Inducing hardening and healability in poly(ethylene-co-acrylic acid) via blending with complementary low molecular weight additives

The design and synthesis of low molecular weight additives based on self-assembling nitroarylurea units, and their compatibility with poly(ethylene-co-acrylic acid) copolymers are reported. The self-assembly properties of the low molecular weight additives have been demonstrated in a series of gelation studies. Upon blending at low percentage weights (≤5%) with poly(ethylene-co-acrylic acid) the additives were capable of increasing the stress and strain to failure when compared to the parent copolymer. By varying the percentage weight of the additive as well as the type of additive the mechanical properties of poly(ethylene-co-acrylic acid) could be tailored. Finally, the healability characteristics of the blends were improved when compared to the original polymer via the introduction of a supramolecular ‘network within a network’.

Blending nitroarylurea gelators with poly(ethylene-co-acrylic acid) copolymers improves the mechanical and healing properties of the bulk polymer via ‘network within a network’ formation.     

Bioinspired pressure-sensitive adhesive: evaluation of the effect of dopamine methacrylamide comonomer as a general property modifier using molecular dynamics simulation

The use of catechol-containing comonomers as a general property enhancer to achieve unique properties has received particular attention for designing bioinspired polymeric materials. In this study, molecular dynamics simulation was used to investigate the role of dopamine methacrylamide (DMA) and N-phenethyl methacrylamide (PMA) comonomers in chain conformation and their effects on the mechanical properties and adhesion of poly(n-butyl acrylate-co-acrylic acid) copolymer. Addition of 4% by weight of DMA comonomer in the terpolymer structure reduces the gyration radius of the poly(n-butyl acrylate-co-acrylic acid) copolymer. This reduction is due to the formation of intramolecular hydrogen bond interactions. A further increase in the DMA up to 12.2% by weight increases the radius of gyration by 5%. The effect of PMA on the gyration radius of the poly(n-butyl acrylate-co-acrylic acid) copolymer is more extensive, compared to DMA. While DMA enhances both van der Waals and electrostatic components of the cohesive energy density through increasing π–π interactions and hydrogen bond formations, PMA only improves the van der Waals component. Assessment of mechanical properties revealed that the addition of DMA comonomer resulted in a transition from brittle to tough behavior in poly(n-butyl acrylate-co-acrylic acid) pressure-sensitive adhesive. Ductility index improvement by DMA is higher than that by PMA. DMA comonomers accumulate on the silica surface resulting in the terpolymer chains approaching the dry silica surface from the hydroxyl groups of the catechol. Accumulation of DMA only enhances the cohesive energy and does not improve the adhesive energy.

The use of catechol-containing comonomers as a general property enhancer to achieve unique properties has received particular attention for designing bioinspired polymeric materials.     

Adsorption and regeneration of leaf-based biochar for p-nitrophenol adsorption from aqueous solution

As an environmentally friendly and low-cost adsorbent, biochar has great potential in wastewater treatment. This study investigated biochar derived from Platanus orientalis L. leaves (PLB) activated by KOH in terms of its capacity and reusability to adsorb p-nitrophenol (PNP). PLB had a large specific surface area and total pore volume, and exhibits good PNP removal with a maximal adsorption capacity of 622.73 mg g⁻¹ at 298 K. Batch experiments showed that PLB had a high PNP adsorption capacity under acidic conditions. Experimental results were well described by the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model. The thermodynamic study showed that PNP adsorption was a spontaneously exothermic process, and increasing temperature was not conducive to adsorption. In addition, PNP adsorption was mainly attributed to hydrophobic interaction. The regeneration experiment showed that PLB had good reusability. After the fifth regeneration, the adsorption capacity of PLB still reached 557.05 mg g⁻¹. The deactivation of oxygen-containing functional groups and pore blockage were the causes for the decrease in adsorption capacity of the recycled PLB. Moreover, the biochar showed good adsorption efficiency and reusability, thereby suggesting its potential to serve as an efficient PNP adsorbent for wastewater treatment.

As an environmentally friendly and low-cost adsorbent, biochar has great potential in wastewater treatment.     

