This study was to investigate the mineralization of wastewater containing methyl orange (MO) in integrated anaerobic-aerobic biofilm reactor with coconut fiber as bio-material. Different aeration periods (3h in phase 1 and 2; 3, 6 and 15 h in phase 3; 24 h in phase 4 and 5) in aerobic chamber were studied with different MO concentration 50, 100, 200, 200 and 300 mg/L as influent from phase 1-5. The color removals estimated from the standard curve of dye versus optical density at its maximum absorption wavelength were 97%, 96%, 97%, 97%, and 96% and COD removals were 75%, 72%, 63%, 81%, and 73% in phase 1-5, respectively. The MO decolorization and COD degradation followed first-order kinetic model and second-order kinetic model, respectively. GC-MS analysis indicated the symmetrical cleavage of azo bond and the reduction in aromatic peak ensured the partial mineralization of MO.
The treatment of single and binary azo dyes, as well as the effect of the circuit connection, aeration, and plant on the performance of UFCW-MFC, were explored in this study. The decolorization efficiency of Remazol Yellow FG (RY) (single dye: 98.2 %; binary dye: 92.3 %) was higher than Reactive Black 5 (RB5) (single: 92.3 %; binary: 86.7 %), which could be due to monoazo dye (RY) requiring fewer electrons to break the azo bond compared to the diazo dye (RB5). In contrast, the higher decolorization rate of RB5 in binary dye indicated the removal rate was affected by the electron-withdrawing groups in the dye structure. The closed circuit enhanced about 2% of color and 4% of COD removal. Aeration improved the COD removal by 6%, which could be contributed by the mineralization of intermediates. The toxicity of azo dyes was reduced by 11-26% and the degradation pathways were proposed. The dye removal by the plants was increased with a higher contact time. RB5 was more favorable to be uptook by the plant as RB5 holds a higher partial positive charge. 127.39 (RY), 125.82 (RB5), and 58.66 mW/m3 (binary) of maximum power density were generated. The lower power production in treating the binary dye could be due to more electrons being utilized for the degradation of higher dye concentration. Overall, the UFCW-MFC operated in a closed circuit, aerated, and planted conditions achieved the optimum performance in treating binary azo dyes containing wastewater (dye: 87-92%; COD: 91%) compared to the other conditions (dye: 83-92%; COD: 78-87%).
Cr2O3/g-C3N4 photocatalyst was successfully synthesized via the one-pot thermal polycondensation method by mixing different ratios of CrCl3.H2O and thiourea. Thiourea was used as the precursor for building g-C3N4. All samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), scanning electron microscope and energy dispersive X-ray spectroscopy (SEM-EDS), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS), and electrochemical experiment (photocurrent and EIS). The photocatalytic performance of the composites was studied by the photodegradation process of tetracycline hydrochloride (TC-HCl) and reactive orange 16 (RO16) under visible light irradiation. The results showed that the 1%Cr2O3/g-C3N4 was the most effective photocatalyst with 94.9% (30 min) and 80.6% (90 min) for degradation of RO16 and TC-HCl, respectively, when compared with the other ratios. Additionally, from the reactive species trapping test, superoxide radical was the major reactive species in this reaction. Finally, this material could be reused with great efficiency with 5 and 7 times for TC-HCl and RO16, respectively. The synthesized composites manifest the great potential for the wastewater treatment industry.
Azo dyes are widely used in textile, fiber, cosmetic, leather, paint and printing industries. Besides their characteristic coloring function, azo compounds are reported as antibacterial, antiviral, antifungal and cytotoxic agents. They have the ability to be used as drug carriers, either by acting as a 'cargo' that entrap therapeutic agents or by prodrug approach. The drug is released by internal or external stimuli in the region of interest, as observed in colon-targeted drug delivery. Besides drug-like and drug carrier properties, a number of azo dyes are used in cellular staining to visualize cellular components and metabolic processes. However, the biological significance of azo compounds, especially in cancer chemotherapy, is still in its infancy. This may be linked to early findings that declared azo compounds as one of the possible causes of cancer and mutagenesis. Currently, researchers are screening the aromatic azo compounds for their potential biomedical use, including cancer diagnosis and therapy. In this review, we highlight the medical applications of azo compounds, particularly related to cancer research. The biomedical significance of cis-trans interchange and negative implications of azo compounds are also discussed in brief.
