Contents lists available at ScienceDirect Journal of Membrane Science journal homepage: www.elsevier.com/locate/memsci Effective recovery of acids from egg waste incorporated PSf membranes: A step towards sustainable development M.S. Jyothi ⁎ , Sudesh Yadav, Geetha Balakrishna ⁎ Center for Nano and Material Sciences, Jain University, Jain Global Campus, Bangalore 562112, Karnataka, India ARTICLE INFO Keywords: Diffusion dialysis Egg shell membrane Sustainable material Proton permeability Polysulfone ABSTRACT A required progress in developing effective membranes for diffusion dialysis provides a platform to explore novel hybrid membranes for acid recovery. This novel study investigated a feasibility of egg shell membrane powder in enhancing proton permeability of polysulfone membrane, thereby promoting a sustainable development in acid recovery. Hybrid membranes with different concentration loading of egg shell membrane to polysulfone were fabricated, characterized and analyzed in terms of water uptake, ion exchange capacity, chemical stability, thermal stability and mechanical stability and the viability towards effective acid recovery. Results revealed that, prepared EP membranes showed almost 5.55 folds greater proton permeability and very high separation factor than most commercially available DF- 120 membrane. Enhancement in performance and acid recovery in the whole work is credited to presence of amino acids groups in egg shell membrane with enormous amount of hydrogen bond donar and acceptor sites which helps in hydrogen bond formation, and occurrence of π- π interactions with polysulfone forming channels to effectively permeate hydrogen ions. Also, these structural interactions remarkably increased the membrane stiffness compared to pristine PSf membrane and showed better mechanical stability. The strategy behind this work is promising for developing high performance, sus- tainable product for rapid acid recovery which could be examined in detail to apply for industrial spent acid recovery. 1. Introduction Next generation products and processes are guided by sustainable ecology, eco-efficiency and green chemistry. Relying on biomass and agricultural feedstock, biopolymer based materials can form a portfolio of above said criteria which can capture and compete the present market of petroleum-based resources. Current research efforts focus on such materials to serve a demand derived from new environmental regulations across the world. Chicken feedstock (egg shell) is well known bio waste disposed off from many industries, restaurants and bakeries. Egg waste mainly composed of two layers, calcium carbonate shell and egg shell membrane (ESM) which is located in between egg white and inner surface of egg shell [1]. ESM consists of protein fibers arranged in the form of semi-permeable membrane having stable and water insoluble intricate lattice network with high surface area [2,3]. Numerous investigations have been done on different applications of egg shell [4–8]. Use of egg shell as adsorbent for water contaminates is thoughtful venture because of its high ion exchange capacity (IEC) [9]. Despite of such fruitful investigations, still there is a need to explore new kind of feasible applications. Taking account of sustainable utilization of ESM, making use of intrinsic pore structure, we aim to prepare an ion exchange membrane for acid recovery via diffusion dialysis (DD) by preparing composite with hydrophobic polymer. DD is a concentration gradient based separation technique which uses semipermeable membrane to separate species with respect to their different rate of diffusion through membrane [10]. However, the common means for treating water such as crystallization, reverse os- mosis (RO), nanofiltration (NF) and electrodialysis (ED) are of high energy consumption and membrane fouling is serious for NF and RO [11]. DD has the advantages of simple operation, low energy con- sumption, low membrane and environmental pollution, less installation and operating cost and high efficiency [12]. Membrane separation using anion exchange membrane (AEM) for acid recovery via DD has been exploited to recover acids from waste water solution [13,14]. Many of the metal finishing industries uses acid bath to remove metal oxide scaling from metal surfaces. When metal starts accumulating in solution, over the time, efficiency of pickling bath reduces leading to necessity for acid recovery [15]. DD for acid recovery method depends on difference in diffusivity between acids and salt waste and only ex- ternal power is required to circulate the solution. The separation of acid https://doi.org/10.1016/j.memsci.2017.12.013 Received 21 August 2017; Received in revised form 4 December 2017; Accepted 6 December 2017 ⁎ Corresponding authors. E-mail addresses: ms.jyothi@jainuniversity.ac.in (M.S. Jyothi), br.geetha@jainuniversity.ac.in (G. Balakrishna). Journal of Membrane Science 549 (2018) 227–235 Available online 08 December 2017 0376-7388/ © 2017 Elsevier B.V. All rights reserved. T