Real Wastewater Samples Research Articles

Cu2S/Ni3S2 nanosheets combined with nickel foam substrate for efficient catalytic ozonation of p-nitrophenol in wastewater

Cu2S/Ni3S2@NF catalyst was prepared by hydrothermal method, and the catalytic ozonation of PNP solution (100 mg/L) was carried out. The removal rate of PNP under optimal experimental conditions was 99.9 % in 40 minutes, which was a significant increase over other systems. ESR revealed that singlet oxygen and superoxide radicals were the primary active ingredients. After the catalyst was used for five times, the catalytic activity remained basically unchanged. The possible degradation pathway and mechanism of Cu2S/Ni3S2@NF catalytic ozonation of PNP were proposed by gas chromatography-mass spectrometry. In real wastewater samples with complex compositions, the Cu2S/Ni3S2@NF/O3 system also achieved efficient degradation. The mechanism and possible pathway of Cu2S/Ni3S2@NF catalytic ozonation of PNP were proposed. This study provides an efficient, durable, and easy-to-recycle ozone catalyst, which provides a feasible pathway for the treatment of phenolic pollutants.

Validity of zinc oxide nanoparticles biosynthesized in food wastes extract in treating real samples of printing ink wastewater; prediction models using feed-forward neural network (FFNN)

In the present study, biosynthesized ZnO nanoparticles in food wastewater extract (FWEZnO NPs) was used in the photocatalytic degradation of real samples of printing ink wastewater. FWEZnO NPs were prepared using green synthesis methods using a composite food waste sample (2 kg) consisted of rice 30%, bread 20 %, fruits 10 %, chicken 10 %, lamb 10%, and vegetable 20%. The photocatalysis process was optimized using response surface methodology (RSM) as a function of time (15–180 min), pH 2–10 and FWEZnO NP (20–120 mg/100 mL), while the print ink effluent after each treatment process was evaluated using UV–Vis-spectrophotometer. The behaviour of printing ink wastewater samples for photocatalytic degradation and responses for independent factors were simulated using feed-forward neural network (FFNN). FWEZnO NPs having 62.48 % of the purity with size between 18 and 25 nm semicrystalline nature. The main functional groups were –CH, CH2, and –OH, while lipid, carbon-hydrogen stretching, and amino acids were the main component in FWEZnO NP, which contributed to the adsorption of ink in the initial stage of photocatalysis. The optimal conditions for printing ink wastewater were recorded after 17 min, at pH 9 and with 20 mg/100 mL of FWEZnO NPs, at which the decolorization was 85.62 vs. 82.13% of the predicted and actual results, respectively, with R2 of 0.7777. The most significant factor in the photocatalytic degradation was time and FWEZnO NPs. The FFNN models revealed that FWEZnO NPs exhibit consistency in the next generation of data (large-scale application) with an low errors (R2 0.8693 with accuracy of 82.89%). The findings showing a small amount of catalyst is needed for effective breakdown of dyes in real samples of printing ink wastewater.

Environmental Pollution Monitoring via Capillary Zone Electrophoresis and UHPLC Simultaneous Quantification of Some Antipsychotic Drug Residues in Industrial Wastewater Effluents

Monitoring and measuring pharmaceutical pollutants in environmental samples is a vital and complex task due to their potential detrimental effects on human health, even at low levels. Using capillary zone electrophoresis (CZE) and ultra-high-performance liquid chromatography (UHPLC), it was possible to separate and measure three commonly used antipsychotic drugs, chlorpromazine (CPZ), haloperidol (HAL), and risperidone (RIS), in wastewater of the pharmaceutical industry. The technique of solid-phase extraction (SPE) was developed and implemented as a very effective method for preparing samples prior to analysis. The settings of the capillary electrophoretic and chromatographic techniques were adjusted to obtain the most efficient separation profile for the medications being studied. The concentration of all the medicines being investigated ranged from 0.5 to 50 µg/mL. SPE was used to treat real wastewater samples after a thorough validation process that followed the rules set by ICH-Q2B. The developed assays were then effectively employed to identify the tested antipsychotic substances in the real wastewater samples. The provided methodologies may be efficiently utilized to monitor the extent of environmental contamination caused by the investigated pharmaceuticals.

