine B (RB) dyes containing synthetic aqueous solutions under varying operation parameters. Notably, 10 and 15 mg of EET removed 98.72% of MO at pH 8 and 92.45% of RB at pH 3. Moreover, EET cross-linked polymer retained stable activities of about 98.6% over five consecutive recycling runs for MO dye. The EET demonstrated a fast adsorption rate and the adsorption data fits well with the pseudo-second-order for both dyes, suggesting chemisorption. Also, considering the correlation coefficient values, the experimental dataset fits suitably with Temkin equation for RB and Langmuir equation for MO. Thermodynamic evaluations for both dyes show spontaneity onto the cross-linked polymer.

Study of the effect of operative conditions on the decolourization of azo dye solutions by using hydrodynamic cavitation at the lab scale

AbstractIn the present study, the potentiality of hydrodynamic cavitation (HC) for the degradation of methyl orange from synthetic aqueous solutions is presented. Hydrodynamic cavitation was set up at laboratory scale using a Venturi tube. Solutions of methyl orange (MO) were subjected to cavitation in order to investigate the efficiency and the potential of this technique for azo dye degradation. Moreover, a HC/H2O2/TiO2 hybrid system was tested with the aim to verify its potential positive impact on the decolourization process and define the best conditions, among those investigated, to remove azo dye from synthetic solutions. The results obtained in this study showed that the maximum efficiency was close to 30% using a Venturi tube at an operating pressure of 400 kPa. The presence of additives, such as titanium dioxide and hydrogen peroxide, increased the performance of the degradation process to slightly above 70%.

Removal of levosulpiride from pharmaceutical wastewater using an advanced integrated treatment strategy comprising physical, chemical, and biological treatment

AbstractIn recent times the impact of pharmaceutical wastes generated from the pharmaceutical industry and domestic sewages on the aquatic ecosystem has become a major concern. The traditional sole treatment processes are not adequate for the elimination of these wastes. To overcome the lack of the individual treatment processes, integrated treatment methodology has been devised in the present study. The degradation of the pharmaceutical, levosulpiride, by using Ozone (O3), activated carbon (AC) and biological treatment by A.faecalis JF339228 and E. aurantiacum KX008295.1in its aqueous solution has been investigated. The percentage removal of Levosulpiride from its synthetic aqueous solution of 600 mg/L concentration using 2 g/L activated carbon and 5.2 g/h ozone and biological treatment by A.faecalis JF339228 and E. aurantiacum KX008295.1 in 72 hr were 51.60, 53.50, 39.97, and 37.51% respectively. Simultaneous treatment using adsorption and ozone followed by biological treatment with A. faecalis JF339228 and E. aurantiacum KX008295.1 has been employed in this study. To overcome the demerits of the individual treatment process, the integrated treatment is employed which has shown a synergistic effect in the degradation of levosulpiride with minimal doses of activated carbon, ozone, and minimum time of operation. The percentage removal of levosulpiride achieved was about 76 and 61% for 800 mg/L levosulpiride wastewater, respectively. Therefore, the integrated treatment system is rendered economical, efficient, and safe.

Adsorption of Cyanide Contained in Aqueous Solution using Activated Carbon Obtained from Coffee Residue: Adsorption Efficiency; Equilibrium and Kinetic Models

This research aimed to evaluate the adsorption process of cyanide ion (CN-) contained in synthetic aqueous solution, using activated carbon obtained from coffee residue, studying its efficiency and equilibrium and kinetic models. Activated carbon was characterized by Fourier Transform infrared analysis (FTIR), X-ray diffraction (DRX), and iodine number determination. A central composite design (CCD) with three factors adapted to three levels each and six central points was applied to study the effect of pH (A), contact time (B) and adsorbent dosage (C); According to the analysis of variance, the factors A, B, C, and the square AA were significant in the adsorption efficiency of cyanide onto activated carbon, whose maximum value reached was 54.68% and 67.65% for the predictive level. According to the coefficient of determination (R2), Freundlich's isothermal model (0.954) and the three kinetic equations of pseudo-second order (0.991, 0.993, 0.993) fit the experimental process. From the results obtained, the active carbon prepared from coffee residue can be used as a potential adsorbent of CN-, contained in aqueous solutions of low concentrations.

