Degradation Of Effluent Research Articles

Designing of waste fruit peels extracted cellulose supported molybdenum sulfide nanostructures for photocatalytic degradation of RhB dye and industrial effluent

Waste fruit peels which are usually discarded as agricultural wastes were utilized to isolate cellulose. The varied amount of isolated cellulose was used as sustainable support with hydrothermally synthesized molybdenum sulphide (MoS2) nano-petals via in-situ approach. The phase purity of all synthesized nanostructures was confirmed by PXRD whereas different oxidation states along with the interaction of cellulose with the MoS2 were examined by XPS analysis. In order to evaluate the performance of catalyst, the photodegradation rate was calculated for RhB dye as well as industrial effluent in visible light. The upgradation in photocatalytic competence was found significant by cellulose supported MoS2 nanostructures as compared to bare MoS2 nano-petals due to slow recombination of electron hole pairs. The maximum rate was pronounced by employing the cellulose at an amount of ~500 mg as a support due to existence of an optimal point where the delay in charge recombination reaches maximum.

Stimulation of [formula omitted]transition of g-C3N4 through ZnAl-layered double hydroxide for solar light assisted phenol degradation

The structural framework of graphitic carbon nitride (g-C3N4) was tuned with Zinc Aluminium layer double hydroxide (ZnAl-LDH), and its photocatalytic activity was investigated through solar light assisted phenol degradation of real effluent. The modified g-C3N4 (70%g-C3N4/ZnAl-LDH) possess more efficient inhibition of electron and hole pairs resulting in red shifting of absorption edge which stimulates the n−π∗ electronic transition. Morphological studies confirm that the LDH flocks consistently covered the g-C3N4 sheets affirming a substantial collaboration between two-layered material through electrostatic interlink and charge exchange synergy. Furthermore, 70%g-C3N4/ZnAl-LDH have an increased surface area of 26.292 m2/g and a reduced bandgap energy of 2.55 eV, which results in enhanced photocatalytic activity. The results of experimental study indicate that after 300 min of illumination in slight acidic condition, with 1.5 g/L chemical oxidant dose at 3 L/h reactor flowrate, 70%g-C3N4/ZnAl-LDH exhibits 79.35% degradation of phenol, and under same conditions, g-C3N4 confers 61.25% degradation.

Synthesis of birnessite-type manganese oxide from two different reducing agents via solvent-free method and the catalytic activity in degradation of POME

Birnessite-type manganese oxide is multifunction material that has been used in various application and the characteristic depends heavily upon its preparation method. In this study, birnessite-type manganese oxide was synthesized using the reaction between KMnO4 (oxidant) and two different reducing agents i.e., citric acid and oxalic acid via a solvent-free method. The characterization of the birnessite was carried out using X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX), and Surface Area Analyzer (SAA). Birnessite from this variation of reducing agents showed different levels of crystallinity, diverse morphology, crystal size, and surface area. The birnessite-type was then applied as a catalyst for the degradation of Palm Oil Mill Effluent (POME) with hydrogen peroxide (H2O2) as an oxidant to reduce the concentrations of Chemical Oxygen Demand (COD). The maximum reduction in COD concentration was obtained using the catalyst concentration of 400 and 800 mg/L for reducing agent of as-synthesized catalyst citric acid and oxalic acid. Birnessite-type manganese oxide shows potential as a catalyst in the degradation of POME with citric acid as reducing agents showed better degradation in reducing COD values.

Facile synthesis of 1D/1D ZnO@h-MoO3 for enhanced visible light driven photo degradation of industrial textile effluent

ZnO@h-MoO3 heteronanostructure with ZnO nano rods on 1D h-MoO3 was successfully synthesized via cost effective facile solid state impregnation-calcination method. XRD results confirm the presence of hexagonal structured ZnO and MoO3 in the heteronanostructures. FESEM and HRTEM images proved that one dimensional rod shaped ZnO has been decorated on 1D h-MoO3 structures. The possible formation and photocatalytic mechanism were explained in detail. Compared to pristine h-MoO3 and ZnO, the heterostructure shows superior visible light activity (>95%) on Methylene Blue degradation. Also, the catalyst was employed to degrade the textile dye effluent (real sample analysis) and degraded effectively under the influence of visible light.