Banana peels as a green bioadsorbent for removing metals ions from wastewater

Bioadsorption using agricultural waste offers a promising approach for removing toxic metals from wastewater. This study explores the potential of chemically activated banana peels (BPs) as a green and cost-effective bioadsorbent for Cu(II) and Zn(II) removal. Fourier-transform infrared (FTIR) spectroscopy revealed the presence of functional groups like alcohols, phenols, and amino acids on activated BPs, potentially responsible for metal ion binding. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of cavities on the BPs surface and the existence of oxygen and potassium. The adsorption capacity of BPs was investigated under various conditions, including pH, contact time, sorbent dosage, metal concentration, and temperature. This study used Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich (D–R) isotherm models to describe the equilibrium results of Cu (II) and Zn (II) adsorption. The Langmuir isotherm model best described the adsorption process, suggesting monolayer coverage of metal ions on the BPs surface. Maximum adsorption capacities were 3.2 mg g−1 for Cu(II) and 2.8 mg g−1 for Zn(II), demonstrating the effectiveness of BPs in metal removal. Kinetic studies indicated pseudo-first-order (PFO) behavior for Cu(II) and pseudo-second-order (PSO) behavior for Zn(II) adsorption. Thermodynamic analysis revealed a spontaneous and exothermic process (negative Gibbes free energy (ΔG°) and enthalpy (ΔH°) with decreased randomness [negative entropy (ΔS°)] at the biosorption interface. Finally, the BPs sorbent was successfully applied to remove different metal ions from real wastewater samples collected from the El Wadi drain.

Complete removal of organophosphate pesticides from wastewaters with sustainable ionic liquid-based aqueous two-phase strategy

Due to extensive food production, organophosphate pesticides (OPs) are widely utilized for crop protection, leading to their presence in the environment. The focus of this study was the design of an efficient aqueous biphasic system (ABS) strategy for OP removal, namely, malathion (MAL), azinphos-methyl (AZM), and chlorpyrifos (CHP) from water. Different ionic liquids (ILs) with symmetrical cations were selected as ABS phase-formers (tetrabutylphosphonium salicylate, tetrabutylammonium salicylate, 1,3-dibutylimidazolium dicyanamide, 1,3-dibutylimidazolium salicylate and 1,3-dibutylimidazolium bromide) with citrate salt as a salting-out agent. Initially, phase diagrams were determined, followed by partition studies revealing that the partition of MAL and CHP aligns with the IL- ABS formation trend, while the AZM partition is governed by specific interactions with ILs. For optimization studies, tetrabutylphosphonium-salicylate i.e. [TBP][Sal]-based ABS was chosen, due to obtained high extraction efficiencies of over 99.3 %. After establishing the effects of pH, temperature, tie-line length, and phase ratio on extraction performance, extraction of OPs from a real wastewater sample further confirmed the effectiveness of the designed method achieving complete removal of each pesticide. Furthermore, recovery of IL was achieved using an antisolvent method to precipitate CHP followed by IL-reuse in three consecutive cycles without efficiency decreased. Finally, it was demonstrated that [TBP][Sal] exhibits low cytotoxic potential, indicating that the presence of low amounts of this IL in aqueous media could be acceptable from ecotoxicological standpoint. This study showcased the exceptional potential of the proposed technology for the efficient and sustainable treatment of wastewater contaminated with OPs, affirming its capability to treat significant wastewater volumes.

