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Cellulosic wastes represent a great environmental challenge, with potential conversion to product-added value through microbial fermentation. Currently, bacterial cellulose (BC) is considered a promising natural polymer for multiple applications. However, the high production cost challenges its wide application. Hence, the current study evaluated the applicability of paper sludge as a cost-effective medium for both cellulases and BC production. The local isolate Streptomyces rochei revealed the highest cellulase production titer (about 3 U/mL) at optimized conditions. For BC production, batch and fed-batch fermentation strategies were evaluated using enzymatically hydrolyzed paper sludge. The results asserted the advantage of fed-batch fermentation for advanced BC production (3.10 g/L) over batch fermentation (1.06 g/L) under the same cultivation conditions. The developed BC membranes were characterized through different instrumental analyses, which revealed an increase in fiber diameters and crystallinity under fed-batch fermentation. Furthermore, BC/magnetite (BC/Fe3O4) nanocomposite was developed by an in-situ approach. The newly developed composite was evaluated for dye removal applications, using methyl orange (MO) as a model. The dye removal conditions were optimized through Box Behnken design (BBD), which indicated maximal MO removal (83.5%) at pH 3.0 and BC/Fe3O4 concentration of 0.1 mg/dL after 60 min. Therefore, the current study asserts the good applicability of enzymatically hydrolyzed paper sludge as a medium for cost-effective BC production and the high capacity of BC/magnetite nanocomposite for MO decolorization. The study paves the way for the cost-effective implementation of BC/magnetite nanocomposite for dye removal.

In the present work, a polymeric nanocomposite adsorbent of cross-linked chitosan-adipic acid and SnO 2 nanoparticles (CS-ADP/SnO 2 ) was created for the adsorption of methyl orange (MO) dye from water. Response surface methodology (RSM) was used to examine how three factors affected the adsorption of the dye MO: time C (10–40 min), pH (4–10), and CS-ADP/SnO 2 dosage (0.02–0.08 g/L). The CS-ADP/SnO 2 nanocomposite has a BET surface area of 28.64 m 2 /g, a total pore volume of 0.0271 cm 3 /g, and a mean pore diameter of 3.79 nm. The several XRD diffraction peaks and average crystallite size of 31.33 nm of the CS-ADP/SnO 2 nanocomposite indicate that it primarily possesses polycrystalline properties. The MO adsorption by CS-ADP/SnO 2 could be well described by the isotherm model, which was validated by the adsorption kinetics and Freundlich and pseudo-first-order kinetic models. The best circumstances for maximum MO elimination (80.54%) were found to be a pH of 4, a CS-ADP/SnO 2 dosage of 0.055 g/L, and a contact period of 40 min, according to the results of the BBD model. At 25 o C, the maximal adsorption capacity of the CS-ADP/SnO 2 nanocomposite toward the MO dye was 344.91 mg/g. The Yoshida H-bonding, electrostatic interaction, hydrogen bonding, and n-π stacking interaction, were postulated as the mechanisms for MO dye adsorption onto CS-ADP/SnO 2 nanocomposite. In summary, this research suggests that the composite has the ability to effectively remove organic dyes from water systems, making it a promising new adsorbent.

Organic ZnCr-LDH (ST-LDH) was synthesized by a facile one-step hydrothermal technique using methyl orange (MO) as a soft template agent, which can efficiently remove methyl orange (MO), Congo red (CR), and orange II (OII) from aqueous solution. The microstructure of ST-LDH by modifying changed obviously, from the cellular structure to the stacking structure formed by the face-face contact of hydrotalcite nanosheets, which resulted in much more exchangeable nitrate ions to remain in the interlayer space. The pre-insertion of benzene sulfonate as a pillar expanded the interlayer gallery, which facilitated the pollutant anions (MO, CR, and OII) into the interlayer of LDH in the subsequent adsorption process. The maximum adsorption capacity of ST-LDH for MO, CR, and OII was 4200.8 mg/g, 1252.0 mg/g, and 1670.6 mg/g, respectively, which is approximately 1.86 times, 1.8 times, and 2.32 times that of the pristine NO 3 -LDH, respectively. The removal mechanism of anionic dyes was determined as anion exchange between NO 3 − anions and dye molecules. The adsorption behavior for MO and OII is multilayer adsorption, while the adsorption behavior for CR is monolayer adsorption. The adsorption process mainly was controlled by the chemical bonding between the dye molecules and adsorbent active sites. The LDH can be effectively regenerated by photocatalysis after MO adsorption. The ST-LDH has a great potential to be used as a high-efficient adsorbent to remove anionic dyes from aqueous solution. Graphical abstract The schematic illustration of the synthetic process of soft template agent modified and unmodified hydrotalcites by one-pot hydrothermal method and the adsorption process of MO by ST-LDH were shown in Fig. 12 . Modified hydrotalcite (ST-LDH) was prepared using methyl orange (MO) as a soft template agent. Compared with unmodified hydrotalcite (NO 3 -LDH), the insertion of benzene sulfonate anions into the hydrotalcite layer resulted in the increase of the interlayer spacing from 8.269 to 8.654Å. The LDH host structure pre-intercalated by benzene sulfonate anions evolved into pillared materials in interlayer; benzene sulfonate anions as a column expanded the interlayer spacing of (003) base plane, which facilitated the pollutant anions (MO, CR, and OII) into the interlayer of ST-LDH and exchanged with NO 3 − anion in the subsequent adsorption process. It can be inferred that in the process of modification hydrotalcite by benzene sulfonate, a small amount of benzene sulfonate anions pre-inserted into the gallery of hydrotalcite with a monolayer model in the process of hydrotalcite modification, and its inclination angle is calculated to be about 29.1°. After ST-LDH sample adsorbed the MO molecules, dye molecules intercalated into the LDH host, and successful exchange with NO 3 − anions, the d 003 value increased to 24.78 Å. A large amount of MO − anions were intercalated into the gallery of ST-LDH with a bilayer model according to the Freundlich isotherm model, and the tilting angle increases to 53.6°. The adsorption capacity of MO by ST-LDH was significantly enhanced to 4200.8 mg/g, which was much higher than that of NO 3 -LDH (2252.8 mg/g). Schematic illustration of the synthetic process of LDH materials and adsorption process of MO by ST-LDH.

