Alginate-based porous polyHIPE for removal of single and multi-dye mixtures: Competitive isotherm and molecular docking studies.

A novel hydrophilic porous alginate-based polyHIPE (AGA) was synthesized via an oil-in-water emulsion templating approach. AGA was used as an adsorbent for removing methylene blue (MB) dye in single- and multi-dye systems. BET, SEM, FTIR, XRD, and TEM were used to characterize AGA to elucidate its morphology, composition and physicochemical properties. According to the results, 1.25 g/L AGA adsorbed 99 % of 10 mg/L MB in 3 h in a single-dye system. The removal efficiency decreased to 97.2 % in the presence of 10 mg/L Cu2+ ions and 40.2 % when the solution salinity increased to 70 %. In a single-dye system, the experimental data do not match well with the Freundlich isotherm, pseudo-first order, and the Elovich kinetic model, however, in a multi-dye system, it fit well with both extended Langmuir and the Sheindorf-Rebhun-Sheintuch. Notably, AGA removed 66.87 mg/g in a dye solution containing only MB, whereas 50.14-60.01 mg/g adsorption of MB was accomplished in a multiple-dye system. According to the molecular docking analysis, the dye removal process involved chemical bonds between the functional groups of AGA and the dye molecules, hydrogen bonds, hydrophobic and electrostatic interactions. The overall binding score of MB decreased from -26.9 kcal/mol in a single-dye system to -18.3 kcal/mol in a ternary system.

Metal-organic framework-based nanomaterials as opto-electrochemical sensors for the detection of antibiotics and hormones: A review.

Increasing trace levels of antibiotics and hormones in the environment and food samples are concerning and pose a threat. Opto-electrochemical sensors have received attention due to their low cost, portability, sensitivity, analytical performance, and ease of deployment in the field as compared to conventional expensive technologies that are time-consuming and require experienced professionals. Metal-organic frameworks (MOFs) with variable porosity, active functional sites, and fluorescence capacity are attractive materials for developing opto-electrochemical sensors. Herein, the insights into the capabilities of electrochemical and luminescent MOF sensors for detection and monitoring of antibiotics and hormones from various samples are critically reviewed. The detailed sensing mechanisms and detection limits of MOF sensors are addressed. The challenges, recent advances, and future directions for the development of stable, high-performance MOFs as commercially viable next-generation opto-electrochemical sensor materials for the detection and monitoring of diverse analytes are discussed.

Bismuth-based nanostructured photocatalysts for the remediation of antibiotics and organic dyes.

A serious threat to human health and the environment worldwide, in addition to the global energy crisis, is the increasing water pollution caused by micropollutants such as antibiotics and persistent organic dyes. Nanostructured semiconductors in advanced oxidation processes using photocatalysis have recently attracted a lot of interest as a promising green and sustainable wastewater treatment method for a cleaner environment. Due to their narrow bandgaps, distinctive layered structures, plasmonic, piezoelectric and ferroelectric properties, and desirable physicochemical features, bismuth-based nanostructure photocatalysts have emerged as one of the most prominent study topics compared to the commonly used semiconductors (TiO2 and ZnO). In this review, the most recent developments in the use of photocatalysts based on bismuth (e.g., BiFeO3, Bi2MoO6, BiVO4, Bi2WO6, Bi2S3) to remove dyes and antibiotics from wastewater are thoroughly covered. The creation of Z-schemes, Schottky junctions, and heterojunctions, as well as morphological modifications, doping, and other processes are highlighted regarding the fabrication of bismuth-based photocatalysts with improved photocatalytic capabilities. A discussion of general photocatalytic mechanisms is included, along with potential antibiotic and dye degradation pathways in wastewater. Finally, areas that require additional study and attention regarding the usage of photocatalysts based on bismuth for removing pharmaceuticals and textile dyes from wastewater, particularly for real-world applications, are addressed.