The use of Fe3O4/MnO2-Ag nano-photocatalyst to remove dyes from real wastewater samples under visible light

The use of Fe3O4/MnO2-Ag nano-photocatalyst to remove dyes from real wastewater samples under visible light

Efficient degradation of Rhodamine B by visible-light-driven biomimetic Fe(III) complex/peroxymonosulfate system: The key role of FeV=O

Advanced oxidation systems (AOS) hold promise for tackling refractory dyes in wastewater, yet the quest for efficient systems tailored to the degradation of dye remains a formidable hurdle. Here, a novel visible-light-driven AOS, consisting of biomimetic Fe(III) salen complex (FeL, salen= N, N-bis(salicylidene)ethylenediamine) and peroxymonosulfate (PMS), was proposed for highly efficient degradation of Rhodamine B (RhB), a model dye. The proposed AOS was capable of degrading 94.8 % RhB in 40 min, outperforming the typical Fe3+-based system, which achieved only 52.6 % pollutant degradation under identical conditions. As indicated by experimental results and theoretical calculations, the unique Fe-N2O2 coordination structure of FeL facilitated the adsorption of terminal O (O3) at PMS site, thereby enhancing the heterolysis of the O-O bond and generating high-valent iron-oxo species (i.e., FeⅤ=O) rather than radicals (SO4•−, HO•). The system demonstrated robust resistance to interference from environmental anions (Cl−, NO3−, HCO3−, SO42−), pH variations (initial pH 3.0–11.0) and humic acid. More attractively, it achieved 87.3 % chroma and 37.6 % chemical oxygen demand (COD) removal in real dye wastewater samples. This work may shed light on the understanding and development of biomimetic Fe complexes-based AOS for wastewater treatment.

An optimised and validated surrogate analyte A-TEEM-PARAFAC-PLS technique for detecting and quantifying the biological oxygen demand in surface water.

A 5-day test duration makes BOD5 measurement unsatisfactory and hinders the development of a quick technique. Protein-like fluorescence peaks show a strong correlation between the BOD characteristics and the fluorescence intensities. For identifying and measuring BOD in surface water, a simultaneous absorbance-transmittance and fluorescence excitation-emission matrices (A-TEEM) method combined with PARAFAC (parallel factor) and PLS (partial least squares) analyses was developed using a tyrosine and tryptophan (tyr-trpt) mix as a surrogate analyte for BOD. The use of a surrogate analyte was decided upon due to lack of fluorescent BOD standards. Tyr-trpt mix standard solutions were added to surface water samples to prepare calibration and validation samples. PARAFAC analysis of excitation-emission matrices detected the tyr-trpt mix in surface water. PLS modelling demonstrated significant linearity (R2 = 0.991) between the predicted and measured tyr-trypt mix concentrations, and accuracy and robustness were all acceptable per the ICH Q2 (R2) and ASTM multivariate calibration/validation procedures guidelines. Based on a suitable and workable surrogate analyte method, these results imply that BOD can be detected and quantified using the A-TEEM-PARAFAC-PLS method. Very positive comparability between tyr-trypt mix concentrations was found, suggesting that tyr-trypt mix might eventually take the place of a BOD-based sampling protocol. Overall, this approach offers a novel tool that can be quickly applied in water treatment plant settings and is a step in supporting the trend toward rapid BOD determination in waters. Further studies should demonstrate the wide application of the method using real wastewater samples from various water treatment facilities.

Simultaneous Determination of 17 Phenolic Compounds in Surface Water and Wastewater Matrices Using an HPLC-DAD Method

