High Color Removal Research Articles

COD removal, decolorization, and energy consumption of electrocoagulation as a wastewater treatment process

The efficiency of color and COD removal in wastewater treatment is one of the essential factors. High color removal can encourage the reuse of wastewater as raw material in the recycled paper industry. Electrocoagulation (EC) process is effective pollutant removal in wastewater due to the adsorption, coagulation, and flotation. In this study, recycled paper industrial wastewater was used; this type of waste has a high content of disturbing pollutants, and treatment with electrocoagulation has not been widely carried out for this type of waste. EC treatment has a relatively high level of effectiveness to remove these pollutants; the influential factors studied include initial pH, applied current, supporting electrolyte, and processing time on a laboratory scale. The degradation of color, COD, and energy used was also evaluated. The best color removal was obtained as 100% at 80 minutes of process, and a COD concentration is 147 mg/L, and the energy used is 13.56 kWh/L.

Highly permeable acid-resistant nanofiltration membrane based on a novel sulfonamide aqueous monomer for efficient acidic wastewater treatment

Thin-film composite (TFC) membrane with high permeability and selectivity is appealing in the field of industrial wastewater treatment. However, polyamide (PA) TFC membranes, the premier choice for water treatment, undergo structure deterioration when continually exposed to acidic environment. Here, we apply surface activation assisted multi-step interfacial polymerization (IP) of 3-aminobenzenesulfonamide (ABSA) and trimesoyl chloride (TMC) to prepare a poly(amide-sulfonamide) (PASA) nanofiltration (NF) membrane with strong acid resistance. Thereinto, stable sulfonamide structure of ABSA effectively prevents the direct attack of acid to the PASA layer. Importantly, the nascent PASA layer acting as a hydrophilic interlayer can promote the subsequent IP reactions to form a less defective separation layer. When the surface activation (water soaking) is carried out during the multi-step IP process, the surface smoothness and hydrophilicity as well as the water permeability of the membrane are improved. Compared to the control, the resultant NF membrane exhibits ~200% increase in water permeability (12.4 Lm−2h−1bar−1) and >95.0% Na2SO4 rejection. Benefiting from the strong steric exclusion, it also has high color removal when treating model acidic dye solutions (>99.3%) or real resin elution wastewater, showing great potential in the acid reuse for decolorization resin regeneration. Moreover, such membrane owns impressive long-term stability after exposure to strong acid (20 wt% of H2SO4 for 30 days), and its hydrophilic surface contributes to excellent anti-fouling performance. This acid-resistant NF membrane with high permeability and stability provides a new perspective in acidic wastewater treatment.

Fouling mitigation and enhanced dye rejection in UF and NF membranes via layer-by-layer (LBL) assembly and altering PVP percentage as pore former

In this study, ultrafiltration (UF) and nanofiltration (NF) membranes with different polyvinylpyrrolidone (PVP) percentages were firstly synthesized to explore membranes with the highest flux and flux recovery ratio (FRR). From the membranes fabricated, the UF membrane containing 1 and 2% PVP, and NF membrane containing 2% PVP were selected as the optimal membranes. In the following step, the selected membranes were modified using a layer-by-layer assembly with poly 4-styrenesulfonic acid-co-maleic acid (PSSMA) (negatively charged) and poly allylamine hydrochloride (PAH) (positively charged). The positively charged membranes were prepared by placing 3 bilayers of the polymers with an extra PAH positive layer [(PAH/PSSMA)3+PAH], while the negatively charged membranes were prepared with only 3 bilayers of the polymers [PAH-PSSMA]3. To investigate the effect of electrostatic attraction and repulsion and their effect on the removal of dye, two anionic (direct red 16) and cationic (methylene blue) dyes were used. Having relatively high flux close to the UF and high color removal efficiency almost similar to the NF was the main achievement of this study with the modified UF membrane (1 wt% PVP). The characterization of the selected membrane was elucidated in detail. The stability of the filtration process for the selected membrane (UF 1 wt%) was confirmed through removing algal color from a stabilization pond effluent (turbidity reduction from 58 to 1 NTU) in a cross-flow filtration setup.

