Methyl Orange Research Articles

Exploration of bismuth based perovskite materials for organic dyes removal from waste water

The scourge of water pollution due to organic matter is a well-known fact. In order to address this issue, we employed a highly facile method of solid state reaction for the synthesis of bismuth potassium titanate, Bi0.5K0.5TiO3 (BKT) photocatalyst. Furthermore, the bandgap tailoring of the BKT is performed by photo-reduction of Ag onto the BKT, which results in the formation of hetero-structure junctions at the surface of the BKT. The as-prepared BKT and BKT-Ag photocatalysts are systematically characterized by x-ray diffraction, scanning electron microscopy, and high resolution transmission electron spectroscopy. Furthermore, the photocatalyst activity of the BKT and BKT-Ag was analyzed against the target organic pollutants by using UV–Vis spectroscopy. Three organic dyes such as methylene blue, eriochrome Black T, and methylene orange (MO) were used as target organic pollutants. The anchoring of Ag for the formation of hetero-structure junctions at the surface of BKT rendered it to be an ideal photo-catalyst with a bandgap reduction from 3.37 to 2.08 eV. Therefore, lowering the bandgap resulted in enhanced photocatalytic activity of the BKT-Ag. Among the three target dyes, BKT-Ag showed remarkable photo-degradation of MO and Erb T by degrading ≥90% of MO and Erb T in 120 min at neutral pH values. It is believed that BKT based photocatalysts can provide a unique platform for the removal of organic pollutants from wastewater.

High performance loose-structured membrane enabled by rapid co-deposition of dopamine and polyamide-amine for dye separation

Textile wastewater poses a significant environmental challenge that demands effective treatment. Membrane separation offers a promising solution, with high-flux tight ultrafiltration membranes recognized as an effective technology for dye separation. Polyamide amine (PAMAM), a dendritic macromolecule renowned for its regular structure, high monodispersity, excellent solubility, and tunable molecular weight, has emerged as a promising material for membrane fabrication. This study introduces a novel, eco-friendly, and time-efficient method for preparing polymer composite membranes through one-step co-deposition of dopamine (DA) and PAMAM, predominantly utilizing Michael addition and Schiff base reactions. The incorporation of ammine-rich PAMAM imparts ultra-high hydrophilicity to the membranes (contact angle of 38°), facilitating strong adhesion of water molecules to the membrane surface. The effects of co-deposition time and concentrations of DA and PAMAM on the separation performance of the resulting membranes were systematically investigated. Notably, the optimal membrane demonstrated a high water flux (126.1 L m-2h−1 bar−1), primarily due to the incorporation of PAMAM, which resulted in a looser selective separation layer. Furthermore, the membrane demonstrated excellent rejection of methyl blue (MB) at 98.9 % and low rejection os methyl orange (MO) at 13.2 %, making it well-suited for the selective separation of mixed dyes. Our approach offers a sustainable and technologically advanced solution for addressing resource recovery from textile wastewater.

Development of a Negatively Charged Polyether Sulfone Membrane Enriched with MIL-101(Cr)-Modified Magnetic Activated Pyrolytic Coke for Enhanced Dye Removal, Permeability, and Antifouling Properties

Developing high-performance nanofiltration membranes for effectively treating wastewater contaminated with organic pollutants has become increasingly important. Given the hazardous nature of these contaminants, proper treatment of wastewater is crucial before it is released into natural water bodies. This study synthesized a novel composite membrane by incorporating Fe3O4@APC@MIL-101(Cr) nanocomposites into a polyether sulfone (PES) matrix using a phase inversion technique. The inclusion of 0.5wt.% Fe3O4@APC@MIL-101(Cr) significantly enhanced the membrane's hydrophilicity, porosity, and surface characteristics. The optimized membrane achieved an impressive pure water flux (PWF) of 90.24L/m²h, reflecting a 400% improvement over pristine PES membranes. Moreover, it exhibited excellent rejection rates of 97.21% for crystal violet (CV) and 99.43% for methylene blue (MB), alongside a rejection efficiency of 57.73% for the anionic dye methyl orange (MO). The antifouling performance was notably improved, as evidenced by an increase in the flux recovery ratio (FRR) from 46% for bare PES membranes to 81.11% for hybrid membranes. Additionally, the effects of various salt types on the membrane's separation performance were investigated. The Fe3O4@APC@MIL-101(Cr) modified PES membranes demonstrate significant potential as effective candidates for treating wastewater contaminated with dye pollutants.