A high-performance liquid chromatography with diode array detector (HPLC-DAD) analytical method was developed for the simultaneous detection of 17 phenolic compounds, including phenols, chlorophenols, alkylphenols, and nitrophenols, in two types of water matrices: wastewater and surface water. Prior to HPLC-DAD determination, a solid-phase extraction (SPE) procedure was optimized. The proposed method uses multiwavelength analysis, with the optimum detection wavelengths selected as 268 nm, 280 nm, 386 nm, 304 nm, and 316 nm. The highest resolution was achieved using a chromatographic column, Eclipse XDB-C18 (150 × 4.6 mm, 5 μm), which was kept at 20 °C. The mobile phase consisted of a gradient elution program, with mobile phase A being a 0.1% H3PO4 aqueous solution and mobile phase B being acetonitrile. The flow rate was set at 0.6 mL/min. The 17 target phenolic compounds were fully separated in less than 27 min. All compounds showed good linear regression, with correlation coefficients higher than 0.999. The method’s quantitation limits ranged from 4.38 to 89.7 ng/L for surface water and 7.83 to 167 ng/L for wastewater. The recovery rates were in the range of 86.2–95.1% for surface water and 79.1–86.3% for wastewater. The SPE-HPLC-DAD method was proven to be fast, sensitive, accurate, and reproducible. The developed method was successfully applied for the analysis of the 17 phenolic compounds in real surface water and wastewater samples, with phenol, 2,4-DNP, and 2,4-DNP being determined at levels greater than the method’s limits of quantitation (LOQs). The proposed analytical method represents an original technical resource for the simultaneous determination of 17 phenolic compounds in environmental water matrices.

High performance adsorptive removal of emerging contaminant paracetamol using a sustainable biobased mesoporous activated carbon prepared from palm leaves waste

In this work, a novel bio-based carbon material was prepared via a facile pyrolysis method using chemically activated dead palm leaves as a sustainable and efficient carbon precursor. The as-prepared activated carbon with KOH activation (AC-KOH) was characterized by XRD, FTIR, SEM, EDS, and BET analysis. The AC-KOH was used for the adsorption of paracetamol (PCT) from aqueous solutions and the effect of experimental conditions such as contact time (0.08–30 hours), pH (2.96–12.1), initial drug concentration (1–50 mg L−1), adsorbent dosage (0.12–1.2 g L−1), and temperature (25–45 °C) was investigated. The system achieved equilibrium in 4 hours and PCT uptake was highly dependent on solution pH. A maximum removal efficiency was achieved at a pH of around 5.86. Kinetic model analysis indicated that the uptake follows the pseudo-second-order model (R2 = 0.989). The maximum monolayer capacity of the developed AC for PCT was found to be 87.87 mg g−1 at time of equilibrium (4 hours), solution pH of 5.86, adsorbent dose of 0.2 g L−1, concentration of 1–50 mg L−1 and temperature of 25 °C. The PCT uptake process was feasible, spontaneous (ΔG0 < 0), and endothermic (ΔH0 > 0) according to the thermodynamics evaluation. The mechanism of PCT adsorption primarily involved pore-filling, π-π interaction, and H-bonding. The adsorbent exhibited reasonable reusability towards PCT adsorption up to two regeneration cycles. The results of this work support that the dead palm leaves are efficient, cheap, and sustainable feedstock for producing activated carbon adsorbent to be used for an efficient removal of PCT from real wastewater samples.

Synthesis and Characterization of Zinc Oxide Nanoparticle Anchored Carbon as Hybrid Adsorbent Materials for Effective Heavy Metals Uptake from Wastewater

Hybrid material-derived adsorbents have shown a great applicable efficiency in various fields, including industrial uses and environmental remediation. Herein, zinc oxide nanoparticle modified with carbon (ZnO-C) was fabricated and utilized for wastewater treatment through the adsorption of Zn(II), Cd(II), Co(II), and Mn(II). The surface and structural characteristics were examined using TEM, SEM, XRD, FTIR spectroscopy, EDS, and the BET surface area. Kinetics and equilibrium investigations were applied to optimize the adsorptive removal of Zn(II), Cd(II), Co(II), and Mn(II) onto ZnO-C. The results indicated that the formation of ZnO-C in crystalline sphere-like granules with a nano-size between 16 and 68 nm together with carbon matrix. In addition, the spherical granules of zinc oxide were gathered to form clusters. FTIR spectroscopy indicated that the ZnO-C surface was rich with OH groups and ZnO. The adsorption capacity 215, 213, 206, and 231 mg/g for Zn(II), Cd(II), Co(II), and Mn(II), respectively, at the optimal conditions pH between 5 and 6, a contact time of 180 min, and an adsorbent dose of 0.1 g/L. The adsorptive removal data modeling for the uptake of Zn(II), Cd(II), Co(II), and Mn(II) onto ZnO-C showed agreement with the assumption of the pseudo-second-order kinetic model and the Freundlich isotherm, suggesting a fast adsorption rate and a multilayered mechanism. The achieved adsorption capacity using the prepared ZnO-C was more effective compared to ZnO, carbon, Fe3O4, and Fe3O4-C. Real wastewater samples were applied, including valley water, industrial wastewater, and rain wastewater, and evaluated for the applicable uptake of Zn(II), Cd(II), Co(II), and Mn(II) using ZnO-C and Fe3O4-C with effective removal efficiency.