Dual function Mg-doped binary metal ferrite: Photocatalytic degradation of trichlorophenol, bactericidal activity and molecular docking analysis.

A new Mg-doped Zn0.5Ni0.5Fe2O4 (Mg-FZN) photocatalyst was synthesised using a simple co-precipitation-doping technique to develop a dual-function material with the ability to degrade hazardous and refractory pollutants and inactivate bacterial strains. The characterization results revealed that Mg-FZN is an n-type semiconductor with a conduction band of -0.413 eV, an average pore width of 2.32 nm, and a crystal size of 31.45 nm. The photocatalytic activity of Mg-FZN was assessed based on the degradation of 2,4,5-trichlorophenol and achieved 83.8% degradation efficiency under optimised conditions. The radical quenching results revealed that h+ significantly contributed to the photodegradation process while •OH, and •O2- played key roles. Additionally, within 60 min, 25 mg of Mg-FZN had bactericidal effects on the bacteria E. coli and S. aureus in both the presence and absence of UV light. Mg-FZN showed H-bonding, electrostatic, and metal-contact interactions with the amino acid residues of the bacterial protein with high binding scores (-4.711 kcal/mol and -5.872 kcal/mol), according to molecular docking.

Efficient removal of antibiotic in single and binary mixture of nickel by electrocoagulation process: Hydrogen generation and cost analysis.

In discharged water, antibiotics and heavy metals frequently coexist, forming stable and recalcitrant complexes. Environmental concerns about how to efficiently treat this type of pollution are growing. Using Fe and Al electrodes, electrocoagulation (EC) was applied to remove tetracycline (TC) as a single pollutant as well as TC-nickel ions in a binary mixture from water. The effects of critical variables and the TC-Ni molar ratio (1:1, 1:2, and 2:1) were studied. The Fe electrode achieved 99.3% TC removal after 60 min in a single pollutant system containing 15 mgL-1 of TC, while the Al electrode achieved 99.8% removal in 20 min at optimal conditions. The EC process demonstrated excellent electrodegradation efficiency towards TC-Ni complexes. When the TC to Ni2+ ratio was 1:1 and 1:2, respectively, TC elimination was 100% in 10 min and 99.6% in 20 min. We noted that a sufficient amount of Ni2+ could increase TC decomposition by electrocatalysis. The amount of hydrogen gas produced after treatment of a 0.2 L TC solution alone is 22.2-13.99 mol m-3, whereas it was 27.2-40.8 mol m-3 in the TC-Ni binary mixture, which can generate more than 35% of the electrical energy needed to power the EC system. To evaluate the generated sludge, FTIR analysis was performed.

CuCr2O4@CaFe-LDO photocatalyst for remarkable removal of COD from high-strength olive mill wastewater.

Wastewater from the olive mill constitutes a serious environmental concern, as it is characterized by a high inorganic and organic load. Here, a hybrid photocatalyst based on calcined Ca-Fe-LDH was successfully synthesized for the degradation of phenolic compounds and the removal of chemical oxygen demand (COD) from the high-strength olive mill wastewater (OMW). The catalyst (CuCr2O4@CaFe-LDO) displayed a stable ~4.48 µA cm-2 photocurrent response, a 2.56 eV bandgap and a wide variety of pores with an average size of 12.51 nm. 1.0 g CuCr2O4@CaFe-LDO achieved 66% COD removal after 300 mins without an oxidant in the dark, while after 180 mins of reaction, CuCr2O4@CaFe-LDO/K2S2O8/sunlight system resulted in ~99% and 98.3% COD and colour removal. Seven phenolic compounds were found in the crude OMW, with hydroxytyrosol (76.84%) and tyrosol (15.14%) being the main ones. The final pH of the sample treated increased from 4.3 to 7.3, which confirmed the degradation of phenolics and fatty acids in the OMW. OH, SO4-, h+ and O2- contributed notably to the degradation of polyphenols and the spent catalyst was easily and rapidly recovered from the bulk solution due to its saturation magnetization of 54.7 emu g-1.