Controllable preparation and multifunctional application of high-strength porous anorthite ceramics

Porous anorthite ceramics, as emerging green materials, garner significant interest in applications such as catalyst carriers, thermal insulation, and sound absorption due to their distinctive structural and functional attributes. In the present study, porous ceramics with anorthite as the main phase were prepared using the natural minerals kaolin, calcite, and quartz as raw materials, combined with a simple and environmentally friendly foam gel-casting method. By adjusting the additive content, we optimized the viscosity and stability of the slurry, and further investigated the impact of the slurry's foaming capacity on the resulting porosity, pore size, mechanical strength, and other key properties of the ceramics. Notably, the porous anorthite ceramic with 15 g/L of foaming agent demonstrated a porosity of 70.57%, a bulk density of 0.81 g/cm3, and a thermal conductivity of 0.26 W/(mK), along with a commendable compressive strength of 8.85 MPa due to the homogeneous sub-spherical pore structure and plate-like anorthite grains. The suitability of these porous ceramics for catalyst carrier applications was confirmed through the effective photodegradation of a methyl orange solution.

Novel visible-light-driven I- doped Bi2O2CO3 nano-sheets fabricated via an ion exchange route for dye and phenol removal

Here, we developed a novel visible-light-driven I- doped Bi2O2CO3 nano-sheet photocatalyst fabricated via a facile ion exchange route at room temperature. This obtained Bi2O2CO3 nano-sheets with I- doping showed several advantages. The specific surface area of I0.875-Bi2O2CO3 was 2.16 times higher than that of Bi2O2CO3, providing more catalytic site for degradation reactions. Moreover, a 3.2 times photocurrent enhancement was observed in I0.875-Bi2O2CO3 comparing with Bi2O2CO3, producing more photogenerated electron-hole pairs for degradation reactions. The synergistic effect between texture property and photoelectric effect boosted the removal of organic pollutants. Under visible light illumination, I0.875-Bi2O2CO3 displayed superior photocatalytic performance for degradation of methyl orange and phenol. Notably, a phenol degradation rate of 88% was achieved over I0.875-Bi2O2CO3 with illuminating for 60 min, which was about 29 times higher than Bi2O2CO3. This finding may provide an opportunity to develop a promising I- doped catalyst for organic pollutants removal.

Magnetic Fe3O4 nanoparticles supported on carbonized corncob as heterogeneous Fenton catalyst for efficient degradation of methyl orange

Magnetic Fe3O4 nanoparticles supported on carbonized corncob as heterogeneous Fenton catalyst for efficient degradation of methyl orange

Dicarboxylate cellulose nanofibrils-supported silver nanoparticles as a novel, green, efficient and recyclable catalyst for 4-nitrophenol and dyes reduction

This study reports dicarboxylate cellulose nanofibrils (DCNF) as a novel reducing and supporting agent for producing silver nanoparticles (AgNPs) with high efficiency (63.82 % reduction) and loading (6.88 %) using UV light. Unlike previous research, AgNPs formation with DCNF doesn't involve cellulose oxidation. Instead, it appears to involve a loss of carboxyl groups from DCNF. In comparative studies, pristine CNF (PCNF) and TEMPO-oxidized CNF (TOCNF) were also examined for AgNPs production. The resulting AgNPs from DCNF exhibited a significantly smaller average size (3.9 ± 0.7 nm) compared to those from PCNF (26.9 ± 10.9 nm) and TOCNF (13.5 ± 4.5 nm). Catalytic activity evaluation by the 4-nitrophenol (4-NP) reduction reaction revealed a high rate constant of 8.47× 10−3 s−1 by AgNPs/DCNF, which surpassed AgNPs/TOCNF (1.79 × 10−3 s−1) and AgNPs/PCNF (0.63 × 10−3 s−1) by 4.7 and 13.4 times, respectively. Besides 4-NP, AgNPs/DCNF aerogels were also applied for methyl orange and Rhodamine B dyes reduction. The aerogels showed excellent reusability, maintaining over 95 % conversion even after five cycles and also effective in treating real samples and mixed dye solutions. This study opens the door for future research exploring DCNF as a support material for various metal, metal oxide, and carbon nanoparticles.