Cellulose-Based Waste in a Close Loop as an Adsorbent for Removing Dyes from Textile Industry Wastewater

In an attempt to reuse fibrous textile waste and, at the same time, to address dye pollution in textile wastewater, waste cotton-based yarn was utilized as a cheap and sustainable adsorbent, as well as a row material for carbon adsorbent production. Unmodified yarn and cotton-based carbon adsorbents were used as adsorbents for dye removal from water. Cotton and cotton/polyester yarn samples underwent thermal modification through carbonization followed by chemical activation with KOH. Various techniques, including scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption isotherms, and surface charge determination, were employed to analyze the morphological and surface characteristics of the cotton-based adsorbents. Adsorption properties were evaluated by testing the removal of selected cationic and anionic dyes from water. The impact of temperature, initial pH and concentration of the dye solution, and contact time on adsorption were investigated, and experimentally obtained data were analyzed using theoretical models. While carbonization alone did not significantly enhance adsorption properties, activated samples exhibited high efficacy in removing both cationic and anionic dyes from water. Despite the negative influence of the polyester component in the carbon precursor on the efficiency of activated samples in removing methyl orange, the results indicated that activated cotton and cotton/polyester yarn could be used to prepare highly efficient adsorbents for the rapid removal of methylene blue from real wastewater samples.

Efficient magnetic solid-phase extraction, UPLC-MS/MS detection, and consumption assessment of five trace psychoactive substances.

Wastewater-based epidemiology (WBE) has become an objective and updated surveillance strategy for monitoring and estimating consumption trends of psychoactive substances (PSs) in the population. Firstly, magnetic shrimp shell biochar-based adsorbent (DZMBC) was synthesized and employed for extraction trace PSs from municipal wastewater. Proper pyrolysis temperature and increased KOH activator content favored the pore structure and surface area, thus facilitating extraction. DZMBC delivered exceptional extraction performance such as pH stability, anti-interference property, fast magnetic separation ability, reusability, and reproducibility. Then, a method based on magnetic solid-phase extraction (MSPE) followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed, validated, and utilized for the quantitative determination of five PSs in real wastewater samples. Methodological validation results indicated a favorable linearity, low method limits of detection (1.00-4.75ng/L), and good precisions (intra-day and inter-day relative standard deviations < 4.8%). Finally, an objective snapshot of Chongqing drug use and consumption pattern was obtained. Methamphetamine (MAMP) and 3,4-methylenedioxymethamphetamine (MDMA) were the prevalent illegal drugs in local. Both concentrations and per capita consumption of MDMA displayed a change (P < 0.05) between July and September, while no statistical differences were observed for each week.

