Hydrophobic–hydrophilic post-cross-linked polystyrene/poly (methyl acryloyl diethylenetriamine) interpenetrating polymer networks and its adsorption properties

Removal of Fermentation Inhibitors from Sugarcane Bagasse Hydrolysate via Post-cross-linked Hydrophilic-Hydrophobic Interpenetrating Polymer Networks

The efficient and economical removal of fermentation inhibitors from the complex system of biomass hydrolysate was one of the basics and keys in bio-chemical transformation. In this work, post-cross-linked hydrophilic-hydrophobic interpenetrating polymer networks (PMA/PS_pc IPNs and PAM/PS_pc IPNs) were proposed to remove fermentation inhibitors from sugarcane bagasse hydrolysate for the first time. PMA/PS_pc and PAM/PS_pc IPNs can obviously enhance the adsorption performance towards fermentation inhibitors due to their higher surface area and hydrophilic-hydrophobic synergetic surface properties, especially PMA/PS_pc IPNs has higher selectivity coefficients of 4.57, 4.63, 4.85, 16.0, 49.43, and 22.69, and higher adsorption capacity of 24.7 mg/g, 39.2 mg/g, 52.4 mg/g, 9.1 mg/g, 13.2 mg/g, and 144.9 mg/g towards formic acid, acetic acid, levulinic acid (LA), 5-hydroxymethylfurfural (HMF), furfural, and acid-soluble lignin (ASL), respectively, in a lower total sugar loss of 2.03%. The adsorption kinetics and isotherm of PMA/PS_pc IPNs were studied to elucidate its adsorption behavior towards fermentation inhibitors. In addition, the cyclic utilization property of PMA/PS_pc IPNs was stable. Synthesizing PMA/PS_pc IPNs is a new strategy to provide an efficient adsorbent for the removal of fermentation inhibitors from lignocellulosic hydrolysate.

Selective Adsorption of CR (VI) onto Amine-Modified Passion Fruit Peel Biosorbent

This study aimed to prepare surface amino-riched passion fruit peel (DAPFP) by amination reaction with low-cost biomaterials and use it as a biosorbent to adsorb Cr (VI). The specific physicochemical and structural properties of DAPFP were characterized by SEM, EDS, XRD, TG, Zeta, XPS, and FT-IR. The effects of pH value, initial concentration, adsorption time, coexisting ions, and temperature on the adsorption of Cr (VI) were systematically investigated. The results showed that within 90 min, DAPFP could reduce the concentration of Cr (VI) solution (1 mg/L−1) to an allowable safe level of drinking water (0.05 mg/L−1) specified by the World Health Organization. The adsorption process complies with pseudo-second-order kinetics and the Langmuir isotherm model. The adsorption capacity of the prepared biosorbent could reach 675.65 mg/g−1. The results of thermodynamic studies confirmed that the adsorption process was a self-discharging heat process. DAPFP also showed good reusability; even after being used repeatedly five times, it still showed excellent adsorption performance. FT-IR and XPS analyses showed that electrostatic attraction and reduction were the main reasons for the adsorption. By virtue of its low cost and excellent adsorption performance, DAPFP has a potential practical application as an adsorbent in treating Cr (VI) containing wastewater.

Surface molecular imprinting on polystyrene resin for selective adsorption of 4-hydroxybenzoic acid

Using chloromethylated polystyrene resin, N,N-diethylaminoethyl methacrylate, and ethylene glycol dimethacrylate as support, functional monomer and cross-linker, respectively, the molecularly imprinted resin (MIR) and non-imprinted resin (NIR) were fabricated by the combination of atom transfer radical polymerization and surface imprinting technique for the selective adsorption of 4-hydroxybenzoic acid (4-HB) from aqueous solutions. The prepared adsorbents were characterized by N₂ adsorption/desorption isotherms, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The adsorption processes of the 4-HB with MIR and NIR followed pseudo-second-order kinetics, and the adsorption isotherms were appreciably described by the Langmuir model. Furthermore, the adsorption efficiencies of MIR and NIR for different compounds in single and binary solutions proved that MIR exhibited high adsorption capacity and favorable selectivity toward 4-HB over other structurally related organic compounds (i.e., benzoic acid, 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, phenol, and 2-hydroxynaphthalene). In addition, MIR could effectively remove 4-HB from a simulated effluent in a dynamic adsorption experiment. This study illustrates in-depth perspectives on the adsorption mechanisms of 4-HB onto MIR; interactions between the adsorbate and adsorbent were proposed based on the adsorption behaviours and instrumental analyses. The resulting MIR is a promising material for the interference-free adsorbent in the selective adsorption of 4-HB from mixed solutions.