Treatment of real industrial-grade dye solutions and printing ink wastewater using a novel pilot-scale hydrodynamic cavitation reactor

A novel pilot-scale hydrodynamic cavitation (HC) reactor was used to decolorize industrial-grade dye solutions and printing ink wastewater (PIW). The effect of the orifice plate geometry (1 hole plate of 1 mm and 2 mm in diameter, 31 holes of 1 mm and 2 mm in diameter, 62 holes of 1 mm and 2 mm in diameter), inlet pressure (4, 5 bar), initial dye concentration (0.3 and 0.6 OD), and the synergistic effect of HC and hydrogen peroxide concentration (0.0, 0.5, 1.0, 2.0 g/L) were investigated. The results showed that the highest color removal was obtained using 31 holes orifice plate of 2 mm holes’ diameter, at 4 bar inlet pressure. Furthermore, although HC could not degrade completely all the industrial-grade dyes, efficiency was enhanced in the presence of H2O2. The optimum concentration of hydrogen peroxide was 1.0 g/L regardless of the initial concentration of the dyes studied. Under optimum operating conditions, color removal reached up to 68% for black, 39% for red, 43% for yellow, 55% for green, and 51% for cyan dye, while color removal in the PIW reached only 15%. The black dye solution presented almost 100% COD removal, while 38%, 25%, 67%, and 78% COD removal values were obtained for the red, yellow, cyan and green dyes, respectively. 55% COD removal was recorded from the PIW. Concerning cavitation yields, black, red, yellow, green, cyan dye yields reached 2.5E(-7), 1.1E(-7), 1.5E(-7), 2.0E(-7), 1.7E(-7) OD⋅L/J, respectively, while PIW yield was 6.3E(-8) OD⋅L/J. The present study demonstrates that HC combined with green oxidants such as hydrogen peroxide could be an alternative treatment approach for real industrial wastewater streams. However, a combination with a post-treatment method should be applied to maximize both color and COD removal.

Photocatalytic degradation of methyl orange dye using bismuth oxide nanoparticles under visible radiation

In this study, Bismuth oxide supported by copper nanoparticles were successfully synthesized by hydrothermal method and the effect of pH, catalyst dose of initial dye concentration was studied. It has shown excellent photocatalytic performance in the degradation of methyl orange dye under UV light, so that 93.76% degradation was obtained at acidic pH and color concentration of 20 mg/l with 0.04 g/l photocatalyst. The kinetic study reacted that the Pseudo-first-order model is the best model for the photocatalytic degradation of methyl orange. In addition, the reuse test showed that the nanocomposite, after 4 reuse periods maintained its stability in high colour removal. Therefore, it can be safely said that the nanocomposite due to its good photocatalytic performance can be used as a promising photocatalyst for the treatment of environmental pollutants on a large scale.

Genipin-mediated immobilization of glucose oxidase enzyme on carbon felt for use as heterogeneous catalyst in sustainable wastewater treatment

Enzyme immobilization is necessary process to improve the bioactivity and stability of the biocatalyst. In this study, glucose oxidase (GOx) enzyme was immobilized on plasma-treated fibrous carbon felt as a textile carrier to produce a heterogeneous catalyst. Genipin, as a naturally occurring crosslinker, that has less cytotoxicity than conventional crosslinkers, was used in the enzyme immobilization process. UV-Vis and FTIR spectra confirmed the crosslinking reaction between genipin and the primary amines of GOx enzyme, by forming blue-pigmented aggregates. GOx relative activity after crosslinking and immobilization on the carbon felt was maintained up to 40%, with stability in performance up to 6 cycles for the plasma treated carbon, while maintaining their bio-electro-activity as shown from cyclic voltammetry scans (CV). The obtained heterogeneous catalysts have been tested for use in sustainable wastewater treatment of Remazol Blue RR (RB) dyestuff by means of Bio-Fenton (BF) and enzymatic Bio-electro-Fenton (BEF) processes. The produced samples resulted in high color removal efficiency, up to 93% discoloration of (RB) for the first use in (BF) process in 3 h. Meanwhile, enzymatic (BEF) process resulted in up to 34% of COD removal, with simultaneous power density generation up to 0.16 ± 0.01 μW.cm−2 at a current density of around 10 ± 2 μA.cm−2 in 12 h. These results highlight the importance of genipin as a bio-based crosslinker for enzymes, and the potential use in both (BF) and (BEF) as sustainable approaches for wastewater treatment and as a step towards zero-energy degradation of organic matter.