Green synthesis of metal nanoparticles from Codium macroalgae for wastewater pollutants removal by adsorption

AbstractAlgae have adsorption properties and reducing agents due to their rich content. In this study, palladium nanoparticles (Pd NP), platinum nanoparticles (Pt NP), and iron oxide nanoparticles (Fe3O4 NP) were prepared from Codium macroalgae using green synthesis. The structure of the synthesized nanoparticles was elucidated by X‐ray diffractometry, Fourier transforms infrared spectroscopy, Brunauer–Emmett–Teller analysis, transmission electron microscopy, ultraviolet‐visible spectroscopy and scanning electron microscopy‐energy dispersive X‐ray spectrometry and their use as nanoadsorbents for the removal of pollutants from aqueous media was investigated in detail. Naproxen (NPX), an anti‐inflammatory drug, and the dyes methylene blue (MB) and cresol red (CR) were selected as pollutants for this study. Batch adsorption experiments were conducted using both real wastewater obtained from the Organised Industrial Zone of Isparta Province and synthetic water samples prepared with tap water from Burdur Province and pure water. Under optimum adsorption conditions, Pd NP showed significant efficiency in the real wastewater sample, with an adsorption capacity of 37.19 and 50.03 mg g–1 for CR and NPX, respectively, within 150 min. In comparison, Pt NP showed an adsorption capacity of 40.01 mg g–1 for MB within the same timeframe. These findings indicate that while Pd NP showed the highest adsorption capacity for both CR and NPX, Pt NP showed the highest adsorption capacity for MB. The Langmuir model and the pseudo‐second‐order equation were more suitable to describe the adsorption behavior of CR, MB, and NPX. In addition, studies on the desorption and reusability of the nanoadsorbents were carried out under the same optimum experimental conditions.

Zr4+-mercaptosuccinate MOF for the uptake and recovery of gold nanoparticles and gold ions under batch and continuous flow conditions

The increasing use of nanomaterials in commercial products has raised concerns regarding their potential effects on water quality and living organisms. So far, most sorbents available for removing nanosized inorganic pollutants from water rely on electrostatic interactions or entrapment in the sorbent pores. However, this limits their applicability in real wastewater samples containing nanomaterials with variable surface properties and sizes, along with high concentrations of competitive species such as inorganic salts and organics. Little attention has also been paid to the recovery of nanoparticles after sorption. In this work, a Zr4+-mercaptosuccinate metal organic framework (MOF) with free thiol groups was investigated as a sorbent for the removal of Au nanoparticles and Au3+ ions from water. Sorption occurs on the surface of the MOF via the formation of strong metal-thiolate chemical bonds enabling the fast uptake of noble metal nanoparticles and noble metal ions from water (within <1 h). The maximum sorption capacity was found to depend on the size of the Au nanoparticles and ranged from 8 to 41.5 mg/g. The surface functionalization of nanoparticles did not influence sorption performance, which was also maintained in natural waters of variable matrix complexity. The material was also efficient in fixed bed columns with an estimated maximum Au sorption capacity of approximately 7 mg/g, which is significantly higher than the environmental concentrations of Au nanoparticles and adequate for their removal from industrial wastewater. Importantly, the sorbed nanoparticles could be quantitatively recovered (>90 %), at the expense of material degradation, enabling their potential reuse.

Application of cobalt-cerium-iron ternary layered double hydroxide for extraction of perfluorooctane sulfonate followed by HPLC-MS/MS analysis

Herein, Ce-doped CoFe layered double hydroxide (LDH), noted as CoCeFe ternary LDH, was prepared using the co-precipitation route. Prosperous synthesis of CoFe LDH and successful partial replacement of iron cations with cerium cations in CoCeFe ternary LDH were confirmed by X-ray diffraction patterns, energy-dispersive X-ray spectroscopy, and elemental dot-mapping images. Nanosheet morphology was recognized for both CoFe LDH and CoCeFe ternary LDH from scanning electron microscopy and transmission electron microscopy micrographs. In the following, a dispersive solid phase extraction (DSPE) method was developed using the synthesized CoCeFe ternary LDH as a sorbent for extracting perfluorooctanesulfonic acid (PFOS) from wastewater samples. For the selective analysis of PFOS, high-performance liquid chromatography-tandem mass spectroscopy (HPLC-MS/MS) in multiple reaction monitoring mode was used. Analytical parameters such as the limit of detection equal to 0.02 μg/L, with a linear range of 0.05–300 μg/L, the limit of quantification equal to 0.05 μg/L, and an enrichment factor equal to 23.3 were achieved for PFOS at the optimized condition (sorbent: 5 mg of CoCeFe ternary LDH, eluent type and volume: 150 μL mobile phase, pH: 3, adsorption time: 3 min, and desorption time: 5 min). The developed strategy for the analysis of PFOS was tested in real wastewater samples, including copper mine and petrochemical wastewater. The amount of analytes in real samples was calculated using the standard addition method, and good relative recovery in the range of 86%–105% was obtained. The main novelty of this research is the application of CoCeFe ternary LDH to extract the PFOS from wastewater using the DSPE method for determination by HPLC-MS/MS.

