Pollutants In Aqueous Solution Research Articles

Visible light induced S-scheme charge transfer mechanism from Bi12TiO20 to CsPbBr3 for photodegradation of organic pollutants in aqueous solution

This work describes the formation of CsPbBr3/Bi12TiO20 S-scheme heterojunction photocatalysts using 3-mercaptopropionic acid (MPA) passivated CsPbBr3 nanocrystals (CPB) combined with Bi12TiO20 (BTO) nanorods. Under illumination, the charge carriers—undergo a process known as the S-scheme charge transfer, which significantly enhances their redox capability. The most efficient photodegradation of Rhodamine B (RhB) was recorded with the fine-tuned 10 %CPB/BTO composite (degradation rate of 95.35 % within 50 min, kapp = 0.06202 min−1). This improvement is primarily due to the MPA passivation, which increases the stability of the catalyst in aqueous solutions, and the S-scheme heterojunction design, which improves carrier separation and utilisation efficiency.

Rational design of CdS-enwrapped polypyrrole nanoparticles for wastewater treatment: removal of hazardous pollutants in aqueous solutions.

The modern world requires a chemical industry that can run at low production costs while producing high-quality products with minimal environmental impact. The development of environmentally friendly, cost-effective, and efficient wastewater treatment materials remains a majorproblem for the sustainable approach. We prepared nanoscale cadmium sulfide (CdS)-enwrapped polypyrrole (PPy) polymer composites for degradation of organic pollutants. The prepared CdS@PPy nanocomposites were characterized by powder X-ray diffraction, scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet-visible(UV) absorption spectroscopy, indicating proper intercalation between CdS and PPy. Consequently, the catalytic efficiency of the synthesized hybrid nanocomposites was analyzed through the degradation of methylene blue (MB) and rhodamine B (Rh B) under visible light irradiation. The measured degradation efficiency of the dye solutions under the photolysis process is about 18% and 23% for MB and Rh B dye, respectively. Furthermore, the recycle test result concludes that the CdS@PPy composite exhibits 91% and 89% of MB and Rh B dye degradation efficiency even at the 4th cycle, respectively. The positive synergistic impact of CdS and PPymay be the result of effective photocatalytic degradation of MB and RhB.

Nanoarchitectonics of lignin-sepiolite bionanocomposite foams for application in environmental remediation

Innovative bionanocomposite foams based on precipitated Kraft lignin (Lig) and Kraft black liquor (BL) loaded with sepiolite (Sep) were prepared. BL/Sep bionanocomposites were synthesized by emulsion templating and Lig/Sep bionanocomposites were prepared by freeze-drying, resulting in stable and rigid foams. BL/Sep bionanocomposites displayed a closed cell structure, a specific area between 19 and 35 m2/g and macropores of varying sizes. The porosity in this technique is achieved by the mechanical agitation of the emulsion. On the other hand, freeze-dried Lig/Sep bionanocomposites showed open cell morphology with surface areas ranging from 1 to 4 m2/g and uniform macropores due to the ice-templating process. The presence of sepiolite in both types of bionanocomposite foams improved their stiffness, with Young's moduli ranging from 0.21 to 9.6 MPa. The capacity of the foams to adsorb metals, drugs and dyes was evaluated and it was found that the synthesized bionanocomposite foams exhibiting similar adsorption capacities as that reported for lignin. Sepiolite significantly improved the adsorption of Cu(II), Cd(II), acetaminophen (ACT), and methylene blue (MB) in BL/Sep bionanocomposites. Meanwhile, the Lig/Sep bionanocomposites demonstrated superior adsorption capacities for the Cr(VI) anion and aromatic ring compounds, including ACT and MB. In this respect, these lignin-sepiolite foams can be considered as promising materials for the removal of pollutants in aqueous solution.