Hybrid MnFe-LDO-biochar nanopowders for degradation of metronidazole via UV-light-driven photocatalysis: Characterization and mechanism studies.

A cost-competitive MnFe-LDO-biochar hybrid catalyst was successfully synthesized via a simple yet efficient technique for the decomposition of metronidazole (MZ). MnFe-LDO-biochar was characterized by various techniques and the results revealed that it has a bandgap of 2.85 eV, high photocurrent response of 3.8 µA cm-2 and can be separated rapidly from the bulk solution by an external magnet due to its saturation magnetization of 28.5 emu g-1. Initially, in the dark condition, 20% of MZ was removed after 30 min when 20 mg L-1 MZ solution was treated with 50 mg MnFe-LDO-biochar in the presence of 6 mM H2O2. The MZ degradation increased remarkably to ∼98% upon exposure to a UV light for 60 min. Under various processes, UV/MnFe-LDO-biochar/H2O2 presented high degradation rate constant of 0.226 min-1 and lowest energy consumption cost of 0.38$ at 7.56 kWh m-3 which is ∼13 times lower than the degradation of MZ by the photolytic process under similar conditions. The MZ photocatalytic decomposition trend revealed a multiprocess mechanism influenced majorly by •OH and partly by h+ and •O2-. Note that in MnFe-LDO-biochar/UV system; 5% of MZ degradation was observed after 120 min and reached 13% after 300 min. MnFe-LDO-biochar maintained ∼88% reuse efficiency after three consecutive recycling tests.

CuO coated olive cake nanocomposites for rapid phenol removal and effective discoloration of high strength olive mill wastewater.

The potential of solid olive wastes-based adsorbent (CuO-OC) with photocatalytic power was established for the removal of total phenolics and photocatalytic discolourization of high strength olive mill wastewater (OMW). Clear insight of the FTIR and Brunauer-Emmett-Teller analyses showed that oxygen-containing functional groups of CuO-OC likely participated in the adsorption of total phenols from the OMW via a π-π interaction, hydrogen bonding and electrostatic interaction. Also, the total pore volume of CuO-OC decreased from 0.068 to 0.052 cm3 g-1 after adsorption, which suggested that phenolics were trapped within the micro- and mesopores of CuO-OC. The adsorption kinetics revealed that ∼82.7-95% of the phenolic compounds were removed within the first 360 min which is relatively faster than adsorbents and methods reported elsewhere. The isotherm results showed that Redlich-Peterson equation fit the experimental data very well with least error (χ2 = 1.46-3.19) and high correlation coefficients (0.992-0.996), which suggested a mixture of hetero- and monolayer coverage of the phenolics on the CuO-OC surface. Results obtained herein are of practical interest and the reuse efficiency of CuO-OC remained ∼60% after 5 successive recycling.

High adsorptive potential of calcined magnetic biochar derived from banana peels for Cu2+, Hg2+, and Zn2+ ions removal in single and ternary systems.

The use of banana peel as a sustainable and low-cost precursor for the fabrication of effective biochar was exploited. Here, calcined magnetic biochar (CMB) was fabricated and characterized. CMB possesses surface acidic functional groups (-OH and COO-), porous structures, high saturation magnetization (39.55 emu/g), and larger surface area than the non-magnetic biochar (CB). The CMB adsorption performance (72.8, 75.9, and 83.4 mg/g for Zn2+, Cu2+, and Hg2+, respectively at pH 6) in a single component was described suitably by pseudo-second order kinetic model, Langmuir, and Redlich-Peterson adsorption isotherms. Notably, the selectivity factor values in the extended Langmuir isotherm indicated that CMB has higher adsorption affinity toward Hg2+ than Cu2+ and Zn2+ in the multi-component system. Owing to its high adsorption efficiency and fast and easy separation, the calcined magnetic biochar is considered promising and effective for the purification of heavy metal-bearing wastewater.