Removal of Tetracycline from Aqueous Solutions using Pomegranate Peels Residues Accessing to ZRL

Antibiotics are harmful pharmaceuticals to ecosystems in general and aquatic systems in particular. Therefore, its remediation from water bodies is a topic of great importance for water treatment and purification workers. This research investigates the removal of one of the most famous types of antibiotics, which was tetracycline from simulated synthetic aqueous solutions by adsorption technique using non-toxic, low cost and available agricultural waste which was pomegranate peels. The adsorption experiments were performed in adsorption laboratory unit of batch mode at different operating conditions and laboratory temperature. The operating parameters studied included pH of solution, dose of adsorbent media, treatment time, agitation speed and initial concentration of tetracycline. The results showed the ability of pomegranate peels to extract tetracycline from aqueous solutions with high efficiency of 81.55%. The results also showed that the percentage of antibiotic adsorption from aqueous solutions was inversely correlated with increasing the initial concentration and acidic function of the tetracycline solution while it was directly proportional to the amount of pomegranate peels, agitation speed and treatment time. In this style, one of the most important types of antibiotics that contaminated water was disposed of by a cheap material and using a simple, economical and environmentally friendly method accessing to the principle of zero residue level (ZRL).

Electrolytic Oxidation as a Sustainable Method to Transform Urine into Nutrients

In this work, the transformation of urine into nutrients using electrolytic oxidation in a single-compartment electrochemical cell in galvanostatic mode was investigated. The electrolytic oxidation was performed using thin film anode materials: boron-doped diamond (BDD) and dimensionally stable anodes (DSA). The transformation of urine into nutrients was confirmed by the release of nitrate (NO3−) and ammonium (NH4+) ions during electrolytic treatment of synthetic urine aqueous solutions. The removal of chemical oxygen demand (COD) and total organic carbon (TOC) during electrolytic treatment confirmed the conversion of organic pollutants into biocompatible substances. Higher amounts of NO3− and NH4+ were released by electrolytic oxidation using BDD compared to DSA anodes. The removal of COD and TOC was faster using BDD anodes at different current densities. Active chlorine and chloramines were formed during electrolytic treatment, which is advantageous to deactivate any pathogenic microorganisms. Larger quantities of active chlorine and chloramines were measured with DSA anodes. The control of chlorine by-products to concentrations lower than the regulations require can be possible by lowering the current density to values smaller than 20 mA/cm2. Electrolytic oxidation using BDD or DSA thin film anodes seems to be a sustainable method capable of transforming urine into nutrients, removing organic pollution, and deactivating pathogens.

Multifunctional Zn0.3Al0.4O4.5 crystals: An efficient photocatalyst for formaldehyde degradation and EBT adsorption

The Zn0.3Al0.4O4.5 nanoparticles (ZnAlONPs) with size of 70–90 nm are used as an efficient photocatalyst for formaldehyde (HCHO) degradation and effective adsorbent for the removal of eriochrome black-T (EBT) dye from synthetic aqueous solution. Degradation of HCHO reactions were studied using TiO2 (homemade), TiO2 (P-25) and ZnAlONPs by irradiating under 18 W daylight lamp source for photocatalytic degradation. The HCHO degradation rate is about 67, 76 and 89% for TiO2 (homemade), TiO2 (P25) and ZnAlONPs during 2 h reaction, respectively at initial formaldehyde gas concentration of 20 ppm. Maximum adsorption capacity was optimized by changing the parameters such as pH, EBT concentration and adsorbent dosage. A 200 mg of ZnAlONPs are useable for quick removal of EBT (>95%). Langmuir isotherm model showed a maximum adsorption capacity of 90.90 mgg−1. The ZnAlONPs could be successfully reused upto 5th adsorption/desorption cycle for EBT dye removal from water samples.

Experimental and modeling of cadmium ions removal by chelating resins

Abstract Nowadays, the concerns regarding cadmium pollution increased steadily, due to its serious damages to the environment and human health. Consequently, stringent limits have been set for this heavy metal ion both in industrial and drinking water. Numerous traditional and unconventional methods were applied to reach these limits. In this paper, two phosphine oxide/phosphine oxide and thiourea chelating resins MPX-310 and MPX-317 produced by Magpie Polymers - Italmatch Chemicals, Italy were comparatively evaluated with a commercial thiourea chelating resin Lewatit® MonoPlus TP 214 produced by Lanxess regarding Cd(II) removal from aqueous synthetic solutions. The physicochemical properties of the resins were studied by FTIR spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TG-DSC) and X-ray Photoelectron Spectroscopy (XPS). Batch tests have been performed to assess the performance of these resins in Cd(II) removal. A value of 3–4 for pH and 600 min of contact time were determined as optimal parameters for the removal process. The experimental results also showed that the Lewatit® MonoPlus TP 214 has a higher removal capacity than MPX-317 and MPX-310 due to the presence of the thiourea and ion-exchange functional groups on the Lewatit® MonoPlus TP 214 backbone, compared with the presence of the phosphine oxide functional groups on the MPX-310 and thiourea and phosphine oxide on MPX-317. A monolayer adsorption on the homogenous adsorbent surface mechanism involved in Cd(II) removal was pointed out by the results regarding adsorption isotherms. The best fit of the pseudo-second kinetic model indicates that the sorption process goes through a mechanism that involves chemical reaction between Cd(II) and functional groups grafted on the resin's backbone. The chelating capacity of the tested resins showed that they are suitable for Cd(II) removal from aqueous synthetic solutions and industrial wastewater.