Degradation of simulated Direct Orange-S (DO-S) textile effluent using nonthermal atmospheric pressure plasma jet.

One of the major environmental issues of textile industries is the discharge of large quantities of textile effluents, which are source of contamination of water bodies on surface of earth and quality of groundwater. The effluents are toxic, non-biodegradable, carcinogenic and prodigious threats to human and aquatic creatures. Since textile effluents can be treated efficiently and effectively by various advanced oxidation processes (AOPs). Among the various AOPs, cold atmospheric pressure plasma is a promising method among many prominent techniques available to treat the effluents. In this paper, we report about the degradation of simulated effluent, namely Direct Orange-S (DO-S) aqueous solution, using nonthermal atmospheric pressure plasma jet. The plasma treatment of DO-S aqueous solution was carried out as a function of various operating parameters such as potential and treatment time. The change in properties of treated DO-S dye was investigated by means of various analytical techniques such as high-performance liquid chromatography, UV-visible(UV-Vis) spectroscopy and determination of total organic content (TOC). The reactive species present in the samples were identified using optical emission spectrometry (OES). OES results confirmed that the formation of reactive oxygen and nitrogen species during the plasma treatment in the liquid surface was responsible for dye oxidation and degradation. Degradation efficiency, as monitored by color removal efficiency, of 96% could be achieved after 1h of treatment. Concurrently, the TOC values were found to decrease with plasma treatment, implying that the plasma treatment process enhanced the non-toxicity nature of DO-S aqueous solution. Toxicity of the untreated and plasma-treated dye solution samples was studied using Escherichia coli (E. coli) and Staphylococcus (S. aureus) organisms, which demonstrated that the plasma-treated dye solution was non-toxic in nature compared with untreated one.

Treatment of Polysilicon Production Wastewater by Ferrate(VI) Microcapsule Oxidation and Biological Aerated Biofilter

Polysilicon production wastewater (PPW) is characterized by complex composition, high chemical oxygen demand (COD) concentration and poor biodegradability. An integrated process comprising of ferrate(VI) oxidation and biological aerated biofilter (BAF) was developed at lab scale for treating PPW with an initial COD of 3630 mg/L, biochemical oxygen demand (BOD5) of 350 mg/L, suspended solids (SS) of 440 mg/L, and turbidity of 430 nephelometric turbidity units (NTU). Firstly, the potassium ferrate(VI) (K2FeO4) microcapsules were synthesized by using the phase separation method in cyclohexane, and ethylcellulose was used as the microcapsule wall materials (WM). The stability could be enhanced greatly when ferrate(VI) was encapsulated in the microcapsules with a mass ratio of K2FeO4:WM of 1:4 in the air compared with pure K2FeO4. The microcapsules exhibited sustained release behaviour and higher oxidation efficiency than pure K2FeO4. The microcapsules were used to pretreat PPW. Under the oxidation conditions of pH 6.0, microcapsule dosage 5.0 g/L and reaction time 70 min, the removal efficiency of COD, suspended solids (SS) and turbidity reached 55.1%, 61.3% and 74.2%, respectively. Subsequently, the oxidation effluent was subjected to BAF treatment. Under a hydraulic residence time of 48 h and a gas:water ratio of 6:1, the final effluent values of COD, SS and turbidity were 308 mg/L, 35 mg/L and 28 NTU, respectively, corresponding to total removal of 91.5%, 92.0% and 93.5%, respectively. Thus, this work demonstrates the feasible and potential application of encapsulated ferrate(VI) samples in the degradation of various toxic effluents.