Porous magnetic resin-g-chitosan beads for adsorptive removal of phenolic compounds.

In this study, porous magnetic resin grafted chitosan (R-g-Ch) beads were prepared for removal of 4-chlorophenol and phenol from aqueous solutions. The R-g-Ch beads were characterized by vibrating sample magnetometer, Fourier-transform infrared spectroscopy, scanning electron microscopy and thermogravimetry methods. The removal of the phenolic compounds was optimized by varying the experimental conditions. Results herein are well fitted to the pseudo-second order kinetic and Langmuir isotherm. The maximum adsorption capacity of phenol and 4-chlorophenol were found to be 188.6 and 99 mg/g, respectively. The thermodynamic studies suggested that the adsorption process was exothermic, irreversible and feasible within the range of 298-318 K.

Engineered mixed oxide-based polymeric composites for enhanced antimicrobial activity and sustained release of antiretroviral drug.

Here, pH-responsive engineered polymeric composites were fabricated from sodium alginate and mixed Cu/Zn oxides. The resulting alginate-CuxZn1-xO composites were characterized by FTIR, SEM and XRD, then used as an efficient carrier for the antiretroviral drug (zidovudine, AZT) and exhibited remarkable antibacterial properties. The resulting polymeric composites had specific surface areas of 185.2-198.6 m2/g as confirmed by the Brunauer-Emmett-Teller analysis. The metal oxide distribution within the alginate matrix was confirmed from the X-ray diffraction and scanning electron microscopy analyses. The zidovudine, an antiretroviral drug was encapsulated in 30 mg of alginate-Cu0.7Zn0.3O with 68% encapsulation efficiency. The release of AZT in simulated intestinal fluid (pH 7.4) was studied, a slow and sustained release of AZT (~96.2%) was observed. The AZT release kinetics is sufficiently described by the Korsmeyer-Peppas model and follows the Fickian transport profile. Results herein demonstrated that A-Cu0.7Zn0.3O, A-Cu0.3Zn0.7O and Cu0.5Zn0.5O exhibited excellent bacterial devastation property. A dose of 8 µg/mL A-Cu0.7Zn0.3O and 13 µg/mL A-Cu0.3Zn0.7O are sufficient to completely killed E. coli DH5a and S. aureus NSUHS-151 within 24 h.

Highly efficient magnetic chicken bone biochar for removal of tetracycline and fluorescent dye from wastewater: Two-stage adsorber analysis.

Magnetic chicken bone biochar (MCB) was fabricated and characterised. The specific surface area, magnetisation value and pHpzc of the MCB were found to be 328 m2 g-1, 64.7 emu/g and 8.3 respectively. The adsorptive performance of MCB for rhodamine B dye (RB) and tetracycline (TC) removal in a single and two-stage stirred adsorber (TSA) was evaluated. The TSA reduced the pressure drops, mass transfer resistances, and fouling of the adsorbent. 63.0 g MCB is required to remove 75% of RB and TC in a single-stage system within 12 h. However, the optimised TSA confirmed that 33.2 g of MCB is needed to achieve 96% removal of TC and 22.2 g for RB within 180 min of 100 mgL-1 effluent solutions. The sorption was suitably described by the Freundlich mechanism. Based on the comparative performance, the MCB is considered a viable efficient and magnetically separable alternative adsorbent.

High-performance magnetic chicken bone-based biochar for efficient removal of rhodamine-B dye and tetracycline: competitive sorption analysis.