Microstructures, Optical, magnetic Properties, and photocatalytic activity of magnetically separable and reusable ZnO-Doped Fe3O4/rGO nanocomposite synthesized via green route

We report magnetically-separable, reusable, green-synthesized Fe3O4/rGO/ZnO, as heterogeneous catalyst for photo-Fenton degradation of organic pollutants in aqueous solution under certain treatments. Fe3O4 nanoparticles was green-synthesized using Moringa oleifera leaf extract, while rGO was synthesized utilizing Amaranthus viridis leaf extract. Fe3O4/rGO was composited under sonication treatment. Afterwards, Fe3O4/rGO was doped with ZnO with various concentration of ZnO. X-ray diffraction and selected area electron diffraction showed that Fe3O4 and ZnO had spinel cubic and hexagonal structure, respectively; another phase appeared as Fe2O3 spinel cubic structure. Crystallite size was decreased as the ZnO concentration increased. Morphology image showed almost spherical, non-uniform, and slightly dispersed particle under agglomerated condition, attaching to rGO sheets. The particle size of Fe3O4, Fe3O4/rGO, and Fe3O4/rGO/ZnO is 14.3; 14.1; and 10.4 nm, respectively. Fourier-transform infrared spectra showed metallic functional groups, such as Fe-O and Zn–O at 562–589 and 462–478 cm−1 also suggests nanocomposite formation. However, blue-shift absorption and band gap widening were observed with ZnO addition. Raman spectroscopy revealed the formation as-synthesized GO and rGO. Vibrating sample magnetometer showed that green-synthesized Fe3O4/rGO/ZnO exhibited superparamagnetic properties. Removal efficiency of photodegradation methylene blue was optimal for green-synthesized Fe3O4/rGO/ZnO under sonication treatment, reached 100 % degradation within 180 min for uptake every 30 min. Photodegradation was also analyzed using Langmuir-Hinshelwood kinetic model, resulting rate constant of 24.7 × 10−3 min−1 and half-life time of 28.1 min at optimum treatment. Reusability of photocatalytic activity after 3 cycles showed only a tiny drop in catalytic efficiency. Meanwhile, it possesses high stability in catalytic activity and structure. The green-synthesized Fe3O4/rGO/ZnO potential as an environmentally friendly reusable photocatalyst for wastewater degradation.

Cobalt etched graphite felt electrode for enhanced removal of organic pollutant in aqueous solution with a solid polymer electrolyte.

In this study, cobalt etched graphite felt electrodes were produced using a simple etching technique. It was used in combination with a solid polymer electrolyte (SPE) for the degradation of the target contaminant Orange II by Electro-Fenton (EF) technique in low conductivity water. In this method, 94% of Orange II in low conductivity water was removed in 90min. The characterization analysis substantiates the hypothesis that the electrodes produced exhibit a three-dimensional porous structure, augmented defect concentration, and enhanced electron transfer capability. In addition, the potential reaction mechanism was inferred from the radical quenching experiments, and hydroxyl radicals (·OH) were deemed the main reactive substances. The combination of cobalt etched graphite felt electrodes with SPE demonstrates remarkable efficacy in the treatment of organic wastewater characterized by low electrical conductivity.

Microwave-assisted synthesis of Schiff base metal complexes: Biological, photocatalytic activity and fabrication of their metal oxide nanoparticles

Three transition metal complexes of the type [M(ABzC)(H2O)(CH3COO)] denoted as M-ABzC where M = Cu(II), Ni(II) & Zn(II), and ABzC = 3-((5‑chloro-2-hydroxybenzylidene)amino)benzoic acid; were synthesized under microwave irradiation and characterized by using spectroscopic methods, including 1H & 13CNMR, UV–vis, FTIR, and EI-MS. All the synthesized compounds were optimized using the DFT approach. The ligand-to-metal coordination was established by spectroscopic and DFT analyses, which suggest that ligand coordinated through O, N donor atoms. According to the electronic and DFT optimized data, Zn(II) complex showed distorted tetrahedral geometry, whereas geometry of Ni(II) and Cu(II) complexes is square planar. The complexes were calcined at 560 °C to obtain the metal oxide nanoparticles (CuO, NiO, and ZnO). XRD, HR-TEM, SEM, EDX, and UV–vis spectrophotometer were used to characterize the nanoparticles. The DNA interaction activity of the synthesized complexes were performed using electronic absorption and fluorescence spectroscopy. The complexes displayed effective intercalative binding mode with CT-DNA having a binding constant in the range 105 M−1. Based on the antioxidant activity data, it can be inferred that Ni(II) and Cu(II) complexes have better activity than Zn(II) complex. Photodegradation experiment of metal complexes and oxide nanoparticles were performed without hydrogen peroxide using crystal violet dye as model pollutant in aqueous solution under sun light. The results established that the highest degradation was achieved with ZnO, which is 95.5 %. Further, the enzyme structures of B-DNA and 1HD2 have been used in molecular docking simulations to determine the potential binding energies of inhibitors.