Preparation of amorphous Nd/Dy-based metal organic framework@MXene for solar driven selective photocatalytic and serving as sensor for fluorescence quenching detection, and biological activity

The development of a new Neodymium/Dysprosium metal–organic framework, referred to as Nd/Dy-BTC MOF, based on benzene-1,2,4-tricarboxylic acid, has been achieved through an in situ growth process on 2D transition metal carbides (MXene) surfaces. This synthesis was conducted via a solvothermal method utilizing a solvent mixture of water, ethanol, and dimethylformamide. The primary objective of this research is to investigate the framework’s efficacy as a photocatalyst for the degradation of anionic dye, as well as its potential for sensing certain explosives. The Nd/Dy-MOF@MXene has been characterized by various analysis techniques. The prepared Nd/Dy-MOF@MXene was utilized as catalyst in selective degradation of methyl orange dye. The study examined the influence of pH and catalyst concentration, revealing that the catalyst achieves peak efficiency of 93.55% when exposed to sunlight in an acidic medium. The reusability of the catalyst shows the highest efficient photocatalyst after four cycles of reusability. The detection of explosives, specifically 2,4,6-trinitrophenol, through photoluminescence techniques has been conducted, utilizing the Stern-Volmer equation to evaluate the quenching efficiency. The findings indicated remarkable efficiency and selectivity of Nd/Dy-MOF@MXene for 2,4,6-trinitrophenol, achieving a quenching efficiency of 91%. Furthermore, the reusability tests demonstrated that Nd/Dy-MOF@MXene exhibits outstanding recyclability, maintaining performance over five cycles. The antibacterial activity of Nd/Dy-MOF@MXene was investigated against Gram-positive and Gram-negative strains due to indication of medicine properties of Nd/Dy-MOF@MXene.

Performance study of the bioreactor for the biodegradation of methyl orange dye by luffa immobilized Stenotrophomonas maltophilia and kinetic studies: A sustainable approach

The biodegradation of methyl orange dye was examined in a biofilm reactor with luffa immobilized Stenotrophomonas maltophilia ((HE963840.1), low-cost packing material. The bacteria were isolated from the sludge collected from a common effluent treatment plant at IOCL refinery Mathura, Uttar Pradesh. The bacteria were characterized using 16rRNA. The reactor performance was studied at 30 ± 5 oC temperatures over a period of thirty days. The reactor was operated with the flow rates of 60 mL/h, 90 mL/h, 240 mL/h, 360 mL/h and 432 mL/h. The pollutant load ranges from 151.6 mg/(L-day) to 1091 mg/(L-day) and the pH of the dye solution was maintained at 7.0 ± 0.4 during the study. The maximum removal efficiency (RE) and elimination capacity (EC) at steady state were determined as 90.2 % and 658.1 mg/(L-day) respectively. The rate of utilization of the methyl orange dye is described by modified stover-kincannon model with kinetic parameters- maximum utilization rate (Umax) and saturation constant (KB) to be 2.70 g/(L-day) and 2.34 g/(L-day) respectively. The toxicity studies confirm the non-toxic nature of the biodegraded products.

Multifunctional hybrid films made from CoT3OTx4 and CoFeT2OT4 nanoparticles inside a poly 3-hydroxybutyrate matrix and study of their impact in methyl orange photodegradation.

