Hydrogen Sulphide Sequestration with Metallic Ions in Acidic Media Based on Chitosan/sEPDM/Polypropylene Composites Hollow Fiber Membranes System

Abstract

This paper presents the preparation and characterization of composite membranes based on chitosan (Chi), sulfonated ethylene–propylene–diene terpolymer (sEPDM), and polypropylene (PPy), and designed to capture hydrogen sulfide. The Chi/sEPDM/PPy composite membranes were prepared through controlled evaporation of a toluene dispersion layer of Chi:sEPDM 1;1, w/w, deposited by immersion and under a slight vacuum (100 mmHg) on a PPy hollow fiber support. The composite membranes were characterized morphologically, structurally, and thermally, but also from the point of view of their performance in the process of hydrogen sulfide sequestration in an acidic media solution with metallic ion content (Cu2+, Cd2+, Pb2+, and/or Zn2+). The operational parameters of the pertraction were the pH, pM, matrix gas flow rate, and composition. The results of pertraction from synthetic gases mixture (nitrogen, methane, carbon dioxide) indicated an efficient removal of hydrogen sulfide through the prepared composite membranes, as well as its immobilization as sulfides. The sequestration and the recuperative separation, as sulfides from an acid medium, of the hydrogen sulfide reached up to 96%, decreasing in the order: CuS > PbS > CdS > ZnS.

Simultaneously Recovery of Thorium and Tungsten through Hybrid Electrolysis–Nanofiltration Processes

“…Membranes of sulfonated polyether–ether–ketone (sPEEK) [ 44 , 45 ] or sPEEK polymer composites [ 46 ] are used in ultrafiltration, nanofiltration, or reverse osmosis processes [ 44 ]. Three samples of 1 cm 2 each from the membrane obtained after fixing with calcium hydroxide and after being kept in ultrapure water are introduced into a Dewar vessel with liquid nitrogen and fractured.…”

“…The membranes based on chitosan have been frequently used to carry out membrane processes for the separation of ions and molecules [ 57 , 58 , 59 , 60 ], but in this work, chitosan membranes are obtained on a polypropylene hollow fiber (C–PHF–M) support. Practically, the polypropylene hollow fiber (PHF) support, which has previously presented ultrafiltration performances [ 44 , 45 , 46 ], is transformed in nanofiltration composite membranes (C–PHF–M) by ultrafiltration of a chitosan solution to obtain in situ a selective layer of chitosan. Samples of 3 cm of the polypropylene hollow fiber membrane and the chitosan–polypropylene hollow fiber membrane were fractured in liquid nitrogen and covered with a superficial layer (50 nm) of gold and characterized by scanning electron microscopy (SEM) ( Figure 8 and Figure 9 ).…”

“…The removal of the sulfate ion is followed by the identification reaction with a 2 mol/L barium chloride solution. The main macroscopic observations, which can be highlighted, in the case of incomplete washing are as follows [ 44 , 45 ]: Undulation of the membrane; The occurrence of defects (microcracks; holes); Local re-solubilizations (transparencies; gelations). …”

“…The permeate, which is made up of the acetic acid solution, is collected inside the membranes. A layer of chitosan is deposited on the polypropylene hollow fiber membrane [ 45 , 46 ].…”