The decolorization of reactive orange 16 dye (RO16) from aqueous solution by CuO/H2O2 was investigated. The amount of dye removed was determined by measuring the concentration of the dye at its characteristic wavelengths by UV-Vis spectrophotometer. The effects of CuO dose, H2O2 concentration and UV light on the decolorization of the dye were investigated. It was found that the removal rate increased with increasing mass of CuO and increasing concentration of H2O2. The combination of CuO, H2O2 and UV light was the best system with dye removal of 100% after 6 h. The removal efficiency observed was in the order: CuO/UV/H2O2 > CuO/H2O2 > CuO/UV = CuO > UV/H2O2 > H2O2 > UV.
Elektrod komposit dwilogam yang disediakan hasil campuran serbuk argentums (Ag) dan 'carbon (C) (dinamakan AgC-Pvc) memberikan hasil elektrolisis larutan pewarna C. I. Reactive Orange 4 (R04) yang tidak berwarna dan tanpa penghasilan enapan lumpur berbanding elektrod komposit dwilogam lain. Perbezaan nisbah komposisi serbuk Ag:C (30:70, 50:50 and 70:30) dalam penyediaan elektrod seterusnya diuji untuk melihat kesan perbezaan komposisi ini terhadap penyahwarnaan R04. Melalui persamaan Tafel yang diperoleh, elektrod Ag285C 665-PVC 5 yang menggunakan komposisi 30% Ag dan 70% C memberikan nilai perubahan ketumpatan arus, io yang lebih tinggi iaitu 3.555 mAl cm2 berbanding elektrod lain. Elektrod ini mempunyai aktiviti pemangkinan elektrokimia yang lebih baik berbanding elektrod lain. Hasil proses elektrolisis elektrod Ag285C66.5-PVC 5 terhadap larutan RO4 telah dianalisis menggunakan spektrofotometer uv-Nampak dan didapati proses degredasi kumpulan azo dalam pewarna tersebut telah berlaku selepas proses elektrolisis yang menghasilkan larutan tidak berwarna.
Analisis terma dan prestasi modul fotovoltan semi-lutsinar yang dipasang pada tetingkap dwi kaca (TDK) telah dikaji. Di dalam TDK terjadi pemindahan haba olakan yang disebabkan oleh perbezaan suhu. Perisian COMSOL digunakan untuk menyelesaikan model matematik dengan empat jenis gas yang berlainan disimulasikan untuk mengisi ruang dalam TDK iaitu udara, argon, kripton dan xenon. Ruang dalam TDK diubah antara 5 hingga 100 mm. Keadaan cuaca di Kuala Lumpur, Malaysia telah digunakan. Modul fotovoltan yang digunakan untuk kajian simulasi ialah jenis silikon amorfus (Si-a). Kajian ini mendapati penggunaan gas xenon dalam ruang TDK memberikan prestasi maksimum dalam mengurangkan beban penyejukan. Ketebalan optimum ruang TDK bergantung kepada jenis gas yang digunakan dan secara umumnya berada dalam julat 10 hingga 20 mm.
