Preparation of polyhedral oligomeric silsesquioxane based cross-linked inorganic-organic nanohybrid as adsorbent for selective removal of acidic dyes from aqueous solution

Surface amphiphilic hybrid porous polymers based on cage-like organosiloxanes for pipette tip solid-phase extraction of microcystins in water

The occurrence of microcystins (MCs) during harmful algal blooms (HABs) represents a major threat to freshwater environments. In this work, a novel surface amphiphilic hybrid porous polymers based on cage-like organosiloxanes (PCSs) was prepared for the enrichment of MCs. The copolymerization of bifunctional amphiphilic monomers, 2-methacryloyloxyethyl phosphorylcholine (MPC) and N-benzylquininium chloride (BQN), with the cross-linker methacryl substituted polyhedral oligomeric silsesquioxane (POSS) was achieved in an ionic liquid-based porogenic medium. The hierarchical porous structure, a variety of surface functional groups and weak hydrophilicity were well characterized on the prepared materials using scanning electron microscopy, nitrogen adsorption/desorption analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential analysis and water contact angle testing, respectively. The as-prepared surface amphiphilic PCSs was used as an adsorbent for pipette tip solid-phase extraction (PT-SPE) to enrich microcystins (MCs) from surface waters before their analysis by capillary electrochromatography (CEC) and liquid chromatography-mass spectrometry (LC-MS). Under the optimal conditions, the established PT-SPE-LC-MS method exhibited a wide linear range (10-10,000 ng L-1), low limits of detection (4.0-8.0 ng L-1) and satisfactory recoveries (89.5-102.8 %) for MCs. An adsorption mechanism involving electrostatic interactions, hydrogen bonding, hydrophilic interactions, and π-π stacking has been proposed. The findings suggest that the use of surface amphiphilic PCSs materials as adsorbents in the PT-SPE platform facilitates efficient enrichment of MCs for subsequent chromatographic analysis. These investigations offer a new perspective on the simple and uncomplicated pretreatment of complex environmental samples.

Hybrid Dendrimer Network based on Silsesquioxane and Glycidyl Methacrylate for Enhanced Adsorption of Iodine and Dyes in Environmental Remediation

A novel hybrid network was synthesized in two steps: the first step involved the attachment of glycidyl methacrylate (GMA) to octa(aminophenyl) silsesquioxane (OAPS) through a ring-opening reaction, forming a hybrid dendrimer structure, and the second step involved the cross-linking of hybrid dendrimer using an azobisisobutyronitrile initiator to create the final hybrid network of OAPS-GMA. The synthesized hybrid material was comprehensively characterized using fourier transform infrared Spectroscopy (FTIR), nuclear magnetic resonance ((1H, 13C, and 29Si NMR) spectroscopy, thermogravimetric Analysis (TGA), and scanning electron microscopy (SEM). The BET surface area was found to be 25.44 m2/g, and significant 2.341 cm3/g of total pore volume was observed. The TGA analysis shows that the material is highly stable up to 450 °C. The synthesized network demonstrated remarkable adsorption capacities for iodine and dyes. It exhibited an iodine adsorption capacity of 3.4 g/g from vapors and 874 mg/g from solution. Additionally, it showed significant adsorption capacities for Rhodamine B and Congo red, with values of 762 mg/g and 517 mg/g, respectively. This study not only provides a novel method for preparing GMA-functionalized silsesquioxane-based porous hybrid polymers but also contributes to advancing solutions for environmental pollution issues.

Regenerated Silk Nanofibers for Robust and Cyclic Adsorption-Desorption on Anionic Dyes

