Aqueous Waste Solutions Research Articles

Influence of Surfactants on the Physical Properties of Silica Nanoparticles Synthesis via Sol-Gel Method

Silica nanoparticles (n-SiO2) have been synthesized using hydrolysis of Tetraethyl orthosilicate (TEOS) as starting material and ethanol as solvent by sol-gel method. The effect of different surfactants such as non-ionic surfactants sorbitan tristearate (Span 65) and sorbitan trioleate (Span 85) and anionic surfactants Sodium dodecyl sulfate (SDS) and emulsifier T-80 (Tween-80) on morphology and size of the particles was investigated. The role of these surfactants in controlling the size and properties of silica nanoparticles has been discussed. The particles size of silica nanoparticles is controlled also using Ammonia as base catalyst. Silica nanoparticles with average particles size 18 nm have been synthesized with span 65. Various analytical methods, i.e., scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV- visible absorption spectroscopy and X-ray diffraction (XRD) were used to comprehensively characterize the obtained silica nanoparticles. The synthesized Si NPs has been used for adsorption of uranium from aqueous waste solution and the best conditions were achieved at pH 4.0. The adsorption isotherms were described by means of Langmuir and Freundlich isotherm models. The maximum sorption capacity of the prepared Si NPs and experimental results showed this to be 20.6 mg.g-1.

High Performance of Chromium Recovery from Aqueous Waste Solution Using Mixture of Palm-oil in Emulsion Liquid Membrane

Industrial effluent containing metal ions especially from semiconductor industry is considered as a serious environmental pollutant. A green emulsion liquid membrane (ELM) has been formulated in this research using an environmental-friendly refined palm oil as the main diluent of ELM to recover the chromium from wastewater. The feasibility of using palm oil–based ELM for chromium extraction and its stability were investigated. Several parameters, including carrier concentration, agitation speed, internal phase concentration, treat ratio, and agitation time, which could affect the extraction and recovery performance of chromium in ELM process, were attempted. The results showed that 0.2M of TOMAC, 600rpm for agitation speed and 1.0M of NaOH, 2:1 for treat ratio provided enhancement of emulsion stability and almost 100% of chromium was extracted and recovered.

Silver Adsorption Enhancement from Aqueous and Photographic Waste Solutions by Mercerized Coconut Fiber

The mercerized coconut fiber (CF-NaOH) was prepared by treating the pristine coconut fiber (CF-Pure) with NaOH solution. The morphology and chemical composition of CF-Pure changed after mercerization process. The maximum Ag(I) adsorption capacity of the CF-Pure and CF-NaOH was 0.502 and 0.612 mmol/g, in which the equilibrium data fitted to the Freundlich and Langmuir isotherm models, respectively. The Ag(I) adsorption rate also increased by using CF-NaOH and the kinetic data of both CF-Pure and CF-NaOH obeyed the pseudo-second order kinetic model. The enhancement of Ag(I) adsorption selectivity from photographic waste solution was also observed for the CF-NaOH.

Highly selective adsorption of phosphate by pyromellitic acid intercalated ZnAl-LDHs: Assembling hydrogen bond acceptor sites

Abstract Selective adsorption of phosphate from a complex solution is the key step for phosphate recovery from industrial wastewater. Despite recent research progress, phosphate removal with high selectivity has been found challenging, largely due to the complicated dynamic adsorption behavior of other competing anions in the aqueous waste solution. In the present study, pyromellitic acid (PMA) intercalated layered double hydroxides ([Zn0.68Al0.32(OH)2](PMA)0.08·0.3H2O, denoted as Zn2Al-PMA-LDHs) were synthesized and shown to possess a high selectivity (97.41% at pH 7.0) towards phosphate in a hybrid solution containing H2PO4−, SO42−, CO32−, NO3− and Cl−. In addition, benzoic acid (BA), terephthalic acid (TA) and trimesic acid (TMA) intercalated LDHs also showed similar adsorption performance. The hydrogen bond between hydroxyl group of phosphate as the donor and oxygen of dissociated aromatic carboxyl group as the acceptor was found to play a key role in phosphate adsorption, as suggested by FT-IR and XPS analysis. This work not only presented a well performed material but also a useful method for better design of efficient LDHs for selective phosphate adsorption.