Phosphate removal from industrial wastewaters using layered double hydroxides

ABSTRACT In the present study, Mg–Al and Zn–Al layered double hydroxides (LDH) were synthesized by the co–precipitation method and employed to remove phosphate from synthetic aqueous solutions and industrial wastewaters. LDH were characterized by X–ray diffraction (XRD), N2 adsorption/desorption isotherms (BET method), thermal analyses (TG–DTA) and Fourier transform infrared spectroscopy (FTIR). XRD and TG–DTA analysis showed that Mg–Al and Zn–Al formed the LDH structure. Experimental adsorption data indicated that pseudo–second order model best described phosphate adsorption kinetics. Data of equilibrium experiments fitted well to Sips and Freundlich models for Mg–Al and Zn–Al, respectively. The effect of co–existing anions on the phosphate adsorption capacity was analyzed by utilizing industrial wastewater. The results showed that the phosphate removal decreases in the presence of other anions. Mg–Al adsorbent exhibited 74% removal of phosphate with a dosage of 5 g/L in industrial wastewater.

Evaluation efficiency of Iranian natural zeolites and synthetic resin to removal of lead ions from aqueous solutions

Heavy metal such as Pb2+ (lead ions) has high toxicity potential, and it can be dangerous for public health and environment. The ion exchange process is one of the methods that can be used for Pb2+ removal from aqueous solutions. The aim of this study was to investigate the removal efficiency of Pb2+ from the synthetic aqueous solutions using Iranian natural zeolite (INZ) (Clinoptilolite) in comparison with a synthetic resin (SR). In this study, the removal of Pb2+ from aqueous solution investigated by INZ and synthetic resin under different experimental conditions. Parameters like initial Pb2+ concentration, contact times, adsorbent dosage, pH and size particles of INZ, and best-fitted isotherm were studied. The results showed that the most removal efficiency of Pb2+ with INZ was obtained at pH 3–5, contact time 15–60 min, adsorbent dosage 20–50 g/L, Pb2+ initial concentration 25 mg/L, and the removal efficiency was increased with decreasing INZ particle size. The high removal of Pb2+ with SR was at pH 4–6, for 25 mg/L initial Pb2+ concentration at 15–60 min and 5–10 g/L SR. Isotherms study with ISOFT software indicates that the Freundlich and Langmuir isotherms expression provides the best fit for Pb2+ sorption by INZ and SR, respectively. This study indicated that for Pb2+ ion removal, the SR was more efficient than INZ for high concentration solutions; however, in low concentration of Pb2+, the removal efficiency was approximately equal.

Potential of virgin and calcined wheat bran biomass for the removal of chromium(VI) ion from a synthetic aqueous solution

Virgin wheat bran (WB) and calcined wheat bran were prepared at 500 or 1000 °C (WB500 or WB1000, respectively), and their physicochemical properties (such as morphological, thermal, specific surface area, point of zero charge pH, and surface functional groups) were investigated to assess their chromium(VI) ion adsorption capability. The amount of chromium(VI) ion adsorbed was in the order WB < WB500 < WB1000. These results showed that the chromium(VI) ion adsorption was related to the WB surface characteristics. Additionally, the amount of chromium (Cr) and oxygen (O) on the WB1000 surface increased after adsorption, which indicated chromium(VI) ions were adsorbed onto the WB1000 surface. Adsorption isotherm and adsorption kinetic data fit the Freundlich (0.879–0.991) and pseudo-second-order models (0.979–0.997), respectively. The optimal pH condition for the removal of chromium(VI) ion from aqueous solution was approximately 2. Finally, WB1000 could be useful for repetition of chromium(VI) ion adsorption/desorption using sodium hydroxide at 1000 mmol/L (at least five times). It was shown that WB1000 has the potential for adsorption and recovery of chromium(VI) ion from aqueous solution using sodium hydroxide.

Optimizing the removal of nitrate by adsorption onto activated carbon using response surface methodology based on the central composite design

This study sheds light on the adsorption process for the removal of nitrate ions from synthetic aqueous solutions. This contaminant pose a potential risk to the environment and can cause health effects including cancers and methemoglobinemia in infants. When the adsorption process is carried out, the effect by the several operating parameters such as initial nitrate concentration, pH, mass of activated carbon, and contact time becomes apparent. The essential process variables are optimized using response surface methodology (RSM) based on the central composite design (CCD) experiments. For this purpose 31 experimental results are required to determine the optimum conditions. The optimum conditions for the removal of nitrates is found to be: initial nitrate concentration = 15 mg/L; initial pH 4.0; mass of activated carbon = 25 mg, and contact time = 70 min. At these optimized conditions, the maximum removal of nitrates is found to be 96.59%.

