Synthetic Waste Solutions Research Articles

Immobilization of Coal Fly Ash in Alginate Beads for Adsorption of Fe (III) Ions

<p><em><span>Various industrial, agricultural, household, mining, smelting, and chemical industrial activities can generate waste containing heavy metals such as Fe(III). Fly ash has the potential as an effective adsorbent to capture heavy metals in wastewater. This study aims to immobilize coal fly ash in alginate beads for the adsorption of Fe(III) ions from synthetic waste solution. To test the adsorption capability of fly ash-alginate beads was performed by varying the contact time (1-24 hours), the mass of fly ash-alginate beads (5, 15, 35, 45, and 55 grams), and the initial concentration of Fe (III) ions at 6, 8, and 10 ppm. The determination of the concentration after adsorption was done using a UV-Vis spectrophotometer. The results showed that fly ash-alginate beads were able to remove Fe(III) ions up to 68.60% at a bead mass of 55 g, ion concentration of 10 ppm, and the equilibrium contact time was reached after 5 hours. The analysis results indicated that the adsorption mechanism followed the Freundlich isotherm model due to the heterogeneous surface exhibited.</span></em></p><p><em><br /></em></p>

Novel iminepyridinium -modified silicas as super-adsorbents for metals ions

For effective removal of toxic metals from waste water, novel bifunctional iminepyridinium- silicas were fabricated and studied in detail to show their high applicability as adsorbents of Pb(II), Cd(II) and Cu(II). The novel adsorbents were synthesized using two-stage procedure to incorporate sillylpropylpyridinium moieties: co-condensation to obtain chloro- and bromopropyl-functionalised silicas, and next quaternisation with N-decyloxy-1-(pyridin-4-yl)ethaneimine and N-decyloxypyridine-4-carboximidamide (MCl-D4EI, MBr-D4EI, and MCl-D4IA, MBr-D4IA, respectively). The fabricated materials were characterized by Raman, SEM, XPS, zeta potential and IGC techniques. Various batch adsorption parameters were investigated to demonstrate high potential of the novel sorbents. The optimum pH for adsorption of Pb(II), Cd(II) and Cu(II) from aqueous solutions was found to be 4–6 and the maximum loading was obtained after a contact time of 15 min. The process took place on the surface through chemisorption, in which imine and amine groups lead to the strong binding of the metals ions. The spherical MBr-D4IA was found to be the most efficient sorbent of Pb(II) and Cd(II) with the adsorption capacity of 339 mg/g and 173 mg/g, respectively, while Cu(II) was co-extracted from the synthetic waste solution in 79%. Moreover, MBr-D4IA displayed extraordinary tolerance to the presence of coexisting ions, good reusability and stability.

Enhancement adsorption of lead and cadmium ions from waste solutions using chemically modified palm fibers

Efficiently chemically modified adsorbents based upon palm fibers were prepared through chemical treatments of palm fibers by sulfuric acid (PF-AC), oxalic acid as a chelating agent (PF-Chel), HNO3 as an oxidizing agent (PF-OX) and Na2SO3 as a reducing agent (PF-Rd). The four produced adsorbents were applied for the removal of Pb(II) and Cd(II) from synthetic waste solutions. The removal capacity of all chemically modified adsorbents has been investigated through the batch tests to determine the optimum parameters for maximum removal. The kinetics and isotherm studies have been applied to identify the adsorption type. All data in this work has been used as determining factors to predict the adsorption process mechanism. The characterization of the surface of the chemically modified adsorbent [FTIR and SEM] was also studied as another contribution to proving the suggested adsorption mechanism. Experimental data were best fitted by Langmuir model while kinetic results were appropriately expressed by the pseudo-second-order model. The results demonstrated the highest capacity values of 56 and 33 mg/g using PF-Rd for both Pb (II) and Cd (II) ions, respectively. Throughout this study, PF-Rd and PF-OX achieved the maximum capacity with the adsorption of both heavy metals.