Many attempts have been made to improve the photocatalytic performance of immobilized photocatalysts for large-scale applications by modification of the photocatalyst properties. In this work, immobilized bilayer photocatalyst composed of titanium dioxide (TiO2) and chitosan-montmorillonite (CS-MT) were prepared in a layer-by-layer arrangement supported on glass substrate. This arrangement allows a simultaneous occurrence of adsorption and photocatalysis processes of pollutants, whereby each layer could be independently modified and controlled to acquire the desired degree of occurring processes. It was found that the addition of MT clay within the CS composite sub-layer improved the mechanical strength of CS, reduced its swelling and shifted its absorption threshold to higher wavelengths. In addition, the band gap energy of the photocatalyst was also reduced to 2.93 eV. The immobilized TiO2/CS-MT exhibited methyl orange (MO) decolourization rate of 0.071 min-1 under light irradiation, which is better than the single TiO2 due to the synergistic processes of adsorption by CS-MT and photocatalysis by TiO2 layer. The MO dye took 6 h to achieve complete mineralization and produced sulfate and nitrate ions as the by-products. Furthermore, the immobilized TiO2/CS-MT could be reused for at least ten cycles of application without significant loss of its activity.
One of mankind's biggest concerns is water pollution. Textile industry emerged as one of the main contributors with dyes as the main pollutant. Presence of dyes in water is very dangerous due to their toxicity; thus, it is important to remove them from water. In these recent years, heterogeneous advance oxidation process surfaced as a possible dyes' removal technique. This process utilizes semiconductor as photocatalyst to degrade the dyes in presence of light and zinc oxide (ZnO) appears to be a promising photocatalyst for this process. In this study, pullulan, a biopolymer, was used to produce porous ZnO microflowers (ZnO-MFs) through green synthesis via precipitation method. The effects of pullulan's amount on the properties of ZnO-MFs were investigated. The ZnO-MF particle size decreased with the increased of pullulan amount. Interestingly, formation of pores occurred in presence of pullulan. The synthesized ZnO-MFs have the surface area ranging from 6.22 to 25.65 m2 g-1 and pore volume up to 0.1123 cm3 g-1. The ZnO-MF with the highest surface area was chosen for photocatalytic degradation of methyl orange (MO). The highest degradation occurred in 300 min with 150 mg catalyst dosage, 10 ppm initial dye concentration, and pH 7 experimental conditions. However, through comparison of photodegradation of MO with all synthesized ZnO-MFs, 25PZ exhibited the highest degradation rate. This shows that photocatalytic activity is not dependent on surface area alone. Based on these results, ZnO-MF has the potential to be applied in wastewater treatment. However, further improvement is needed to increase its photocatalytic activity.
Photo-Fenton oxidation is one of the most promising processes to remove recalcitrant contaminants from industrial wastewater. In this study, we developed a novel heterogeneous catalyst to enhance photo-Fenton oxidation. Multi-composition (Fe-Cu-Zn) on aluminosilicate zeolite (ZSM-5) was prepared using a chemical process. Subsequently, the synthesized catalyst was characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (spectroscopy) (EDX), and Brunauer-Emmett-Teller (BET). Activity of the synthesized catalyst is analysed to degrade an azo dye, methyl orange. Taguchi method is used to optimize color removal and total carbon content (TOC) removal. The dye completely degraded, and 76% of TOC removal was obtained at optimized process conditions. The amount of catalyst required for the desired degradation of dye significantly reduced up to 92% and 30% compared to conventional homogenous and heterogeneous Fenton oxidation processes, respectively.
Response surface methodology-Box–Behnken design (RSM-BBD) was employed to optimize the methyl orange (MO) dye removal efficiency from aqueous solution by cross-linked chitosan-tripolyphosphate/nano-titania compsite (Chi-TPP/NTC). The influence of pertinent parameters, i.e. A: TiO2 loading (0- 50 %), B: dose (0.04-0.14 g), C: pH (4-10), and D: temperature (30-50 oC) on the MO removal efficiency were tested and optimized using RSM-BBD. The F-values of BBD model for MO removal efficiency was 93.4 (corresponding p-value < 0.0001). The results illustrated that the highest MO removal efficiency (87.27 %) was observed at the following conditions: TiO2 loading (50% TiO2), dose (0.09 g), pH = 4.0, and temperature of 40 oC.