Characterization and Application of Carbon Paste Electrode Modified by Moringa Oleifera Seed Powder to the Electrochemical Detection of Mercury

Heavy metal pollution of surface waters from anthropogenic activities is constantly increasing. Monitoring techniques must therefore be more precise and more sensitive. One of the effective methods available is the development of sensitive electrochemical sensors, dedicated to the analysis of pollutants in aqueous solution. The carbon paste electrode (CPE) in this study was modified with Moringa Oleifera seed powder, a flocculant-adsorbent used to treat water. This chemically modified electrode presented improved electrochemical reactivity in cyclic votammetry towards the redox marker Ferri / Ferrocyanide compared to the bare carbon paste electrode. The 10 % modifier presented the most interest during the analysis. The Modified electrode was used to detect mercury (II) in anodic stripping voltammetry. The detection current of mercury (II) is seven times that of carbon paste electrode (CPE). The calibration curve is linear in the range from 0.002 μmol/L to 0.009 μmol/L (0.4 μg/L to 1.8 μg/L) with a detection limit of 0.4 ηmol/L (i.e.0.08 μg/L). This new technique can be used for routine monitoring of real aqueous matrices.

True Order Determination of Sonochemical Degradation Kinetics of Organic Contaminants in Water Using the Half-lives Method

In the literature, the modeling of the sonolytic decomposition kinetics of organic contaminants in water has been carried out using the pseudo-first and pseudo-second order equations. The results obtained with this method are totally biased because it requires the assumption of the order of the degradation reaction, which is a real limitation, and the sonochemical oxidation mechanism is a very complex phenomenon that cannot be described by such simple models. In this paper, for the first time, the true order of the sonochemical degradation kinetics of organic pollutants in aqueous solutions at various initial substrate concentrations was determined using the half-lives method combined with the general rate law model, i.e., the pseudo-nth order equation. Linear and nonlinear regression techniques were used to determine the order of the sonolytic destruction reaction. The half-life technique for the general rate law model can adequately describe the experimental results of the sono-destruction of the investigated pollutants. For rhodamine B and naphthol blue black, the sono-destruction mechanism for both contaminants does not change as the initial contaminant concentration varies over the range examined, while for 4-isopropylphenol and furosemide, the sono-destruction mechanism changes as the initial substrate concentration varies. A fractional order of the sonolytic destruction reaction was determined for all the pollutants tested. These fractional orders of sono-destruction reactions indicate the complex nature and behavior of the reactions, often involving multiple steps or mechanisms. They also reveal a more complex interaction between pollutant concentration and sonolytic destruction rate. In a word, the method developed in this paper should be used to determine the real order of the sono-oxidation reaction of nonvolatile organic pollutants in aqueous phase.

Use of murici (Byrsonima crassifolia) and jabuticaba (Plinia cauliflora) residues in the preparation of porous materials: Effect of pH on the adsorption efficiency of the contaminants phenol, diethylphthalate and amoxicillin

