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Novel polyamidoamine (PAMAM) dendrimer-functionalized palygorskite (Pal) adsorbents, up to generation 4.0, with high adsorption capacity, were designed and efficiently synthesized by grafting PAMAM onto 3-aminopropyltriethoxysilane-modified palygorskite (NH 2 -Pal) surfaces. This was carried out using a divergent method including the Michael addition of methyl acrylate (MA) and amidation of the resultant ester moieties with ethylenediamine (EDA). The optimal conditions for Michael addition were achieved using 88.8 mmol MA (relative to 4.0 g NH 2 -Pal) at 323 K for 24 h. The optimal conditions for amidation of the resultant esters were achieved using 179.3 mmol EDA (relative to 2.1 g Pal-PAMAM G0.5) at 323 K for 48 h. All of the amino-terminated Pal-PAMAM G( n ) ( n = 0, 1, 2, 3 and 4) adsorbents exhibited very high density amino-terminated groups and adsorption capacities for both Pb 2 + and Reactive Red 3BS, which increased with increasing generation number. The maximum adsorption capacity for Pb 2 + at 293 K was 68.5 ± 3.3, 151.1 ± 5.7, 196.5 ± 6.1, 389.1 ± 9.6 and 694.4 ± 12.9 mg/g for Pal-PAMAM G( n ) ( n = 0, 1, 2, 3 and 4), respectively. The maximum adsorption capacity for Reactive Red 3BS at 293 K was 34.2 ± 2.7, 69.9 ± 4.3, 122.0 ± 6.4, 242.7 ± 7.1 and 322.6 ± 6.9 mg/g for Pal-PAMAM G( n ) ( n = 0, 1, 2, 3 and 4), respectively. [ABSTRACT FROM AUTHOR]

Abstract: Surface modification of palygorskite is one of the important ways to enlarge its application field. This study adopts palygorskite modified by 3-aminopropyl triethoxysilane (APTES) as adsorbent of three reactive dyes. The surface modification of palygorskite was characterized by Fourier transform infrared spectroscopy and X-ray diffraction. Batch studies were carried out to investigate various experimental parameters such as adsorbent dosage, contact time, initial dye concentration and initial pH. The kinetics of the adsorption followed the pseudo-second-order model. Adsorption equilibrium data were fitted by the Langmuir isotherm. The adsorption of the three dyes by palygorskite was low but was strongly increased by the silylated palygorskite. The maximum adsorption capacity calculated by the Langmuir model was 34, 38, 60mg/g for Reactive Red 3BS, Reactive Blue KE-R and Reactive Black GR, respectively. [Copyright &y& Elsevier]

Membrane technology can realize wastewater recycling in industry, but its efficiency is threatened by fouling. In this study, magnetic palygorskite (m-Pal) nanofibers were obtained by anchoring Fe 3 O 4 nanoparticles onto the surface of palygorskite. Then, composite membranes composed of poly(vinylidene fluoride) (PVDF) and m-Pal were prepared during a magnetic field assisted phase inversion process. The m-Pal can be elevated to the membrane surface due to magnetic force, thus adjusting membrane performance. The PVDF/m-Pal composite membrane prepared with magnetic field displayed higher water flux and better hydrophilicity than that of pristine PVDF membrane. The water flux can be increased to 343.2 L·m−2·h−1·bar−1, and water contact angle decreases to 71.8° with the addition of 7% m-Pal. Moreover, the anti-fouling and easy-cleaning performance of the composite membrane was demonstrated in bovine serum albumin (BSA) solution separation, with BSA flux and flux recovery ratio increased by 41.3% and 155.4%, respectively, compared with the control PVDF membrane. [Display omitted] • Magnetic palygorskite (m-Pal) was prepared by anchoring nano-Fe 3 O 4 on Pal nanofibers. • Composite membrane was obtained by blending m-Pal with PVDF. • m-Pal was elevated to membrane surface by a magnetic field during preparation. • The anti-fouling and easy-cleaning performance of membrane was improved with m-Pal. [ABSTRACT FROM AUTHOR]

The natural hydrophilic nanofiber-like palygorskite (Pal) particles were incorporated into the quaternary ammonium functionalized polysulfone (QPSf) to prepare high performance anion exchange membranes. Due to the mutual compatibility between quaternary ammonium groups in quaternized polysulfone and hydrophilic Pal particles, a hydrophilic domain could aggregate, thereby forming a hydrophilic-hydrophobic microphase separation structure. Meanwhile, the small-angle X-ray scattering (SAXS) was utilized to characterize the hydrophilic ionic cluster domain in the composite membrane. The results showed that the corresponding average inter-domain spacing of the QPSf/Pal-0.5 membrane was about 30 nm. Then, the new composite membrane had not only highly efficient hydrophilic ion transport channels but also adjustable hydrophilic-hydrophobic microphase separation structures. Compared with original quaternized polysulfone membranes, the hydroxide conductivity of the QPSf/Pal-0.5 membrane reached 93.0 mS·cm−1 at 80 °C, increasing by 48%, while the methanol permeability was kept between 4.2 × 10−7 and 5.8 × 10−7 cm2·s−1. Quaternary ammonium functional groups were grafted on the polysulfone side chain by chloromethylation and Menshutkin reaction. The hydrophilic palygorskite and quaternary ammonium functionalized polysulfone were mixed and self-assembled to form hydrophilic-hydrophobic microphase separation structure, which is conducive to rapid transport of hydroxide ions. Unlabelled Image • AEMs with high-efficiency ion channels were prepared by incorporating Pal into QPSf. • Ion transport channels can be precisely regulated by controlling the addition of Pal. • The composite AEMs exhibited high hydroxide ion conductivity. • The composite AEMs exhibited excellent mechanical properties. [ABSTRACT FROM AUTHOR]

Palygorskite (PGS) was incorporated into a polyvinylidene fluoride (PVDF) matrix and PVDF/PGS nanocomposite UF membranes were prepared successfully via a combination of non-solvent-induced phase separation (NIPS) and thermally-induced phase separation (TIPS) processes. The influence of the size of the PGS particles (PGS-L, 450 nm and PGS-S, 302 nm) on the membrane pore structure, morphology, mechanical strength, filtration performance and antifouling property were investigated. The results showed that the PVDF/PGS-S composite membranes had higher porosity and lower overall membrane thickness and skin layer thickness. This directly resulted in better PWF, BSA flux, BSA rejection and FRR for the membranes loaded with PGS-S, when compared with the characteristics of PVDF/PGS-L membranes. Thus, the physical structures are dominant factors in determining the separation performance of PVDF/PGS composite membranes. However, the surface roughness and thermal stability of PVDF/PGS-L membranes were greater than those of PVDF/PGS-S membranes and their surface was also more hydrophilic. Moreover, they exhibited higher mechanical strength owing to stronger binding forces and lower porosity. Thus, the composite properties of PVDF/PGS UF membranes could be adjusted by controlling the scale of the inorganic filler. Unlabelled Image • Effects of PGS particle scale on membrane structure and properties were studied. • PVDF/PGS-S membranes had higher porosities and lower overall membrane thicknesses. • PVDF/PGS-L membranes had better thermal stabilities and mechanical strengths. • PVDF/PGS-S membranes displayed better separation and antifouling performances. [ABSTRACT FROM AUTHOR]