Pistachio nutshells-derived biochar (PNS-BC) was utilized as a cost-effective adsorbent for competently removing a model dye, methyl orange (MO) from wastewater. Three concentrations of TiO 2 ; 1%, 2%, and 3% were used to decorate the biochar. Analysis of morphology, stability, and structure of the three adsorbents (PNS, PNS-BC, and the TiO 2 functionalized biochar; TiO 2 @PNS-BC) was extensively explored using various characterization techniques. The synergistic photocatalytic-adsorptive efficiency of the three adsorbents was compared. In this regard, a Box-Behnken (BB) design-based multivariate scheme was inaugurated with the target of maximizing MO removal (%R) while using the minimum possible of chemicals and resources. The impact of five variables; %TiO 2 , dose of TiO 2 -PNS, reaction time, dye concentration, and pH on the magnitude of %R was investigated. Results show that 97.69% removal of MO could be recognized over 120 min using adsorption compared to 99.47% removal over 30 min using 3% TiO 2 @PNS-BC as a photocatalyst. A 3% TiO 2 @PNS-BC was the best catalyst (compared to 1% and 2%) with a decolorization rate constant of 0.12741 min −1 , ~ 1.5 × faster compared to the decolorization of MO using adsorption alone. Adsorption of MO conformed well to Langmuir isotherm. A maximum adsorption capacity ( q max ) of 142.38 mg/g was achieved. Adsorption kinetics fitted well with the pseudo-second order (PSO) model. Results obtained indicated that biochar of PNS is a promising, cost-effective, and economical adsorbent.

A facile single-step hydrothermal method was used for the decoration of titania (TiO₂) nanoparticles (diameter ca. 40–250 nm) on the surface of cellulose fibers. These cellulose fibers decorated with TiO₂nanoparticles were used to prepare paper matrices by the handsheet-making procedure. The papers showed excellent photocatalytic activity by degrading methyl orange in the presence of UV light and also showed promising antibacterial activity against Escherichia coli. Both the photocatalytic and antibacterial applications of these paper matrices were studied by varying the TiO₂contents from 1 to 10 wt%.

In this research work, the photocatalytic degradation of methyl orange dye was studied on nickel oxide supported on a natural Moroccan clay (Ni/NC). These catalysts have been prepared by dry impregnation of a nickel nitrate solution with different weight percentages (5, 10, 20% NiO). Experimental responses were obtained by a Box-Behnken (BBD) experimental design by varying the catalyst mass, solution pH, and initial dye concentration at three levels (low, medium, and high). The prepared catalysts were characterized using powder X-ray diffraction (XRD) to assess crystallinity and structure, Fourier transform infrared spectroscopy (FTIR) to detect different functional groups, scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis to study the surface morphology, and the optical characteristics of the catalysts were studied using absorption and diffuse reflectance measurements in the UV–visible range. The photocatalytic activity of the catalysts was evaluated in aqueous solutions under UV irradiation. ANOVA (analysis of variance) test is employed to recognize the significant factors and their interactions and then give the model equation for the percent dye degradation. The optimal values of the studied factors were determined by numerical optimization, and the results showed that about 100% degradation of the methyl orange dye could be achieved under the following optimal conditions, which are pH = 4.38, catalyst concentration of 0.99 g/L, and initial dye concentration of 30.42 mg/L.

