Effect of modified attapulgite addition on the performance of a PVDF ultrafiltration membrane

Attapulgite (APT), which is a highly hydrophilic fibrillar mineral in nature, is a promising new additive for preparation of ultrafiltration (UF) membranes. In this work, APT particles were first grafted with NH2 using the silane coupling agent APTES to detach the crystal bundles to single crystal and enhance the uniform dispersion in an organic polymer matrix; these components were subsequently incorporated into a polyvinylidene fluoride (PVDF) matrix to develop a hybrid membrane via a phase inversion method. The modified APT mineral was characterized using SEM and FTIR to confirm the presence of the amine group on the surface. Other techniques (i.e., FTIR-ATR, XRD and TGA) and parameters (i.e., porosity, the average pore size, contact angle and filtration measurements of water and bovine serum albumin (BSA)) were applied and measured to study the performance of the UF membranes. Compared with the pure PVDF sample, the APT particle blended membranes exhibited better thermal stability, smaller pore size and higher hydrophilicity. More importantly, the values for pure flux, flux recovery ratio (FRR) and rejection of BSA solution all indicated that the PVDF/APT hybrid membranes offer excellent hydrophilicity, water permeability and good antifouling performance.