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Reactive dyes are pernicious pollutants in textile effluent, which are to be treated passably before discharging into the environment. In the present study, a potential dye degrading bacterial strain Pseudomonas guariconensis was isolated from paddy rhizosphere and was characterized by 16S rRNA gene sequencing. The biodegradation ability of the strain was evaluated by time-based study with immobilized bacterial cells in calcium alginate biocarrier matrix and also with free cells. The results indicated that the strain exhibited maximum degradation of 91% when immobilized in the biocarrier matrix. The enzymatic study revealed the production of oxidoreductase enzymes. The degraded products were identified as 2-amino-3-phenylpropanoic acid and benzoquinone by gas chromatography-mass spectroscopy (GC-MS) analysis, and a degradative pathway was derived based on the enzymatic profile. A packed bed column was designed using P. guariconensis VITSAJ5 immobilized in calcium alginate beads as a biosorbent for the removal of Reactive Red 120. The immobilized bacterial cells exhibited 87% uptake of RR120, whereas the nonimmobilized bacterial cells exhibited a maximum uptake of 37%. The phytotoxicity analysis by seed germination assay revealed an enhanced plumule and radicle length, indicating the nontoxic byproducts after the treatment of Reactive Red 120 by VITSAJ5 compared to the untreated Reactive Red 120 solution. PRACTITIONER POINTS: Current study is the first report on Pseudomonas guariconensis capable of degrading reactive dyes (Reactive Red 120) It was observed that the degradation potential was maximum when cells were immobilized with Ca-Ag biocarrier matrix Breakdown metabolism of Reactive Red 120 was derived through pathway prediction Employing immobilized bacteria in a packed bed column found to possess a prominent biosorption ability on the matrix enhancing the degradation process Toxic reactive dye was converted into nontoxic compounds, evidenced by phytotoxicity studies.

Facilitated transport of Orange 3R was performed by means of emulsion liquid membrane (ELM) technique containing double extractants of Aliquat 336 and D2EHPA as extractant and synergist extractant, respectively. Cooking palm oil, sorbitan monooleate (Span 80), and sodium hydroxide were used as diluent, surfactant and stripping agent, respectively. Several parameters influencing the extraction of Orange 3R via ELM, namely effect of extraction time, agitator speed, Span 80 concentration and treatment ratio, were experimentally investigated and optimized using response surface methodology (RSM). Results demonstrated that about 91% of Orange 3R was successfully extracted under optimum conditions of 12 minutes of extraction time, 413 rpm of agitator speed, 3.2% (w/v) of sorbitan monooleate, and 1:9.8 of treatment ratio. Additionally, the aforementioned optimum conditions were found to be more suitable to treat low concentration of Orange 3R (less than 100 ppm) from simulated textile wastewater. The findings reveal that reactive Orange 3R dye is able to be selectively extracted using double extractants via sustainable ELM process as well as providing high potential application in the dye removal from industrial textile wastewater.

Aims:: We aim to evaluate the potential application of amine reactive fluorogenic reagents for estimating enzymatic proteolysis. Background:: Proteolytic enzymes play important roles in regulating many physiological processes in living organisms. Objectives:: Assessment of protein degradation by using reagents for protein assay techniques. Methods:: We have assayed samples at the start and after 30-60 minutes incubation with trypsin by Chromeo P503 (Py 1 pyrylium compound) and CBQCA (3-(4-carboxybenzoyl) quinoline-2-carboxaldehyde) as amine reactive reagents and NanoOrange as non-amine reactive dye. Results:: All BSA prepared samples with trypsin have shown significantly higher fluorescence intensity (FI) versus controls (which reflects proteolysis) when assayed by Chromeo P503 (Py 1 pyrylium compound) and CBQCA (3-(4-carboxybenzoyl) quinoline-2-carboxaldehyde) as amine reactive reagents. However, same samples assayed with NanoOrange as non-amine reactive reagent did not show any significant variation between samples containing trypsin and controls. Conclusion:: These results are confirming reliability of highly sensitive protein assays utilizing amine reactive fluorogenic reagents for general estimation of proteolysis.

Rice bran is a major by-product of the rice milling industry and is abundant in Taiwan. This study proposed a simple method for modifying rice bran to make it a low-cost adsorbent to remove reactive blue 4 (RB4) from aqueous solutions. The effects of independent variables such as dye concentration (100–500 ppm), adsorbent dosage (20–120 mg) and temperature (30–60 °C) on the dye adsorption capacity of the modified rice bran adsorbent were investigated by using the response surface methodology (RSM). The results showed that the dye maximum adsorption capacity of the modified rice bran adsorbent was 151.3 mg g−1 with respect to a dye concentration of 500 ppm, adsorbent dosage of 65.36 mg, and temperature of 60 °C. The adsorption kinetics data followed the pseudo-second-order kinetic model, and the isotherm data fit the Langmuir isotherm model well. The maximum monolayer adsorption capacity was 178.57–185.19 mg g−1, which was comparable to that of other agricultural waste adsorbents used to remove RB4 from aqueous solutions in the literature. The thermodynamics analysis results indicated that the adsorption of RB4 onto the modified rice bran adsorbent is an endothermic, spontaneous monolayer adsorption that occurs through a physical process.

In this study, papermaking sludge was used as the raw biomass material to produce the lignin-based flocculant (LBF) by grafting quaternary ammonium groups and acrylamide. LBF was used as a coagulant aid with polyaluminum chloride (PAC) to treat reactive and disperse dyes wastewater. Effects of dosing method, pH, hardness and stirring speed on the coagulation behavior and floc properties were studied. Results showed that the superior coagulation efficiency and recovery factor were achieved by PAC+LBF compared with PAC and LBF+PAC. The primary mechanisms of LBF in the treatment of disperse and reactive dye solutions were charge neutralization and bridging effect, respectively. In the dual-coagulation, the impact of pH on the coagulation efficiency was weak during pH range of 5-9. Moderate hardness could enhance the floc properties due to the decrease of electrostatic repulsion and the chelation of Ca(II) and LBF. Besides, flocs coagulated by PAC+LBF had a stronger anti-crush ability.