Retention behavior studies for the removal of some hazardous metal ions from waste solutions using polyaniline silicotitanate as composite cation exchanger

Polyaniline silicotitanate as “organic–inorganic” composite material has been synthesized and utilized as adsorbent for the removal of Co2+, Cu2+, Cd2+, Cs+, and Pb2+ ions from aqueous waste solutions. The experimental data were analyzed by Langmuir, Freundlich, and D–R isotherm models of adsorption. The results suggest that the adsorption of the studied metal ions (Cu2+, Zn2+, Cd2+, and Pb2+ ions) on polyaniline silicotitanate is favorable for the Freundlich isotherm more than Langmuir and D–R isotherms. The numerical values of (1/n) for the studied metal ions were found to be smaller than one, which implies heterogeneous surface structure with minimum interaction between the adsorbed atoms. The adsorption energies (E) at 25°C were less than 8 kJmol−1 suggesting that the sorption process was dominated by physisorption (physical adsorption). Based on the results obtained, practical separation experiments for the above-mentioned cations on polyaniline silicotitanate column from aqueous waste solutions were carried out.

Liquid Membrane Formulation for Removal of Kraft Lignin from Simulated Liquid Waste Solution

Extraction of lignin from pulping wastewater as an external biofuel and in specialty chemicals will additionally benefit the chemical and automobile industries. Though lignin is nontoxic, it imparts brownish black colouration to the water bodies can cause environmental problems. Emulsion liquid membrane (ELM) technology is proposed to extract and recover the kraft lignin (KL) compound from the aqueous waste solution. This study investigated on development of a liquid membrane formulation for lignin removal from aqueous waste solution. Several parameters such as types and concentration of carrier, types of diluents and types of stripping agentswere studied. The results showed that the most favorable liquid membrane formulation is using Aliquat 336 as extractant, kerosene as diluents and sodium bicarbonate (NaHCO3) as stripping agent which is almost 93% of lignin was extracted.

Ion-exchange properties of ternary CaO–MgO–Al2O3 spinels in pH-controlled aqueous radioactive waste solutions

Spinel ion-exchange materials, composed of CaO–MgO–Al2O3 ternary systems were prepared via sol–gel reactions followed by sintering at different temperatures. Ca3MgAl4O10, Ca3Al2O6, CaMg2Al16O27, Ca2Mg2Al26O45, corundum, periclase, and monoxide lime were detected at room temperature, while CaAl2O4 and MgAl2O4 spinels were ascertained at 1,200–1,400 and 1,725–1,900°C, respectively. They were characterized using scanning electron microscopy, X-ray diffraction, X-ray fluorescence, FTIR, DTA–TGA, N2-gas adsorption, and laser diffraction particle size analyzer. We proved that they are chemically and thermally stable in their face-centered array spinel configurations with different surface, morphological, and topographical structures. They were used for removal of 134Cs+, 60Co2+, and 152−154Eu3+ from waste solutions; preliminary kinetic and pH were investigated. Langmuir, Freundlich, Dubinin–Radushkevich, Temkin, Harkins–Jura, and Halsey isothermal prototypes were applied to describe the equilibria between adsorbed phase metal ions and those in solution at different concentrations. The adsorption of 134Cs+, 60Co2+, and 152−154Eu3+ was critically affected by temperatures and ambient pH; spontaneous and exothermic nature of adsorption was found at specific pH values, beyond which the adsorption is restricted. The mechanism of adsorption was found to be chemical reaction combined with ion exchange rather than pure ion exchange.

Membrane crystallization for the recovery of a pharmaceutical compound from waste streams

The recovery of the active pharmaceutical compound 1-(5-bromo-fur-2-il)-2-bromo-2-nitroethane (denoted as G-1) in a crystalline form from waste aqueous solutions using membrane crystallization is addressed in this work. The process conditions were evaluated, observing that a low flowrate of the feed solution (5.0ml/min) is required to crystallize G-1. In addition, the use of Vitrofural as the feed solution, which is a mixture of G-1 and PEG, allows operating with higher concentrations due to the higher solubility of Vitrofural in water. However, the presence of PEG affects the mass transfer, leading to a lower transmembrane flux compared to the use of pure G-1.SEM images were used to evaluate the surface morphology of the crystallized G-1. It was concluded that the crystals obtained by membrane crystallization have the same morphology as the commercial G-1. Thus, the application of membrane crystallization for G-1 recovery can be considered as a novel technique with high potential to recover pharmaceutical compounds from waste streams.