Formation mechanism of zigzag patterned P(NIPAM-co-AA)/CuS composite microspheres by in situ biomimetic mineralization for morphology modulation

Poly(N-isopropylacrylamide-co-acrylic acid)/copper sulfide (P(NIPAM-co-AA)/CuS) composite microspheres with variable zigzag patterned surfaces have been synthesized by employing an in situ biomimetic mineralization reaction between H₂S and Cu²⁺ immersed in P(NIPAM-co-AA) microspheres for morphology modulation. The morphology and composition of the P(NIPAM-co-AA)/CuS composite microspheres with zigzag patterned surfaces prepared in different conditions were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FT-IR). The polymeric microgels swelled by Cu(Ac)₂ solution after freeze-drying treatment were of porous structure, indicating that there were polymeric frameworks and rich-water domains in the microgels before the deposition. Furthermore, due to the limited uneven deposition of metal sulfide on the polymeric skeleton of the hydrogel surface, the surface polymeric skeleton will be anisotropically shrunk when the composite microspheres lose water and shrink, thus forming a wrinkle pattern on the surface of the composite microspheres. The factors affecting the deposition amount and distribution of metal sulfide will affect the zigzag patterned morphology. Based on the experimental results, a formation mechanism of the P(NIPAM-co-AA)/CuS composite microspheres with zigzag patterned surface, “the deformed shrinkage of the surface texture”, has been proposed. The formation mechanism of the surface morphology in the composite microspheres is helpful for understanding and controlling the process of mineralization, for preparing materials expected by controlling the experiment conditions, and for expanding the application of the composites.

P(NIPAM-co-AA)/CuS composite microspheres with zigzag patterned surfaces were synthesized, and a mechanism for “the deformed shrinkage of the surface texture” was proposed. The surface morphology is sensitive to factors such as K_sp, pH, temperature, deposition amount, etc.     

RAFT-mediated Pickering emulsion polymerization with cellulose nanocrystals grafted with random copolymer as stabilizer

The synthesis of a RAFT-mediated Pickering emulsion was firstly achieved by using cellulose nanocrystals (CNCs) grafted with a random copolymer as the stabilizer. Firstly, poly(acrylonitrile-r-butyl acrylate) (poly(AN-r-nBA)) was synthesized by Cu(0)-mediated CRP, which was further modified via a click chemistry strategy to obtain poly(ethylene tetrazole-r-butyl acrylate) (poly(VT-r-nBA)). Then, poly(VT-r-nBA) was grafted onto the CNCs through a Mitsunobu reaction to obtain poly(VT-r-nBA)-g-CNCs. Stabilized by poly(VT-r-nBA)-g-CNCs, an O/W RAFT-mediated Pickering emulsion was formed for the preparation of well-controlled poly(methyl methacrylate) (PMMA) particles with water-soluble potassium persulfate (KPS) as an initiator and oil-soluble 4-cyanopentanoic acid dithiobenzoate (CPADB) as a chain transfer agent. Rheological analysis suggested that the prepared Pickering emulsion possessed good stability under the influences of changes in strain, time, frequency and temperature. Furthermore, the recycling and further utilization of the poly(VT-r-nBA)-g-CNCs could be simply realized through centrifugal separation.

A RAFT-mediated Pickering emulsion with cellulose nanocrystals grafted with a random copolymer was used for the preparation of poly(methyl methacrylate) particles..     

Silver nanoparticle-loaded microgel-based etalons for H2O2 sensing

Silver nanoparticles (AgNPs) were generated inside the network structure of poly(N-isopropylacrylamide)-co-acrylic acid (pNIPAm-co-AAc) microgels that were sandwiched between two thin Au layers (15 nm) of an etalon. This was done by introducing Ag⁺ to the etalons composed of deprotonated microgels, followed by its subsequent reduction with NaBH₄. The resultant microgels were collected and then characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), verifying the loading of AgNPs with relatively uniform diameter (5–7 nm) within the microgels. Furthermore, the optical properties of the resultant etalons and their response to H₂O₂ were evaluated by reflectance spectroscopy. Specifically, upon the addition of H₂O₂, the AgNP-loaded etalons exhibited both a red shift in the position of the reflectance peaks and an increase in reflected wavelength intensity. We hypothesize that the dual signal response of the devices was a result of oxidative decomposition of the AgNPs, enabling the microgels to swell and for more light to be reflected (due to the loss of the light absorbing AgNPs). Finally, we showed that the AgNPs could be regenerated in the used etalons multiple times without a loss in performance. This work provides a cost-effective means to detect H₂O₂, which could be modified to sense a variety of other species of physiological and environmental importance through rationally loading other functional nanomaterials.