Comparative Anaerobic Decolorization of Azo Dyes by Carbon-Based Membrane Bioreactor

This study used a novel integrated technology of ceramic supported carbon membrane (CSCM) to degrade azo dyes through an anaerobic mixed culture. The CSCM worked simultaneously as biofilm support, redox mediator, and nano-filter to enhance the dye decolorization efficiency. The decolorization of Acid Orange 7 (AO7) was initially investigated with and without microorganisms in both ceramic support (CS) and CSCM reactors. The CSCM bioreactor (B-CSCM), operated with microorganisms, gave a maximum decolorization of 98% using a CSCM evolved from 10% weight (wt.) of Matrimid 5218 solution. To know the influence of permeate flow, feed concentration, and dye structure on the decolorization process, different B-CSCMs for dye removal experiments were studied over monoazo AO7, diazo Reactive Black 5 (RB5), and triazo Direct Blue 71 (DB71). The highest color removal, operated with 50 mg·L−1 feed solution and 0.05 L·m−2·h−1 of permeate flux, was 98%, 82%, and 72%, respectively, for AO7, RB5, and DB71. By increasing these parameters to 100 mg·L−1 and 0.1 L·m−2·h−1, the decolorization rate of dye solution still achieved 37% for AO7, 30% for RB5, and 26% for DB71. In addition, the system was run for weeks without apparent loss of activity. These findings make evident that the combined phenomena taking place in CSCM bioreactor result in an efficient, cost-effective, and ecofriendly azo dye decolorization method.

Hybrid Sono-Electrocoagulation Process for the Treatment of Landfill Leachate Wastewater: Optimization through a Central Composite Design Approach

The effectiveness of the process of ultrasonication (US), electrocoagulation (EC) and hybrid sono-electrocoagulation (US+EC) on landfill leachate wastewater treatment was evaluated based on the removal efficiency of % color and % Chemical Oxygen Demand (COD) along with power consumption. The experimental results showed that the hybrid US+EC had a high color (100%) and COD (94%) removal efficiency with a lower power consumption of 4.50 kWh/m3 compared to the individual EC and US processes. In this hybrid US+EC process, the effects of various operating parameters were investigated and optimized using Design-Expert (12) based on the central composite design approach. The optimization results indicated a maximum COD removal efficiency of 71.05% with a minimum power consumption of 2.33 kWh/m3 at the following optimal experimental conditions: electrolyte concentration (X1) = 0.76 g/L, current density (X2) = 2.75 A/dm2, COD concentration (X3) = 3919.50 mg/L, sonication power (X4) = 100 W and treatment time (X5) = 36.05 min. The synergistic effect was calculated using the US, EC and US+EC process based on the % COD removal efficiency and has a positive effect of 20.51%. The % COD and % color removal efficiency were analyzed using a closed reflux method and UV-VIS spectrophotometer. Thus, the hybrid US+EC process, significantly enhances the efficiency of pollutants removal from landfill leachate wastewater.

Low-cost nanoparticulate oxidation catalysts for the removal of azo and anthraquinic dyes.

This study aimed to test the activity of Mn ferrite, hematin-Mn ferrite and colloidal maghemite in decomposition of Orange II (O-II) and Alizarin Red S (ARS) in model aqueous solutions. Color removal was explored at room temperature using magnetic stirring with and without a magnetic bar, taking advantage of the solids' magnetism. Decomposition of H2O2 was also studied separately and as radicals provider in dye decomposition. Catalyst/dye solution was fixed at 10mg/4mL. pH and dye concentration were variable. Absorbance was measured during 120min by UV-Vis. Reuse of catalysts was also performed. Azo dyes such as O-II are more resistant to oxidative removal using hydrogen peroxide than anthraquinone-like ARS. CITMD5 reduced ARS absorbance up to 71.9% when dye was less than 250mg/L. HEM-Mn-MAG completely decolorized a 62.5mg/L O-II solution at pH11 while CITMD5 reached half of that conversion under the same conditions. The highest color removal in O-II/ARS mixtures was obtained with HEM-Mn-MAG, 40% absorbance reduction in 2h. Mn-MAG is not active to remove O-II in presence of hydrogen peroxide in the 3-9 pH range at rt. The high activity of Mn-MAG in hydrogen peroxide decomposition may be assigned to the combination of Mn+2/Mn+3 and Fe+2/Fe+3, because the MnOx is active in the decomposition of hydrogen peroxide. Mn-MAG can be reused, preserving high activity in this reaction. Mn-based magnetic nanoparticles should be considered as inexpensive materials to treat textile wastewaters. The online version contains supplementary material available at 10.1007/s40201-021-00640-x.