Activated charcoals with the chemical activator (H3PO4) were synthesized from agro-industrial residues, Murici seeds (CA-MU) and Jabuticaba (CA-JA). The synthesized charcoals were characterized by thermogravimetric analysis (TG), N2 adsorption and desorption isotherms, Fourier transform infrared spectroscopy (FTIR), point of zero charge (pHPZC) and scanning electron microscopy (SEM). The charcoals produced presented mesoporous characteristics, surface areas of 884.226 m2.g−1 for CA-JA and 556.97 m2.g−1 for CA-MU, mean pore diameters suitable for adsorption of phenol (PHE), diethylphthalate (DEP) and amoxicillin (AMX). The chemical characterization indicated the acid profile of the surface of the charcoals, which presented pHPZC of 6.3 (CA-JA) and 6.7 (CA-MU). The adsorption studies, in aqueous solution of the pollutants (PHE), (DEP) and (AMX), indicated that the removal capacity is strongly influenced by the pH of the solution. Toxicity tests demonstrated that the adsorption process was responsible for decreasing the toxicity of the pollutants studied. Thus, given the results presented, the activated charcoals synthesized can be considered high potential adsorbents for applications in the removal of organic pollutants in aqueous solutions.

The adsorption of direct red 23 as a toxic pollutant in aqueous solution by using surface modified metal-organic framework containing tricarboxylic acid benzene ligand

In this research, Cu-BTC (C-BTC) metal-organic framework (MOF) was prepared and characterized. The synthesized C-BTC was modified with 3-aminopropyltrimethoxysilane to synthesize C-BTC-NH2. The ability to remove the direct red 23 (DR-23) dye by the synthesized materials (C-BTC and C-BTC-NH2) as adsorbents was investigated. The effect of operational parameters on dye removal was investigated. The results showed that the ability of the modified adsorbent (C-BTC-NH2) to adsorbed dye is more than the raw adsorbent (C-BTC). The amount of dye adsorption is high in acidic pH values. Increasing the amount of adsorbent and decreasing the pH of solution causes an increase in the percentage of dye adsorption and enhance in the DR-23 concentration causes a decrease in the percentage of DR-23 removal. The results of dye adsorption were matched with different isotherms and removal process followed the Langmuir isotherm. The experimental data exhibited a good fit with the Langmuir isotherm model (R2 = 0.9637), with the maximum adsorption capacity (Q0) of the calculated as 89.2857 and 2500 mg/g for DR-23 removal by C-BTC and C-BTC-NH2, respectively. Dye adsorption follows pseudo-second-order kinetics and k2 is PSO rate constant 0.0028 and 0.010 for by C-BTC and C-BTC-NH2, respectively. The data presented that C-BTC-NH2 as a modified adsorbent has high removal ability and is appropriate adsorbent for dye adsorption from aqueous solution.

Self-assembled nano-disk architecture of broccoli-shaped Bi4V2O11 anchored with Ag-Ag3O4 co-catalyst as 3D/0D solar-light-driven Z-scheme photocatalyst: Textile industry effluents remediation

In this study, self-assembled nano-disk architecture of broccoli-shaped Bi4V2O11 anchored with Ag-Ag3O4 co-catalyst as 3D/0D solar-light-driven Z-scheme nanophotocatalyst was synthesized for the first time and applied in the process of photocatalytic degradation of several dye pollutants in aqueous solutions. To evaluate the photodegradation performance, Ag-Ag3O4/Bi4V2O11 nanophotocatalysts of various compositions were synthesized and characterized via X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller, Barrett-Joyner-Halenda (BET-BJH), transmission electron microscopy (TEM), photoluminescence (PL), and diffuse reflectance spectroscopy (DRS) analyses. The XRD proved the nanophotocatalyst's crystallinity without the presence of additional substances. The observation analyses revealed the 3D broccoli-shaped Bi4V2O11 with a self-assembly nano-disk-like architecture in which each nano-disk includes an assembly of the nano-sphere particles. The BET-BJH showed that Ag-Ag3O4/Bi4V2O11 nanophotocatalysts consist of macropores (0.0875 cm3/g) that increase light absorption without scattering and contaminant adsorption. According to the DRS analysis, Ag-Ag3O4(25%)/Bi4V2O11 nanophotocatalyst had two absorption edges (proving the formation of the heterojunction photocatalyst), plasmonic properties, and the ability to capture visible light. This sample showed a decrease in the charge carriers’ recombination rate based on the PL analysis. The photodegradation tests indicated that within 180 min of irradiation, Ag-Ag3O4(25%)/Bi4V2O11 removed 99.76%, 99.52%, 94.05%, and 81.71% of crystal violet, acid orange 7, methylene blue and rhodamine B pollutants respectively, indicating the high photodegradation capability of this nanophotocatalyst.