Adsorption profiles of some heavy metal ions from aqueous waste solutions using sodium-doped zirconium titanoslicate

Adsorption profiles of Co2+, Cu2+, Ni2+, and Cr6+ ions from aqueous waste solutions were studied on novel sodium-doped zirconium titanoslicate (SDZTS) that was topographically transient pH characterized by a step change in ionic strength of buffer solutions. Using XRD, FTIR, and DTA–TGA, SDZTS-I, II, and III with single orthorhombic phases of Umbite [K2(Zr0.8Ti0.2)Si3O9 × H2O], Penkvilksite [(Ti0.9Zr.1)Si4Na2O13H4], and Umbite [K2(Zr0.86Ti.14)Si3O10H], with P 21 21 21 (19), P n c a (60), and P 21 21 21 (19) space groups, were recognized, respectively. According to the transient pH procedure, they could be classified as cation ion-exchange chromatographic supports; the order of strength is SDZTS-III ##xgt; SDZTS-II ##xgt; SDZTS-I. The duration of the pH transient was linearly proportional to the total ionic capacity and was used to estimate active binding capacity of the resin. The breakthrough capacities, BTCs, obtained during dynamic measurements through the column experiments were less than the recorded static ion-exchange capacities, SIECs. The BTCs recorded for Cu2+, Co2+, Ni2+, and Cr6+ /SDZTSs were SDZTS-III (2.45, 2.76, 2.25, and 3.97 meq/g), SDZTS-II (2.23, 2.65, 1.95, and 3.85 meq/g), and SDZTS-I (2.11, 2.42, 1.86, and 2.97 meq/g). The STIECs for Cu2+, Co2+, Ni2+, and Cr6+ were in the order of SDZTS-III (6.42, 6.45, 4.57, and 5.25 meq/g)##xgt; SDZTS-II (5.82, 5.25, 4.14, and 4.96 meq/g ##xgt; SDZTS-I (4.93, 4.35, 3.96, and 5.92 meq/g), respectively. Kinetic approaches, including the Lagergren first-order kinetic model (LFOKM), pseudo second-order kinetic model (PSOKM), and Morris–Weber kinetic model (MWKM), were used. They indicated that particle and/or film diffusion is the rate-determining step for Co2+, Ni2+, and Cr6+/SDZTS-III, while chemical reaction is the controlling step in case of Cu2/SDZTS-III. Langmuir and Freundlich models were selected as basic models for studying the different isotherms. Freundlich approach is a better fit for Co2+, Ni2+, and Cr6+/SDZTS-III, while Langmuir is more appropriate in case of Cu2+/SDZTS-III.

Application of nanofiltration membrane and ethyleneimine oligomer mixture for selective separation of Strontium from a simulated nuclear waste solution

Efficient radioactive waste management calls for maximum volume reduction and selective separation of elements from a radioactive waste solution. Ethylenimine (EI) oligomer mixture and GE Osmonics nanofiltration membrane has been used for selective strontium separation from an aqueous synthetic nuclear waste solution. Effect of concentration of EI, presence of cesium and sodium ions in strontium rejection, and effect of feed pH on strontium rejection, volume reduction, and permeate flux has been studied.

Removal of chromium(III) from aqueous waste solution by predispersed solvent extraction

The extraction experiments of chromium(Ш) from aqueous waste solution by predispersed solvent extraction (PDSE) process with extractant (HEHPEHE) and its mixture, including acidic extractant (D2EHPA), alkaline extractant (TOA) and neutral extractant (TBP) were carried out respectively. It is found that the extractant HEHPEHE exhibited high extraction selectivity to chromium(III) from aqueous waste solution. The colloidal liquid aphrons (CLAs) were successfully generated using kerosene as a solvent, HEHPEHE as an extractant, sodium dodecyl benzene sulphate (SDBS) as a surfactant in aqueous phase and polyoxyethylene sorbitol anhydride monolaurate (Tween-20) in oil phase. To study the extraction efficiency and advantages of the PDSE process in the removal of chromium(Ш), the effects of major factors, such as initial chromium(Ш) concentration, volume of colloidal gas aphrons (CGAs), HEHPEHE volume fraction, phase ratio (solvent phase to water phase), mass fraction of dodecyl trimethylammonium bromide (HTAB), mass fraction of SDBS, mass fraction of Tween-20 and initial pH of aqueous waste solution were also investigated and the appropriate process conditions were obtained. Under the appropriate conditions, the extraction efficiency of chromium(III) above 99.9 % can be achieved and the treated aqueous waste solution can be discharged directly without polluting the environment.

Study on the removal of chromium(III) by solvent extraction

abstract The extraction of chromium(Ш) from aqueous waste solution by extractants 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (HEHPEHE), di(2-ethylhexyl) phosphoric acid (D2EHPA), and mixture of D2EHPA with other extractants is carried out, respectively. It is found that the extractant HEHPEHE exhibited high extraction selectivity for chromium(III) from aqueous waste solution. Based on the molecular structure of HEHPEHE, it is confirmed that the extraction mechanism of chromium(III) by HEHPEHE is mainly determined by cation exchange and chelation. Furthermore, the influences of major factors, such as the initial pH, the initial concentration of extractant, phase ratio, and the extraction temperature on the extraction efficiency of chromium(III) are also investigated and the appropriate process conditions are obtained. At the appropriate conditions, the extraction efficiency of chromium(III) above 99% can be achieved and the treated aqueous waste solution can be discharged directly without polluting the environment.