Silver nanoparticle (AgNP)-loaded poly(N-isopropylacrylamide)-co-acrylic acid (pNIPAm-co-AAc)-based microgels were generated and used to make etalons. The etalons were shown to exhibit optical properties that depended on the concentration of H₂O₂ in solution.     

Comparative study of uranium and thorium metal ion adsorption by gum ghatti grafted poly(acrylamide) copolymer composites

Uranium and thorium ions were selectively removed from aqueous solution using synthesized gum ghatti grafted poly(acrylamide) gum-g-poly(AAm) composite. A gamma radiation induced free radical copolymerization technique was used to synthesize the copolymer composite of gum-g-poly(AAm). Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize the graft copolymer gum-g-poly(AAm). The adsorption of uranium ions and thorium ions using the gum-g-poly(AAm) copolymer composites has been investigated in batch mode. The adsorptive characteristics were investigated by varying the pH, concentration and time for both ions. The adsorption method depends on the pH of each metal ion, and the highest adsorption percentage was achieved at pH 6.0. The adsorption statistics were justified by isotherm, kinetic and thermodynamic models. The Langmuir adsorption model was revealed to be the best fitted monolayer arrangement, with a maximum adsorption capacity of 367.65 mg g⁻¹ for the uranium ions and 125.95 mg g⁻¹ for the thorium ions. The adsorption of metal ions occurred by the ion exchange process, which was specified through the rate controlling step with a best-fitted pseudo-second order kinetic rate model. Thermodynamic analysis shows that the ΔH and ΔS values for the uranium ions and thorium ions were positive. The negative ΔG values decreased with an increase in temperature, suggesting that the metal ion adsorption process was endothermic and spontaneous in behaviour.

Uranium and thorium ions were selectively removed from aqueous solution using synthesized gum ghatti grafted poly(acrylamide) copolymer composite.     

Porous carbon material derived from fungal hyphae and its application for the removal of dye

In this work, fungal hyphae (FH, Irpex lacteus) was used as the carbon resource for the preparation of porous carbon materials (PCFH) using mixed alkali as the activator. The SEM, N₂ adsorption/desorption, FT-IR, XRD, Raman, and XPS were used to characterize the structure and surface properties of PCFH. The results showed that the PCFH not only has a huge Brunauer–Emmett–Teller (BET) surface area (2480 m² g⁻¹), but also has abundant functional groups containing carbon, oxygen, and nitrogen. Rhodamine B (RhB) was selected to evaluate the adsorption properties of the PCFH prepared under different conditions in dyeing wastewater. A fast adsorption rate was observed, and an uptake capacity of 765 mg g⁻¹ was achieved in the initial 5 min. The maximum adsorption capacity of PCFH to RhB reached 1912 mg g⁻¹ at the pH value of 9, which could efficiently remove RhB from the aqueous solution. The adsorption process was fitted better by a pseudo-second order model, and the adsorption isotherm for the RhB was well fitted by the Freundlich model. Moreover, the probable mechanism of adsorption was analyzed. In short, the good adsorption performance of PCFH indicated that it has a broad application prospect for dye water pollution control.

A highly porous carbon material based on fungal hyphae was prepared using mixed alkali and its application for removal of dye investigated.     

Synthesis of highly stable fluorescent poly(methacrylic acid-co-itaconic)-protected silver nanoclusters and sensitive detection of Cu2+

Stable fluorescent silver nanoclusters (AgNCs) were synthesized through one-step UV photoreduction using the multiple carboxyl copolymer poly(methacrylic acid-co-itaconic acid) P(MAA-co-IA) as a novel template. The fluorescence lifetime and the quantum yield of the obtained AgNCs were 1.84 ns and 8.9% in an aqueous solution, respectively. Owing to the multiple carboxyls of the protective P(MAA-co-IA) template, the obtained AgNCs have excellent advantages such as good dispersity, and high stability, which make them suitable for highly sensitive and selective detection of Cu²⁺ by fluorescence quenching. A good linear relationship exists between the degree of fluorescence quenching for silver nanoclusters and Cu²⁺ concentration ranging from 0 to 10 μM. The limit of detection (LOD) is 6.36 nM. The result implies that the as-synthesized AgNCs show great potential in the analysis field.