Use of biogenic copper nanoparticles synthesized from a native Escherichia sp. as photocatalysts for azo dye degradation and treatment of textile effluents

Textile wastewater contains a huge amount of azo dyes and heavy metals and catastrophically deteriorates the agricultural field by affecting its phyisco-chemical/biological and nutritional properties when directly drained to agricultural lands without any treatment. Recently, biogenic copper nanoparticles (CuNPs) have gained considerable attention for photocatalytic degradation of wastewater pollutants owing to their unique physico-chemical and biological properties, low cost and environmental sustainability. The current study reports the synthesis of CuNPs by a native copper-resistant bacterial strain Escherichia sp. SINT7 and evaluation of the photocatalytic activity of the biogenic CuNPs for azo dye degradation and treatment of textile effluents. Scanning electron microscopy and transmission electron microscopy revealed the spherical shape of biogenic CuNPs with particle size ranging from 22.33 to 39 nm. Moreover, X-ray diffraction data revealed that the CuNPs have spherical crystalline shapes with an average particle size of 28.55 nm. FTIR spectra showed the presence of coating proteins involved in the stabilization of nanomaterial. Azo dye degradation assays indicated that CuNPs decolorized congo red (97.07%), malachite green (90.55%), direct blue-1 (88.42%) and reactive black-5 (83.61%) at a dye concentration of 25 mg L−1 after 5 h of sunlight exposure. However, at 100 mg L−1 dye concentration, the degradation percentage was found to be 83.90%, 31.08%, 62.32% and 76.84% for congo red, malachite green, direct blue-1 and reactive black-5, respectively. Treatment of textile effluents with CuNPs resulted in a significant reduction in pH, electrical conductivity, turbidity, total suspended solids, total dissolved solids, hardness, chlorides and sulfates as compared to the non-treated samples. Thus, the promising dye detoxification and textile effluent recycling efficiency of biogenic CuNPs may lead to the development of eco-friendly and cost-efficient process for large-scale wastewater treatment.

Alkali halide tailored graphitic carbon nitride with an extended optical absorbance for solar photocatalytic degradation of phenol

The structural, optical, textural, and photocatalytic properties of graphitic carbon nitride (g-C3N4) has been modified thru the elemental doping with Sodium and potassium salts. The skeletal distortion of g-C3N4 enables the tuning of electronic structure and positions of valence and conduction band. It also has reduced the charge separation rate, which activates the n-π* transitions resulting in an improved light absorption capacity. Furthermore, the +1 oxidation state of Na and K has incorporated in the structure of g-C3N4 and reduces the in-plane long-range periodic arrangement. Though there was no significant change in surface area was observed, but these factors govern an improved photocatalytic performance for phenolic effluent degradation in natural solar light, the current experimental studies indicate that slight acidic condition, i.e., pH 5 with 800 mg/L chemical oxidant dose at 4 L/h of effluent flow denotes 91.25, and 86.30% degradation of phenol, while in case of g-C3N4 it was 67.95%.

Ultrasonic cavitation tailored wastewater purification and desalination using thick sand of highly permeable deep aquifer

Pulp and paper industry generates large wastewater volumes containing recalcitrant and toxic compounds in various forms. These compounds are highly toxic and standard primary/secondary treatments are unable to filter heavy metal contaminants besides organic species. An emerging demand of advance level treatment is the motivation of current work that explores possibility of using thick sand of deep aquifers as an adsorbent to remove inorganic and organic contaminants simultaneously from wastewater besides desalination. Popular ultrasonic cavitation is used to accelerate degradation of toxic organic effluent into less toxic open ring structures besides curing heavy metals to form new bonds during adsorption. Because of extreme local environment due to cavitation, heavy metals coagulate in silicon-aluminum atomic meshes and carbon nano tubes for less toxic new crystalline structure. Significant changes in physico-chemical investigations like pH, chemical oxygen demand and colour towards drinkable water standards indicate effective adsorption resulting into wastewater purification.

