Dyestuff Wastewater Treatment Research Articles

Construction of immobilized laccase hydrogels via sodium alginate-dopamine/polyethylene glycol and its efficient degradation of dyeing wastewater

Laccases with highly catalytic properties have been widely used in developing green applications for water remediation. However, the poor stability and low reutilization rate of free laccase make it difficult to be applied practically. Hence, in this study, an immobilized laccase was prepared using dopamine (DA) functionalized sodium alginate (SA)/polyethylene glycol (PEG) composite hydrogels to realize the recyclability of the laccase. The SA/PEG composite hydrogels, as the protective carrier for laccase, exhibited excellent catalytic stability in various interfering environments. After 30 days, Lac@SA-PDA/PEG beads could remain 70.23 % of the initial activity, as the residual activity of free laccase was only 12.35 %. When free laccase and Lac@SA-PDA/PEG beads were used for decolorization of Reactive Blue 19 (RB-19,100 mg/L), the degradation rate of Lac@SA-PDA/PEG is 6.88 times higher than free laccase. More importantly, the SA-PDA/PEG composite hydrogel exhibited a high reutilization rate, which after six cycles, Lac@SA-PDA/PEG beads retained 90.23 % of its initial activity. Besides, the degradation effect of Lac@SA-PDA/PEG on different dyes was analyzed. In addition, the conjectured degradation pathways of RB-19 by laccase were analyzed. The work showed that immobilized laccase has tremendous potential for the treatment of dyestuff wastewater.

Environmental engineering approach using Fe-Co-S nanomaterials for removal of Rhodamine B in wastewater: Preparation, performance, and mechanism

Fe-Co-S (FeCoS) nanomaterials with good recycling abilities were prepared by a hydrothermal method, and their adsorption properties twords Rhodamine B (RhB) were investigated. Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometer (EDS), X-ray Diffraction (XRD), N2 adsorption-desorption isotherms, Brunel Emmett Taylor (BET) surface area, and Fourier Transform Infrared Spectroscopy (FTIR) were used to characterize the materials and analyze their physicochemical properties. The effects of temperature, pH, and adsorbent dosage on the adsorption performance of FeCoS were also investigated. The results showed that the equilibrium time for the adsorption of rhodamine B by FeCoS was 150 min. The adsorption process followed the Langmuir isotherm with a pseudo-second-order kinetic model. It suggests that the adsorption is mainly controlled by chemisorption and belongs to homogeneous monolayer adsorption. The thermodynamic fitting of the adsorption process showed that the adsorption of RhB by FeCoS is spontaneous and accompanied by an endothermic reaction, and the maximum adsorption capacity reached 578.03 mg/g at 318 K with a removal rate of 98.3%. The removal rate of FeCoS was maintained at 89.95% after five cycles, which was of great potential for practical application in the treatment of dyestuff wastewater.

NIR-driven PtCu-alloy nanocages via photothermal enhanced fenton catalytic degradation of pollutant dyes under neutral pH

In this work, near-infrared (NIR) light driven concave octopod PtCu alloy nanocages (OPtCu-NCs) were fabricated and first developed as photothermal synergetic Fenton catalyst for degradation of pollutant dyes. Moreover, by irradiating with NIR laser (808 nm), the obtained OPtCu-NCs exhibit excellent NIR absorption capacity and thus produce hyperpyrexia over 50 °C. Concomitantly, by the photothermal effect, the OPtCu-NCs nanocatalysts was used for elimination of organic dyes such as Methylene blue (MB) and Rhodamine B (RhB). The NIR-driven photothermal degradation mechanism under NIR irradiation can be attributed to the Fenton-like catalytic performance of Cu ions, then -NC- and/or C-C bonds in the molecular skeleton were fractured and electrons were donated intensively. As confirmed by a typical radical trapping experiment, electrons trigger the formation of miscellaneous reactive species (O2-, HO2, especially •OH) subsequently. Moreover, the photothermal Fenton-catalytic activity of the as-prepared OPtCu-NCs had maintained at 93.15% (for MB) and 91.87% (for RhB) after ten circulating degradation processes. All acquired results reveal that the OPtCu-NCs have the potential applied value in dyestuff-wastewater treatment under neutral pH.