Silver nanoclusters were synthesized through one-step UV photoreduction using the multiple carboxyl copolymer poly(methacrylic acid-co-itaconic acid) as a novel template, which can be used for highly sensitive and selective detection of Cu²⁺ by fluorescence quenching.     

Removal of brilliant green dye from synthetic wastewater under batch mode using chemically activated date pit carbon

In this research, a single-stage batch adsorber was designed for removal of brilliant green dye (BG) from aqueous solutions using activated carbon derived from date pits (ADPC) based on the Freundlich isotherm which was the best-fitted isotherm model. Experimental work was carried out within the range of 10–50 ppm initial dye concentration to determine the optimum operating conditions which were 55 min contact time, 0.06 g adsorbent mass, 25 °C, and pH = 8. Process kinetics was best-fitted with the pseudo-second order model, which revealed that the intra-particle diffusion stage is the rate-controlling stage for the process. The process efficiency was assessed by infrared spectroscopy (FTIR), scanning microscopy (SEM), X-ray spectroscopy (EDXS), and Brunauer–Emmett–Teller (BET) where the latter showed that the specific surface area of the adsorbent is 311.38 m² g⁻¹, which gives a favorable maximum monolayer adsorption capacity (77.8 mg g⁻¹). The thermodynamic study proved that BG adsorption on ADPC was physiosorptive (ΔG = −5.86 kJ mol⁻¹) and spontaneous at low temperature (ΔH = −17.7 kJ mol⁻¹, ΔS = −0.04 kJ mol⁻¹ K⁻¹).

In this research, a single-stage batch adsorber was designed for removal of brilliant green dye from aqueous solutions using activated carbon derived from date pits based on the Freundlich isotherm which was the best-fitted isotherm model.     

Development of highly gas-permeable polymers by metathesis copolymerization of 1-(p-trimethylsilyl)phenyl-1-propyne with tert-butyl and silyl group-containing diphenylacetylenes

The development of highly gas-permeable membranes is required for gas separation applications. In this study, 1-(p-trimethylsilyl)phenyl-1-propyne (SPP) was copolymerized with diphenylacetylenes bearing tert-butyl (BDPA) and SiMe₃ (SDPA) groups at various feed ratios to obtain poly(SPP-co-BDPA) and poly(SPP-co-SDPA) copolymers, respectively. Free-standing membranes were fabricated from toluene solutions of the copolymers, the gas permeability of which increased as the SPP ratio decreased (P_O2: 550–2100 barrers). Interestingly, poly(SPP-co-BDPA) and poly(SPP-co-SDPA) at a 1 : 4 ratio of SPP:BDPA and SPP:SDPA, respectively, showed higher permeabilities than the respective homopolymers. Desilylation of the poly(SPP-co-BDPA) membrane increased the gas permeability, whereas desilylation of the poly(SPP-co-SDPA) membrane had the opposite result.

Metathesis copolymerization of 1-(p-trimethylsilyl)phenyl-1-propyne with diphenylacetylenes was achieved and the gas permeability of polymer membranes was improved by the incorporation of 20% phenylpropyne unit.     

Efficient removal of pentachlorophenol from aqueous solution by 4-tert-butylcalix[8]arene modified thermally sensitive hydrogels

We prepared poly(N-isopropylacrylamide-co-4-tert-butylcalix[8]arene) (PNIPAM-TBCX) hydrogels by copolymerization of N-isopropylacrylamide (NIPAM) with 4-tert-butylcalix[8]arene (TBCX) to capture hazardous pentachlorophenol (PCP) from aqueous solution. Adsorption experiments showed that the adsorption capacities of PNIPAM-TBCX hydrogels reached 1.96, 2.08 and 2.02 mg PCP per 1 g of hydrogel, while the molar percentage ratio of TBCX in the hydrogels was as low as 0.5%, 0.7% and 1%. The equilibrium adsorption of PCP on the hydrogels was studied using different adsorption models. In addition, the PNIPAM-TBCX hydrogel still retained its performance when regenerated several times by immersing in water at 323 K.

We synthesized 4-tert-butylcalix[8]arene modified poly(N-isopropylacrylamide) hydrogels to enhance the adsorption ability for pentachlorophenol in aqueous solutions.     