This work aims to produce hybrid materials with potential applications in dye photodegradation. Therefore, hybrid films were obtained by incorporating cobalt (II, III) oxide (Co3O4) or cobalt ferrite (CoFe2O4) nanoparticles (NPs) with 18 ± 1.6 nm and 26 ± 1.3 nm, respectively, into a poly 3-hydroxybutyrate (P3HB) polymeric matrix. The Co3O4@P3HB and CoFe2O4@P3HB hybrid films were fabricated by solvent casting in a ratio of 85 mg to 15 mg (P3HB-NPs). Different spectroscopic and microscopy techniques characterized the Co3O4 and CoFe2O4 NPs and the P3HB, Co3O4@P3HB and CoFe2O4@P3HB films. The optical band gap for Co3O4 and CoFe2O4 NPs was estimated from their diffuse reflectance spectra (DRS) around 2.5 eV. X-ray diffraction (XRD) of the hybrid films revealed that the nanometric sizes of the Co3O4 and CoFe2O4 nanoparticles incorporated into the P3HB are preserved. The magnetic hysteresis curve of CoFe2O4 nanoparticles and CoFe2O4@P3HB film showed a ferromagnetic behaviour at 300 K. Transmission electron microscopy (TEM) confirmed the formation of nanocrystals, and scanning electron microscopy (SEM) provided evidence for the successful incorporation of the NPs into the P3HB matrix. The surface roughness and hydrophilicity of the hybrid films are increased compared to the P3HB film. The impact of the nanoparticles and the hybrid films on the photodegradation of methyl orange (MO) in its acidic form was studied. The photodegradation tests were carried out by direct sunlight exposure. The CoFe2O4@P3HB hybrid film achieved 85% photodegradation efficiency of a methyl orange solution of 20 ppm after 15 minutes of exposure to sunlight. After 30 minutes of exposure to sunlight, the nanoparticles and the hybrid films reached about 90% of the MO degradation. The results suggest that combining nanoparticles with the polymer significantly enhances photodegradation compared to isolated nanoparticles.

Preparation of Hierarchical Porous ZIF-67 and Its Application in Zinc Battery Separator

This study successfully prepared a hierarchically porous ZIF-67 (H-ZIF-67) by incorporating the polyvinylpyrrolidone (PVP) at room temperature. Compared to standard control ZIF-67 (C-ZIF-67) with a yield of 81% and a BET specific surface area of 1228 m2·g−1, the H-ZIF-67 not only exhibited improved crystallinity and pore structure but also achieved a yield of up to 93% and a BET specific surface area of 1457 m2·g−1. Due to its hierarchically porous structure, H-ZIF-67 demonstrated excellent adsorption capacity and efficiency for methylene orange (MO). Additionally, the composite separator created by combining H-ZIF-67 with nanocellulose (CNF) exhibited remarkable uniformity and dispersion in zinc batteries. In comparison to a conventional CNF separator, the porous structure and high specific surface area of H-ZIF-67 significantly enhanced its electrolyte wettability and Zn2+ transport rates. Its abundant Lewis acid sites effectively promoted the uniform deposition of Zn2+, thereby suppressing the formation of zinc dendrites and improving the cycling and safety performance of zinc-ion batteries. Experimental results indicate that the ion conductivity of the membrane was 4.31 mS·cm−1, the electrolyte absorption rate was 316%, and it could cycle stable for over 4000 h at a current density of 1 mA·cm−2 with a discharge capacity of 1 mAh·cm−2. This achievement will open up new avenues for the preparation and application of ZIF-67 composite separators in aqueous zinc-ion batteries.

Selective separation of dyes and tetracycline hydrochloride in polymer‐nucleotide coacervate droplets

AbstractThis paper reports the formation of coacervates by the electrostatic interaction of poly (diallyldimethylammonium chloride) (PDDA) and adenosine triphosphate (ATP) in aqueous solution, examining its formation conditions, stability, and efficiency in separation. The ideal concentration for creating coacervate droplets in pure water, HEPES buffer, and NaCl solution was determined to be 20 mM of PDDA and ATP. Enhancing the stability of coacervates was achieved by incorporating phospholipid vesicles on their surface, presenting a novel strategy for building cell models. Ostwald Ripening was employed to comprehend the growth mechanism of the coacervates, while the Hofmeister Ion Series and Schulze‐Hardy's rule were utilized to elucidate the stability differences in solutions containing NaCl, Na2SO4, and MgCl2. These coacervates were stable at concentrations below 90 mM NaCl, 200 mM Na2SO4, and 30 mM MgCl2, respectively. We also explored the specific separation of dyes and tetracycline hydrochloride (TC) in the coacervates. Separation efficiencies of 92.98% for methylene blue (MB), 94.19% for methyl orange (MO), and 85.94% for TC, were achieved by the coacervates, which can be attributed to the synergistic effects of hydrophobicity, electrostatic forces, and π‐π interactions. The proposed coacervates have great potential in cell mimicry and water treatment.