NiFe2O4/SiO2/NiO magnetic was successfully synthesized using NiFe2O4, SiO2, and NiO as the core, interlayer, and shell, respectively. NiFe2O4/SiO2/NiO under UV light irradiation was used for photocatalytic degradation of methyl orange dye with different pH, catalyst dose, and initial dye concentration. This composite was characterized by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR), Scanning Electron Microscopy-Electron Dispersive X-ray Spectroscopy (SEM-EDs), Vibrating Sample Magnetometer (VSM), UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS), and Point of Zero Charge (pHpzc). The results showed that the composite is a superparamagnetic material with a saturation magnetization value of 44.13 emu/g. It also has a band gap of 2.67 eV with a pHpzc of 6.33. The optimum conditions for photocatalytic degradation were at pH of 4; 0.50 g/L catalyst dose, and 10 mg/L initial concentration. NiFe2O4/SiO2/NiO degradation efficiency to methyl orange dye was 95.76%. The photocatalytic degradation in different concentrations follows the pseudo-first-order, where the greater the concentration, the smaller the constant rate (k). After five cycles of repeated usage, NiFe2O4/SiO2/NiO has good catalytic performance as well as efficient and favourable of a recyclable photocatalyst. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

The revolutionary applications of seaweed extracts show promising potential to change the way of research and commercial applications based on seaweed. A commercial liquid extract (True Algae Max, TAM ® ), derived from three seaweed species ( Pterocladiella capillacea, Jania rubens , and Ulva lactuca ), contains a variety of several nutrients, bioactive compounds, and biomolecules, thereby exhibiting potent biological activities. Due to their extensive industrial use, organic dyes constitute a substantial constituent of wastewater. The adsorption process of anionic methyl orange (MO) dyes onto TAM ® in an aqueous solution as a potential and a new adsorbent has been investigated. Energy dispersive X-ray spectroscopy (EDS), Mass spectra, and Infrared analysis (FT-IR) were applied to verify the adsorption performance. Batch adsorption experiments were performed to estimate the influence of several factors such as pH, the amount of TAM ® sorbent, temperature, agitating time, and initial concentration of MO dye parameters. Maximum dye adsorption of 90.34%and 46.09 mg g –1 was recorded at doses of biomass at 0.4 g and 16.88 mg g − 1 at pH 1. Adsorption kinetics data were investigated by the first, pseudo-second-order, and intraparticle diffusion models. Kinetic studies showed that the adsorption process was followed by intraparticle diffusion models and a pseudo-second-order reaction. The investigational isotherm data were studied using four isotherm models to evaluate the adsorption equilibrium using regression analysis. With maximum sorption capacities of 156.25 mg g − 1 for MO. Regeneration of the consumed adsorbent was effectively emphasized for two cycles of desorption/sorption process for MO removal from the aqueous solution. According to the findings, TAM ® biomass is a novel, inexpensive alternative adsorbent that shows promise for removing MO from aqueous solutions. Additionally, the usage of TAM’s methanol extract exhibits substantial antibacterial action at concentrations of 500 mg ml − 1 against Staphylococcus aureus, Salmonella typhimurium , and Pseudomonas aeruginosa , and 250 mg ml − 1 against Escherichia coli .

In this study, we synthesized cobalt-doped molybdenum supported on silica (Co/MS) nanocomposites with varying concentrations of cobalt (1, 5, 10, 15, and 20 wt%) using the sol-gel method. We investigated their physico-chemical properties, photocatalytic activity, and antimicrobial efficacy. The synthesized nanocomposites were characterized using a range of techniques, including X-ray powder diffraction (XRD) to determine crystal structure, UV-vis spectroscopy for optical properties, Fourier transform infrared spectroscopy (FT-IR) for functional group analysis, and scanning electron microscopy coupled with energy-dispersive X-ray microanalysis (SEM-EDX) for morphological and elemental composition analysis. The photocatalytic performance of these catalysts was assessed by their ability to degrade organic dyes, specifically methyl orange and methylene blue, under visible light irradiation. Our results demonstrated that the photocatalytic efficiency increased with higher cobalt content, with the 20 wt% Co/MS nanocomposite showing the highest degradation rates. Additionally, we evaluated the antibacterial activity of the nanocomposites against a range of microorganisms, including Gram-positive and Gram-negative bacteria, as well as fungal species. The 20 wt% Co/MS nanocomposite exhibited superior antimicrobial activity compared to the other samples, indicating its potential for applications in environmental remediation and antimicrobial treatments.

In this study, a novel activated carbon adsorbent from the press mud of a sugarcane industry was used to remove methyl orange dye (MOD) from aqueous solution and was optimized via response surface methodology using the central composite design. The adsorbent was characterized by FTIR and SEM analysis and showed the presence of functional groups such as alcohols, nitriles, amides, alkane, alkyl halides, and alkenes, and it also showed fibrous surface morphological appearance. The factors affecting MOD adsorption, such as initial concentration, adsorbent dose, and contact time were examined, and optimal pH 2.0 to remove MOD in an aqueous solution that is found in various studies is also utilized. The results showed maximum MOD removal rate of 98.68% when the initial concentration, adsorbent dose, and contact time were optimally set as 24.17 mg/L, 0.5 g, and 20 min, respectively. The analysis of the equilibrium data revealed that MOD adsorption using press mud activated carbon best fitted the Langmuir isotherm (R2 = 0.96103) which implies monolayer adsorption process. Also, the kinetics of MOD adsorption using press mud activated carbon followed a pseudo-first-order model (R2 = 0.96096) which means that the active sites are proportional to the non-active sites during the adsorption process.