The objective of this work was to investigate the characteristics of polyaniline-chitosan membrane by SEM, FTIR, tensile strength and percentage elongation and to determine the adsorption behavior of reactive dyes (Yellow 145, Red 195, Blue 222) onto the polyaniline-chitosan membrane. The removal of reactive dyes was investigated in a batch experiment. Parameters influencing the adsorption including pH (2-10), contact time (0-150 min), equilibrium study (30 min to 16 h) and initial concentration (10, 25, 50, 100, 250 and 500 mg×L-1) were studied at room temperature. The dye concentrations were determined by a UV/VIS Spectrophotometer at the wavelengths 423, 540 and 620 nm for Yellow 145, Red 195 and Blue 222, respectively. The results indicated that the tensile strength and percentage elongation of polyaniline-chitosan membrane were 0.032 kN/mm2 and 15.53%, respectively. It was found that optimum pH for adsorption of all dyes on polyaniline-chitosan membrane was pH 2. When the adsorption time increased, the adsorption efficiency increased accordingly. The adsorption equilibrium was found to be reached at 3 h in all adsorptions. Moreover, the isotherm study showed that the polyaniline-chitosan membrane adsorption corresponded to Freundlich model. Moreover, it was also found that polyaniline-chitosan membrane exhibits higher adsorption efficiency for reactive dyes than chitosan.

This work investigates the possibility of utilizing carbonized fish ( Labeo rohita ) scales (CFS) as low-cost materials for the adsorption of reactive orange 16 dye (RO16) through batch processing. The textural and morphological characteristics of CFS were evaluated which showed mesoporous structure with BET surface area of 213.82 m 2 /g and average pore diameter of 5.116 nm. The effects of initial RO16 concentration (25–400 mg/l), solution pH (3–13), and temperature (30–50 °C) on the adsorption efficiency of the prepared CFS were demonstrated. The equilibrium isotherm data were best correlated using the Freundlich equation. The prepared CFS exhibited maximum adsorption capacities of 105.8, 107.2, and 114.2 mg/g at 30 °C, 40 °C, and 50 °C, respectively. The pseudo-second-order model well represented the adsorption kinetics. The prepared CFS had a high adsorption capacity for RO16 and could be utilized effectively for the removal of reactive dyes from wastewater.

Reactive dyes represent the most important class of dyes used in the colouration of cellulose fibre based textiles. Due to a limited degree of dyestuff fixation and competitive hydrolysis of the reactive anchor group in the alkaline dyebath substantial amounts of hydrolysed dyestuff are released at the end of the dyeing process. Assuming a rather high degree of dyestuff fixation with 90%, still 20,000 tonnes of hydrolysed dyestuff are released per year thus forming heavily coloured effluents. A number of techniques have been proposed to treat such waste water streams, e.g. coagulation, precipitation, absorption, chemical destruction and electrochemical decolourisation. A clean alternative presented in this article utilises the direct cathodic reduction of the azo-chromophores, which up to now has been proposed for treatment of concentrated dyestuff solutions. A distinct problem arises from the much low concentrations of reactive dyes in exhausted dyebaths, which has been investigated in this study. As technically relevant representatives three bifunctional reactive dyes Levafix Amber CA, Levafix Fast Red CA and Levafix Blue CA, which can form a trichromy have been studied. The cathodic electron transfer has been analysed with cyclic voltammetry on a hanging mercury drop electrode. Potentiometric titration with Fe(II)-triethanolamine complexes was used to determine the reducing equivalents for complete dyestuff reduction. A multi-cathode electrolyser was applied to study the cathodic dyestuff decolourisation in batch experiments as basis for extrapolation to full scale operation. Successful reductive decolourisation could be obtained for all three investigated dyes. In case of Leavfix Amber CA the original colour recovered some hours after the experiment had been terminated due to air oxidation of the reduced dyestuff. Due to the low dyestuff concentrations present in the dyebath current efficiency was determined with 2.8–8.0% and energy consumption was estimated with of 5.6 kWh/m3 of wastewater to achieve 80% dyestuff decolourisation. The results demonstrate the potential of the technique however also indicate that careful selection of all dyes with regard to their electrochemical behaviour is required for successful implementation of this technology.

The adsorption performance of chitosan beads was investigated after coffee residue blending for the removal of Reactive Red 152 as an anionic dye. The study of the dye removal of chitosan/coffee residue composite beads as a function of coffee residue concentration indicated that mass ratio of chitosan to coffee residue of 60/40 was the most useful for enhancing the dye removal. The effects of contact time, initial pH, and adsorbent dosage on the adsorption efficiency were investigated systematically. The equilibrium adsorption isotherm of chitosan/coffee residue composite beads exhibited better fit to the Langmuir isotherm model than to the Freundlich isotherm model. The maximum adsorption capacity of composite bead was 4.27 mg/g. The dye desorption of composite bead was 24.83%. SEM images confirm that after adsorption the dye were dispersed onto the composite bead surface. This study demonstrated that the chitosan/coffee residue composite can effectively remove reactive dye from aqueous solution and simply with low cost.

The potential of bottle gourd peel, an agricultural waste, for adsorption of Reactive red 195-A (RRD) and Reactive blue 222 (RBD) from aqueous solution was evaluated. Batch adsorption experiments were conducted as function of contact time (0–250 min), initial dye concentration (50–200 mg/l), initial pH (2–10), sorbent dosage (0.2–1 g/l) and temperature (303, 313 and 323 K). The Langmuir and Freundlich and Temkin models were used to study the adsorption isotherms. The experimental data fitted well with the Temkin isotherm for adsorption of RRD to both the adsorbents and RBD to formaldehyde treated adsorbent. The maximum adsorption capacities at 303 K were found to be 245.5, 242.4 mg/g for RRD on to formaldehyde and acetic acid treated adsorbents respectively. Not with much significant difference, RBD was adsorbed on to formaldehyde treated and acetic acid treated adsorbent with adsorption capacities 244.9, 245.8 mg/g at 303 K, respectively. The kinetic data were analyzed using pseudo-first-order and pseudo-second-order models and results indicated that adsorption process follows pseudo-second order kinetics with correlation coefficient R 2 > 0.90. The thermodynamic analysis provided insights to the endothermic and spontaneous nature of the adsorption process. The results indicated that bottle gourd peel could be used as an alternative to the costly adsorbents used for dye removal.