Ultrasound-assisted adsorption of organic dyes in real water samples using zirconium (IV)-based metal-organic frameworks UiO-66-NH2 as an adsorbent

The utilization of dye adsorption through metal-organic frameworks represents an eco-friendly and highly effective approach in real water treatment. Here, ultrasound assisted adsorption approach was employed for the remediation of three dyes including methylene blue (MB), malachite green (MG), and congo red (CR) from real water samples using zirconium(IV)-based adsorbent (UiO-66-NH2). The adsorbent was characterized for structural, elemental, thermal and morphological features through XRD, XPS, FTIR, thermogravimetric analysis, SEM, BET , and Raman spectroscopy. The adsorption capacity of adsorbent to uptake the pollutants in aqueous solutions was investigated under different experimental conditions such as amount of UiO-66-NH2 at various contact durations, temperatures, pH levels, and initial dye loading amounts. The maximum removal of dyes under optimal conditions was found to be 938, 587, and 623 mg g−1 towardMB, MG, and CR, respectively. The adsorption of the studied dyes on the adsorbent surface was found to be a monolayer and endothermic process. The probable mechanism for the adsorption was chemisorption and follows pseudo-second-order kinetics. From the findings of regeneration studies, it was deduced that the adsorbent can be effectively used for three consecutive cycles without any momentous loss in its adsorption efficacy. Furthermore, UiO-66-NH2 with ultrasound-assisted adsorption might help to safeguard the environment and to develop new strategies for sustainability of natural resources.

Preparation of Fenton Catalysts for Water Treatment

In the heterogeneous Fenton reaction, a solid catalyst reacts with H2O2 to generate highly oxidizing free radicals, that degrade organic pollutants in aqueous solutions. In this study, impregnation calcination was used to modify activated carbon and load it with various metal compounds. The synergistic catalysis of the various metal compounds showed improved catalytic activity, and the prepared heterogeneous Fenton catalyst exhibited high catalytic activity, a wide pH range, and good stability. The concentration ratios of the Fenton catalyst impregnation solutions-were as follows: Fe3+, Cu2+, Mn2+, and Ce3+ at 0.45, 0.72, 0.19, and 0.11 mol/L, respectively. The optimal sintering temperature of AC impregnation was determined through TGA/DSC, SEM, SEM-EDS, XPS, and XRD testing. At a final calcination temperature of 900 °C, the degradation efficiency of 10 ppm methylene blue reached 98.25% at pH 5 with 5 mM H2O2. After ten soaking cycles, the degradation efficiency exceeded 90%. The structure and performance of the catalysts were characterized using EPR, BET, ICP, and UV spectroscopy, demonstrating the excellent performance of the catalyst and providing an improved treatment plan for solving wastewater problems.

Graphenic molybdenum disulfide nanocomposites as heterogeneous nano-catalyst for reduction of nitroanilines

In this study, a new graphenic molybdenum disulfide nanocomposite (MoS2/rGO NC) and its magnetic derivatives (MoS2/Fe3O4/rGO NC and Fe3O4/MoS2/rGO NC) were synthesized. Structural and chemical properties of synthesized NCs were characterized by FT-IR, XRD, BET, SEM, TEM, EDAX and TGA techniques. These NCs were designed as a heterogeneous nano-catalyst for reduction of nitroaromatic compounds with strong and recoverable catalytic properties. Large amounts of aromatic pollutants, including nitro compounds such as 2-nitroaniline (2-NA) and 4-nitroaniline (4-NA) which are produced in many industries and they are classified in the category of highly toxic pollutants in aqueous solution. The prepared NCs emerged to be of high catalytic activity in the reduction of nitroarenes under mild conditions. The conducted investigations prove that the reduction reaction with synthesized nano-catalyst follows pseudo first-order kinetic. MoS2/rGO NC converted 2-NA in 360 s (Kapps (s−1) 1.6 × 10−3) and 4-NA in 240 s (Kapps (s−1) 4.7 × 10−3) to the desired amines. While MoS2/Fe3O4/rGO NC and Fe3O4/MoS2/rGO NC completed reduction reaction of 2-NA to o-PDA in 20 s (Kapps (s−1) 4.82 × 10−2) and 42 s (Kapps (s−1) 2.41 × 10−2) while converted 4-NA to p-PDA in 12 s (Kapps (s−1) 1.43 × 10−1) and 35 s (Kapps (s−1) 2.92 × 10−2). All of the data confirmed that the synthesized NCs show very good catalytic properties and has good stability. Also, they have the ability to be reused several times without a significant loss of activity.