In recent years, adsorption-based membranes have been widely investigated to remove and separate textile pollutants. However, cyclic adsorption-desorption to reuse a single adsorbent and clear scientific evidence for the adsorption-desorption mechanism remains challenging. Herein, silk nanofibers were used to assess the adsorption potential for the typical anionic dyes from an aqueous medium, and they show great potential toward the removal of acid dyes from the aqueous solution with an adsorption rate of ∼98% in a 1 min interaction. Further, we measured the filtration proficiency of a silk nanofiber membrane in order to propose a continuous mechanism for the removal of acid blue dye, and a complete rejection was observed with a maximum permeability rate of ∼360 ± 5 L·m^-2·h^-1. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy studies demonstrate that this fast adsorption occurs due to multiple interactions between the dye molecule and the adsorbent substrate. The as-prepared material also shows remarkable results in desorption. A 50-time cycle exhibits complete adsorption and desorption ability, which not only facilitates high removal aptitude but also produces less solid waste than other conventional adsorbents. Additionally, fluorescent 2-bromo-2-methyl-propionic acid (abbreviated as EtOxPY)-silk nanofibers can facilitate to illustrate a clear adsorption and desorption mechanism. Therefore, the above-prescribed results make electrospun silk nanofibers a suitable choice for removing anionic dyes in real-time applications.

Porous polymers from octa(amino-phenyl)silsesquioxane and metalloporphyrin as peroxidase-mimicking enzyme for malathion colorimetric sensor

Rapid and efficient pesticide detection methods are particularly important due to the growing problems of pesticide residues. Here, a new azo-based porous organic polymer, Azo(Fe)PPOP, was prepared from octa(amino-phenyl)silsesquioxane (OAPS) and iron(III) 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin (FeTPP(NO₂)₄) via a simple coupling reaction without the participation of metal catalysts. The inorganic cage units of OAPS endowed Azo(Fe)PPOP a porous framework, high surface area, favorably thermal and chemical stability. In Azo(Fe)PPOP, iron(III) porphyrin units were individually isolated in a fixed location, which could effectively avoid dimerization or self-oxidation as happens as in the case of porphyrin monomers. Such a unique structure made Azo(Fe)PPOP exhibit an excellent peroxidase-like catalytic performance in the presence of H₂O₂ and 3,3',5,5'-tetramethylbenzidine (TMB). Because of these advantages, we established a selective, facile, and sensitive colorimetric platform for direct detection of malathion within a very short time (3 min) with a low detection limit (8.5 nM). In addition, the recognition mechanism between Azo(Fe)PPOP and malathion was verified using X-ray photoelectron spectroscopy spectra. The practicality of the constructed platform was further executed by the detection of the pesticide in soil and food samples.

A POSS-assisted fluorescent probe for the rapid detection of HClO in mitochondria with a large emission wavelength in dual channels

Hypochlorous acid (HClO) is closely related to many diseases and is an inevitable part of the physiological processes. It is significant to detect HClO in mitochondria for getting meaningful physiological and pathological information. However, adequate tools to detect HClO with emissions in two channels are rarely reported. To achieve this target, in this work, a "turn-off" visual and near infrared (NIR) fluorescent dual emission probe D6 based on polyhedral oligomeric silsesquioxanes (POSS) was successfully designed and synthesized. D6 showed high selectivity and sensitivity to HClO. Notably, the emission wavelength of D6 reached 820 nm due to the assistance of the POSS cage. In addition, bioimaging experiments clearly showed that probe D6 promoted the visualization of exogenous and endogenous HClO in living HepG2 cells and zebrafish models.

A silsesquioxane-porphyrin-based porous organic polymer as a highly efficient and recyclable absorbent for wastewater treatment

Effective capture of pollutants from wastewater is crucial for protecting the environment and human health. An azo-based porous organic polymer (AzoPPOP) containing porphyrin and inorganics cage polyhedral oligomeric silsesquioxane units was synthesized via a catalyst-free coupling reaction. Results showed that AzoPPOP possess a high surface area, a hierarchically porous structure, good thermal stability, abundant adsorption sites, and an electronegative nature. Based on these properties, AzoPPOP had an extremely high adsorption capacity (1357.58 mg g^-1) for RhB, a fast adsorption rate, and good selectivity. Study of the mechanism revealed that in addition to electrostatic interactions, the high specific surface area, existence of -NH₂, and the strong π-π interaction between AzoPPOP and RhB also play important roles for the adsorption of RhB. AzoPPOP also displayed excellent adsorption properties for heavy metal ions (230.45, 192.24 and 162.11 mg g^-1 for Ag⁺, Hg²⁺, and Pb²⁺, respectively). More importantly, simulation of the purification experiment of waste water and the recycling regeneration experiment revealed that AzoPPOP has good high-level recyclability and could remove multi-pollutants in one pass through a simple adsorption column.

