A polyamide (PA) nanofiltration (NF) membrane and a preparation method thereof by regeneration from a scrapped microfiltration (MF) membrane are provided. The method adopts a cleaning-repairing-interfacial polymerization upgrading strategy, where, sodium hypochlorite and oxalic acid are used for deeply cleaning a scrapped MF membrane. PDA is used as a repairing agent to construct a reaction platform on the membrane surface, and finally a reaction system of piperazine and trimesoyl chloride (TMC) are used to form a PA NF membrane with a PA active layer. The repairing can construct a coating with a given thickness and prominent hydrophilicity on the membrane surface, which provides favorable base membrane conditions for upgrading and preparing an NF membrane.

A polyamide (PA) nanofiltration (NF) membrane and a preparation method thereof by regeneration from a scrapped microfiltration (MF) membrane are provided. The method adopts a cleaning-repairing-interfacial polymerization upgrading strategy, where, sodium hypochlorite and oxalic acid are used for deeply cleaning a scrapped MF membrane. PDA is used as a repairing agent to construct a reaction platform on the membrane surface, and finally a reaction system of piperazine and trimesoyl chloride (TMC) are used to form a PA NF membrane with a PA active layer. The repairing can construct a coating with a given thickness and prominent hydrophilicity on the membrane surface, which provides favorable base membrane conditions for upgrading and preparing an NF membrane.

A process for recycling and reusing supported Pd membranes includes the separation of the Pd (or Pd alloy) layer from the support by contacting the Pd membrane with hydrogen under pressure and at low temperature and then with a second gas that is different from hydrogen. The Pd layer separated from the support can then be treated to solubilize the Pd and, where appropriate, the alloy metal(s) to obtain salts that can be reused, for example in the preparation of new Pd membranes. The recovered supports are also reusable.

A process for the manufacture of a polyarylethersulfone PAES (P2) using recycled polymeric material, comprising heating a reaction medium (RM) comprising a recycled polymeric material containing a polyarylethersulfone PAES (P1), at least one monomer (M), an alkali salt-forming agent (A) and a polar aprotic solvent (S) to reach a reaction temperature of at least 150 C. to form a PAES (P2); and separating the forned PAES (P2) from the reaction medium. The PAES (P1) recycle ratio may be from 100 wt. % to 1 wt. %. The recycled polymeric material added to the reaction medium may further include other polymer(s), solid fillers, and/or additives. The monomer (M) may be at least one aromatic diol monomer (AA) and/or at least one aromatic dihalo monomer (BB). The diol (AA) may comprise bisphenol A, bisphenol S, biphenol, a 1,4:3,6-dianhydrohexitol sugar diol and/or tetramethyl bisphenol F, and the dihalo (BB) may comprise non-sulfonated and/or disulfonated dihalodiphenylsulfone.