Bioremoval capacity of recalcitrant azo dye Congo red by soil fungus Aspergillus arcoverdensis SSSIHL-01

Industrialization and urbanization have enormously contributed to water pollution. About 10 − 15% of all dyes used in processes in textile and other allied industries, have impacted aquatic ecosystem by discharge of several toxic chemicals and organic pollutants. Biological approach has always been advantageous over chemical and physical treatment methods of dye polluted wastewaters owing to cost effectiveness, mineralization of toxic chemicals and transforming them into harmless products. Present study was conducted to investigate the ability of soil fungus Aspergillus arcoverdensis SSSIHL-01 in the bioremoval of a common azo dye Congo red (CR). At the initial CR dye concentration of 100 mg/L, 3 g of wet fungal mycelia at 30 °C could decolorize about 95% and 98.6% of CR in dye solution and simulated wastewater respectively. Optical light microscopy through bright field and epi-fluorescence imaging modalities revealed the presence of CR dye in the fungal biomass by biosorption. Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) analysis revealed the amorphous nature of the fungus and its affinity to CR dye. UV-Vis and HPLC studies showed that decolorization occurred by both biosorption and biodegradation. Decolorization by live cells (98.61%) and dead cells (94.36%) illustrated that major part of dye removal was through biosorption, however 4.25% was by enzymolysis in living cells. Enzyme assay revealed that SSSIHL-01 produced about 22.73 ± 2.02 U/L lignin peroxidase enzyme, indicating its possible role in CR degradation. Overall findings showed that Aspergillus arcoverdensis SSSIHL-01 could be explored as a potential bio-remediating agent in dyestuff wastewater treatment. This is the first report on evaluating the performance of the fungus Aspergillus arcoverdensis SSSIHL-01 on CR dye removal.

Removal of AOX in Activated Sludge of Industrial Chemical Dyestuff with Bimetallic Pd/Fe Particles

Pd/Fe bimetallic particles were synthesized by chemical deposition and used to remove absorbable organic halogens (AOX) in the activated sludge of a chemical dyestuff wastewater treatment plant. Bath experiments demonstrated that the Pd/Fe bimetallic particles could effectively remove AOX. It indicated several factors, such as Pd loading, the amount of Pd/Fe used, initial activated sludge pH, and reaction time, which could affect the removal effect. The results showed that increasing the Pd content in Pd/Fe particles, from 0.01 to 0.05 wt %, significantly increased the removal efficiency of AOX in activated sludge. The Pd/Fe particles had a much higher removal efficiency of AOX in the activated sludge than bare Fe particles. A slightly acidic condition with a Pd content of 0.05% and 10 g/L of Pd/Fe was beneficial to the process of removing AOX in activated sludge. In detail, the removal efficiency of AOX in the activated sludge could reach 50.7% after 15 days of reaction with 10 g/L of Pd/Fe (Pd loading 0.05 wt %) and at an initial pH of 6.0 during the experiments. It also showed that the control samples without Fe0 and Fe/Pd additions only removed 7.9% of AOX under the same conditions. Meanwhile, the concentrations of AOX in the supernatant of activated sludge were lower than the initial AOX concentration in the supernatant during the activated sludge remediation with Pd/Fe bimetallic particles. The results indicated that the AOX removal from the activated sludge matrix might be mainly due to the Pd/Fe bimetallic particles, and not just by phase transfer.