Advances in photo-catalysis approach for the removal of toxic personal care product in aqueous environment

Removal of personal care products (PCPs) has become one of the challenging aspects around the globe. From the last few decades, it has been introduced as one of the emerging pollutants to the environment that affects directly or indirectly our ecosystem mainly aqueous environment. From biodegradation to photo-degradation mechanism, there are different categories of treatment methods, while the priority is based upon being cheaper, effective, reliable, environmental and economically friendly that should be compatible to water chemistry. Currently, photo-catalysis is considered as one of the most reliable and efficient non-conservative technologies for the degradation of PCPs industrial effluents from the aqueous environment. A recent development of photo-catalysis technology for the removal of PCPs gives efficient performance by using carbonaceous TiO2 composites. By using hybrid nature of photo-catalyst, one can achieve suitably high and attractive efficiency with comparable low cost. In this review article, the different photo-catalysis mechanism while moving from non-photo-catalysis to photo-catalysis approach and its practical application for the removal efficiency of various polluting agents have been discussed. A critical evaluation on the various parameters for this approach is highlighted. Future perspective refers to the need for coupling of different semiconducting nano-materials with photo-catalysis that could yield higher efficiency than those of previous one. This facilitates further insight into photo-catalysis approach for the efficient degradation of PCPs to ensure healthy aqueous environment, and some points regarding fate of PCPs should be discussed in future perspective.

TiO2/anthill clay as a heterogeneous catalyst for solar photocatalytic degradation of textile wastewater: Catalyst characterization and optimization studies

This present study aims at revealing the activity of TiO2–anthill clay in photocatalytic degradation of textile effluent. It also aims to investigate the effects of parameters affecting the photocatalytic degradation process such as catalyst dose (0.5–25 wt.%), reaction time (1–3 h) and solution pH (2–10) through central composite design. The synthesized photocatalyst was characterized using BET, SEM, EDX, FTIR, and XRF techniques. The results obtained from the optimization studies revealed that there were good agreements between the predicted and observed values of photocatalytic degradation efficiency. The maximum decolorization efficiency of 70.92% was obtained under the optimum experimental conditions of 2.50 wt.% catalyst dose, 1.07 h reaction time, and dye solution pH of 2.0. The TiO2-anthill photocatalyst was found to be efficient for complete decolorization of dye solution as it was able to be reused for up to four cycles.

Catalytic degradation of anthraquinones-containing H2O2 production effluent over layered Co-Cu hydroxides: Defects facilitating hydroxyl radicals generation

Anthraquinones from H2O2 production effluent (AHE) was remediated over a Co-Cu Layered Double Hydroxide (LDH) through a Fenton-like reaction process. The variation of synthesis pH value has found to significantly influence the catalyst performances for hydroxyl radical generation. Defects (oxygen vacancies) in the catalyst surface which facilitates H2O2 decomposition was systematically studied with adjusting the synthesis pH value. The framework of catalyst with LDH feature was thoroughly characterized by several spectroscopy techniques. The formation of Co-O-Cu oxo-bridged bond is assumed to be responsible for the electron transfer and the generation of defects. However, the surface electronic structure was altered with the changes in Co and Cu contents. The defect-rich LDH framework with abundant defects (oxygen vacancies) promote electron transfer, and H2O2 dissociation are primarily to account for the excellent catalytic performance. The application of this catalyst and its optimization of operational parameters in AHE removal were thoroughly performed as well.

Preparation and Application of ZnFe2O4/α-Al2O3 for Photocatalytic Degradation of Methylene Blue Dye and Real Textile Effluent

Present work was aimed at the development of α-Al2O3 supported ZnFe2O4 visible-light responsive photocatalysts. ZnFe2O4 and α-Al2O3 supported ZnFe2O4 were synthesized using co-precipitation method followed by calcination at 500 °C. The synthesized photocatalysts were characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The synthesized ZnFe2O4 has low crystallinity. The particle size of ZnFe2O4 is much smaller than that of the α-Al2O3 support, and ZnFe2O4 particles are dispersed on the surface of the crystalline α-Al2O3 support. 30 wt % ZnFe2O4/α-Al2O3 exhibited the highest photocatalytic activity for degradation of methylene blue dye than ZnFe2O4 and other α-Al2O3 supported photocatalysts containing 10 wt%, 20 wt% and 40 wt% ZnFe2O4. Kinetics of photocatalytic degradation of methylene blue dye using 30 wt% ZnFe2O4/Al2O3 obeys Langmuir–Hinshelwood kinetic model. Photocatalytic treatment of real textile wastewater resulted in more effective (when compared to photolytic treatment) in the reduction of wastewater’s chemical oxygen demand (COD), pH, conductivity and total dissolved solids (TDS). 30 wt% ZnFe2O4/Al2O3 was found to be more effective than unsupported ZnFe2O4 for the reduction of wastewater’s COD, pH, conductivity and TDS.