Decolorization of Reactive Yellow 17 in aqueous solution by ozonation in a semi-batch bubble column reactor

In this study, the factors influencing the rate of chemical oxygen demand (COD) of a synthetic waste solutions containing water soluble reactive dye [Reactive Yellow 17 (RY17)] by ozone gas was investigated. The research was conducted using a semi-batch bubble column to take the advantage of the intensive back-mixing that prevails in bubble columns. As a result, the COD of disperse dyestuff wastewater was reduced to 78.58%, and decolorization was remarkable under the basic condition of pH 12, complete each dye degradation occurs in 12 min, ozone consumption goes on for a further 30 min after which time most degradation reaction is completed. Kinetic studies were exhibited that direct ozonation of the aqueous dyes were a pseudo-first-order reaction with respect to the dyes. The apparent rate constant increased with both applied ozone dose and higher pH values, declined logarithmically with the initial dye concentration.

Recovery of Copper from Effluents by Cementation on Aluminum in a Multirotating Cylinder-Agitated Vessel

Recovery of copper from synthetic waste solution using cementation technique in a new agitated vessel employing multirotating aluminum cylinders impeller was investigated. Parameters studied are cylinder diameter, rotation speed, initial copper ion concentrations, and effect of surfactants. Solution analysis and scanning electron microscopy were employed to investigate the kinetic and mechanism of the process. The rate of recovery was found to be at its maximum value at the operating conditions of 350 rpm rotation speed, 5000 ppm initial CuSO4 concentration, and 1.2 cm cylinder diameter. All data were correlated by the dimensionless equation: $$ {\text{Sh}} = 1.16 {\text{Sc}}^{0.33} {\text{Re}}^{0.63} \left( {\frac{{d_{\text{c}} }}{L}} \right)^{0.54}, $$ with an average deviation of ±8.5 pct and a standard deviation of 5.88 pct. Presence of nonylphenol ethoxylate surfactant in the solution decreased the rate of recovery by an amount ranging from 2.94 to 38.57 pct depending on the operating conditions. The present geometry gave higher rates of recovery compared to both the single rotating cylinder and rotating disc reactor.

Decolorization and Degradation of Reactive Dye in Aqueous Solution by Ozonation in a Semi-batch Bubble Column Reactor

The decolorization and degradation of anionic sulphonated azo dye (Reactive orange 16 (RO16)), which is suspected to be carcinogenic, were investigated using ozone. The decolorization process of the reactive dye was carried out by bubbling ozone at the bottom of a bubble column reactor containing the dye solution. The effect of pH, reaction time, dye concentration, ozone concentration, and decolorization time was studied. Also, degradation products and possible degradation mechanism were investigated. The results showed that ozonation was a highly effective way to remove color from wastewater. The color of a synthetic waste solution containing water-soluble reactive dye was reduced to 69.69 % under the basic condition (pH 12), with complete RO16 degradation occurring in 8 min. Ozone consumption continued for a further 16 min after which time most of the degradation reactions were complete. Kinetic studies showed that direct ozonation of the aqueous dyes represented a pseudo-first-order reaction with respect to the dye. The apparent rate constant increased with both the applied ozone dose and higher pH values and declined logarithmically with the initial dye concentration. Intermediates such as 6-acetylamino-3-aminonaphthalene-2-sulfonic acid, 2-(4-nitrosophenyl) sulfonylethyl hydrogen sulfate, and 6-acetamido-4-hydroxy-3-nitroso naphthalene-2-sulfonic acid were detected by gas chromatograph coupled with mass spectrometry in the absence of pH buffer, while nitrate and sulfate ions and formic, acetic, and oxalic acids were detected by ion chromatography.