Preparation of surfactant modified magnetic expanded graphite composites and its adsorption properties for ionic dyes

To enhance the surface hydrophilicity, adsorption capacity to various ionic dyes, and recovery efficiency, modified expanded graphite (MEG) was fabricated by surfactant-based intercalating reagent CTAB/KBr modification of expanded graphite (EG). Then magnetic composite adsorbents (Fe3O4/xMEG) were following synthesized with introduction of in-situ formed magnetic Fe3O4 by two different ways. The adsorption of Orange-II on Fe3O4/3MEG-I was evaluated to understand its effectiveness for dyestuff wastewater treatment. The Fe3O4/3MEG-I exhibited a rapid adsorption efficiency (47% within 2 min) and tunable adsorption properties with adjusting MEG amount, the adsorption process fitted better to the Langmuir isotherm and pseudo-second-order kinetic models. The removal efficiencies of a variety of dyes suggested that Fe3O4/3MEG-I could efficiently adsorb both the anionic and cationic dyes under neutral condition. The regeneration and reusability of the adsorbent were investigated in six consecutive adsorption-desorption cycles. Furthermore, Fe3O4/3MEG-I can be readilycollected by an external magnet, which make it a promising candidate for dyes effluent treatment in practical application.

Removal of gentian violet and rhodamine B using banyan aerial roots after modification and mechanism studies of differential adsorption behaviors.

A novel adsorbent derived from banyan aerial roots was prepared via modification and employed to aqueous gentian violet (GV) and rhodamine B (RhB) removal. The surface morphology and physicochemical properties of modified banyan aerial roots (MBARs) were investigated by SEM, EDS, N2 adsorption/desorption, zeta potential, XRD, and FT-IR characterization experiments. Adsorption factors were tested, and the optimal conditions for GV and RhB removal were pH of 6 and 3, doses of 0.02g and 0.03g, and reaction time of 540min. Adsorption isotherm simulation illustrated that theoretical monolayer adsorption capacities of GV and RhB were 456.64mg/g and 115.23mg/g, respectively. Kinetics data was assessed with pseudo-first-order and pseudo-second-order models, and the latter described GV and RhB adsorption better at 288K, 298K, 308K, and 318K. Thermodynamic analysis indicated that GV and RhB adsorption processes were endothermic and spontaneous. From the research results, it could be inferred that GV adsorption was mainly dominated by electrostatic interaction, while RhB adsorption might be primarily attributed to electrostatic interaction and hydrogen bonding. The study based on full utilization of waste plant fibers facilitates recycling of biomass resources, and due to simplicity, safety, and eco-friendliness of the preparation, as well as low cost and high efficiency of the application, MBARs may be potential absorbents for the treatment of dyestuff wastewater.

Synthesis of anionic ionic liquids@TpBd-(SO3)2 for the selective adsorption of cationic dyes with superior capacity.

The discharge of industrial printing and dyeing wastewater is one of the main reasons for the increasing water shortage and deterioration. The treatment of dyestuff wastewater is an issue and needs to be urgently solved. In this work, anionic ionic liquid functional covalent organic materials (COMs) were firstly synthesized and used for the selective adsorption of cationic dyes. First, a series of sulfonic acid group (SO3H)-functionalized anionic TpPa-SO3, TpBd-(SO3)2, and TpCR-(SO3)2 were prepared, respectively, and then imidazole was grafted onto TpBd-(SO3)2 to obtain ImI@TpBd-(SO3)2. The full characterization using X-ray diffraction, FT-IR spectroscopy, 13C cross-polarization magic-angle spinning NMR spectroscopy, zeta-potentials, BET surface and pore analysis indicated that these COMs and ImI@TpBd-(SO3)2 exhibited different morphologies, porosities, and potentials. The effects of the type of dye, adsorption time, initial dye concentration, and pH on the adsorption of dyes on ImI@TpBd-(SO3)2 were systematically investigated, respectively. The results revealed that ImI@TpBd-(SO3)2 possessed good adsorption performance for nine different cationic dyes with adsorption capacities in the range from 2865.3 mg g−1 for methylene blue (MB) to 597.9 mg g−1 for basic orange 2 (BO), but little adsorption for anionic and neutral dyes, revealing charge selectivity. The adsorption ratio of ImI@TpBd-(SO3)2 for MB was as high as 74.0% at 10 min by using 1.0 mg material, owing to the post modification of TpBd-(SO3)2 with imidazole. The adsorption of MB on ImI@TpBd-(SO3)2 was pH dependent. The adsorption isotherm and kinetics fitted well with the Freundlich and pseudo second-order kinetic model, respectively. Finally, the very outstanding advantages of superior selective adsorption, desorption, convenient preparation, and low density of ImI@TpBd-(SO3)2 predicted its research and application potential in dye wastewater recovery.