Shape-Controlled Fabrication of ZnO Architectures for Palm Oil Mill Effluent Degradation.

Shaped-controlled ZnO architectures including spherical, rod, rice-like and flower-like were fabricated via a reflux method in which the morphology, crystallinity, functional group and optical properties were tailored under different pH values in the precursor solution. The photoactivities of the prepared ZnO were evaluated under UV irradiation and the findings implied that the flower-like ZnO synthesized at pH 12 displayed superior activities on palm oil mil effluent degradation than those of other structures. The photocatalytic enhancement of flower-like ZnO was ascribed to its unique architecture, good crystallinity and superior optical properties. The flower-like ZnO with excellent photocatalytic performance have been confirmed by formation of hydroxyl radicals using a terephthalic acid-photoluminescence test. There was an optimal photocatalyst amount of 1.0 g/L, at which a maximum chemical oxygen demand removal of palm oil mill effluent was achieved under exposure of UV light. The phytotoxicity experiment via mung beans demonstrated a decrease in phytotoxicity.

Fatty acids, C and N dynamics and stable isotope ratios during experimental degradation of shrimp pond effluents in mangrove water

Intensive shrimp farming generates high loads of wastewaters that are released along tropical coastlines with potential impacts on the ecosystems. In this study, we used an experimental approach to analyze the behavior of shrimp pond effluents released in the Can Gio mangrove waterways (Southern Vietnam). We incubated shrimp pond effluents (EF), river water (RV), and a mixture of both (MI; 90% RV + 10% EF) in a dark room and measured fatty acid (FA) compositions, C and N concentrations and stable isotopes ratios (δ13C and δ15N) of suspended particulate matter during 16 days. Fatty acid concentrations rapidly decreased in EF with a 50% loss of FA during the first 24 h of the experiment and a 75% loss after 4 days of incubation. Proportions of the FA 18:1ω7 increased in MI during incubation, suggesting that this FA may be used as a tracer of anthropogenic substances release in marine environments.

Catalytic Degradation of Textile Wastewater Effluent by Peroxide Oxidation Assisted by UV Light Irradiation

Textile industries produce a complex wastewater which is difficult to be treated. In this work, a catalytic degradation of wastewater effluent composed of sulphur black coloring agent discharged by industry was studied. UV lamp power, peroxide concentration, pH, and iron oxide catalyst were varied to determine the best conditions for oxidative treatment. Kinetic parameters were evaluated based on the reaction model proposed. In the absence of iron oxide catalyst, chemical oxygen demand (COD) and biological oxygen demand (BOD) degradation of up to 80% and 75%, respectively, were observed as resulting from using an H2O2 concentration of 0.61 moles/L, UV lamp power of 30 watts, and pH of 6. When using an iron oxide catalyst combined with UV light irradiation, the degradation rate could be increased significantly, while similar final COD and BOD degradation percentages resulted. It is found that the reaction rate order was shifted from first order to second order when using an H2O2/UV/Fe2O3 system. The results could be an alternative for treating textile industry wastewater, and the parameters obtained can be used for equipment scale-up.

Electrochemical process and Fenton reaction followed by lamellar settler to oil/surfactant effluent degradation