Establishing the process kinetics and appraising model predictive behavior for coagulation treatment of tannery industry wastewater

The residual coloring agents present in tannery wastewater degrades the quality of ecosystem and limits photosynthetic activity in aquatic biosphere apart from causing displeasing appearance. This study is conducted to test the ability of protein coagulant extracted from Moringa oleifera (MO) seeds for removing the color from tannery wastewater. Different salt solutions such as NaCl, KCl, MgCl2 and NH4Cl were used individually to extract the coagulant from MO seeds. The color removal efficiency was the highest for NaCl extracted coagulant (75.14%) and least for MgCl2 extracted coagulant (62.38%). The coagulant extracted for 30 min duration and stored for one day at 278 K removed 75.14% coloring agents from wastewater. The efficiency of NaCl-extracted coagulant was investigated by varying the parameters such as NaCl concentration (0.1 N–0.4 N), initial pH (3–10), coagulant dose (10 mL–50 mL) and coagulant storage temperature (278 K–298K). The differential method of analyzing kinetic data indicates that process obeys second order mechanism because a plot between the rate of change in color intensity and square of the fraction of residual color is a parabolic curve. The interrelationship between response and process variables was studied using linear, exponential, logarithmic, second order polynomial and power law models. Highest color removal of 75.14% was achieved at optimal conditions of 0.2 N NaCl solution, pH 8, 40 mL dose and 278 K storage temperature. It was ascertained that the power law model (R2 = 0.906) truly reflected the system behavior, while the linear model (R2 = 0.797) had poor prediction capability.

Life Cycle Analysis for Hibiscus Sabdariffa Powder Manufactured by Freeze Drying for Wastewater Application

Synthetic coagulants currently used to treat dye wastewater in the water treatment industry has been found to produce large amounts of waste and is bad for the environment. The research then presents two different methods of preparing Hibiscus Sabdariffa as a natural coagulant which are direct method and freeze-drying method to possibly replace synthetic coagulant in treating dye wastewater. The two different methods of preparing natural coagulant Hibiscus Sabdariffa are compared in terms of protein retention and coagulation performance at removing dye from dye wastewater. This is to determine which method of preparation is better at preparing a Hibiscus Sabdariffa as a natural coagulant to be used in the water treatment industry. Three analysis are done to determine the optimum concentration of Hibiscus Sabdariffa powder and freeze-drying duration is based on (i) surface morphology, (ii) water solubility and (iii) water activity. Optimum concentration of Hibiscus Sabdariffa powder is 20wt% and 24-hour freeze-drying duration. Another analysis is done to compare protein retention of each methods of preparation using (iv) Fourier Transform Infrared (FTIR) spectroscopy testing. Protein in Hibiscus Sabdariffa prepared using freeze drying is completely retained based on Fourier Transform Infrared spectroscopy results. Supporting data of protein retention properties of freeze drying is proven by water activity in Hibiscus Sabdariffa powder is at 0.478 and below the 0.6 threshold value. Water activity of 0.478 means that there is not enough water content in Hibiscus Sabdariffa powder for microorganisms to grow and degrade the protein. Optimum coagulant dosage and pH value that Hibiscus Sabdariffa prepared using the two different methods best works in is determined based on two experiments called (v) effects of coagulant dosage on dye removal percentage and (vi) effect of pH value of preparation methods on colour removal percentage. Coagulation performance of both preparation methods are also determined using experiment (v) and (vi). Hibiscus Sabdariffa prepared using freeze drying has better coagulation performance with higher colour removal percentage at lower required coagulant dosage and higher dye removal percentage at varied pH values compared to direct method. As a result, freeze drying is better in terms of coagulation performance compared to direct method at preparing natural coagulant Hibiscus Sabdariffa. Coagulation performance of natural and chemical coagulant is compared using (vii) jar test comparison between natural and chemical coagulant on colour removal. This is to determine if coagulation performance of natural coagulant is comparable to chemical coagulant. Coagulation performance of natural coagulant is only slightly lower than synthetic coagulant at colour removal percentage of 91.2% compared to 92.3%. This makes the coagulation performance of natural coagulant comparable to synthetic coagulant allowing it to be an alternative to synthetic coagulant based on coagulation performance. Therefore, Life Cycle Analysis (LCA) will then be conducted to compare the better method of preparation of natural coagulant which is freeze-drying of natural coagulant Hibiscus Sabdariffa to chemical coagulant alum. Life Cycle Analysis done is to determine, evaluate and compare natural against chemical coagulant based on 3 sustainability aspects economic, environment and social aspects. This is to determine the feasibility of natural coagulant Hibiscus Sabdariffa in the water treatment industry on whether it is a possible alternative or replacement to the currently used synthetic coagulant alum. Based on Life Cycle Analysis natural coagulant is the better alternative compared to chemical coagulant based on impact towards the environment and health and well-being of society. However, the implementation of natural coagulant in the water treatment industry is still not feasible as production cost of natural coagulant is 126.86 times more expensive compared to chemical coagulant. As a result, currently Hibiscus Sabdariffa as a natural coagulant is not able to replace synthetic coagulant alum in the water treatment industry.