Carbon-dot modified polyacrylonitrile fibers: Recyclable materials capable of selectively and reversibly adsorbing small-sized anionic dyes

Amine-rich carbon dot (CD) functionalized polyacrylonitrile fibers (PANF-g-CDs) were prepared by a facile hydrothermal method. These fibers are fluorescent and contain nano-sized pores. Dye adsorption experiments demonstrated that PANF-g-CDs preferred to adsorb small-sized anionic dyes with high aspect ratio, such as methyl orange (MO). The maximum adsorption capacity for MO reached 422 mg/g. The adsorption kinetics satisfied the pseudo second-order adsorption model, and the adsorption behavior was monolayer uniform adsorption. After adsorption, PANF-g-CDs could be separated conveniently just by taking it out from the solution. Moreover, the used PANF-g-CDs could be regenerated in an alkaline aqueous solution very rapidly within 30 min. Its adsorption performance was so stable that it did not show obvious performance loss even after ten adsorption-desorption cycles. In addition, the fluorescence of the fiber exhibited periodical change during the adsorption-desorption processes. Thus, this CD modified fibers with the combined advantages of simple synthesis, high dye-adsorption efficiency and selectivity, moderate dye-adsorption rate, fast dye-desorption, easy recyclability, stable adsorption performance and photoluminescent nature could be promising adsorbents for practical dyestuff wastewater treatment.

Mixed matrix membranes incorporated with sonication-assisted ZIF-8 nanofillers for hazardous wastewater treatment

Mixed matrix membranes (MMMs) provide a unique pathway to treat hazardous industrial effluents. MMMs containing zeolitic imidazolate framework-8 (ZIF-8) as filler in polydimethoxysilane (PDMS) matrix were synthesized. ZIF-8 was prepared using a modified recipe and characterized by different techniques to evaluate its morphology, thermal stability, surface area, pore volume, and other characteristics. The performance of membranes was evaluated for their application in industrial dye-stuff wastewater treatment and solvent-resistant nanofiltration. The results demonstrated that increase in the percentage of ZIF-8 loading in PDMS led to simultaneous increase in the solvent permeability as well as solute rejection from wastewater. The permeability of MMMs increased up to 32% as compared with neat PDMS membrane. The organic dye rejection was achieved more than 87% with MMMs incorporated with 20% loading of nanofillers. Rejection of MMMs was 22% higher than that of unfilled PDMS membrane due to the effect of reduced polymer swelling and size exclusion of the nanofillers. Membrane swelling tests with toluene and isopropanol demonstrated that nanofiller amount has inverse relation with membrane swelling, which implied that nanofillers were in good interaction with polymer and allowed defect free membranes with higher solute rejections and reduced membrane swelling.

Ultra-high efficient pH induced selective removal of cationic and anionic dyes from complex coexisted solution by novel amphoteric biocomposite microspheres

The substandard discharge of highly toxic dyestuff wastewater will pose a serious threat to the environment and human beings, even causing unimaginable irreversible damages. In the current study, novel amphoteric carboxymethyl chitosan/gelatin microspheres (CCGMs), synthesized by a facile inverse suspension route with two-step successive crosslinking process, were evaluated as a potential adsorbent for high efficient pH induced selective removal of azo-dyes. The as-prepared CCGMs were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Various influential factors such as solution pH, temperature, and contact time were employed to ascertain the optimal condition for representative azo-dyes adsorption, including methyl orange (MO) and methylene blue (MB). The maximal adsorption of MO and MB on the CCGMs at pH values of 3 and 11 were 383.142 mg g−1 and 584.795 mg g−1, respectively. The adsorption mechanism were demonstrated as the synergistic effect of electrostatic interaction and π-π stacking between dyes and CCGMs. Besides, the outstanding and stable regeneration of as-prepared CCGMs were also verified with five consecutive recycling. Thus, the newly developed CCGMs could be a highly promising candidate for dyestuff wastewater treatment.