Remediation of malachite-green dye from textile wastewater using biosorbent almond shell-based cellulose

The presence of malachite green (MG) in surface waters represents a major health hazard for aquatic organisms and communities living near contaminated water sources. In this study, almond shell adsorbents prepared from the four almond types Marcona (M), Fournat de Brézenaud (FZ), Ferraduel (FD) and Ferriages (FG), used to clean wastewater from the textile industry that had been contaminated with the color MG. Optimal adsorption parameters were determined through batch experiments using a standard dye solution. Further, SEM, XRD, BET, and FTIR were employed for characterizing the biosorbents. The examination of the experimental data using isotherms and kinetic models revealed that the adsorption of the MG occurs in a monolayer, with chemical adsorption as the rate-controlling step. The maximum adsorption capacities, under pH around 7 and temperature of 35 °C were 41.0, 61.0, 48.1, and 118.0 mg/g for M, FD, FG, and FZ, respectively. In addition, Monte-Carlo simulation models, and density functional theory calculations were performed to provide a more detailed understanding of the adsorption mechanism. Topological studies such as NCI, RDG, LOL, and ELF were conducted and discussed using Multiwave function (Multiwfn) and VMD programs in liquid phase. In conclusion, chemisorption limits the rate of the adsorption process, and that green cation malachite is more susceptible to nucleophilic than electrophilic attacking. Based on these experimental and theoretical results, it is possible to consider these materials as an inexpensive and viable solution to eliminate MG from wastewater. Adsorption on cellulose can be considered as a feasible strategy for wastewater treatment, and the adsorbents can be optimized for use in real wastewater samples at even lower concentrations. This approach offers an inexpensive and effective technological alternative to conventional methods for the retention of MG.

Distinguishable photorecycling of PVDF nanocomposites membrane for reactive yellow 145 dye and real industrial wastewater treatment by different photocatalytic processes

This paper investigates the photocatalytic performance and recyclability of PVDF-MWCNTs-TiO2 nanocomposite membranes for the treatment of textile wastewater under sunlight irradiation. The nanocomposites were fabricated by incorporating varying weight ratios of MWCNTs-TiO2 (1 %, 3 %, 6 %, and 9 %) into PVDF matrices using a solvent casting method. Optimal loading of MWCNTs-TiO2 at 9 wt% resulted in nanocomposites with enhanced surface area (94.15 m2/g), reduced band gap (2.38 eV), uniform dispersion of nanoparticles, and abundant surface hydroxyl groups. Under Xenon lamp irradiation, the optimized PVDF-9 %(MWCNTs-9 %TiO2) nanocomposite achieved a high apparent reaction rate constant (kapp) of 9.92 × 10−3 s−1 for photocatalytic degradation of the model dye Reactive Yellow 145. Significantly, when tested on-site at a Saudi Arabian textile facility over 6 months, this nanocomposite effectively reduced the chemical oxygen demand (COD) of real wastewater samples to regulatory limits of 1000 ppm under natural sunlight irradiation. The COD values were lowered from an initial 5050–6200 ppm to a final range of 785–945 ppm using the PVDF-9 %(MWCNTs-9 %TiO2) membrane. Furthermore, the optimized nanocomposite exhibited good recyclability, retaining around 87 % of its initial activity after 8 reuse cycles for industrial wastewater treatment. The excellent photocatalytic efficiency and reusability of the MWCNTs-TiO2 modified PVDF nanocomposite under solar irradiation highlight its promise as a sustainable membrane technology for environmental remediation.