Enhanced photocatalytic efficiency in C3N4 via particle and surface engineering of Graphene quantum dots

Graphene quantum dots (GQDs) have been employed to enhance the photocatalytic performance of carbon nitride (C3N4), leveraging their superior physicochemical characteristics. The photovoltaic attributes of GQDs, influenced by their particle sizes and surface states, are contingent upon their synthesis methods. This research focused on the synthesis of GQDs with diverse particle sizes and surface features by modifying carbon nanotubes (CNTs) using HNO3. The findings indicate that prolonging the reaction time decreases the size of GQD particles and augments the presence of surface functional groups. Upon forming heterojunctions with C3N4, the GQDs-96/HC3N4 composite showcased superior photocatalytic degradation performance towards tetracycline hydrochloride (TC) and methyl orange (MO). This enhancement is attributed to the improved dispersibility and oxygen-containing functional groups of GQDs-96, facilitating effective interaction with HC3N4. This research provides a new guideline and idea for regulating the particle size and surface state of GQDs for their application in enhancing the photocatalytic performance of C3N4 for the degradation of water pollutants.

Tailoring anisotropic ZnO/wood-structural holocellulose hybrids for dye degradation through controlled nanoinsertion

Nanostructured inorganic/wood-structural holocellulose hybrids offer new potential applications, including mechanical energy conversion, superhydrophobic materials, gas adsorption and so on. Owing to the anisotropy of wood, controlling the morphology of mineral particles inside porous holocellulose scaffold is still far from satisfactory. In this work, a homogeneous zinc oxide (ZnO) decoration inside wood-structural holocellulose scaffold was achieved while the morphology, distribution and content of ZnO micro-nano particles were controllable through changing the conditions of hydrothermal growth. The holocellulose scaffold was prepared through delignification and periodate oxidation, which is favorable for Zn2+ capture and ZnO nuclei formation because of the surface charge increased. The controlled ZnO insertion was realized by changing metal salt concentration, temperature and hydrothermal time. The obtained multilayer ZnO could provide multiple light refractions and reflections and enhance the utilization of light. Consequently, with a minor ZnO loading (15 wt%), the ZnO/wood-structural hybrids could totally degrade methyl orange and methyl blue in 6 h. This novel and scalable synthesis method shows potential for both the design and photocatalytic activity of holocellulose hybrids.

A Supramolecular‐Nanocage‐Based Framework Stabilized by π‐π Stacking Interactions with Enhanced Photocatalysis

Abstractπ frameworks, defined as a type of porous supramolecular materials weaved from conjugated molecular units by π‐π stacking interactions, provide a new direction in photocatalysis. However, such examples are rarely reported. Herein, we report a supramolecular‐nanocage‐based π framework constructed from a photoactive Cu(I) complex unit. Structurally, 24 Cu(I) complex units stack together through π‐π stacking interactions, forming a truncated octahedral nanocage with sodalite topology. The inner diameter of the nanocage is 2.8 nm. By sharing four open faces, each nanocage connects with four equivalent ones, forming a 3D porous π framework (π‐2). π‐2 shows good thermal and chemical stability, which can adsorb CO2, iodine, and methyl orange molecules. More importantly, π‐2 can serve as a photocatalyst for hydrogen evolution reaction. With ultrafine Pt subnanometer particles (0.9±0.1 nm) incorporated into the nanocages as a co‐catalyst, the hydrogen evolution rate reaches a record‐high value of 524012 μmol/gPt/h in the absence of any additional photosensitizers. The high photocatalytic activity can be ascribed to the ultrafine size of the Pt particles, as well as the fast electron transfer from π‐2 to the highly active Pt upon illumination. π‐2 represents the unique stable supramolecular‐cage‐based π framework with excellent photocatalytic activity.

A Supramolecular-Nanocage-Based Framework Stabilized by π-π Stacking Interactions with Enhanced Photocatalysis.