In this paper, adsorptive performance of natural clay has been investigated as a potential reactive dye adsorbent, on the basis its promising physical-chemical and morphological properties which were compared to several previous works. Sample used in this work, collected from Grombalia (North-East of Tunisia), has been characterized at the first time. Following its physicochemical study, this sample has been employed and tested as an ion exchange medium, for an anionic toxic textile dye removal from textile effluent and watercourse. Physicochemical experiences confirm that the used clay mineral was a clay of bentonite type having the following structure formula Ca0.014Na0.404K0.16(Si7.65Al0.35)(Al2.910Fe0.762Mg0.376)O22. Dye removal from aqueous solution onto raw (GRb) and purified (GRp) bentonite was investigated, using a batch adsorption technique, as a function of various parameters such as initial dye concentration, contact time, temperature and pH medium. Results prove that the amount of dye removed by the raw and the purified bentonite was found to be around 142 and 294 mg/g respectively. According to previous works this quantity of dye removed from aqueous solution (294 mg/g) reach the anionic exchange capacity of bentonitic sample. A contact time (clay/dye solution) of 20 to 30 min was sufficient to reach adsorption equilibrium. Adsorption rate was fast, more than half of the adsorbed dye was removed from the aqueous solution (C = 10–4 M). The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. Experimental data fit well with Freundlich model (the correlation coefficients, R 2, was found to be equal to 0.98).

Fluorescent dyes that binds irreversibly to cellular amines, come in several available emission spectra, and do not poses health concerns were used to evaluate membrane integrity in fish sperm cells. The objectives of the present study were to determine: (1) a working dye concentration for fish sperm samples, and (2) if the traditional propidium iodide/SYBR-14 staining combination was comparable with the amine reactive dye (ARD) methods at identifying cell populations with intact and compromised membranes after sperm activation, refrigerated storage, and exposure to cryoprotectant and surfactant. Zebrafish (Danio rerio) sperm were obtained by stripping, and pooled samples (in triplicate) were used in all tests. Six dilutions of the amine dye (ranging from 0.625 to 0.02 μl/ml) were evaluated, and compared with the traditional staining protocol. A concentration of 0.5 μl/ml ARD was selected to be used in subsequent assays. Sperm suspensions were activated with deionized water to simulate urine contamination. After 10 s, osmolality was increased to stop activation, and the procedure was repeated in 10-s intervals until the sperm remained activated for 120 consecutive sec; membrane integrity was analyzed at each time interval. For the storage assay, sperm suspensions were prepared in Hanks' balanced salt solution at 302 mOsm/kg osmolality (HBSS302), HBSS354 and HBSS402, and evaluated every 2 h for 8 h, and every 24 h for 72 h. Cryoprotectant toxicity was tested by diluting sperm suspensions in HBSS340 with methanol at 5, 10 and 15% final concentrations. Surfactant toxicity was tested by diluting sperm suspensions in HBSS354 with Triton X-100 at 0.2, 0.15 and 0.1 mM final concentrations. In each toxicity assay, membrane integrity was tested every 20 min for 80 min. The number of membrane-intact cells significantly decreased across time in all treatments (P < 0.05). Significant differences between staining protocols were observed after activation and after exposure to methanol at 10 and 15%, and to Triton X-100 (P < 0.05). The average difference, however, was minor (between 1 and 6% in average) in relation to the typical values used for decision making based on this assay. Results showed that this method has the potential to contribute greatly to the standardization of cryopreservation in aquatic species.

Ink dot distribution on cotton fabrics determines the colour performance of reactive dye inkjet printing, and ink drop spreading is one of the important factors influencing the ink dot distribution. In order to reveal the relationship between fabric pretreatment and ink drop spreading, two pieces of cotton fabric were pretreated respectively with sodium alginate and sodium alginate plus high fatty acid derivative solutions. Results indicate that the surface energy of the cotton fabrics was reduced from 73.79 to 69.45 and 58.49 mJ m−2 after the pretreatment with sodium alginate and sodium alginate plus high fatty acid derivative respectively. Correspondingly, the spreading area of cyan ink drops on these fabrics was reduced from 104.9 to 92.5 and 72.3 mm2. Furthermore, on the fabric treated with sodium alginate plus high fatty acid derivative, the strip-like ink dots were narrow and short, which means the dye was concentrated in an area on the fabric surface. Colorimetric values of the inkjet-printed fabrics demonstrated that the high fatty acid derivative would enhance the ability of sodium alginate to control ink droplet spreading, thereby improving the colour performance.

Attempts were made to investigate the effectiveness of a combined process of coagulation–flocculation and adsorption for the removal of reactive dye (Reactive Red 3BS) from aqueous solution. The effluent obtained from the coagulation–flocculation process was the raw solution for the second step of the coupling process, i.e. adsorption. The coagulation–flocculation process and the adsorption method were also studied individually. The optimum pH and the optimum dosages of alum and calcium oxide for the coagulation–flocculation process were determined. Aluminium sulphate (alum), calcium oxide and papaya leaf were used as the coagulant, coagulant aid and adsorbent, respectively. Complete dye removal from raw solution having a concentration of 100 mg L-1 could be achieved by using 300 mg L-1 of alum, 80 mg L-1 of calcium oxide and 0.20 g of papaya leaf adsorbent. Adsorption tests showed that papaya leaf could be used as a potential adsorbent for the removal of Reactive Red 3BS from aqueous solution. Themaximum sorption capacities of papaya leaf in the case of sorption from pretreated solution and pure solution were 50.23 mg g-1 and 21 mg g-1, respectively. The combined coagulation–flocculation/adsorption process may be a useful treatment technique for wastewater contaminated with reactive dye.

PubMedID: 27685968 In the present study, Eucalyptus camaldulensis bark/magnetite composite (EBMC) was used for a potential application as a low-cost adsorbent for the removal of Reactive Black 5 (RB5). The adsorption experiments were performed with aqueous solution (RB5 + distilled water) and synthetic dye bath wastewater (SDBW) in order to investigate the potential application of EBMC in the textile industry. The effects of the various parameters, the initial dye concentration, the temperature, the pH, and the EBMC dosage on the adsorption were investigated. It was found that the adsorption capacity of EBMC increases by increasing the RB5 concentration and temperature and by decreasing the dosage of EBMC. 0.8 g EBMC was found to be sufficient for the removal of 250 mg/L RB5 from 150 mL SDBW with ~85% removal efficiency. The Koble-Corrigan isotherm model described the adsorption process more effectively (R2 = 0.997) than the Langmuir, Freundlich, the Dubinin- Radushkevich and the Jovanovic isotherm models. The Langmuir isotherm predicted a 370.7 mg/g maximum adsorption capacity. The thermodynamic analysis showed that the adsorption of RB5 onto the EBMC was an endothermic process. The multiple linear regression analysis was used in order to determine the cumulative effects of independent variables on the adsorption capacity. © IWA Publishing 2016.