Adsorption ability of activated carbons from Phoenix dactylifera rachis and Ziziphus jujube stones for the removal of commercial dye and the treatment of dyestuff wastewater

The activated carbons were prepared from Phoenix dactylifera rachis (PRAC) and Ziziphus jujuba stones (JSAC) using chemical activation by H3PO4. Then, they applied to eliminate a commercial reactive dye BEZAKTIV Red S-Max (BRSM). The resultant carbons PRAC and JSAC were characterized by N2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), thermo gravimetric analysis (TGA), scanning electron microscopy (SEM) and Boehm titration method. The BET apparent surface area of the PRAC and JSAC was 1283 and 1896 m2/g, respectively, with predominance acidic character. The effects of initial dye concentration and contact time, pH and temperature on the adsorption were investigated, and it was showed that the elimination percentage decreases as the initial concentration increases, but it rose with the temperature. The experimental equilibrium data were studied using Langmuir, Freundlich and Temkin models, and it was found that the Langmuir model described well the BRSM adsorption (R2 ≥ 0.96), showing a maximum adsorption capacity of BRSM onto PRAC and JSAC of 196.08 and 37.04 mg/g, respectively. The BRSM adsorption kinetic was examined by pseudo-first-order, pseudo-second-order, elovich and intraparticle diffusion models, and it was showed that BRSM adsorption onto used carbons followed pseudo-second-order. The obtained thermodynamic parameters indicated that the phenomenon is spontaneous and endothermic. In addition, the thermal regeneration of the examined carbons revealed that they can be reused on adsorption test. Finally, the results indicated that the Phoenix dactylifera rachis carbon could be considered as low cost material for the elimination of BRSM dye and dyes from dyestuff wastewater (DW).

Eco-electrogenic treatment of dyestuff wastewater using constructed wetland-microbial fuel cell system with an evaluation of electrode-enriched microbial community structures

This work studied eco-electrogenic treatment of real dyestuff wastewater along with characterization of electrode-enriched microbial community structures in Fimbristylis dichotoma planted closed-circuit constructed wetland-microbial fuel cell (CW-MFC) system. The CW-MFC-2 (experimental system) achieved 82.2 ± 1.7% ADMI removal and 70 ± 2% COD reduction; that were found to be 9% and 7.4% higher than the standalone constructed wetland (CW) system (bioremediation control) respectively. Likewise, the CW-MFC-2 system achieved maximum power density of 198.8 mW/m2, which was 85.6 ± 2.47% higher than the CW-MFC-1 system (eco-electricity control). Quantitative reverse transcription PCR (qRT-PCR) assays revealed significant down-regulation of hepatic oxidative stress response biomarker genes in Oreochromis niloticus exposed to CW-MFC-2 system treated dyestuff wastewater as compared with untreated wastewater. The biofilms associated with the anode and cathode of the CW-MFC-2 system exhibited selective enrichment of electrochemically active and dye degrading microbial communities.