Treatment of dye-producing chemical industry wastewater by persulfate advanced oxidation

A dye-producing chemical industry wastewater in Çorlu (Tekirdağ) is treated by the coagulation-flocculation process of the wastewater. However, the wastewater discharged after coagulation-flocculation still has a very high COD (4402 mg L-1) with very high proportion of dissolved COD (4316 mg L-1). Therefore, the aim of this study is to achieve higher COD and color removal in wastewater using Fe2+/S2O8 or UV/S2O8 oxidation process after coagulation-flocculation. The processes in the oxidation of this industrial wastewater using Fe2+/S2O8 and UV/S2O8 were examined and the effect of COD/Fe2+/S2O8 ratio (in Fe2+/S2O8) or COD/S2O8 ratio (in UV/S2O8), pH and oxidation time were evaluated in the study. While high organic matter and color removal was observed in acidic conditions for both processes, optimum pH were 3 and 6 in Fe2+/S2O8 and UV/S2O8 oxidation processes, respectively. In Fe2+/S2O8 oxidation, 61.1% of COD removal and above 97% of color (UV436, UV525 and UV620) removal was obtained at 1/8/8 of COD/Fe2+/S2O8 ratio and pH 3 after 1 h oxidation. In UV/S2O8 oxidation (COD/S2O8 ratio 1/8, pH 6), 54.4% of COD and 98% of color (UV436, UV525 and UV620) removals were achieved after 4 h oxidation. As a result, both Fe2+/S2O8 and UV/S2O8 oxidation processes were applied to ensure discharge standards for color removal from this chemical industry wastewater are effective methods as they provide over 97% color removal. Moreover, COD removal efficiency was approximately 55-60% in both methods.

Novel polyvinylidene fluoride/lead-doped zinc oxide adsorptive membranes for enhancement of the removal of reactive textile dye

Novel hybrid polyvinylidene fluoride/lead-doped zinc oxide nanoparticles ultrafiltration membranes were successfully fabricated for the removal of Reactive Black 5 textile dye. The matrix membranes embedded with various weights of nanoparticles (5, 10 and 20 wt% of polyvinylidene fluoride) prepared by non-solvent induced phase separation wet process method. The membranes’ morphology structure, surface, chemical composition and hydrophilicity were characterized by scanning electron microscope, energy-dispersive X-ray spectrometer analysis and water contact angle. The performances in terms of permeability, porosity, permeate flux and capacities of Reactive Black 5 textile dye retention were evaluated. Whereas the addition of low concentration of lead-doped zinc oxide nanoparticles doesn’t significantly modify polyvinylidene fluoride membranes structure and performance, the addition of 20 wt% of nanoparticles to casting solution modified the morphology, led to reduce the contact angle from 77° to 67° and enhanced the hydrophilicity of membranes. Static sorption and dynamic filtration were performed to evaluate the capacity of membrane to remove the Reactive Black 5 dye. Results showed the polyvinylidene fluoride/lead-doped zinc oxide composite membranes exhibit high efficiency in the adsorption and retention of Reactive Black 5 textile dye in comparison with polyvinylidene fluoride neat. The addition of 20 wt % of nanoparticles in membrane matrix showed high color removal rate (98%) and high adsorption properties in comparison with pure polyvinylidene fluoride membrane. With simple water cleaning, without addition of any chemical agent, the membranes recovered high performance.