Superadsorbents for Strontium and Cesium Removal Enriched in Amidoxime by a Homo-IPN Strategy Connected with Porous Silica Texture

In light of the fact that two with good compatibility are better than one, the homo-interpenetrating polymer network (IPN) strategy was used in this work to design novel amidoxime (AOX)-interpenetrating networks into porous silica (PSi) with the final aim to enhance the sorption performances of composite sorbents toward Cs⁺ and Sr²⁺. To achieve this goal, first, a homo-IPN of poly(acrylonitrile) (PAN) was constructed inside the channels of two kinds of porous silica, one mesoporous (PSi1) and one macroporous (PSi2), the textural properties of silica being exploited in controlling the sorption performances of the composites. The novel composites were fully characterized by thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and the nitrogen sorption/desorption isotherms (Brunauer-Emmett-Teller (BET) analysis). The sorption properties of the PSi1/AOX and PSi2/AOX composite sorbents for Sr²⁺ and Cs⁺ were investigated in the batch mode to determine the effect of solution pH, contact time, initial metal ion concentration, temperature, and the presence of competitive ions on the adsorption performances. The fast kinetics of sorption was supported by the fact that ∼80% of Sr²⁺ and ∼65% of Cs⁺ were adsorbed in the first 30 min, the kinetic data being better described by the pseudo-second-order kinetic model. The experimental isotherms were well fitted by the Langmuir and Sips isotherm models. The superadsorption of Sr²⁺ and Cs⁺ is demonstrated by the values of the maximum sorption capacity of the best sorbent constructed with mesoporous silica (PSi1/IPN-AOX), which were 344.23 mg Cs⁺/g and 360.23 mg Sr²⁺/g. The sorption process was spontaneous and endothermic for both metal ions. The presence of interfering cations (Na⁺, K⁺, Ca²⁺, and Mg²⁺), at a concentration of 10^-2 M, only slightly influenced the sorption capacity for the main cation. The composite sorbents were still highly efficient after five sorption/desorption cycles.

RAFT coupling chemistry: a general approach for post-functionalizing molecularly imprinted polymers synthesized by radical polymerization

Herein we describe a straightforward protocol for the surface functionalization of free-radically synthesized imprinted nanoparticles via polymer grafting.

Adsorption performance of salicylic acid on a novel resin with distinctive double pore structure

Two approaches were used to synthesize two resins with different pore structures. In one way, the CH₂Cl groups in macroporous chloromethylated polystyrene resin were transformed to methylene bridges, and achieved a hypercrosslinked resin with plentiful micropores (denoted GQ-06). In the other way, 50% of the CH₂Cl groups in chloromethylated polystyrene resin was used to produce micropores, while the residual 50% of the CH₂Cl groups was reacted with 2-aminopyridine, and prepared another resin with double pore structure of hypercrosslinked resin and macroporous resin (denoted GQ-11). The adsorption of salicylic acid (SA) on GQ-11 was investigated using GQ-06 as the reference adsorbent. The effect of pH on the adsorption of SA on GQ-06 was consistent with the dissociation curve of SA. The maximum adsorption capacity of SA on GQ-11 was observed at the solution pH of 2.64. The greater adsorption rate of SA on GQ-11 than that of GQ-06 was attributed to its double pore structure. The multifunctional adsorption mechanism of anion exchange and hydrophobic interaction resulted in the larger equilibrium capacity of SA on GQ-11 than that of GQ-06. GQ-06 and GQ-11 could be regenerated by absolute alcohol and 80% of alcohol -0.5mol/L of sodium hydroxide aqueous solution, respectively.

Comparison of hyper-cross-linked polystyrene/polyacryldiethylenetriamine (HCP/PADETA) interpenetrating polymer networks (IPNs) with hyper-cross-linked polystyrene (HCP): structure, adsorption and separation properties

HCP/PADETA IPNs can separate salicylic acid efficiently from phenol in a mixed solution.

LED-cured self-replenishing hydrophobic coatings based on interpenetrating polymer networks (IPNs)

LED-cured IPN-based coatings bearing hydrophobic functional groups have been developed in order to obtain hydrophobic self-replenishing surfaces with improved mechanical properties.