Apatite material obtained from natural sources of Tunisian mineral has been used for the development of membrane over clay–alumina-based microporous supports. For this purpose, supports of single-channel and 19-channel circular configurations were used. The apatite powder used for membrane preparation had average pore diameter of 4.02 μm. Coating formulation has been optimized to obtain stable suspension. Powder loading of 4 wt.% was found as optimum for obtaining a proper microfiltration membrane with 0.2 μm pore diameter. Single-channel membrane was used for characterization. The application to color removal from synthetic reactive dye solution was performed using membrane with 19-channel configuration. An average water flux of 200 and 80 l/m2 h was obtained for 19-channel support and membrane, respectively, in laboratory scale setup. Reactive red dye removal from synthetic dyeing solution was achieved up to 99%. Resulting saturated membrane was successfully regenerated using H2O2 at various con...

The study describes the synthesis of modified immobilized activated alumina (MIAA) and its application for the removal of textile dye from aqueous media. Immobilization was carried out by using the sol–gel method while modifications were made during the synthesis by adding powder activated alumina. Batch adsorption experiments were carried out at 20 ± 1 °C to see the effect of different parameters like contact time, stirring rate, initial concentration of the dye and dose of MIAA. The removal efficiency of Cibacron reactive yellow dye with an initial concentration of 400 mg/L was greater than 90% for 90 min contact time. Langmuir and Freundlich adsorption isotherms were applied which fitted the data with an R2 value of 0.99. The maximum adsorption capacity of MIAA was 25 mg/g at the initial dye concentration of 400 mg/L. MIAA can be regenerated thermally and chemically with the dye removal efficiency remained above 85% during the first 4 regeneration cycles. Thermal regeneration was achieved in a muffle furnace at 450 °C while chemical regeneration was done by immersing MIAA in 0.1 M NaOH solution for 2 h. MIAA also proved effective for the adsorption of dyes from actual textile wastewater giving a removal efficiency of 75%. National University of Sciences and Technology (NUST), Islamabad, Pakistan Scopus

Polyurethane (PU) was evaluated for its possibility as an immobilization matrix for the raw biomass of Corynebacterium glutamicum. Initially, different blending ratios of the raw biomass to PU weight were tested, and the ratio of 7: 3 was identified as the optimal condition. PU-immobilized biosorbent (PUIB) with a particle size ranging from 0.425 to 0.18mm was selected for the adsorption of Reactive Yellow 2 (RY2). The uptake of RY2 on the PUIB was favorable at acidic pH, especially below 3. According to the Langmuir model, the maximum RY2 uptakes were estimated to be 104.0, 93.3, and 87.3mg/g at pH 2, 3, and 4, respectively. The pseudo-first-order and pseudo-secondorder models were applied to fit the biosorption kinetic data; the latter model fitted the data well with a high coefficient of determination (R2) and low average percentage error (e) values. The RY2-sorbed PUIB was able to be regenerated and reused for five cycles of the adsorption and desorption processes.

Micellar-enhanced microfiltration (MEMF) was studied to remove reactive dyes from aqueous solution. In this study, simultaneous removal of Reactive Black 5 (RB5) and Reactive Orange 16 (RO16) via MEMF using palm based esterquat (PBE) as cleavable surfactant was investigated. The effect of surfactant concentration, operating pressure, and initial pH on the permeate flux, dyes and surfactant removal were discussed to assess the efficiency of MEMF process. Results obtained in this study shows that the MEMF process achieved almost complete decolourization of both RB5 and RO16 from aqueous solution.

Contamination of water sources by synthetic dyes is a problem of global concern given their potential toxicities and environmental impacts. A significant increase has been noted in the studies related to developing alternative and efficient systems for the treatment of coloured effluents. This study focused on the development of an environmentally friendly process for the treatment of dye contaminated aqueous media. A natural biosorbent prepared from spent biomass of Pisum sativum was characterized and employed for the removal of a reactive dye for the first time in the literature. Experimental design, modelling and optimization techniques were applied to the batch biosorption process. Process variables were screened using response surface methodology coupled with a Box-Behnken design matrix. Solution pH, biosorbent dosage, reaction time and temperature were considered as key factors. The interactive effects of factor variables on the biosorption, characteristics of the biosorbent and possible dye–biosorbent interactions were discussed. The maximum decolourization yield of biomaterial was 83.2% at an initial concentration of 100 mg L −1 . The best operating conditions were as follows: pH: 2.0, biosorbent amount: 0.6 g (in 25 mL dye solution), reaction time: 56.9 min and temperature 27.3 °C. The Langmuir isotherm model satisfactorily described the equilibrium biosorption data. IR spectra of unloaded and dye-loaded biosorbent indicated the functional groups on the biosorbent, such as a carbonyl that interacted with Reactive Violet 1 dye molecules. SEM micrographs indicated that microprecipitation can also play a role in the decolourization process. This study demonstrates that developed waste biosorbent could be successfully employed as an effective and eco-friendly alternative cleaner to remove reactive dyes from wastewaters.

Currently, an extractive green palm oil-based emulsion liquid membrane (ELM) has been used for simultaneous extraction and enrichment of Reactive Red 3BS from simulated synthetic dye wastewater. The ELM consists of two main phases, which are organic liquid membrane (LM) and stripping solution. During the extraction process, the ELM was dispersed into the simulated synthetic dye wastewater containing the Reactive Red 3BS complexes. The organic LM contains tridodecylamine (TDA), Sorbitan Monooleate (Span 80) and palm oil as a carrier, surfactant and diluent, respectively. The sodium bicarbonate (NaHCO3) was used as stripping solution for the enrichment process. Several important parameters that affected the simultaneous extraction and enrichment of Reactive Red 3BS, such as carrier and stripping agent concentrations, extraction time and treat ratio, were investigated. The results showed that almost 90% of Reactive Red 3BS ions were successfully extracted with 10 times enrichment in the stripping phase at the optimum conditions of 0.2 M TDA, 0.1 M NaHCO3, 5 min of extraction time and 1:5 of treat ratio. Hence, it can be concluded that palm oil possesses a high potential as green diluent in future technology, especially in ELM process for the removal and recovery of Reactive Red 3BS from synthetic dye wastewater.