π frameworks, defined as a type of porous supramolecular materials weaved from conjugated molecular units by π-π stacking interactions, provide a new direction in photocatalysis. However, such examples are rarely reported. Herein, we report a supramolecular-nanocage-based π framework constructed from a photoactive Cu(I) complex unit. Structurally, 24 Cu(I) complex units stack together through π-π stacking interactions, forming a truncated octahedral nanocage with sodalite topology. The inner diameter of the nanocage is 2.8 nm. By sharing four open faces, each nanocage connects with four equivalent ones, forming a 3D porous π framework (π-2). π-2 shows good thermal and chemical stability, which can adsorb CO2, iodine, and methyl orange molecules. More importantly, π-2 can serve as a photocatalyst for hydrogen evolution reaction. With ultrafine Pt subnanometer particles (0.9±0.1 nm) incorporated into the nanocages as a co-catalyst, the hydrogen evolution rate reaches a record-high value of 524012 μmol/gPt/h in the absence of any additional photosensitizers. The high photocatalytic activity can be ascribed to the ultrafine size of the Pt particles, as well as the fast electron transfer from π-2 to the highly active Pt upon illumination. π-2 represents the unique stable supramolecular-cage-based π framework with excellent photocatalytic activity.

Insights into mixed dye pollutant degradation by oxygen and air plasma bubbling array

Abstract Synthetic organic dye pollutants pose a serious threat to the aquatic ecological environment due to their difficulty in complete degradation. This study employed a plasma bubble array reactor to degrade individual and mixed dye pollutant solutions of Sunset Yellow (SY), Methyl Orange (MO), and Methyl Violet (MV). The degradation efficiencies and mechanisms of the plasma were investigated under different working gas atmospheres. It was found that oxygen plasma degraded the target dyes and their mixtures more significantly than air plasma. Specifically, compared with air plasma, the removal of single dyes SY, MO and MV by oxygen plasma was increased by 76.6%, 13.8% and 3%, respectively, after 20 min of treatment. As for mixed dyes, after 25 min treatment, oxygen plasma removed 99.1%, which was 31.6% higher than air plasma. However, the degradation kinetic order in oxygen plasma was SY > MO > MV, while that in air plasma was MV > MO > SY. Combined with the detection of reactive oxygen-nitrogen species (RONS), the results showed that the reactive oxygen species (ROS) played an important role in the degradation of SY, and it was also important for the degradation of MO, whereas both the ROS and reactive nitrogen species (RNS) were important for the degradation of MV. Scavenger experiments revealed that hydroxyl (·OH) and superoxide anion (·O2-) played the most important roles in the degradation process. The three dyes were basically completely degraded within 14-20 minutes of treatment, with corresponding yields of 1.94-2.79 g/kWh. Possible degradation pathways for each dye were deduced based on LC-MS and the toxicities of solutions were evaluated by phytotoxicity tests and ion chromatography. The results showed that the biotoxicity of the intermediates was significantly reduced. This study may provide a feasible option for effective application of plasma technology in organic dye wastewater treatment.

Sustainable Activated Carbon from Agricultural Waste: A Study on Adsorption Efficiency for Humic Acid and Methyl Orange Dyes