Ozonation as a pre-treatment of landfill leachate

Ozone is an oxidizing agent with a potential for removing complex molecules, including those of difficult microbiological decomposition, such as the molecules found in landfill leachates. This effluent presents high organic content, including recalcitrant molecules. Therefore, this study evaluated the efficiency of ozonation in the treatment of raw leachate at the Primavera landfill, located in Mato Grosso, Brazil. The experiments were carried out using the batch system. The leachate pH value was set at 7 and 10, and the contact times between the gas and the leachate were 20, 40, 60, 80, and 100 minutes. Throughout the study, we analyzed color, turbidity, pH value, chemical oxygen demand (COD), and ultraviolet absorbance at 254 nm (UV abs) of the leachate, both before and after ozonation. Results show that ozonation presented high removal of color, COD and UV abs when pH was 7. In contrast, turbidity removal was higher when the pH value was 10. Regarding contact time, we observed a high removal of color (between 80% and 90%) and UV abs (between 60% and 70%) at 40 minutes, depending on the pH value. Removal was also high for turbidity (approximately 75%) starting at 20 minutes with the pH value at 10, and at 70 minutes with pH at 7. The removal relation within all analyzed parameters (due to ozone consumption) decreased throughout the reaction time. Thus, we concluded that ozonation as a pre-treatment of leachate is indeed satisfactory because of its great capacity for organic material removal.

Enhanced anaerobic treatment of azo dye wastewater via direct interspecies electron transfer with Fe3O4/sludge carbon

In this study, enhancement of anaerobic treatment of azo dye wastewater with Fe3O4/SC is investigated. Fe3O4/sludge carbon (SC) is prepared from waste activated sludge using a simple impregnation method. Two identical laboratory-scale upflow anaerobic sludge blanket reactors with a working volume of 1.5 L are filled with 2 g/L of SC (reactor 1) and 2 g/L of Fe3O4/SC (reactor 2). Another reactor (reactor 0) is operated as a control. FTIR, XPS, SEM, and BET results indicate that Fe3O4 is successfully loaded on the SC. Addition of Fe3O4/SC to the reactor results in high chemical oxygen demand (78.13%) and color (97.60%) removal rates. Furthermore, Fe3O4/SC effectively decreases the amount of aniline generated and increases CH4 production. The Fe3O4/SC anaerobic system is stable with fast recovery in terms of both organic matter removal and aniline control with high toxic substance concentrations and fluctuating organic loads. Moreover, Fe3O4/SC greatly enhances enzymatic activity and sludge granulation, which could greatly improve anaerobic reactor stability. High electron transport system and conductivity values and the enrichment of Geobacter and Methanosaeta species confirm that direct interspecies electron transfer occurs with Fe3O4/SC in the reactor. These results provide a scientific basis for further applications to azo dye wastewater treatment and promote resource utilization of waste sewage sludge.

Plant-Based Tacca leontopetaloides Biopolymer Flocculant (TBPF) Produced High Removal of Turbidity, TSS, and Color for Leachate Treatment

Wastewater treatment is crucial to ensure a sustainable supply of clean water, especially for human use. Natural flocculants can overcome the disadvantages of chemical flocculants in wastewater treatment. This study proposes a new natural-based flocculant from the Tacca leontopetaloides plant for leachate treatment. The plant tuber was processed through gelatinization to produce Tacca leontopetaloides biopolymer flocculant (TBPF). The characterization of TBPF for flocculant properties was investigated, and the performance of TBPF on leachate treatment using a standard jar test procedure was examined at different pH values of leachate and TBPF dosages. The characteristics of TBPF in terms of amylose/amylopectin fraction, viscosity, and zeta potential were 26:74, 0.037–0.04 Pa·s, and −13.14 mV, respectively. The presence of –COOH and –OH structure in TBPF indicates the flocculant properties. TBPF reduced the turbidity, total suspended solids (TSS), and color from 218 NTU, 214 mg/L, 14201 PtCo to 45.8–54.5 NTU, 19.3–19.9 mg/L, and 852–994 PtCo, respectively, using 240 mg/L of TBPF at pH 3. These results show a high potential of the new plant-based TBPF for leachate treatment and water industry applications.