The liquid-liquid extraction (LLE) and supported liquid membrane (SLM) studies of reactive dyes namely Gold Yellow (GYHE-R) and Reactive Green HE 4BD (RGHE-4BD) from aqueous solution using Aliquot 336 as the carrier has been investigated. Polytetrafluoroethylene (PTFE) membrane with 0.5 μm pore size has been used after impregnated with Aliquot 336 in dichloromethane. In liquid liquid extraction the following parameters had been optimized; pH of feed, diluent, carrier , strip and dye concentration and the same parameters have been applied to supported liquid membrane (SLM) study to transport dye from aqueous solution.The main advantages SLM study is; the extraction and stripping as single stage process and low consumption of carrier in the membrane phase compared to the solvent extraction process. The other parameters such as transport time, stirring speed and mechanism of dye transport has also studied by SLM. The percentage of transport of dye and flux rate increases with increasing time. The stability of membrane is satisfactory over 5 days.

In present research a powerful adsorbent was fabricated and employed for removal of anionic reactive dye, Reactive Black 5 (RB5) from aqueous solutions. Polyethylenimine (PEI)–polyvinyl chloride (PVC) composite fiber was prepared by spinning PEI–PVC blend into the mixture of water and methanol. To evaluate the dye sorption performance of PEI–PVC fiber, various parameters that included the effect of pH, dye concentration, contact time, and salt concentration in a batch process were studied. The optimal pH for hydrolyzed RB5 adsorption was observed in the range of pH 2.0–5.3. The sorption kinetic data were better fitted to the pseudo-second-order kinetic model compared with the pseudo-first-order kinetic model. Adsorption isotherm experiments were fitted to the Langmuir model and the maximum uptake of the PEI–PVC fiber was estimated. At a low initial dye concentration, the effect of salt concentration was negligible. However, RB5 uptake was significantly decreased with increasing salt concentration at a high initial dye concentration. By using 0.01 M NaOH, RB5 was easily desorbed from the dye-loaded PEI–PVC fiber. These findings suggested that PEI–PVC fiber can be successfully used as an adsorbent for removal of anionic reactive dyes from aqueous effluents.

The most widely used dyes for coloration of cotton textiles are from reactive class. However, the large amount of unfixed dye causes color in the wastewater, which is environmentally unacceptable. Decolorization of various commercially important reactive dyes in aqueous solutions was attempted by microbial treatment using the bacteria Proteus vulgaris and Proteus mirabilis, individually as well as in a consortium. Different parameters such as treatment temperature, pH, dye solution concentration, and the seed age of the bacteria were optimized to achieve maximum decolorization. Although both bacteria displayed good growth in a shake culture, the color removal was better in an anoxic static culture. The selected dyes were based on azo and anthraquinone chromophores and complete decolorization under optimized conditions could be achieved at a concentration of 30 mg/L. Good results were obtained also at dye concentrations of 60 and 90 mg/L.

Textile industries produce a large quantity of wastewater containing different dyes which can impose a significant risk to environment. In this study, the performance of a commercial polyamide nanofilter membrane for the removal of binary mixture of dyes of reactive (ionic) and disperse (non-ionic) dyes was investigated. The synergic effects of both dyes on the removal performance of the membranes were also studied. The experiments were performed at different dye concentrations of 60, 120, and 180 mg/l for each dye, pH of 6, 8, and 10, and for constant feed pressure of 800 kPa. Results showed that increasing pH from 6 to 10 and also disperse concentration from 60 to 180 mg/l enhanced the removal efficiency of both dyes about 10%. Whereas, by increasing the reactive dye concentration, disperse removal efficiency decreased by 3%. Response surface methodology was also used to optimize the effect of experimental parameters on the dye removal percentage.

Adsorption of the reactive red 141 dye from aqueous solutions onto sesame hull waste, as a kind of useless agricultural waste, in a batch process was studied. The biosorbent was characterized by scanning electron microscope and Fourier transform infrared spectroscopy. There were hydroxyl groups, carboxyl groups, etc. on the surface of the sorbent, as shown by Fourier transform infrared spectroscopy. Adsorption was investigated as a function of the particle size, the amount of adsorbent, the pH, the initial dye concentration, and the agitation speed with time. The maximum removal of dye molecules was found to be 95% at pH 1.1, the initial dye concentration of 30 mg L−1, the adsorbent dose of 4 g L−1, and the temperature of 20°C. The experimental equilibrium data were analyzed, showing that the adsorption behavior of the reactive red dye could be described well reasonably by Langmuir isotherm model with the maximum sorption capacity of 27.55 mg g−1for the biosorbent. Kinetics studies also revealed t...

Adsorption characteristics of three clay adsorbents – sepiolite, kaolin and synthetic talc – were investigated to determine their applicability to remove an anionic reactive dye – Reactive Yellow 138:1 – from a water stream. Results showed that synthetic talc had the highest maximum monolayer adsorption capacity of 10.07 mg/g, followed by kaolin (3.73 mg/g) and sepiolite (3.23 mg/g), for the removal of Reactive Yellow 138:1. Synthetic talc and sepiolite removed dyes from aqueous solutions mainly through physical adsorption depending on the surface area. By contrast, the adsorption mechanism of kaolin was strongly influenced by the anion exchange mechanism. Zeta potential analysis revealed that the adsorption capacity of clay adsorbents increased under acidic rather than alkaline conditions, owing to protonation of the clay surface. Moreover, synthetic talc was successfully regenerated by heating at more than 400°C, effectively restoring its original adsorption capacity.

Waste tire-derived char prepared from hazardous waste scrap tires was physicochemically characterized and used for the removal of reactive red textile dye color on fixed bed column. The color removal efficiency was carried out using response surface methodology based on three levels, three factorial Box–Behnken design. The significance of independent variables and their interactions were tested by means of the analysis of variance with 95% confidence limits. High regression coefficient between the variable and response (R2 = 99.9%) showed good evaluation of experimental data by polynomial regression model. The color removal conditions were optimized for flow rate (5–15 mL/min), concentration (0.2–0.4 mg/L) of dye, and pH (2–6). The optimum conditions suggested by the model for the three variables such as flow rate, pH, and initial color concentration were 10 mL/min 2.5 and 0.15 mg/L, respectively, with maximum removal of 97.9%. The experimental value was 98.6%, very close to predicted value in model.