Magnetic chicken bone-based biochar (MCBB) was successfully prepared and efficiently adsorbed rhodamine-B (RB) dye and tetracycline (TC) in multi-component systems. The magnetisation value, surface area, and pHpzc of the MCBB were found to be 66.5 emu/g, 328 m2/g, and 8.3, respectively. RB has higher saturation capacity (96.5 mg/g) and occupies more active sites on MCBB, thus limiting the sorption of TC with lower saturation capacity (63.3 mg/g). Langmuir isotherm suitably describes the sorption process in a single-component system; however, the multi-component system was well fitted to the Sheindorf-Rebhun-Sheintuch model. The selectivity factor values confirmed that MCBB had higher adsorption affinity toward RB than TC. The intraparticle diffusion model played a significant role in the sorption process. The MCBB can be easily desorbed with base-spiked H2O and reused without loss in stability or structural integrity.

Efficient boron abstraction using honeycomb-like porous magnetic hybrids: Assessment of techno-economic recovery of boric acid.

Porous magnetic hybrids were synthesized and functionalized with glycidol to produce boron-selective adsorbent. The magnetic hybrid (MH) comparatively out-performed the existing expensive adsorbents. MH had a saturation magnetisation of 63.48 emu/g and average pore diameter ranging from meso to macropores. The magnetic hybrids showed excellent selectivity towards boron and resulted in 79-93% boron removal even in the presence of competing metal ions (Na+ and Cr2+). Experiments were performed in a column system, and breakthrough time was observed to increase with bed depths and decreased with flow rates. The batch experiments revealed that 60 min was enough to achieve equilibrium, and the level of boron sorption was 108.5 mg/g from a synthetic solution. Several adsorption-desorption cycles were performed using a simple acid-water treatment and evaluated using various kinetic models. The spent adsorbents could be separated easily from the mixture by an external magnetic field. The cost-benefit analysis was performed for the treatment of 72 m3/year boron effluent, including five years straight line depreciation charges of equipment. The net profit and standard percentage confirmed that the recovery process is economically feasible.

Facile synthesis of glucose-sensitive chitosan-poly(vinyl alcohol) hydrogel: Drug release optimization and swelling properties.

The study describes the development of glucose-sensitive hydrogel and optimization of bovine serum albumin release profile from the hydrogel. To enhance the glucose sensitivity and improve the swelling behaviors of the hydrogel system, boric acid crosslinking, and freeze-thawing cycle techniques were used to prepare chitosan-poly(vinyl alcohol) hydrogel. The structure of the resultant hydrogel was confirmed by scanning electron microscopy and Fourier transform infrared spectroscopy. The experimental results revealed that the swelling of the hydrogel was influenced by the pH of the medium, and the hydrogel displayed explicit glucose-sensitivity under physiological conditions. The values of the diffusion exponent range between 0.34 and 0.44 and the diffusion of water into the gel system are assumed to be pseudo-Fickian in nature. Under optimized conditions, the cumulative Bovine serum albumin (BSA) drug releases ranged between 69.33±1.95% and 86.45±1.16% at 37°C in the presence of glucose and pH 7.4, respectively.

Bifunctional composite from spent "Cyprus coffee" for tetracycline removal and phenol degradation: Solar-Fenton process and artificial neural network.

Removals of tetracycline and photocatalytic degradation of phenol by Fe3O4/coffee residue (MCC) were investigated. Brunauer-Emmett-Teller (BET), vibrating sample magnetometer (VSM) and Boehm titration were employed to characterize MCC. Artificial neural network (ANN) model was developed to predict the tetracycline (TC) concentration in the column effluent. Maximum tetracycline adsorption capacity of 285.6mg/g was observed in a batch system. High removal efficiency (87%) was obtained at 3.3mL/min flow rate, 8.0cm bed height and 50mg/L influent TC concentration in a column system. Complete degradation of phenol by solar-Fenton was attained at 60min irradiation time. Total organic carbon (TOC) removal increased to 63.3% in the presence of 1.0g/L MCC, 1.2g/L H2O2 and solar irradiation. MCC showed remarkable potential to remove antibiotics from wastewater even in the presence of heavy metal (Ni(2+)) via magnetic separation.