Methods and apparatus relate to recovery of carbon dioxide and/or hydrogen sulfide from a gas mixture. Separating of the carbon dioxide, for example, from the gas mixture utilizes a liquid sorbent for the carbon dioxide. The liquid sorbent contacts the gas mixture for transfer of the carbon dioxide from the gas mixture to the liquid sorbent. Contacting of the sorbent with the gas mixture and/or desorption of the carbon dioxide from the liquid sorbent utilize hollow-fiber contactors that have permeable walls and incorporate particles distinct from a remainder of the walls to influence wetting properties of the contactors.