The biosorbent was obtained from municipal solid waste (MSW) of the Mostaganem city. Before use the MSW was dried in air for three days and washed several times. The sorption of yellow procion reactive dye MX-3R onto biomass from aqueous solution was investigated as function of pH, contact time and temperature. The adsorption capacity of MX-3R was 45.84 mg/g at pH 2–3 and room temperature. MX-3R adsorption decreases with increasing temperature. The Langmuir, Freundlich and Langmuir–Freundlich adsorption models were applied to describe the related isotherms. Langmuir–Freundlich equation has shown the best fitting with the experimental data. The pseudo first-order, pseudo second-order and intra-particle diffusion kinetic models were used to describe the kinetic sorption. The results clearly showed that the adsorption of MX-3R onto biosorbent followed the pseudo second-order model. The enthalpy (Δ H° ), entropy (Δ S° ) and Gibbs free energy (Δ G° ) changes of adsorption were calculated. The results indicated that the adsorption of MX-3R occurs spontaneously as an exothermic process.

In this study, photocatalytic decolorization of an Azo reactive dye (Reactive yellow 84, RY84) from aqueous solutions by ZnO nanoparticles supported on light expanded clay aggregate (LECA) was investigated. The response surface methodology for evaluating the effects of experimental variables such as ZnO loading, initial concentration of solution, pH, and UV intensity on the dye removal efficiency was applied for optimization of the photocatalytic degradation of RY84. The results showed a good agreement with the experimental values and the sensitivity analysis revealed the UV intensity, initial solution concentration, and catalyst dosage as the most effective variables on the decolorization efficiency. Analysis of variance (ANOVA) showed a high determination coefficient value (R2 = 0.909 and adjusted-R2 = 0.863) and satisfactory prediction second-order regression model. The result of optimization showed the maximum efficiency of color removal (99.5%) at the optimal conditions of initial pH = 4, catalyst dosage 0.2 (g ZnO/g LECA), initial dye concentration 50 ppm, and UV intensity 250 W.

A composite coagulant, polymeric aluminum ferric chloride-poly-epichlorohydrin-ethylenediamine (PAFC-EPI-ETA), was synthesized and then used for the treatment of synthetic reactive brilliant red (RBR) dyeing wastewater. Effects of (Fe + Al) to EPI-ETA mass ratio (P) on the color removal and zeta potential were investigated under different coagulant dosages and initial pHs. Experimental results indicate that the removal of reactive dye and the charge neutralization ability of composite coagulant were improved by increasing the content of organic EPI-ETA. PAFC-EPI-ETA with P = 1 achieved the best color removal percentage and strongest charge neutralization ability. Decolorization efficiency using PAFC-EPI-ETA was quite effecient with pH range of 6.0–7.5 for RBR dye removal. Characteristics of the formed floc were investigated with the dosage of PAFC-EPI-ETA under different P values. The low (Fe + Al) to EPI-ETA mass ratio contributed to the formation of flocs with high growth rate, large size and large size variation.

Batch and fixed bed experiments were carried out for the removal of Reactive Turquoise Blue Q-G125% (TB) dye from aqueous solution using cashew apple bagasse (CAB) as non-conventional adsorbent. CAB, a lignocellulosic material, used in this study contained 20.56% ± 2.19% cellulose, 10.17% ± 0.89% hemicellulose, and 35.26% ± 0.90% lignin and was characterized as nonporous material and its surface area cannot be determined by nitrogen adsorption at 77 K. Kinetic and equilibrium study were performed in batch systems, evaluating the effects of pH, contact time, initial concentration, adsorbent loading, and temperature on the adsorption. The pseudo-second-order model best described the adsorption kinetic data. The adsorption isotherms of TB onto CAB were well fitted by the Freundlich model. The maximum adsorption capacity of the biomass was 145.10 mg/g and high levels of dye removal (> 90%) at 60°C. According to thermodynamic results, the adsorption of TB onto CAB is a spontaneous endothermic process. Dynamic ...

Real reactive brilliant red K-2BP (C. I. Reactive Red 24) dye wastewater is characterized by its very high chemical oxygen demand (COD), high concentration of sodium salt, and low biodegradability....

In this study, Moringa oleifera seed extract was applied as coagulant under different pH values (2.5 - 9.5), coagulant dosages(200-600 mg/L), initial dye concentrations (50-300 mg/L) and different settling times (0- 60 minutes) for R. Blue 19 and R. Red120 dyes removal. Results revealed that with increase in pH (from 2.5 to 9.5), removal efficiency decreased from 95% to 87.3%for R. Blue 19 and from 97.2% to 62% for R. Red 120. By increasing coagulant dosage to 400 mg/L, removal efficienciesincreased up to 93% for both dyes. Higher dosages (more than 400 mg/L) could not achieve more than 93% removal of the dyes.No suspension of formed flocs nor desorption of the dyes was observed after long settling times up to 24 hours. Moringa oleiferadid not change the pH of solution through experiments. This natural coagulant revealed a high capacity in reactive dyes removal.Key words: coagulation, decolourization, Moringa oleifera, natural coagulant, reactive dye

Reactive dyes are the principal dyes used in batik industry in Malaysia. From the environmental point of view the dyes should be removed from wastewater because they are toxic in nature. Therefore, the removal and recovery of dyes from batik industry wastewater is absolute necessity in order to save raw materials and to protect environment from hazardous compounds. An experiment was carried out using emulsion liquid membrane (ELM) process in batch system to study the extraction behaviour of Turquoise Blue which is commonly used in batik industry. Several parameters have been studied such as carrier and surfactant/emulsifier concentrations, stripping agent and extraction time. The liquid membrane was formulated using kerosene as diluent, SPAN 80 as emulsifier and tri-dodecylamine (TDA) as a carrier. Hydrodynamic condition to generate extraction process was at 1:3 treat ratio and 250 rpm stirring speed for 10 minutes while the emulsification was done at 12000 rpm for 5 minutes using homogenizer. The result obtained shows that, more than 70% of Turquoise Blue was extracted at favourable condition of 0.07 M TDA, 7% (w/v) SPAN 80 and 0.5 M Thiourea in 1 M NaOH.