Poly-l-lysine-functionalized magnetic graphene for the immobilized metal affinity purification of histidine-rich proteins

Metal affinity-poly-l-lysine functionalization on a magnetic graphene substrate for simultaneously improving the adsorption selectivity toward histidine-rich proteins and inhibiting the non-specific adsorption.

Recent progress in using hybrid silicon polymer composites for wastewater treatment

Heavy metal ions, oil and organic pollutants in water does not only cause serious water pollution, but also pose serious threats to ecosystems and human health. To this end, water pollution has gradually gained human attention, and various wastewater treatment methods are emerging. Organosilicon polymer composites are a class of materials that contain organic-inorganic hybrid structures with the characteristics of hydrophobicity, thermal stability and easy modification, which provides a brand new solution for wastewater treatment. In this review, various structural features including amorphous, linear, and cage structure of silicon containing polymer composites and the removal mechanism targeting at heavy metal ions, oil and organic pollutants of silicon containing polymer composites are summarized. The viewpoints and challenges in adsorption and engineering application are discussed, and possible solutions are proposed.

A modified hybrid silsesquioxane/histidine composite for copper and zinc adsorption and it behavior in the electro-oxidation of ascorbic acid

Octa-(3-chloropropryl)silsesquioxane was chemically modified with histidine (SSQ-H) and characterized by spectroscopy in the infrared region (FT-IR), X-ray diffraction (XRD), X-ray Dispersive Energy Spectroscopy (EDX), Scanning Electron Microscopy (SEM). The analytical properties of SSQ-H were tested regarding of Cu²⁺ and Zn²⁺ adsorption and as an electrochemical sensor for the detection of ascorbic acid. The metal sorption results indicate that maximum amount of Cu²⁺ and Zn²⁺ adsorbed (Nf_max) were 1.58 × 10^-3 and 5.67 × 10^-4 mol g^-1, respectively. After Cu²⁺ and Zn²⁺ ion adsorption and interaction with potassium hexacyanoferrate (III), the investigated materials displayed electroactivity for ascorbic acid detection. The anodic peak currents responses of a graphite paste electrode containing CuHCFSSQ-H presented a linear response in the concentration range of 4.0 × 10^-4 to 4.0 × 10^-3 mol L^-1 for ascorbic acid detection. The limit of detection was of 2.99 × 10^-4 mol L^-1, with an amperometric sensitivity of 1.69 μA/mol L^-1. The intensity of the anodic peak currents of the graphite paste electrode containing ZnHCFSSQ-H in the concentration range of 9.0 × 10^-5 to 9.0 × 10^-4 mol L^-1 also displayed a linear response. The limit of detection was of 6.76 × 10^-5 mol L^-1, with an amperometric sensitivity of 0.0206 A/mol L^-1.

Nano-engineered Adsorbent for the Removal of Dyes from Water: A Review

Background:

The huge quantity of wastewater, containing poisonous and hazardous dyes, is released by various industries which pollute water in direct and indirect ways. Most of the dyes are a dangerous class of water contaminants which have affected the environment drastically. Some dyes such as congo red, rhodamine B, methylene blue, methyl violet, and crystal violet are a serious threat to human beings.

Remediation Method:

Numerous methods are available for the removal of dyes from water. Adsorption, being a superior and eco-friendly technique, has advantage of eliminating organic dyes because of the availability of materials as adsorbents. The inexpensive nanomaterials are a more attractive choice for remediation of various dyes due to their unique properties and offer an adequate pathway to adsorb any organic dye from water to overcome its hazardous effects on human health.

Results:

In this review, we have discussed the latest literature related to various types of synthesis, characterization and uses as adsorbent for highly adsorptive removal capacity of nanoparticles for organic dyes.

Conclusion:

Adsorption technology provides an attractive pathway for further research and improvement in more efficient nanoparticles, with higher adsorption capacity, for numerous dyes to eliminate the dyes discharged from various industries and thus reduce the contamination of water. Therefore, nanocomposites may contribute to future prospective water treatment process.