Degradation of simulated oil-surfactant effluent was tested using electro-oxidation with commercial Dimensionally Stable Anode (DSA®) and Fenton reaction followed by lamellar settler to remove iron sludge. Chemical Oxygen Demand (COD), turbidity, iron monitoring, Total Current Efficiency (TCE) and Power consumption for electrolytic reactions were used to evaluate the efficiency of the degradation process. Fenton experiments showed good COD and Turbidity removal, mainly when catechol (0.5 mM) was used as catalyst, and promoted the COD removal from 37 to 67% ([Fe2+] = 0.5 mM; [H2O2] =200 mM), however, 88% was removed when [Fe2+] = 0.7mM. The lamellar settler was effective for iron waste removal, reducing the overall time for the whole process. Electrochemical degradation provided good results, either by direct oxidation at the electrode surface or indirect, by the strong oxidants electrogeneratedfrom electrolytes, achieving 82 and 89% of COD removal for H2SO4(90 mA cm−2) and HCl (60 and 90 mA cm−2), respectively. First order constant showed sulfate base reaction faster, with 72% removal at 30 min. Turbidity, TCE and Energy analysis corroborate COD, revealing the possibility of lower reaction time when sulfate was used and lower current density with chloride, leading to economic viability of the process.

New insights into surface functionalization and preparation methods of MWCNT based semiconductor photocatalysts

Abstract The manuscript primarily describes the influence of various synthesis strategies on the photocatalytic properties of MWCNT/TiO2 binary nanohybrids. The multiwalled carbon nanotube modified titania hybrids synthesized via two-step reaction involving the covalent functionalization with green and mild oxidizing agent like H2O2, followed by simple surfactant/template free hydrothermal synthesis exhibited the maximum photocatalytic efficiency. The Total Organic Carbon (TOC) analysis showed complete mineralization of the persistent Rhodamine B dye in about 8 h. These synthesized nanohybrids in varying MWCNT content were tested for their photocatalytic efficiency in the degradation of explosive effluents like 4-nitrophenol and picric acid. The UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller Surface area analysis (BET), Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM) and Raman spectra analysis evidently revealed the effective synergistic interaction between the MWCNT and titania at the interface that has contributed to the significant enhancement of photocatalytic performance.

Highly efficient CaCO3-CaO extracted from tap water distillation for effective adsorption and photocatalytic degradation of malachite green dye

The present work demonstrated the extraction, characterization, adsorption and photocatalytic properties of hardness causing minerals obtained from tap water distillation. The resulting white powder material is sintered at different temperature. XRD and EDS analysis revealed that powder residue consists of mainly calcium carbonate (CaCO3) having surface area 35.4 m2g−1 that decomposed to CaO after sintering at 900°C for 4h. This CaCO3 powder displayed effective adsorption and photocatalytic degradation of malachite green dye under sunlight relative to the commercial sample. The impact of different parameters like concentration of dye, amount of catalyst on adsorption and photodegradation was studied in details. The adsorption behavior follows the Freundlich adsorption isotherm and photodegradation process exhibited a higher rate constant of k = 5.1 x 10−2 min−1. Therefore, the use of this material could be a greener approach for effective removal and degradation of toxic effluent in wastewater for large-scale industrial applications.

An innovative transformation of waste toner powder into magnetic g-C3N4-Fe2O3 photocatalyst: Sustainable e-waste management

In this work, we report an ecofriendly and sustainable approach to recycle the waste toner powder enriched in organic residues and magnetic Fe3O4. The direct calcination of waste toner powder at 600 °C ensures the complete decomposition of organic residues and transformation of Fe3O4 into useful magnetic Fe2O3 without any single chemical treatments. We also exploit the e-waste derived Fe2O3 as an iron precursor and thiourea for the fabrication of g-C3N4-Fe2O3 photocatalyst through facile one-step calcination process. The obtained Fe2O3 and g-C3N4-Fe2O3 were characterized by XRD, TGA, SEM-EDS, TEM, BET, XPS, UV–vis. DRS, FT-IR, PL, EIS and VSM. The photocatalytic activity of the g-C3N4-Fe2O3 was evaluated by the degradation of Methyl Orange (MO) and Textile Effluents (TE) under sunlight. The resultant g-C3N4-Fe2O3 exhibited better photocatalytic activity than the Fe2O3 and g-C3N4. Owing to the excellent stability and magnetic separation ability, g-C3N4-Fe2O3 composite displayed superb recyclability without loss of significant photocatalytic activity up to five repeated runs and more significantly, it can be recovered magnetically. This novel e-waste recycling strategy may provide new possibilities for a large-scale and low-cost transformation of waste toner powder into magnetically separable photocatalyst for wastewater treatment.