The red-bellied form of Calliophis intestinalis (Laurenti, 1768) sensu lato was originally reported from Pahang, west Malaysia. To determine the taxonomic status of this form, we examined the type specimens of Elaps sumatranus Lidth De Jeude, 1890, Calliophis intestinalis everetti (Boulenger, 1896), and Callophis furcatus var. nigrotaeniatus Peters, 1863. The results indicated that the red-bellied form of C. intestinalis should be named as Calliophis nigrotaeniatus comb. nov., whose valid species status was based on morphological and molecular analyses. We designate a lectotype and redescribe the species, which is genetically close to Calliophis bilineatus (Peters, 1881) from the Philippines, and is clearly distinguishable from other congeners by possessing a pair of gray or dark blue lateral stripes and by being bright red on the ventrum. Elaps sumatranus and C. i. everetti are relegated to subjective junior synonyms of C. nigrotaeniatus.
The crystal structure of the title compound, C(15)H(14)N(2)O(2). H(2)O, is in the keto tautomeric form and the configuration at the azomethine C=N double bond is E. The molecule is non-planar, with a dihedral angle of 27.3 (1) degrees between the aromatic rings. The crystal structure is stabilized by extensive hydrogen bonding involving the water molecule and hydrazone moiety.
The photocatalytic fuel cell (PFC) system was developed in order to study the effect of several operating parameters in degradation of Reactive Black 5 (RB5) and its electricity generation. Light irradiation, initial dye concentration, aeration, pH and cathode electrode are the operating parameters that might give contribution in the efficiency of PFC system. The degradation of RB5 depends on the presence of light irradiation and solar light gives better performance to degrade the azo dye. The azo dye with low initial concentration decolorizes faster compared to higher initial concentration and presence of aeration in PFC system would enhance its performance. Reactive Black 5 rapidly decreased at higher pH due to the higher amount of OH generated at higher pH and Pt-loaded carbon (Pt/C) was more suitable to be used as cathode in PFC system compared to Cu foil and Fe foil. The rapid decolorization of RB5 would increase their voltage output and in addition, it would also increase their Voc, Jsc and Pmax. The breakage of azo bond and aromatic rings was confirmed through UV-Vis spectrum and COD analysis.
Herein, a quadruple biomagnetic nanocomposite of cross-linked chitosan-ethylene glycol diglycidyl ether/organo-nanoclay (MCH-EGDE/ORNC) was designed for the uptake of remazol brilliant blue R (RBBR) dye from aqueous environment. The adsorption process was systematically improved via the Box-Behnken design (BBD) to determine the influence of key uptake parameters, including MCH-EGDE/ORNC dosage, pH, and time, on the RBBR removal. The highest RBBR removal of 87.5 % was achieved at the following conditions: MCH-EGDE/ORNC dosage: 0.1 g/100 mL; pH: 4.0; contact time: 25 min. The findings of the kinetics and equilibrium studies revealed an excellent fit to the pseudo-second order and the Freundlich models, respectively. The adsorption capacity of the MCH-EGDE/ORNC for RBBR was found to be 168.4 mg/g, showcasing its remarkable adsorption capability. The present work highlights the potential of MCH-EGDE/ORNC biomaterial as an advanced adsorbent and lays the foundation for future applications in water purification and environmental remediation.