Solvation behavior of phenolic pollutants in aqueous solutions of imidazolium-based ionic liquids: A molecular dynamics simulations study

In this study, the solvation behavior of phenolic pollutants (PPs) in 1-octyl-3-methylimidazolium tetrafluoroborate ([C8MIM][BF4]) ionic liquid (IL) aqueous solutions was simulated using molecular dynamics (MD) simulations. The study found that the cationic part of IL was the most interactive and played the most important role in the extraction of PPs. It also demonstrated that stronger hydrophobic interactions between PPs and the cationic portion resulted in higher extraction efficiency, with the exception of resorcinol, whose stronger hydrogen bonds (HBs) with water molecules reduced extraction efficiency. The study discovered that van der Waals forces governed interaction energies (IEs) between PPs and ILs, while HBs played a minor role. Since the cationic part plays a major role in the extraction process of PPs, the efficiency of the extraction process can be improved by making structural changes to this part.

Recent advancement in NiFe2O4-based nanocomposites for the photocatalytic degradation of pollutants in aqueous solutions: a comprehensive systematic review

Abstract Nanocomposites with diameters of 1 to 100 nm have modified properties such as uniform size distribution, small size, high surface-to-volume ratio, high absorbability, porosity, and various potential roles, including in catalytic and biological activities. The purpose of this research study was to systematically review all research studies on the photocatalytic decomposition of pollutants by NiFe2O4-based nanocomposites and evaluate the optimal laboratory conditions and the results of these studies. The present systematic review was conducted by searching Scopus, PubMed and Web of Science databases until March 2022. The parameters of nano catalyst type and size, synthesis methods, pollutant type, optimal pH, optimal initial pollutant concentration, optimal catalyst concentration, optimal time, radiation and removal efficiency were investigated. 454 studies were screened and using the inclusion and exclusion criteria, in total, 31 studies met our inclusion criteria and provided the information necessary to photocatalytic degradation of pollutants by NiFe2O4-based nanocomposites. In the investigated studies, the percentage of photocatalytic degradation of pollutants by NiFe2O4-based nanocomposites was reported to be above 70%, and in some studies, the removal efficiency had reached 100%. From the results of this systematic review, it was concluded that the photocatalytic process using NiFe2O4-based nanocomposites has a high effect on the degradation of aqueous solution pollutants.

Synergistic effects on the degradation of a mixture of pharmaceutical pollutants in aqueous solution, raw sewage, and hospital wastewater using UV light-assisted Fenton process

The widespread pharmaceutical pollutants enter the aquatic environment through wastewater, and it poses a threat to aquatic organisms and human health. Advanced oxidation process (AOPs) is one of the widely used treatment methods for the degradation of pharmaceutical pollutants by utilizing Ultraviolet light (UV), iron (Fe2+), and hydrogen peroxide (H2O2). This study investigates the application of AOP (UV/Fe2+/H2O2) for the degradation kinetics of mixed pollutants (amoxicillin, acetaminophen, and ciprofloxacin), mineralization, and degradation products. The sources for these pollutants are hospitals, households, manufacturing industries, etc. The effects of degradation were evaluated by varying pH, Fe2+, H2O2, the mixed pollutants, and time respectively. The results revealed that the optimal conditions were observed at UV light 15 W, mixed pollutant 5 mg/L, Fe2+ 0.04 mM, H2O2 3 mM, and time 10 min. The maximum degradation was achieved at >99 % in the mixed pollutants with the kinetics in the order of ACET > CIP > AMX. The maximum mineralization was observed at 68 % and transformation products were identified using LC-ESI-MS. In addition, the process performance of the UV/Fe2+/H2O2 method was assessed by applying optimum conditions in real wastewater (raw sewage and hospital wastewater). The study revealed that the UV/Fe2+/H2O2 method had a high performance in the removal of multiple pollutants in real wastewater.