Application of TiO2-loaded fly ash-based geopolymer in adsorption of methylene blue from water: Waste-to-value approach

This paper aims to explore the removal of methylene blue from wastewater using fly ash-based geopolymer (FAG) modified with titanium dioxide (TiO2) nanoparticles referred to as FAG-TiO2. Using several analytical techniques, the modified geopolymer was physically and chemically characterized. Additionally, it was investigated how pH, MB concentration, and temperature affected the MB adsorption process utilizing FAG-TiO2. Scanning electron microscopy images exhibited a porous morphology. Furthermore, transmission electron microscopy images revealed a nanostructured shape, with nanoparticles clumping together to form small channels suitable for MB adsorption. The stretching vibration of the alumina silicate was seen using the Fourier transform infrared, indicating that geopolymerization was successfully conducted. The developed FAG-TiO2 showed a remarkable capacity for MB adsorption from the aqueous phase. The Langmuir isotherm model was the best-fitting adsorption model, with a maximum adsorption capacity of 103.19 mg/g at pH 6 and 35 °C. The thermodynamics investigations revealed negative values for Gibbs free energy (ΔGo), emphasizing the spontaneous nature of the processes. While the positive entropy (ΔSo) indicated a significant affinity between the two phases, the positive enthalpy (ΔHo) implies an endothermic reaction. Additionally, hydrogen bonds, n-π, and electrostatic interactions between MB and FAG-TiO2 facilitated the adsorption process. Furthermore, desorption studies with two different chemicals were used to investigate MB retention onto FAG-TiO2. The adsorbents were desorbed using an HCl (0.5 M) reagent where the maximum MB desorption reached 41.95%. Real wastewater samples were also tested, and promising results were found, indicating the possible use of the prepared adsorbent in industrial applications.

Multitasking needle-shaped copper oxide nanorods decorated cystine modified polymer/graphene oxide nanocomposite for 4-nitrophenol reduction, dye degradation, and textile effluent treatment

Nitroaromatic chemicals, including 4-nitrophenol (4-NP) and dyes, pose substantial risks to human health and the environment. Various catalysts that facilitate the reduction of 4-NP to 4-aminophenol (4-AP) have been documented to reduce its toxicity. Herein, we developed a novel nanocomposite consisting of needle-like copper oxide nanorods immobilized with L-cystine functionalized polyglycidyl methacrylate integrated graphene oxide (Cys-PGMA@GO-CuO) nanocomposite. The formation of this nanocomposite was comprehensively characterized using various analytical techniques. X-ray diffraction revealed a semi-crystalline nature for pure PGMA/GO with a prominent peak at 2θ = 19.25°. The introduction of inherently crystalline CuO nanoparticles in Cys-PGMA@GO-CuO rendered the entire composite completely crystalline. Further, the photocatalytic efficiency of the Cys-PGMA@GO-CuO nanocomposite was evaluated through advanced oxidation processes (AOP) for treating various toxic pollutants in wastewater remediation. The nanocomposite efficiently degraded dyes like methyl orange (99.8%) and methylene blue (99.9%) in just 50 mins and reduced toxic 4-NP to 4-AP within 40 mins. We further investigated the optimal degradation conditions based on [oxidant], [dye], and the presence of scavengers to understand the rate of degradation. Notably, the composite exhibited remarkable recyclability and stability. The performance of Cys-PGMA@GO-CuO was further evaluated using real wastewater samples, achieving a remarkable decolorization of 99.5% in textile dyeing wastewater and 97.1% in methylene blue-contaminated tap water. These results demonstrate the promising potential of this nanocomposite as an economically viable alternative approach for removing various organic pollutants from wastewater. Additionally, its successful application in real water sample analysis suggests its significant potential for practical implementation in water treatment processes.