Uranium adsorption from a liquid waste using thermally and chemically modified bentonite

In this work, uranium adsorption from aqueous (waste) solution onto thermal and chemical modified bentonite (TCMB) has been studied. The relevant factors affecting uranium adsorption onto our TCMB adsorbent were studied. These factors involved contact time, initial uranium concentrations, pH, adsorption temperature, foreign ion and the effect adsorbent (TCMB) amount using synthetic solution. The theoretical capacity of TCMB adsorbent is about 29 mg/g TCMB. The optimum adsorption conditions were choiced. Uranium elution from the loaded TCMB adsorbent has been carried out using CH3COONa as an effective eluent. Uranium adsorption from Gattar liquid waste by TCMB adsorbent was carried out in columns. The low uranium adsorption efficiency (37.5 % of the theoretical capacity of TCMB) may be due to the adsorption competition between uranium and difference foreign ion present in the solution (as iron). More than 92 % of the loaded uranium amount on the TCMB adsorbent has been eluted using CH3COONa as an efficient eluent.

Recovery of Hg(0) from the Aqueous Hg(I/II) Present in Analyte Solution after Quantitative Determination of Iron

An easy and feasible approach to recover HgCl2, used in quantitative determination of iron values, as Hg(0) was described. Both Hg(I) and Hg(II), present in the solution after quantitative determination of iron, was completely reduced to Hg(0) by the addition of aluminium chips in more slightly excess than the stoichiometric amount. The purity of recovered Hg(0) was verified by comparing the value of density with pure mercury. This simple method may be useful to remove the mercury from other waste aqueous solutions before their discharge into the environment.

Peroxynitrite: A Re-examination of the Chemical Properties of Non-thermal Discharges Burning in Air Over Aqueous Solutions

The main compounds of non-thermal plasmas generated by a discharge in humid air at atmospheric pressure are re-examined to explain the twin chemical properties of discharges over aqueous waste solutions, i.e. the acid and oxidizing effects. The acid effects are attributed to transient nitrous and peroxynitrous acids and to stable nitric acid. The matching oxidizing power of the discharge species onto solutes is due to water soluble H2O2 provided by the dimer formation of °OH and also to peroxynitrous acid ONOOH and its salt which are involved in the oxidation process of nitrous to nitric acid.

Equilibrium and Kinetic Studies on the Removal of Basic Violet 10 from Aqueous Solutions Using Activated Carbons Prepared from Industrial Wastes

ABSTRACT Low-cost adsorbents prepared from industrial wastes such as sugarcane bagasse (BC), rice husk (RC), and textile waste cloth (TC) are identified as suitable sorbents for removing basic violet 10 (BV). Fourier transform infrared (FTIR) and scanning electron microscopic (SEM) studies were carried out to characterize the prepared sorbents. The effects of dosage, time, and pH on dye removal were examined. It was observed that BV sorption takes place in acidic, neutral, and alkaline aqueous solutions. The work discussed the best-fit sorption isotherms among Freundlich and Langmuir, in addition to the reaction- and diffusion-based kinetic models. Based on the data obtained, it was found that the BV sorption took place in acidic, neutral, and alkaline aqueous solutions and sorption kinetics found to be controlled by pseudo-second-order and pore diffusion models. Also, thermodynamic parameters such as ΔG o, ΔH o, ΔS o, and E a were calculated in order to understand the nature of the sorption process. The maximum dye removal capacity (DRC) was found to be 5608, 1244, and 27,495 mg/kg for BC, RC, and TC, respectively. Collectively, it can be concluded that the activated carbon sorbents, prepared from the named wastes, can used to adequately remove the basic violet dye from its aqueous waste solution.