Preparation of hyper-cross-linked hydroxylated polystyrene for adsorptive removal of methylene blue

A series of hydroxylated polystyrene (PS-OH) resins were prepared from macroporous poly(styrene-co-divinylbenzene) by nitration, reductive amination, diazotation and hydrolysis in sequence, and then a series of hyper-cross-linked hydroxylated polystyrene (HCPS-OH) resins were successfully prepared from the PS-OH resins by the Friedel–Crafts post-cross-linking using dichloromethane as an external cross-linker. Benefiting from the synthetic protocol, the HCPS-OH resins showed better adsorption performance for methylene blue in aqueous solution as compared with the corresponding PS-OH resins. HCPS-OH-4, one of the fabricated HCPS-OH resins which had the hydroxyl content of 5.0 mmol g⁻¹ and BET specific surface area of 69.0 m² g⁻¹, showed the highest adsorption capacity and selectivity for methylene blue. Higher temperature, higher pH, and higher ionic strength were beneficial to adsorption of methylene blue from aqueous solution. HCPS-OH-4 could be regenerated by treatment with 1.0 M HCl methanol solution and deionized water sequentially. Moreover, HCPS-OH-4 retained good adsorption performance for methylene blue even after 5 cycles of adsorption and regeneration, which implied that it was a good candidate for adsorptive removal of methylene blue dye in waste water.

This study presents the preparation of hyper-cross-linked hydroxylated polystyrene (HCPS-OH) resins using dichloromethane as an external cross-linker for the adsorption of methylene blue.     

Two-dimensional MXene enabled carbon quantum dots@Ag with enhanced catalytic activity towards the reduction of p-nitrophenol

A composite of cuttlefish ink-based carbon quantum dots@Ag/MXene (CQD@Ag/MXene) was firstly synthesized by solvothermal method as a catalyst for reduction of p-nitrophenol (PNP) to p-aminophenol (PAP). CQD@Ag/MXene was characterized by scanning electron microscopy (SEM), field emission transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman. The results show that loading on 2D material MXene can prevent the aggregation of CQD@Ag and expose more active sites, which contributes to a superior catalytic activity with a pseudo-first-order rate constant k (2.28 × 10⁻² s⁻¹) and mass-normalized rate constant k_m (5700 s⁻¹ g⁻¹), nearly 2 times higher than CQD@Ag without MXene (k = 1.09 × 10⁻² s⁻¹ and k_m = 2725 s⁻¹ g⁻¹). Besides, CQD@Ag/MXene showed excellent reusability which even retained about 65% activity in successive 10 cycles. The high adsorption rate to PNP and the promotion of forming H radicals may be the reason for the outstanding catalytic activity of CQD@Ag/MXene. CQD@Ag/MXene can be a potential candidate in the removal of environmental pollutants due to its facile synthesis and high catalytic efficiency.

CQD@Ag/MXene has an outstanding catalytic activity for the PNP reduction with high mass-normalized rate constant of 5700 s⁻¹ g⁻¹. It is mainly due to the high adsorption rate to PNP and the efficient promotion of forming H radicals.     

A three-dimensional electrode bioelectrochemical system for the advanced oxidation of p-nitrophenol in an aqueous solution

Three-dimensional electrodes serve as more efficient cathodes for the in situ generation of H₂O₂ in microbial fuel cells (MFCs) than two-dimensional electrodes and possess significant electric potentials in the advanced oxidation of organics. In this study, we investigated the performance of a three-dimensional MFC-Fenton system in degrading p-nitrophenol (PNP) in an aqueous solution with the objective of optimizing the operating parameters, including the initial pH, iron dosage, and loading resistance. A corresponding reaction pathway for PNP in the system was also proposed. The results showed that the three-dimensional electrode bioelectrochemical system efficiently oxidized PNP and removed total organic carbon over a short period (64 h). In addition, experiments showed that a lower initial pH enhanced the removal of PNP by the system. The highest removal efficiency of PNP was achieved with an initial iron concentration of 0.025 mol L⁻¹, and a lower or higher iron concentration resulted in decreased PNP degradation. Furthermore, the treatment capacity of the system was remarkably enhanced at a low loading resistance of 20 Ω. Under optimal conditions, the three-dimensional MFC-Fenton system achieved 95.7% PNP removal (within 8 h). Furthermore, the system showed a stable high treatment efficiency of approximately 90% for low PNP concentrations in wastewater over as long as 96 h.