Treatment of Rose Processing Wastewater By Sunlight/TiO2 Photocatalysis Process

The objective of this study was to investigate the photocatalytic treatment of rose processing wastewater by using sunlight and TiO2. Rose processing wastewater contains high concentrations of chemical oxygen demand, high amount of solid matters and dark color. The effect of various operating conditions such as irradiation time, catalyst loading and pH on COD and color removal were determined. The highest color removal and COD removal was found to be 51.7 % and 15.7%, respectively with 2 g/L TiO2 catalyst dose at pH 4. Sunlight was used as an economic irradiation source for photocatalytic treatment of rose processing wastewater.

Cerium oxide nanoparticles for color removal of indigo carmine and methylene blue solutions

In this work, CeO2 nanoparticles (NPs) were synthesized by sol-gel method, characterized and used for color removal of indigo carmine and methylene blue dye solutions under visible light. The structural properties and crystallinity of NPs were determined by X-ray diffraction (XRD) and a cubic phase of ceria with 13.5 nm crystallite size was confirmed. In addition, the morphology was studied by using Scanning Electron Microscopy (SEM) and a semi-spherical morphology was observed. The surface chemical analysis of CeO2 NPs was performed by using an X-ray photoelectron spectroscopy (XPS), and the presence of functional groups and the absorption spectra in CeO2 NPs were investigated by Fourier-transform infrared spectroscopy (FTIR) and by UV-vis spectroscopy, respectively. The experimental results showed that the highest color removal was obtained for indigo carmine (≈ 90% at pH 2.5 within 180 min). Thus, CeO2 NPs may be suitable for removal of anionic dye effluents at room temperature.

Removal of chemical oxygen demand (COD) and total suspended solid (TSS) using electrocoagulation process for treatment of oleochemical wastewater

Wastewater from oleochemical industry contains high concentration glycierin, chemical oxygen demand (COD) and total suspended solids (TSS) that can cause environmental pollution if discharged without proper treatment method. Currently, oleochemical industry used reverse osmosis membrane and submerged bed biofilm reactor to treat their wastewater. In this work, other method namely electrocoagulation treatment that capable to achieve a high removal of color, COD, biological oxygen demand (BOD) is employed. The objective of the study is to determine the optimum operating condition such as initial pH (6-9), applied current (4.0-8.0A), type of electrode (aluminium & stainless steel & and retention time (10 – 40 min) on degradation of COD and TSS in wastewater from an oleochemical industry using this process. The experimental results showed that the pollutant removal efficiencies of COD and TSS can be achieved at 62.64% and 66.12% respectively, of the initial concentration of parameters using aluminium electrode at the optimum conditions of pH 7.5, applied current 6 A and reaction time of 30 min. All the findings of the study revealed that treatment of oleochemical wastewater by electrocoagulation process at optimum conditions can be used as a treatment.

Catalytic degradation of Acid Orange 7 in water by persulfate activated with CuFe2O4@RSDBC

In this study, a novel series of rectorite/sludge derived biochar (RSDBC) supporting CuFe2O4 (CuFe2O4@RSDBC) composites were prepared as an effective catalyst to active persulfate (PS) for the removal of Acid Orange 7 (AO7) in water. The character of catalyst was analyzed by scanning electron microscope (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD). Various influencing factors including initial pH, PS concentration, catalyst dosage, initial dye concentration and reaction temperature were investigated. The optimal reaction conditions were found to be: PS concentration 2 mM; catalyst dosage 0.6 g l−1; initial pH value 7.0 and 25 °C of reaction temperature. Further radical quenching tests were performed by using ethanol, tert-butanol (TBA) and benzoquinone (BQ), which confirmed that sulfate radicals () and hydroxyl radicals (HO•−) were the reactive species in the degradation process. The Gas chromatography-mass spectrometry (GC-MS) analysis was employed to determine the intermediate products and a plausible degradation pathway is proposed. In addition, the CuFe2O4@RSDBC sample exhibited high color removal ability (95%) and stable performance after three successive runs. At last, the catalyst proved a good removal effect for actual dye wastewater. These results indicate that CuFe2O4@RSDBC hybrids could be as effective catalysts for PS activation on dye pollutants elimination.