Synthesis of β-Cyclodextrin Immobilized Starch and Its Application for the Removal of Dyestuff from Waste-Water

A natural polymeric adsorbent, β-cyclodextrin immobilized starch (CS-βCD) was prepared by introducing host functional molecule β-cyclodextrin (β-CD) onto starch in presence of citric acid. The immobilization conditions were optimized to: m CA:m CS = 1:2, reaction time of 2 h and reaction temperature at 120 °C, by varying the input levels of the reactant, CS-βCD with a series of immobilization ratio (IR) and carboxyl content (CC) could be obtained. The FT-IR and 13C-NMR analysis indicated the β-CD molecules have been immobilized onto starch via the formation of ester linkages. The XRD and SEM analysis showed CS-βCD had more looser structure and more irregular surface compared with native starch. The GPC analysis showed CS-βCD had a reduced molecular weight but a more complicated molecular configuration. The adsorbing capacities of CS-βCD to three cationic dyes (methylene blue, methyl purple and basic fuchsin) were significantly improved compared with native starch, diatomite and zeolite. The adsorption behaviors of CS-βCD to the three dyes had high fitting degrees to both Langmuir and Freundlich models (R2 > 0.98). The decolourization ratio of CS-βCD to the mixed dyestuff waste-water had reached 88.75%, which was much higher than other absorbents. The results indicated the CS-βCD would become a high-efficiency dyestuff adsorbent, and would have a promising application in the industrial dyestuff waste-water treatment.

Easy-separative MoS2-glue sponges with high-efficient dye adsorption and excellent reusability for convenient water treatment

This study demonstrated high-efficient dye adsorption for wastewater using MoS2-glue sponge as an easy-separative and regenerative adsorbent. Flower-like molybdenum disulfide (MoS2) nanopowders with rich polar edge sites were firstly synthesized by a facile one-pot hydrothermal method. Chemical and morphological features of MoS2 nanoflowers were then examined by XRD, XPS, SEM and TEM. Afterwards, different concentrations of the MoS2-glue sponges with easy separability were successfully fabricated by a convenient two-step dip-coating method. The adsorption performance was estimated by the removal of Rhodamine B (RhB) dyes. The results proved that the maximum adsorption capacity of MoS2-glue sponge was 127.39 mg RhB/g product in 60 min. The RhB uptake behaviors can be well described by the Sips isotherm model and pseudo-second-order kinetic model, indicating a multilayer and chemical adsorption process. The adsorption mechanism proposed that the zwitterionic RhB molecules in aqueous solution would aggregate on the surface of negative charged MoS2 in a head-to-tail way through electrostatic interaction. Furthermore, RhB dyes could desorb easily from MoS2-glue sponges when changing the polarity of solvent and the reusability experiment showed that the MoS2-3% glue sponge could be reused for 15 times with above 85.8% of the adsorption capacity retained. Thus, the novel MoS2-glue sponge is considered as a competitive adsorbent for treatment of dyestuff waste water.

Enhancing nitrogen removal efficiency in a dyestuff wastewater treatment plant with the IFFAS process: the pilot-scale and full-scale studies.

The activated sludge (AS) process is widely applied in dyestuff wastewater treatment plants (WWTPs); however, the nitrogen removal efficiency is relatively low and the effluent does not meet the indirect discharge standards before being discharged into the industrial park's WWTP. Hence it is necessary to upgrade the WWTP with more advanced technologies. Moving bed biofilm processes with suspended carriers in an aerobic tank are promising methods due to enhanced nitrification and denitrification. Herein, a pilot-scale integrated free-floating biofilm and activated sludge (IFFAS) process was employed to investigate the feasibility of enhancing nitrogen removal efficiency at different hydraulic retention times (HRTs). The results showed that the effluent chemical oxygen demand (COD), ammonium nitrate (NH4+-N) and total nitrogen (TN) concentrations of the IFFAS process were significantly lower than those of the AS process, and could meet the indirect discharge standards. PCR-DGGE and FISH results indicated that more nitrifiers and denitrifiers co-existed in the IFFAS system, promoting simultaneous nitrification and denitrification. Based on the pilot results, the IFFAS process was used to upgrade the full-scale AS process, and the effluent COD, NH4+-N and TN of the IFFAS process were 91-291 mg/L, 10.6-28.7 mg/L and 18.9-48.6 mg/L, stably meeting the indirect discharge standards and demonstrating the advantages of IFFAS in dyestuff wastewater treatment.