Polyhydroxyalkanoates (PHAs) are promising alternatives to non-degradable polymers in various applications. This study explored the use of biologically recovered PHA as a biofilm carrier in a moving bed biofilm reactor for acid orange 7 treatment. The PHA was comprised of 86 ± 1 mol% of 3-hydroxybutyrate and 14 ± 1 mol% of 3-hydroxyhexanoate and was melt-fused at 140 °C into pellets. The net positive surface charge of the PHA biocarrier facilitated attachment of negatively charged activated sludge, promoting biofilm formation. A 236-µm mature biofilm developed after 26 days. The high polysaccharides-to-protein ratio (>1) in the biofilm's extracellular polymeric substances indicated a stable biofilm structure. Four main microbial strains in the biofilm were identified as Leclercia adecarboxylata, Leuconostoc citreum, Bacillus cereus, and Rhodotorula mucilaginosa, all of which exhibited decolourization abilities. In conclusion, PHA holds promise as an effective biocarrier for biofilm development, offering a sustainable alternative in wastewater treatment applications.
Extensive use of recalcitrant azo dyes in textile and paper industries poses a direct threat to the environment due to the carcinogenicity of their degradation products. The aim of this study was to investigate the efficiency of Curvularia clavata NZ2 in decolorization of azo dyes. The ability of the fungus to decolorize azo dyes can be evaluated as an important outcome as existing effluent treatment is unable to remove the dyes effectively. C. clavata has the ability to decolorize Reactive Black 5 (RB5), Acid Orange 7 (AO7), and Congo Red azo dyes, utilizing these as sole sources of carbon and nitrogen. Ultraviolet-visible (UV-vis) spectroscopy and Fourier infrared spectroscopy (FTIR) analysis of the extracted RB5's metabolites along with desorption tests confirmed that the decolorization process occurred due to degradation and not merely by adsorption. Enzyme activities of extracellular enzymes such as carboxymethylcellulase (CMCase), xylanase, laccase, and manganese peroxidase (MnP) were also detected during the decolorization process. Toxicity expressed as inhibition of germination was reduced significantly in fungal-treated azo dye solution when compared with the control. The cultivation of C. clavata under sequential batch system also recorded a decolorization efficiency of above 90%. The crude enzyme secreted by C. clavata also showed excellent ability to decolorize RB5 solutions with concentrations of 100 ppm (88-92%) and 1000 ppm (70-77%) without redox mediator. This proved that extracellular enzymes produced by C. clavata played a major role in decolorization of RB5.
In this study, effect of degree of deacetylation on property and adsorption capacity of chitosan/polyvinyl Alcohol electrospun membrane has been investigated. Resulting nanofibers were characterized by FESEM, FTIR, XRD, TGA, tensile testing, weight loss test and adsorption test. FESEM result shows, finer nanofiber was fabricated from 42h hydrolyzed chitosan and PVA blend solution. FTIR and XRD result showed a strong interaction between chitosan and polyvinyl alcohol. Higher tensile strength was observed for the nanofiber having 42h hydrolyzed chitosan. Blend solution of chitosan/PVA having low DD chitosan had higher viscosity. The nanofibrous membrane was stable in distilled water, acidic and basic medium. The isotherm study shows that the adsorption capacity (qm) of nanofiber containing higher DD chitosan was higher for Cr(VI). In contrary, the membrane containing chitosan with lower DD showed the higher adsorption capacity for Fe(III) and methyl orange. Moreover, the effect of DD on removal percentage of adsorbate was dependent on the initial concentration of the adsorbate.
In this study, AB113 dye was successfully sequestered using a novel adsorbent made of mixed fish scales (MFS). The influence of adsorbent dosage, initial pH, temperature, initial concentration and contact time on the adsorption performance was investigated. The surface chemistry and morphology of the adsorbent were examined by FTIR, TGA and SEM. Amides, phosphate and carbonate groups were evidently responsible for the high affinity of MFS towards the dye. The adsorption equilibrium and kinetic were well described by Langmuir and pseudo-second-order models, respectively. The maximum adsorption capacities of MFS were 145.3-157.3mg/g at 30-50°C. The adsorption of AB113 dye onto the adsorbent was exothermic and spontaneous as reflected by the negative enthalpy and Gibbs energy changes. The results support MFS asa potential adsorbent for AB113 dye removal.