In this study, porous activated carbon was produced from coffee waste and used as an effective adsorbent for the removal of humic acid (HA) from seawater and methyl orange (MO) dye from aqueous solutions. Phosphoric acid H3PO4 was used as an activating agent for the chemical activation of these agricultural wastes. The characterization of the activated carbon obtained using a scanning electron microscope (SEM), Fourier-transform infrared (FTIR) spectroscopy analysis, X-ray diffraction (XRD) and the Brunauer–Emmett–Teller (BET) method revealed that the activated carbon products exhibited high porosity and the formation of various functional groups. The effects of different parameters were examined using batch adsorption experiments, such as the adsorbent masses, pH, initial pollutant concentration and contact time. The results show that the performance increased with an increased adsorbent mass (up to 0.25 g/L) and decreased initial concentration of the adsorbent tested. On the other hand, this study clearly showed that the adsorption efficiency of the MO on the raw spent coffee grounds (SCGs) waste was around 43%, while no removal was observed for the humic acid. The experiments demonstrated that the activated carbon synthesized from the used coffee grounds (the efficiency was compared with commercial activated carbon (CAC) with a difference of 13%) was a promising alternative to commercially available adsorbents for the removal of humic acid from seawater. To understand and elucidate the adsorption mechanism, various isothermal and kinetic models were studied. The adsorption capacity was analyzed by fitting experimental data to these models. The experimental data for methyl orange dyes were analyzed using Langmuir and Freundlich isothermal models. The Freundlich isotherm model provided a superior fit to the equilibrium data, as indicated by a higher correlation coefficient (R2) than that of the Langmuir model. The maximum adsorption was observed at pH 3. The Freundlich adsorption capacity was found to be 333 mg/g adsorbent. The PAC showed a high adsorption capacity for the MO and HA. The PAC showed the highest adsorption capacities for the HA and MO compared with the other adsorbents used (SCGs and CAC) and would be a good material to increase the adsorption efficiency for humic acid removal in the seawater pretreatment process. In addition, the prepared AC BET surface area was 520.40 m2/g, suggesting a high adsorption capacity. This makes the material potentially suitable for various applications that require a high surface area. These results indicate that high-quality sustainable activated carbon can be efficiently produced from coffee waste, making it suitable for a wide range of adsorbent applications targeting various pollutants.

Preparation of Composites Derived from Modified Loess/Chitosan and Its Adsorption Performance for Methyl Orange.

A modified loess/chitosan composite (ML@CS) was prepared via solution. The microstructure and physicochemical properties of ML@CS were characterised via scanning electron microscope (SEM), Zeta potential, X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), and thermogravimetric analysis (TGA). An aqueous solution of methyl orange (MO) was used as simulated wastewater from which the influence of the initial concentration and pH of MO, the dosage amount and regeneration performance of ML@CS, adsorption temperature, and time on the adsorption effect of MO were systematically investigated. The adsorption kinetics, isothermal adsorption, and adsorption mechanism were also analysed. The results indicate that ML@CS had a good adsorption effect on MO. When the initial concentration of MO was 200 mg/L, pH was 5.0, and ML@CS dosage was 1.0 g/L, the adsorption equilibrium could be reached within 180 min at room temperature, and the equilibrium adsorption capacity and removal rate reached 199.52 mg/g and 99.75%, respectively. After five adsorption-desorption cycles, the MO removal rate remained above 82%. The adsorption behaviour of ML@CS for MO conforms to the pseudo-second-order kinetic model and the Langmuir isotherm adsorption model. The spontaneous exothermic process was mainly controlled by monolayer chemical adsorption and the physical adsorption only played an auxiliary role. ML@CS efficiently adsorbed MO in water and can be used as a high-efficiency, low-cost adsorbent for printing and dyeing wastewater treatment.

Physical and enhanced photocatalytic MO dye degradation behaviour of Zn doped β-Ga2O3 microrods

This work explored the effects of Zn doping on the structural, micrographic, optical and photocatalytic behaviour of gallium oxide (β-Ga2O3) microrods. The X-ray diffractogram (XRD) and Raman spectral analyses confirmed the monoclinic structure of β-Ga2O3, with a shift to lower angles in the XRD pattern indicating Zn incorporation into the Ga2O3 lattice. The Scanning electron microscopy (SEM) images revealed a rod-like shape, with the diameter decreasing from 604 nm to 573 nm with Zn doping. Further analysis using TEM, HR-TEM, SAED, EDX, and elemental mapping confirmed the shape, crystallinity, crystal structure, and elemental distribution. The interplanar spacings were measured as 0.4 and 0.2 nm, corresponding to the (002) and (−311) planes of β-Ga2O3. UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) showed a slight shift in the absorption edge, while photoluminescence (PL) analysis demonstrated strong UV and weak visible light emission. Photocatalytic results revealed a high efficiency of dye degradation,(i.e) 98 % (20 ppm) and 89 % (30 ppm) against methyl orange (MO) dye aqueous solution over 150 min, with a rate constant of 0.02/min and 0.01/min, respectively for 1.5 wt% Zn doping. This suggests that the Zn-doped material holds promise as a photocatalyst for wastewater treatment applications.