The color matching and levelness of cotton fabrics dyed with reactive dye, in a non-aqueous environmentally-friendly medium of decamethylcyclopentasiloxane (D5), was investigated using the non-ionic surfactant reverse-micellar approach comprised of poly(ethylene glycol)-based surfactant. The calibration dyeing databases for both conventional water-based dyeing and D5-assisted reverse micellar dyeing were established, along with the dyeing of standard samples with predetermined concentrations. Computer color matching (CCM) was conducted by using different color difference formulae for both dyeing methods. Experimental results reveal that the measured concentrations were nearly the same as the expected concentrations for both methods. This indicates that the D5-assisted non-ionic reverse micellar dyeing approach can achieve color matching as good as the conventional dyeing system. The levelness of the dyed samples was measured according to the relative unlevelness indices (RUI), and the results reveal that the samples dyed by the D5 reverse micellar dyeing system can achieve good to excellent levelness comparable to that of the conventional dyeing system.

To reduce environmental pollution by CI reactive red 195, solvent extraction of the dye from water was performed by using reverse micelles prepared from hexadecyltrimethylammonium bromide and amyl alcohol. The effects of dye concentration, surfactant concentration, sodium chloride concentration, and pH on the removal percentage of the dye were investigated. A pseudo-first-order kinetic model and an ion-exchange reaction model were used to fit the experimental data. Ultraviolet-visible absorption spectra and particle size distribution were analyzed to evaluate the state of the dyes in the reverse micelles. In addition, the dyes were recovered by backward extraction and then reused for dyeing cotton fabric. The removal percentage of CI reactive red 195 increased with increasing concentrations of surfactant and sodium chloride. Increasing dye concentration and pH values resulted in less removal of dyes. The dye extraction process could be described by the pseudo-first-order kinetic model and by the ion-exchange reaction equations. The state of the dye in the reverse micelles was similar to that in bulk water. The mean particle diameter of the reverse micelles was 10.8 nm. Dye recovery was improved by adding a counterionic surfactant. The recovered CI reactive red 195 had a good dyeing property for cotton fabric.

The sonocatalysis, photocatalysis, and sonocatalysis followed by photocatalytic process has been studied to treat the decolorization of reactive red dye using heterogeneous TiO2 catalysts. Effects of various operating parameters such as reactor system, reaction time, amount of catalyst, and pH on sonocatalysis and photocatalytic treatment were investigated. The ultrasonication of dye was enhanced by the addition of catalyst, which results an increase in the color removal of the photocatalytic process. The results of sonocatalysis followed by photocatalytic color removal of reactive dye showed 98.23% that it could be used as an efficient and environmentally friendly technique for the wastewater treatment. Factorial deign has been used for the experiment to optimize the process variables and to study the interaction of variables for the color removal. The color removal has been modeled and it follows the pseudo-second-order adsorption kinetics for the sonocatalysis followed by photocatalytic process.

Peniophora cinerea is a white-rot fungus with ability to decolorize dyes in saline textile effluent. After cultivation in a medium composed by sucrose, corn steep liquor, copper, and other minor components, P. cinerea produced 1000 U/L of laccase, but no lignin peroxidase or manganese peroxidase. The produced laccase was purified by precipitation with ammonium sulfate (80%) and anion exchange chromatography. Isoelectric focusing revealed a total of eight salt tolerant laccase isoenzymes with pI between 3 and 6, and molecular weights in the range of 26.2 and 72.6 kDa. Five compounds were then tested and compared for their ability to act as mediators in the decolorization of the reactive blue 19 dye by these laccases of P. cinerea. Syringaldehyde was the best mediator since it increased in almost 3-fold the dye decolorization when compared to the decolorization by using laccase alone. Addition of Mn2+ and oxalate to this system increased in 4.8-fold the initial decolorization rate (178 μmol/L min). When applied for real effluent decolorization, this system promoted the highest decolorization after 72 h at 50 °C and pH 4. This laccase-mediator system was considered promissory for application on the treatment of industrial dye effluents.

The adsorption of Everzol Black (EB) from synthetic aqueous solution onto active carbon (AC) and dried fungal biosorbent (Rhizopus arrhizus) was studied under the same experimental conditions. The effects of initial dye concentration, adsorbent dosage and contact time were examined at a batch-scale level. As an alternative to AC, fungus was investigated as a low-cost adsorbent for dye removal. The amount of EB adsorbed onto AC was lower compared with fungal biosorbent; dye adsorption capacity of AC and fungal biosorbent were 94.48 and 106.61 mg/g, respectively. The adsorbent dosage experiments showed that 4 g/L biosorbent removed 100% of EB (Co: 114.39 mg/L) after 2 hours. The results obtained from this study showed that biosorbent effectively removed reactive dye from dye-containing water in a short time period. Langmuir and Freundlich adsorption isotherm models were used for mathematical description of the biosorption equilibrium data; the Freundlich model was found to exhibit good fits to the experimental data. According to the Freundlich isotherm, the maximum dye adsorption capacities of AC and biosorbent were calculated as 344.82 and 357.14 mg/g, respectively. The Fourier transform infrared spectroscopy spectral analysis showed the involvement of functional groups for dye bindings.

A combined approach of electrochemical and biological process is applied for the decolorization and degradation of reactive dye Turquoise Blue G (TBG). The complete decolorization of TBG through electrolysis was observed within 15 min using IrO 2 –RuO 2 –TiO 2 –Ti electrode as an anode and Ti as cathode in 5gpl NaCl at pH 7 and a current density of 10 mA/cm 2 . A new approach for degradation of the electrolyzed dye was carried out using pre-adapted bacterial consortium isolated from petroleum pipelines, which have the ability to grow aerobically in electrochemically decolourized TBG solution. UV–Vis spectra reveal the removal of chromophore and aromatic peaks in electrochemical and biological treatment respectively. The samples were analyzed by high performance liquid chromatography (HPLC). The results suggest that the major dye components were reduced 41.3% by electrochemical and 90% by microbial route and the new peaks generated after biological treatment might be the metabolites of degradation process.

The batik industry is considered to be one of the largest textile cottage industries in the Southeast Asian region. Batik processing utilizes wax as a physical resistant and consumes a large amount of water during dyeing, fixing, and washing process; thus, generating harmful wastewater including dye, wax, and other auxiliaries. Respectively, an efficient wastewater treatment method is deemed necessary to meet legal emission standards. In this study, application of polyamide nano-membrane to remove dyes was evaluated for five different fiber reactive dyes’ wastewater, namely reactive blue 15, reactive red 194, reactive yellow 145, reactive black 5, and reactive orange 16. The discussed dyes were tested in low concentration (16 mg/l) during a 60 min filtration process. The efficiency of filtration was calculated based on pre-process and post-process analytical experiments. The flux for all the samples ranged between 7.8 and 9.2 ml/cm2 s. The permeate pH value of the samples was observed to slightly ...