Photo-electrochemical degradation of rhodamine B using electrodeposited Mn3(PO4)2.3H2O thin films

Mn3(PO4)2·3H2O thin films have been grown using the cathodic electrodeposition method. The samples were characterized in terms of structural, morphological, optical and photo-electrochemical characteristics using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) combined with energy dispersive X-ray spectrometer (EDX), mott-Schottky and gap energy determination and electrochemical impedance spectroscopy (EIS), respectively. The photo-electrocatalytic performance of the resulting electrode has been performed towards the decomposition of rhodamine B (RhB). The achieved results have indicated that the decomposition attained was 95%, while the highest Chemical oxygen demand value was 79% after 25 min of reaction time, the efficiency of the operation was attributed to the creation of OH° and holes oxidizing species. The Mott-Schottky investigation has revealed the n-type conduction of Mn3(PO4)2·3H2O and EIS results are modelled to an equivalent circuit by using the Zview software consisting of a pair of resistors in parallel with a CPE. Moreover, the prepared thin films exhibit excellent stability for 4 cycles, rendering them a viable candidate for the decomposition of organic pollutants in aqueous solutions.

The potential of reusing fruit bio-adsorbents for water purification: A minireview

Fruit peels, cortexes or rinds are sourced from a wide range of fruits including watermelon, banana, orange, mango, pineapple and lemon among others. They are readily available materials that can be used as bio-sorbents for various pollutants found in contaminated water. This study reviews reported works on the usability of different fruit bio-peels as adsorbents for water pollutants. The findings show that fruit peels must undergo various physicochemical modifications to be used as bio-sorbents. The peels have functionalized moieties such as –OH, –COOH and –NH2 groups that can attract cations of pollutants in aqueous solutions facilitating adsorption. Furthermore, the bio-adsorbents can be regenerated for reuse in several adsorption cycles. Most of the reviewed studies showed that bio-peels are effective in decontaminating various dyes and heavy metals in polluted waters. The decontamination efficacy differs based on the pollutant targeted, quantity and volume of adsorbate, concentration of adsorbent, pH, temperature and surface area. To enhance the effectiveness of fruit bio-sorbents in water purification, there is need to extend research to optimize biosorption processes, combine it with other water purification processes, control the parameters influencing the process and effectively processes resultant waste for environmental conservation.

Bi-metalic ZIFs(Zn-M) (M: Co, Ni) for photocatalytic removal of organic pollutants in aqueous solutions

In this study, we successfully synthesised bi-metallic ZIF(Zn-M) of 2-methyl imidazole with a second metal (cobalt or nickel) binding to the ZIF network. All ZIF samples were synthesised at room temperature and characterised by using XRD, FT-IR, SEM, DRS, and nitrogen adsorption and desorption isotherms. The materials have high crystallinity with a large surface area. The materials’ photocatalytic ability was examined via the degradation of indigo carmine under a sun-light simulator. The second metal enhanced the photon harvesting ability of ZIF(Zn) because the materials can absorb photons in both UV and visible regions. Of the two catalysts, ZIF(Zn-Co) exhibited high photocatalytic ability when it removed 100% of indigo carmine from an aqueous solution. The catalyst adsorbed 45% of indigo carmine after 2 h and entirely degraded the remaining dye dring 1.5 h of solar irradiation. While Co2+ increased the catalyst’s surface area, Ni2+ reduced it, leading to lower photocatalytic efficiency.