Modeling kinetics and thermodynamics of Cs+ and Eu3+ removal from waste solutions using modified cellulose acetate membranes

Removal of Cs+ and Eu3+ ions using cellulose acetate (CA) and modified CA was studied. Cellulose acetate was modified using acrylamide (AAm) and polyethylene glycol (PEG). Specifically, CA, CA/AAm, and CA/PEG were used to remove Cs+ and Eu3+ from aqueous waste solutions. The CA-metal and modified CA-metal interactions were studied under different conditions such as concentration of metal ions and temperature in the range 298K–333±1K. Experimental equilibrium sorption data were analyzed using Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models. These data were better fitted to both Langmuir and D–R isotherms compared to Freundlich model. On the other hand the sorption processes were better represented by pseudo-second order kinetic model. The sorption processes were endothermic with ΔHo values 16.20, 23.55, and 21.70 (kJ/mol) for sorbed Cs+ ions onto CA, CA/AAm, CA/PEG, whereas that for sorbed Eu3+ are 21.79, 23.87 and 75.34 (kJ/mol), respectively. The entropy values ΔSo for Cs+ ion sorbed onto CA, CA/AAm, and CA/PEG are 50.72, 80.15, and 77.10 (J/molK), whereas that for the sorbed Eu3+ ion are 75.0, 87.30 and 256.10 (J/molK) respectively. The activation energy, Ea, for Cs+ and Eu3+ ions sorbed onto all studied sorbent materials lies in the range 8.73–26.32 (kJ/mol) and 24.27–78.11 (kJ/mol), respectively. The negative values of Gibbs free energy, ΔGo, confirm the feasibility and the spontaneous nature of both Cs+ and Eu3+ ions sorption removal using CA and AAm and PEG modified CA and indicating that the sorption processes are chemi-sorption mechanisms. The sorption removal capacities of both Cs+ and Eu3+ were in the order CA/PEG>CA/AAm>CA. The batch and dynamic sorption results show that the modified CA/PEG, CA/AAm, and CA membranes can be used to remove Cs+ and Eu3+ ions from wastewater.

Recovery of 137Cs from Laboratory Waste using Solvent Extraction with Sodium Tetraphenylboron (TPB)

The paper describes a method for the recovery of 137Cs from an aqueous radioactive laboratory waste solution containing 137Cs (2 µg/mL) in the presence of high concentration of Na+ using solvent extraction technique. The method comprises of adjustment of pH to the acidic range (pH = 2), contacting the aqueous radioactive solution with sodium tetraphenylboron (TPB) in nitrobenzene, whereby 137Cs binds with tetraphenylboron anions and gets separated. Results of this investigation indicate that 137Cs could be efficiently and selectively extracted from an aqueous solution media containing high concentration of Na+ under mildly acidic pH into an organic phase and back extracted with small volume of 3 M HNO3, thus enabling concentration. The proposed method was successfully applied in real samples.

Magnetic Self-Assembled Zeolite Clusters for Sensitive Detection and Rapid Removal of Mercury(II)

We reported here the fabrication of a hierarchical mesoporous zeolite nanocomposite using 20 nm crystalline domins of zeolite L as building "bricks" by a simple and general one-step synthetic approach. By taking advantages of the large pore volumes, superparamagnetic iron oxide nanocrystals could be encapsulated into the nanocomposite conveniently for further facilitate separation and detection. In addition, by covalent coupling of fluorescent receptor (rhodamine-hydrazine), the combination of well-defined inorganic nanomaterials and organic receptors could be applied to selective detection of Hg(2+). Importantly, the unique adsorption capacity enabled by the hierarchical mesoporous zeolite and the efficient removal ability form complex multiphase systems by the magnetic characteristic made this multifunctional nanomaterial an excellent probe for detection, adsorption, and removal of Hg(2+) from waste aqueous solution.

DNA damage and repair following In vitro exposure to two different forms of titanium dioxide nanoparticles on trout erythrocyte

TiO2 has been widely used to promote organic compounds degradation on waste aqueous solution, however, data on TiO2 nanotoxicity to aquatic life are still limited. In this in vitro study, we compare the toxicity of two different families of TiO2 nanoparticles on erythrocytes from Oncorhynchus mykiss trout. The crystal structure of the two TiO2 nanoparticles was analyzed by XRD and the results indicated that one sample is composed of TiO2 in the anatase crystal phase, while the other sample contains a mixture of both the anatase and the rutile forms of TiO2 in a 2:8 ratio. Further characterization of the two families of TiO2 nanoparticles was determined by SEM high resolution images and BET technique. The toxicity results indicate that both TiO2 nanoparticles increase the hemolysis rate in a dose dependent way (1.6, 3.2, 4.8 μg mL(-1) ) but they do not influence superoxide anion production due to NADH addition measured by chemiluminescence. Moreover, TiO2 nanoparticles (4.8 μg mL(-1) ) induce DNA damage and the entity of the damage is independent from the type of TiO2 nanoparticles used. Modified comet assay (Endo III and Fpg) shows that TiO2 oxidizes not only purine but also pyrimidine bases. In our experimental conditions, the exposure to TiO2 nanoparticles does not affect the DNA repair system functionality. The data obtained contribute to better characterize the aqueous environmental risks linked to TiO2 nanoparticles exposure.