The pistachio shell, an agriculture waste, was studied as a no-cost and readily accessible potential dye adsorbent for the removal of the commercially important reactive azo dye, Remazol Red (C.I. 18221) from its aqueous solution. For this purpose, a series of batch adsorption tests were carried out to assess the effect of various experimental parameters such as adsorbent concentration, mixing time, initial dye concentration, pH and temperature. The experimental results indicated that the maximum dye removal could be attained at pH 2. The equilibrium between the dye and the adsorbent in the solution was established within 10 min. The maximum adsorption capacity of pistachio shell was determined around 108 mg g−1 at 20°C. The pseudo-second-order model provided close fit with the experimental data (R2 > 0.99) for the reactive dye. Equilibrium data also fitted well to the Freundlich isotherm model in the studied concentration range of Remazol Red at 20°C. The negative values of ΔG indicated that the ...

In this study, the potential of sugarcane bagasse, to remove Novacron Orange P-2R dye from aqueous solution by adsorption was investigated in batch mode. Different process parameters were optimized for biosorption process. Equilibrium biosorption isotherms, kinetics and thermodynamics were investigated in batch mode. The biosorption data were fitted well to the Langmuir isotherm. The kinetic data obtained at different concentration have been analyzed using pseudo-first-order, pseudo-second-order and intra-particle diffusion models. The best fitted kinetic model was found to be pseudo-second-order. The FTIR spectrum was recorded to find out the functional groups involved.

The removal of color from wastewater is a major problem for textile industries. The best option to remove color is to combine conventional treatments with additional processes, such as adsorption. Industrial waste has been studied for use as adsorbents, specifically red mud (RM), which is an insoluble residue that is generated in large quantities during the processing of bauxite. In this study, a typical reactive dye, reactive blue 19 dye (RB 19), used in the textile industry was selected, and its ability to adsorb RM that was thermally treated at 500°C (RM 500°C) was evaluated. The adsorption of RB 19 was highest when the pH values were lower than the pHPCZ (7.0). The experimental adsorption capacity data were analyzed using the Langmuir and Freundlich models. The Langmuir model was more appropriate for describing this phenomenon in acidic conditions, with a maximum adsorption capacity of 178.4 mg g−1 (R2 of 0.84). Kinetics studies indicate that a pseudo-second-order reaction mechanism is respons...

Holocellulose was separated from Coir fibre by Sodium chlorite bleaching procedure. The adsorbent was synthesized by graft-copolymerization of acrylamide onto separated cellulose using potassium persulfate as a free radical initiator. Grafting percentage and grafting efficiency were measured and found to be 74.5 and 58% respectively. Prepared adsorbent was characterized by applying Fourier Transform- Infrared Spectrophotometer, Thermogravimetric/Differential Thermal Analyzer and Scanning Electron Microscope. Adsorbent prepared from holocellulose was successfully used at different adsorbent dosage, contact time, initial dye concentration and temperature to remove "Reactive Orange-16", a reactive dye from aqueous solution. Ultraviolet-Visible Spectrophotometric measurement of the dye in untreated and treated solutions showed that 0.2 g Holocellulose and Polyacrylamide-grafted holocellulose can remove 42% and 72% of Reactive Orange-16 dye from its 10 ppm aqueous solution within 1 hrs respectively. It may be proposed that Polyacrylamide-grafted holocellulose can be used in a traditional Textile Effluent Treatment Plant (ETP) as a cost effective adsorbent/alternative for decreasing the concentration of the reactive dye in the effluent. DOI: http://dx.doi.org/10.3329/bjsir.v48i4.18277 Bangladesh J. Sci. Ind. Res. 48(4), 271-280, 2013

In this paper, various physical and chemical characteristics of electro-coagulated (ECC) and chemical-coagulated (CC) aluminum hydroxide flocs were explored comparatively in the context of their impacts on the pollutant removal performance of the processes. First, the sedimentation rate, floc size and zeta potential of the flocs at different pH values were measured in solution. Furthermore, flocs dried at 105 °C were characterized by various techniques such as TGA,FT-IR, SEM, XRD, BET and XPS as well as by chemical analysis. It was found that ECC flocs were bigger in size, faster in sedimentation and better pressed, while they had higher BET area, less water and higher isoelectric pH than CC flocs. Furthermore, pollutant removal tests using various chemicals such as benzoquinone, hydroquinone and a reactive dye showed that ECC flocs outperformed CC flocs, due to superior physical-chemical characteristics.

The adsorption characteristics of Reactive Black 5 (RB5) dye on alkaline-treated biomass fly ash (TFA) were investigated in aqueous solutions in a fixed-bed column. The breakthrough curves increased with decreasing initial dye concentration and the flow rate, and with increasing bed depth. In this column study, the optimum flow rate and bed depth were 5 ml min−1 and 10 cm, respectively. The Thomas model provided a good prediction of the breakthrough curve of RB5 removal by the TFA. The maximum adsorption capacity from the column study was in accordance with the equilibrium capacity in a batch experiment. The bed-depth service time model was used to describe the effect of bed depth on the breakthrough curves, and it revealed a good fit with the experimental data. These results suggest that the fixed-bed TFA is suitable for treating dye wastewater.

This study investigates the transport of dye ions across a supported liquid membrane (SLM) by using tridodecylamine as a carrier and sodium hydroxide (NaOH) as a stripping agent. A microporous polypropylene membrane was used as a membrane support and prepared by the thermal induced phase separation (TIPS) technique. Two different TIPS techniques were used when preparing membranes: solidification and without solidification with polymer concentrations varied at 10, 15 and 20%. The results revealed that both techniques produced membranes with similar morphologies, but different pore size structures. The membrane with 15% polymer concentration which was prepared by the solidification technique produced a microporous membrane with a symmetric structure, defined pore size and high stability, and thus is feasible as the support material. The fabricated membrane was tested and the results revealed that 100% of reactive dyes was succesfully removed with 58% recovery from an aqueous solution. The fabricated membrane also exhibited high stability up to 25.5 h of extraction, thereby demonstrating an improved method for the separation of reactive dyes using a SLM.