Liquid-Liquid Extraction/Recovery of Chromium(VI) From Some Industrial Waste Solutions Using Alamine 336 in Kerosene

Liquid-liquid extraction of chromium(VI) from synthetic waste solution using Alamine 336/kerosene was investigated. The extraction conditions were evaluated by varying the experimental parameters. On the basis of the slope analysis data, the composition of the extracted species was found to be R3NH2CrO4 or (R3NH)2Cr2O7. Alamine 336/kerosene solvent extracts Cr(VI) ions under the optimized conditions in three stages at an O/A ratio of 1 according to McCabe-Thiele diagram. Sodium hydroxide was found more efficient for Cr(VI) stripping. It was accomplished in two stages at an A/O ratio of 1. Finally, the method was applied for extraction Cr(VI) from electroplating and leather tanning waste solutions.

Decolorization of textile basic dye in aqueous solution by ozone

In this study, the factors affecting the rate of chemical oxygen demand (COD) of a synthetic waste solution containing a water soluble basic dye [Methylene Blue] were investigated. Decolorization of the dye was achieved by ozonation. The research was conducted using a batch bubble column to take the advantage of the intensive back-mixing that prevails in bubble columns. As a result, the COD of basic dyestuff wastewater was reduced to 64.96% and decolorization was observed under basic conditions (pH 12), complete MB degradation occurring in 12 min. Ozone consumption continued for a further 16 min after which time most of the degradation reactions were complete. Kinetic studies showed that direct ozonation of the aqueous dyes represented a pseudo-first-order reaction with respect to the dye. The apparent rate constant, which increased with both the applied ozone dose and higher pH values, declined logarithmically with the initial dye concentration.

Separation and determination of components of high level waste using IC and dynamically modified reversed-phase HPLC in ‘actinide partitioning’ studies using synthetic waste solution

Ion-chromatography (IC) as well as high performance liquid chromatography (HPLC) techniques have been used as analytical tools for the separation and estimation of some of the relevant metal ions present in the high level liquid waste (HLLW). IC was applied for the estimation of alkali and alkali earth metal ions, viz. Na, Cs, Ba and Sr using methane sulphonic acid as the eluent on a cation exchange column. On the other hand, dynamically modified (with sodium salt of n-octane sulphonic acid) reverse phase HPLC was followed for the estimation of lanthanides viz. La, Pr, Nd and Sm using α-hydroxy isobutyric acid as the eluent on a C-18 column. Sample acidity of 0.01 M HNO3 was optimized for best analytical results. The interferences of one group of metal ions on the quantification of the other group of metal ions were studied. The solvent extraction data (distribution coefficient data) of Na, Cs, Sr, Ba, La, Pr, Nd and Sm from their mixture was obtained by analyses of the aqueous samples before and after extraction with extractants used for actinide partitioning, viz., octyl(phenyl)N,N-diisobutyl carbamoyl methylene phosphine oxide (CMPO), N,N′-dimethyl-N,N′-dibutyl tetradecyl malonamide (DMDBTDMA) and N,N,N′,N′-tetraoctyl diglycolamide (TODGA). The solvent extraction data obtained by IC/HPLC techniques was compared with those obtained by ICP-AES technique. A good agreement between the results of the two techniques validated the present analytical method.

Development of a continuous homogeneous process for denitration by treatment with formaldehyde

Removal of nitric acid from high level liquid wastes (HLLW) of nuclear fuel reprocessing plants is warranted for simplifying the procedure for waste fixing. Chemical denitration aims to reduce the waste volume by destroying the acidity and subsequent concentration by adding suitable reductants. Reduction of nitric acid to gaseous products is an attractive way to accomplish denitration. Nitric acid reduction with formaldehyde proceeds with the formation of CO2, NO2, NO or N2O depending on the reaction conditions and all the reaction products except water can be eliminated from the system in gaseous form. The HNO3–HCHO reaction is governed by a complex mechanism of exhibiting relatively long induction period, depending upon the temperature, concentration of reactants and nitrous acid reaction intermediate. In the present work, a homogeneous denitration process with formaldehyde which offers safety and is governed by controlled kinetics was demonstrated on a laboratory scale. The induction period before commencement of the reaction was eliminated by maintaining the reaction mixture at a pre determined temperature of 98 °C. Based on the results accrued from lab scale experiments, the equipment for pilot plant scale operation was designed, the reaction efficiency for continuous denitration was determined and the investigation of nitric acid destruction was extended to full-scale plant capacity. The role of organics in the waste in foaming up of the reaction mixture was also studied using a synthetic waste solution.