Enhanced sonocatalytic degradation of organic dyes from aqueous solutions by novel synthesis of mesoporous Fe3O4-graphene/ZnO@SiO2 nanocomposites

Fe₃O₄-graphene/ZnO@mesoporous-SiO₂ (MGZ@SiO₂) nanocomposites was synthesized via a simple one pot hydrothermal method. The as-obtained samples were investigated using various techniques, as follows: scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and specific surface area (BET) vibrating sample magnetometer (VSM), among others. The sonocatalytic activities of the catalysts were tested according to the oxidation for the removal of methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) under ultrasonic irradiation. The optimal conditions including the irradiation time, pH, dye concentration, catalyst dosage, and ultrasonic intensity are 60min, 11, 50mg/L, 1.00g/L, and 40W/m², respectively. The MGZ@SiO₂ showed the higher enhanced sonocatalytic degradation from among the three dyes; furthermore, the sonocatalytic-degradation mechanism is discussed. This study shows that the MGZ@SiO₂ can be applied asa novel-design catalyst for the removal of organic pollutants from aqueous solutions.

Synchronized methylene blue removal using Fenton-like reaction induced by phosphorous oxoanion and submerged plasma irradiation process

In this study, a combination of phosphorus (PP) oxoanions in a submerged plasma irradiation (SPI) system was used to enhance the removal efficiency of dyes from wastewater. The SPI system showed synergistic methylene blue removal efficiency, due to the plasma irradiation and Fenton-like oxidation. The ferrous ions released from the iron electrode in the SPI system under plasmonic conditions form complexes with the PP anions, which can then react with dissolved oxygen (O₂) or hydrogen peroxide (H₂O₂) via Fenton-like reactions. The experimental results revealed that a sodium triphosphate (TPP) combined SPI system has a higher dye removal efficiency than a tetrasodium pyrophosphate (DP) or a sodium hexametaphosphate (HMP) combined SPI system under similar dissolved iron ion concentrations. To confirm the accuracy of the proposed removal mechanism via Fenton-like oxidation, it was compared to SPI systems under an oxygen environment (TPP/SPI/O₂ (k = 0.0182 s^-1)) and a nitrogen environment (TPP/SPI/N₂ (k = 0.0062 s^-1)). The results indicate that the hydroxyl radical (OH) in the TPP/SPI/O₂ system is the major oxidant in methylene blue removal, because the dye degradation rates dramatically decreased with the addition of radical scavengers such as tert-butanol (k = 0.0023 s^-1) and methanol (k = 0.0021 s^-1). On the other hand, no change was observed in the methylene blue removal efficiency of the TPP/SPI/O₂ system when it was subjected to a wide range of pHs (3-9). In addition, it was proved that this system could be used to eliminate six different commercial dyes. The results of this study indicated that the TPP/SPI/O₂ system is a promising advanced oxidation approach for dye wastewater treatment.

Polymeric ionic liquid-assembled graphene-immobilized silica composite for selective isolation of human serum albumin from human whole blood

Polymeric ionic liquids (PILs) with 1-vinyl-3-ethylimidazolium cations and two different anions of Br^- and PF₆^- were assembled onto the surface of graphene (G) nanosheets. The derived two composites, i.e., PIL(Br)-G and PIL(PF₆)-G, were further efficiently immobilized onto the surface of silica nanoparticles via self-assembly technique. The obtained two PIL-G/SiO₂ nanocomposites exhibited diverse adsorption performances toward proteins through adjusting the anions of PILs. Electrostatic attractions between proteins and the nanocomposites dominated protein adsorption, while the presence of PF₆^- anions weakened electrostatic interactions and deteriorated the selective adsorption of target protein, i.e., bovine serum albumin (BSA) in this case. Specifically, PIL(Br)-G/SiO₂ nanocomposite displayed high selectivity toward BSA and a high adsorption efficiency of ca. 98% was achieved for 100 mg L^-1 BSA in a Britton-Robinson (B-R) buffer at pH 5. HPLC analysis demonstrated the selectivity of PIL(Br)-G/SiO₂ nanocomposite toward BSA in the presence of abundant hemoglobin and cytochrome c. The practical applicability was verified by performing selective isolation of human serum albumin (HSA) from human whole blood. Graphical abstract Selective isolation of human serum albumin from blood by polymeric ionic liquid assembled graphene immobilized silica nanocomposite with tunable anions.