Ceramic membrane separation coupled with catalytic ozonation for tertiary treatment of dyestuff wastewater in a pilot-scale study

An apparatus coupling catalytic ozonation with ceramic membrane separation was designed and piloted for the tertiary treatment of dyestuff wastewater from Anaerobic–Anoxic–Oxic effluent. The apparatus’s water treatment capacity was about 10t/d at the average permeate flux of 110L/(m2⋅h). After the treatment of the dyestuff wastewater, CODCr decreased from 100±20mg/L to <10mg/L, suspended solids drastically reduced from 20±5mg/L to <0.1mg/L and Escherichia coli was completely removed from the initial concentration of >2.4×106MPN/L. Chroma also got a large decrement from 90±10 to <2 at dilution times. Furthermore, genotoxicity showed an effective abatement detected by comet assay. The high performance of the designed apparatus in the treatment of the dyestuff wastewater was associated with the synergistic effects of catalytic ozonation and membrane separation. This work indicates that the system coupling catalytic ozonation with membrane separation will be an alternative approach for the advanced wastewater treatment in practical application.

Theoretical analysis of the adsorption properties of methyl violet dye on iron-doped mesoporous silica microspheres

The optimum adsorption conditions of methyl violet (MV) dye from aqueous solutions by iron-doped mesoporous silica microspheres (Fe-MSM) were investigated through adsorption experiments to improve the effect of advanced treatment of dye wastewater. The novel adsorbents were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption isotherms, and scanning electron microscopy. The effects of adsorbent dosage, adsorption time, initial dye concentration, and pH on the adsorption performance were analyzed. Given these effects, the kinetics equation, related parameters, and the adsorption mechanisms were obtained. Results indicate that the different Fe contents had a slight influence on the adsorption capacity of the samples. The adsorption efficiency reached 98% for an MV solution with an initial concentration of 50 mg/L, adsorbent dosage of 10 mg, equilibrium time for adsorption of 30 min, and an alkaline pH. The adsorption process followed the pseudo-second-order kinetic model. The intra-particle diffusion of dye molecules into interior surface was achieved through rate-controlled process, and further adsorption mechanisms were involved except for ion exchange. Fe-MSM could be an ideal material for the treatment of dyestuff wastewater because of its relatively high performance and rapid sorption velocity.

Characteristics and Sonocatalytic Degradation Effect of Co/N/Er3+: Y3Al5O12/TiO2 in Organic Dyestuff Wastewater Treatment

Characteristics and Sonocatalytic Degradation Effect of Co/N/Er3+: Y3Al5O12/TiO2 in Organic Dyestuff Wastewater Treatment

Rapid dye degradation with reactive oxidants generated by chloride-induced peroxymonosulfate activation

Transition-metal is known to catalyze peroxymonosulfate (PMS) decomposition to produce sulfate radicals. Here we report reactions between PMS and chloride, without a need of transition metals, also can be used to degrade organic dye pollutant (Rhodamine B, (RhB)). Some important operating parameters, such as dosages of PMS and Cl(-), pH of solution, temperature, ionic strength, and several common cations, were systematically investigated. Almost complete decoloration of RhB was achieved within 5min ([PMS] = 0.5mM, [Cl(-)] = 120mM, and pH3.0), and RhB bleaching rate increased with the increased dosages of both PMS and chloride ion, following the pseudo-first-order kinetic model. However, the total organic carbon (TOC) removal results demonstrated that the decoloration of RhB was due to the destruction of chromophore rather than complete degradation. RhB decoloration could be significantly accelerated due to the high ionic strength. Increasing of the reaction temperature from 273K to 333K was beneficial to the RhB degradation, and the activation energy was determined to be 32.996kJ/mol. Bleaching rate of RhB with the examined cations increased with the order of NH4 (+) < Na(+) < K(+) < Al(3+) < Ca(2+) < Mg(2+). Some major degradation products of RhB were identified by GC-MS. The present study may have active technical implications for the treatment of dyestuff wastewater in practice.