Reverse osmosis and electrodialysis are truly the only water desalination processes currently in practice for the entire range of total dissolved solids (TDS) from 400–40,000 mg/L. For high recovery of 80% or more, membrane processes are energy intensive even for a feedwater with a TDS of 1000 mg/L and demand significant pretreatment to avoid precipitation and consequent membrane fouling. In this study, we present for the first time a hybrid ion exchange desalination (HAIX-Desal) process that does not require any semipermeable membrane and can desalinate lean brackish water (TDS ≤ 1500 mg/L) using CO₂ as the sole source of energy and chemical regenerant. A hybrid anion exchanger with dispersed ZrO₂ nanoparticles (HAIX-NanoZr) and a shell–core weak-acid cation exchange (SC-WAC) resin form the heart of the process. Carbon dioxide or CO₂ at 10 atm pressure is the only chemical needed to sustain the process. In contrast to a conventional deionization plant, the anion exchanger, i.e., HAIX-NanoZr, precedes the cation exchanger or SC-WAC to take advantage of the unique carbonate chemistry for desalination. CO₂ serves concurrently as both an acid (i.e., H₂CO₃) and a base (HCO₃^–) for the HIX-Desal process. Municipal secondary wastewater (Bethlehem, PA) and synthetic brackish water were used in the experimental study to validate the basic premise of the process.

中文翻译：

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使用加压二氧化碳（CO ₂）作为能源和再生剂的弱咸水混合离子交换脱盐（HIX-Desal）

实际上，对于总溶解固体（TDS）范围从400至40,000 mg / L的整个范围，反渗透和电渗析确实是目前唯一的水淡化过程。对于80％或更高的高回收率，即使对于TDS为1000 mg / L的给水，膜工艺也需要消耗大量能源，并且需要进行大量预处理才能避免沉淀和膜污染。在这项研究中，我们首次提出了一种混合离子交换淡化（HAIX-Desal）工艺，该工艺不需要任何半透膜，并且可以利用CO ₂作为唯一来源的淡咸水（TDS≤1500 mg / L）进行淡化。能源和化学再生剂。具有分散ZrO _2的混合阴离子交换剂纳米颗粒（HAIX-NanoZr）和壳核弱酸性阳离子交换（SC-WAC）树脂形成了该过程的核心。在10个大气压下的二氧化碳或CO ₂是维持该过程所需的唯一化学物质。与常规的去离子厂相反，阴离子交换剂（即HAIX-NanoZr）在阳离子交换剂或SC-WAC之前，以利用独特的碳酸盐化学物质进行脱盐。在HIX脱盐工艺中，CO ₂同时用作酸（即H ₂ CO ₃）和碱（HCO ₃ ^–）。实验研究中使用了市政二次废水（宾夕法尼亚州伯利恒）和合成微咸水，以验证该过程的基本前提。