Optimization, kinetics, equilibrium isotherms, and thermodynamics studies of Coomassie violet dye adsorption using Azadirachta indica (neem) leaf adsorbent

Removal of color from dye wastewater is of primary importance because they are highly toxic and carcinogenic to many life forms. To protect the environment, studies need to be conducted to make the use of inexpensive adsorbent for the removal of color from dye wastewater. To the best of our knowledge, there has practically been no work reported for describing the potential of using neem leaf fine powder (NLP) as adsorbent for the decolorization of Coomassie violet (CV) from wastewater either in batch or continuous mode. The present batch study is concerned with the removal of CV dye from synthetic aqueous solutions using NLP as an adsorbent. Decolorization experiments were conducted by varying experimental factors such as initial pH, initial dye concentration, adsorbent dosage, particle size, and agitation speed. The process parameters were optimized using response surface methodology to attain the maximum % decolorization. Further, the batch experiments were conducted to study the effect of a mixture of dyes, and temperature on dye decolorization. The adsorbent was characterized by Brunauer–Emmett–Teller surface area, pore-volume, particle size, attenuated transmission reflector, field emission scanning electron microscopy/energy-dispersive X-ray spectroscopy, X-ray diffraction, and thermogravimetric analysis. The experimental equilibrium data were analyzed with various isotherm models. The results showed that the best fit was achieved with the Langmuir isotherm model with the maximum monolayer adsorption capacity (qmax) was 39.64 mg g–1 at 303 K. Thermodynamic studies were performed to determine the change in Gibbs free energy (ΔG), change in enthalpy (ΔH), and change in entropy (ΔS) of the adsorption process. Thermodynamic parameters were evaluated using qmax at different temperatures. From the results, the adsorption was found to be spontaneous, endothermic in nature and favored at high temperatures. The value of ΔH and activation energy confirmed that the studied adsorption process was chemisorption. Kinetic rate constants were found using different kinetic models. The adsorption kinetics for CV dye removal by NLP adsorbent follows a pseudo-second-order kinetic model. The adsorption mechanisms were described by pore diffusion, Bangham and Boyd plots. The overall rate of adsorption was controlled by both film diffusion and pore diffusion of dye molecules. It was found that external film diffusion controlled the dye uptake in the earlier stages, followed by pore diffusion, which controlled the rate at later stages. A number of various desorbing reagents were tested to explore the possibility of regenerating the NLP adsorbent and ethanol had the maximum desorption efficiency. The reusability studies of NLP adsorbent for the adsorption of CV was carried out in three runs. The adsorption of solute from textile industrial Congo red dye effluent was carried out in batch studies using NLP adsorbent. The chemical oxygen demand removal efficiency of industrial dye effluent was 69.18%.

Removal of methylene blue dye from synthetic aqueous solutions using dimethylglyoxime modified amberlite IRA-420: kinetic, equilibrium and thermodynamic studies

Removal of methylene blue dye from synthetic aqueous solutions using dimethylglyoxime modified amberlite IRA-420: kinetic, equilibrium and thermodynamic studies

Adsorption of Lead (II) and Copper (II) Ions from Mono Synthetic Aqueous Solutions Using Bio-Char from &amp;lt;i&amp;gt;Ficus natalensis&amp;lt;/i&amp;gt; Fruits

Many science-based institutions in most developing countries use heavy metal containing salts in practical teaching sessions. The commonly used chemicals are the salts of lead (II) and copper (II) and the wastes generated end up into the environment when untreated. Thus, a study was done to remove lead (II) and copper (II) ions from mono synthetic aqueous solution using bio-char from Ficus natalensis fruits (FNF). This was done at varied pH, contact time, temperature, bio-char dosage level, salinity and metal ion concentration using the batch approach. The residual metal concentrations were determined using the atomic absorption spectrophotometer. The optimum pH for the adsorption of copper (II) and lead (II) ions was found to be 4.0 and 5.0 respectively. The maximum percentage adsorption of copper (II) and lead (II) by the FNF bio-char was established at 60 minutes contact time, 47.5&degC and 0.4 g adsorbent dose. Increase in the metal ion concentration and the presence of interfering ions in the aqueous solution lead to decrease in the percentage adsorption. The highest adsorption capacity was found to be 161.29 mg/g and 1250 mg/g for copper (II) and lead (II) ions respectively. The thermodynamic parameters indicated the feasibility of the adsorption of copper (II) and lead (II) on the bio-char of FNF. Thus, bio-char from FNF may be used as an adsorbent in waste management where copper (II) and lead (II) ions are present at a concentration range of between 5 and 100 mg/l.