Flux decline analysis in micellar-enhanced ultrafiltration of synthetic waste solutions for metal removal

It is known that micellar-enhanced ultrafiltration (MEUF) is an efficient and economic process for the removal of trace metal ions and organics from aqueous media. In this work, flux decline behavior in MEUF of aqueous solutions containing trace Cu(II) (1.6–8 mM) and anionic surfactants sodium dodecyl sulfate (SDS) or sodium dodecyl benzene sulfate (SDBS) was studied at 25 °C in batch mode. An UF membrane that had average pore size comparable to those of Cu(II)-adsorbed micelles was adopted. All experiments were performed as a function of stirring speed (200–400 rpm), solution pH (3.0–5.0), molar concentration ratio of surfactant to metal (S/M, 2.5–12.7), and applied pressure (69–345 kPa). It was shown that more than 90% of Cu(II) could be removed at an S/M ratio of 12.7 and pH 5 using SDS. The blocking filtration law was used to identify the mechanism(s) of flux decline during the MEUF processes. Finally, the specific cake resistances in both SDS and SDBS systems were evaluated and compared.

Treatment and degradability of direct dyes in textile wastewater by ozonation: A laboratory investigation

In this study the factors affecting the rate of chemical oxygen demand of a synthetic waste solution containing water soluble direct dyes (Sirius Red F3B and Sirius Blue SBRR) by ozone gas were investigated. The research was conducted using a batch bubble column to take the advantage of the intensive back-mixing that prevails in bubble columns. In result of our experimental study, we have shown that the COD of direct dyestuff wastewater was reduced 58.89% for Sirius Red F3B and 60.95% for Sirius Blue SBRR after ozone bubbling treatment for 2 h. In addition the results indicate that during the ozonation, even though complete Sirius Red F3B and Sirius Blue SBRR degradation occurs in 10 min, ozone consumption goes on for a further 20 min after which time most degradation reactions are completed. Results of kinetic study showed that ozonation of the aqueous direct dyes were a pseudo-first-order reaction with respect to the dye. The apparent rate constant increased with both applied ozone dose and temperature, but declined logarithmically with the initial dye concentration. The main ozonation by-products, identified by HPLC, IC and GC-MS are formaldehyde, acetaldehyde, glyoxal, acetone, acetic acid, formic acid, oxalic acid and carbonic acid, plus nine Sirius Red F3B and twelve Sirius Blue SBRR derivatives are scarcely degradable.

Novel polymer inclusion membrane containing a macrocyclic ionophore for selective removal of strontium from nuclear waste solution

A new polymer inclusion membrane (PIM) containing cellulose triacetate (CTA) as the monomer, di-tert-butylcyclohexano-18-crown-6 (DtBuCH18C6) as the carrier and 2-nitrophenyl octyl ether (NPOE) as the plasticizer was developed for the selective transport of Sr2+ from aqueous nitrate medium. Studies with crown ether concentration variation have indicated a linear dependence on the permeability coefficient (P) suggesting a diffusion mechanism for ion transport. Effects of membrane thickness, nature of plasticizer and plasticizer concentration on the transport of Sr2+ were studied. The effect of feed acidity was also investigated for a possible application in the nuclear waste solution. Selective Sr2+ transport was observed in a synthetic waste solution containing metal ions such as UO22+, MoO22+, Zr4+, Ce3+, Nd3+, Ru3+, Pd2+, Ba2+ and Cs+, etc., in 1 M HNO3 and 2 M NaNO3. Greater than 70% transport of Sr2+ was observed in 24 h while most of the other metal ions were negligibly transported (<0.01%).