PNP absorbed in and surrounded by GPEs has kinetic favorability in the degradation process by a three-dimensional electrode MFC-Fenton system.     

Synthesis and stereocomplex formation of enantiomeric alternating copolymers with two types of chiral centers,poly(lactic acid-alt-2-hydroxybutanoic acid)s

Stereocomplex (SC) formation was reported for the first time for enantiomeric alternating copolymers consisting of repeating units with two types of chiral centers, poly(lactic acid-alt-2-hydroxybutanoic acid)s [P(LA-alt-2HB)s]. l,l-Configured poly(l-lactic acid-alt-l-2-hydroxybutanoic acid) [P(LLA-alt-l-2HB)] and d,d-configured poly(d-lactic acid-alt-d-2-hydroxybutanoic acid) [P(DLA-alt-d-2HB)] were amorphous. Blends of P(LLA-alt-l-2HB) and P(DLA-alt-d-2HB) were crystallizable and showed typical SC-type wide-angle X-ray diffraction profiles similar to those reported for stereocomplexed blends of poly(l-lactic acid) and poly(d-lactic acid) homopolymers and of poly(l-2-hydroxybutanoic acid) and poly(d-2-hydroxybutanoic acid) homopolymers, and of l,l-configured poly(l-lactic acid-co-l-2-hydroxybutanoic acid) [P(LLA-co-l-2HB)] and d,d-configured poly(d-lactic acid-co-d-2-hydroxybutanoic acid) [P(DLA-co-d-2HB)] random copolymers. The melting temperature values and melting enthalpy values at 100% crystallinity for stereocomplexed solvent-evaporated and precipitated P(LLA-alt-l-2HB)/P(DLA-alt-d-2HB) blends were correspondingly 187.5 and 187.9 °C, and 98.1 and 91.8 J g⁻¹. Enantiomeric polymer blending of P(LLA-alt-l-2HB) and P(DLA-alt-d-2HB) can confer crystallizability by stereocomplexation and the biodegradable materials with a wide variety of physical properties and biodegradability are highly expected to be prepared by synthesis of alternating copolymers of various combinations of two types of chiral α-substituted 2-hydroxyalkanoic acid monomers and their SC crystallization.

Stereocomplex formation was reported for alternating copolymers of chiral α-substituted 2-hydroxyalkanoic acids which can be utilized for preparation of biodegradable materials with a variety of physical properties and biodegradability.     

Preparation of activated carbon from Dipterocarpus alatus fruit and its application for methylene blue adsorption

Activated carbons were prepared from three parts of Dipterocarpus alatus fruit (wing, endocarp and pericarp), an abundant and renewable waste in Southeast Asia, by chemical activation using ZnCl₂, FeCl₃, H₃PO₄ and KOH and physical activation using CO₂ and steam. This study indicated that activated carbon prepared from Dipterocarpus alatus fruit could be employed as a promising adsorbent for the removal of methylene blue from aqueous solution. ZnCl₂ activation led to an activated carbon with a surface area of 843 m² g⁻¹ and was able to remove methylene blue from aqueous solution. Adsorption studies were performed and analysed using Langmuir and Freundlich isotherm equations. Adsorption data demonstrated an excellent fit with the Langmuir isotherm model, with the maximum adsorption capacity of 269.3 mg g⁻¹ at equilibrium. Pseudo-first order and pseudo-second order kinetic models were used in this study to describe the adsorption mechanism. The results show that methylene blue adsorption is pseudo-second order, indicating that liquid film diffusion, intra-particle diffusion and surface adsorption coexisted during methylene blue adsorption on the activated carbon. The activated carbon prepared from Dipterocarpus alatus fruit is a low cost and effective adsorbent with a fast rate for the removal of methylene blue from aqueous solutions when compared with a number of activated carbons studied in the literature.

Activated carbons were prepared from Dipterocarpus alatus fruit by chemical and physical activation and used for the removal of methylene blue from aqueous solution.     