Chromium(III, VI) speciation analysis with preconcentration on a maleic acid-functionalized XAD sorbent

Chromium may exist in environmental waters as Cr(III) and Cr(IV), the latter being the toxic and carcinogenic form. Since atomic absorption spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry can only yield information on total Cr concentration, a polymer resin bearing O,O-donor chelating groups such as the maleic acid-functionalized XAD–(CO)CH=CH–COOH resin was synthesized to selectively retain Cr(III) at pH 4.0–5.5. The dynamic breakthrough capacity of the resin for Cr(III) at pH 5.0 was 7.52mgg−1, and the preconcentration factor extended to 250–300. Chromium(III) in the presence of 250-fold Cr(VI)—which was not retained—could be effectively preconcentrated on the NH4+-form of the resin and determined by AAS or diphenylcarbazide (DPC) spectrophotometry. When Cr(VI) was reduced to Cr(III) with Na2SO3 solution brought to pH 1 by the addition of 1M H2SO4, and preconcentrated on the resin, total Cr could be determined. The developed method was validated with a blended coal sample CRM-1632. Since the adsorption behavior as a function of pH of possible interferent metal ions, e.g. Ni(II), Co(II), Cu(II), Cd(II), Zn(II), Pb(II) and Fe(III), was similar to that of Cr(III), selective elution of Cr(III) from the resin was realized using a mixture of 1wt.% H2O2+1M NH3. The eluate containing Cr as chromate could be directly analyzed by diphenyl carbazide spectrophotometry without any adverse effect from the common interferents of this method, i.e. Fe(III), Cu(II) Hg(II), VO3−, MoO42− and WO42−. Various synthetic waste solutions typical of electroplating bath effluents containing Cr, Cu, Ni, Zn, Na, Ca, cyanide (and chemical oxidation demand (COD), achieved by glucose addition) were subjected to pretreatment procedures such as hypochlorite oxidation (of cyanide) and catalytic oxidation (of COD) with peroxodisulfate. Chromium determination gave satisfactory results. The combined column preconcentration—selective elution—diphenylcarbazide spectrophotometric determination was also successfully applied to the determination of Cr in artificial and real seawater.

Crevice Corrosion of Stainless Alloys in Liquid Waste Environment of the Nuclear Power Plant

Abstract The comparative capabilities of type 316L (UNS S31603) and a duplex stainless steel (SS) and three high-nickel stainless alloys were studied for use in the waste processing plant of nuclear power stations. Exposure tests were carried out in the synthetic waste solutions of different pHs at boiling point using multiple crevice assemblies. The frequency and the depth of crevice attack were evaluated statistically. Type 316L SS and duplex SS exhibited almost an equivalent incidence of crevice corrosion. However, deep and severe attack was observed only for type 316L SS, whereas uniform and shallow attack was seen for duplex SS. The high-nickel stainless alloys showed a considerably higher crevice corrosion resistance than type 316L SS. They were immune against crevice attack in a pH 8 solution, but not in a pH 5 solution.

Separation of Americium, Curium, and Trivalent Lanthanides from High-Level Wastes by Oxalate Precipitation: Experiments with Synthetic Waste Solutions

The separation of trivalent actinides and rare earths from other fission products in high-level nuclear wastes by oxalate precipitation followed by ion exchange (OPIX) was experimentally investigated using synthetic wastes and a small-scale, continuous-flow oxalic acid precipitation and solid-liquid separation system. Trivalent actinide and rare earth oxalates are relatively insoluble in 0.5 to 1.0 M HNO/sub 3/ whereas other fission product oxalates are not. The continuous-flow system consisted of one or two stirred-tank reactors in series for crystal growth. Oxalic acid and waste solutions were mixed in the first tank, with the product solid-liquid slurry leaving the second tank. Solid-liquid separation was tested by filters and by a gravity settler. The experiments determined the fraction of rare earths precipitated and separated from synthetic waste streams as a function of number of reactors, system temperature, oxalic acid concentration, liquid residence time in the process, power input to the stirred-tank reactors, and method of solid-liquid separation. The crystalline precipitate was characterized with respect to form, size, and chemical composition. These experiments are only the first step in converting a proposed chemical flowsheet into a process flowsheet suitable for large-scale remote operations at high activity levels.