Iron oxide coated hollow poly(methylmethacrylate) as an efficient adsorption media for removal of arsenic from water

Adsorption of arsenic onto iron-based adsorption media has been established as a convenient method for the removal of arsenic from contaminated water. The study describes the efficiency of iron oxide coated hollow poly(methyl methacrylate) microspheres (FHM) as an adsorptive media for the removal of arsenic from water. Hollow poly(methyl methacrylate) microspheres (HPMM) were synthesized by solvent evaporation and an electroless plating technique and the surface of the polymer was coated with iron oxide (FeO) particles. Structural characterization was performed using Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectroscopy (FTIR), Energy Dispersive X-ray diffraction (EDAX), and Thermogravimetric Analysis (TGA). A study on the effect of the varying initial concentration of arsenic ions on percentage removal was performed in the laboratory and the adsorption capacity of the adsorbent was measured. Adsorption isotherm studies were carried out to evaluate the adsorption efficiency of FHM in removing arsenic from contaminated water. The Langmuir and Freundlich isotherm models were used to analyze the equilibrium experimental data. The isotherm study revealed that Langmuir adsorption data are well fitted and the maximum adsorption capacity of FHM in removing arsenic is 10.031 mg g⁻¹. This high arsenic uptake capability combined with a low density of FHM makes it a potential material for arsenic removal particularly during the fabrication of lightweight portable water purification devices.

Adsorption of arsenic onto iron-based adsorption media has been established as a convenient method for the removal of arsenic from contaminated water.     

Development of a new efficient and economical magnetic sorbent silicone surfactant-based activated carbon for the removal of chloro- and nitro-group phenolic compounds from contaminated water samples

In this study, activated carbon (AC) coated with a green silicone surfactant (SS) was further incorporated with magnetite particles (Fe₃O₄) via a co-precipitation method to enhance the separation of the newly designed magnetic AC–SS (Fe₃O₄@AC–SS) in a magnetic field. The properties of this magnetic adsorbent were characterized via Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The adsorption characteristics of the Fe₃O₄@AC–SS adsorbent were examined using 2,4-nitrophenol and 2,4-dichlorophenol as adsorbates. Experiments were performed to investigate the adsorption kinetics, isotherms, thermodynamics as well as the effects of adsorption dosage and solution pH on the removal of both analytes. The kinetic data were well-fitted by the pseudo-second order model and the Freundlich model best described the adsorption isotherm for both analytes. The maximum adsorption capabilities for 2,4-dinitrophenol and 2,4-dichlorophenol reached 43 and 98 mg g⁻¹, respectively. The analysis was further validated using real industrial effluent, and a removal efficiency of 62.2–98.1% and relative standard deviation value less than 7.2% were attained for both analytes. Thus, the multifunctional adsorbent has potential to function as an adsorbent for the fast, convenient, economical and highly efficient removal of pollutants from wastewater, which is significant for the purification of natural water and industrial effluent.

In this study, activated carbon (AC) coated with a green silicone surfactant (SS) was further incorporated with magnetite particles (Fe₃O₄) to enhance the separation of the newly designed magnetic AC–SS (Fe₃O₄@AC–SS) in a magnetic field.     

Aqueous-based electrospun P(NIPAAm-co-AAc)/RSF medicated fibrous mats for dual temperature- and pH-responsive drug controlled release

This paper presents a green method for fabricating dual temperature- and pH-responsive electrospun fibrous mats from an aqueous-based blend poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAAm-co-AAc)) and regenerated silk fibroin (RSF) by employing electrospinning technique. P(NIPAAm-co-AAc) was synthesized by free radical solution polymerization and its low critical solution temperature (LCST) was in the physiological range (38.8 °C). The P(NIPAAm-co-AAc)/RSF fibers were prepared by electrospinning technology in the presence of the crosslinking agents (EDC·HCl and NHS) with water as solvent. After in situ crosslinking and water-annealing process, the water-stable composite fibrous mats were obtained. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to analyze the crosslinking process. Temperature and pH dual stimuli-responsive swelling-shrinking behavior of the fibrous mats were observed when the temperature was below and above the LCST of the copolymer at different pHs. In addition, rhodamine B-loaded the fibrous mats also showed dual temperature and pH controlled release behavior, demonstrating the potential use of the fibrous mats for “smart” controlled drug delivery applications.

This paper presents a green friendly method for preparing dual temperature- and pH-responsive electrospun P(NIPAAm-co-AAc)/RSF fibrous mats for drug release.