Dear Hyunjun Song I am not sure whether I understand your question correctly but your question is easily answered looking at the famous solubility table (see for example https://sciencenotes.org/solubility-rules-chart-and-memorization-tips/ ).

If you want to precipitate chloride ions than you need to use a Ag+ or Pb2+ containing salt.

Best regards.

you can deploy Copilot, Here’s a detailed explanation of chloride ion removal methods, supported by recent references:

---

### 1. **Chemical Precipitation**

Chemical precipitation involves adding reagents to water to react with chloride ions, forming insoluble compounds. Recent research has highlighted the use of Friedel's salt (Ca₂Al(OH)₆Cl·2H₂O), formed by reacting calcium hydroxide and sodium aluminate. This compound effectively traps chloride ions within its layered structure, making it suitable for high-salinity wastewater. A study published in *Minerals* (2025) demonstrated that optimizing pH and temperature significantly enhances precipitation efficiency.

https://www.jstage.jst.go.jp/article/matertrans/59/2/59_M2017273/_html/-char/en

https://www.deswater.com/DWT_articles/vol_299_papers/299_2023_110.pdf

---

### 2. **Electrocoagulation**

Electrocoagulation uses aluminum electrodes as sacrificial anodes to remove chloride ions. The process involves co-precipitation and electrostatic adsorption, forming chlorine-containing metal hydroxyl complexes. A 2023 study in *Environmental Science and Pollution Research* explored the influence of current density, plate spacing, and coexisting ions. Magnesium ions were found to promote chloride removal, while calcium ions inhibited it.

Article Removal of high concentration of chloride ions by electrocoa...

https://link.springer.com/content/pdf/10.1007/s11356-023-25792-1.pdf

---

### 3. **Ion Exchange Resins**

Strong anionic resins are highly effective for chloride ion removal. Examples include:

- **Purolite A400**: Known for its durability and high capacity for chloride removal.

- **Lewatit® MonoPlus MP 500**: Produced by LANXESS, optimized for industrial applications.

- **Amberlite IRA-400**: Manufactured by DuPont, widely used in water treatment.

Recent research has focused on optimizing operating conditions, such as temperature (around 50°C) and pH, to enhance resin performance. Regeneration of these resins using caustic solutions ensures their long-term usability.

https://www.deswater.com/DWT_articles/vol_221_papers/221_2021_76.pdf

Article Experimental study of order and constant rate of chlorine re...

Article Laboratory evaluation of operating conditions for chloride r...

https://www.deswater.com/DWT_articles/vol_299_papers/299_2023_110.pdf

---

### 4. **Reverse Osmosis (RO)**

Reverse osmosis employs semi-permeable membranes to filter out chloride ions and other dissolved solids. Innovations in membrane technology, such as the incorporation of graphene oxide, have improved efficiency and lifespan. RO systems from producers like Dow FilmTec and Hydranautics are widely used in seawater desalination and industrial wastewater treatment. A 2023 study emphasized the importance of addressing membrane fouling and reducing energy consumption to make RO systems more sustainable.

https://www.researchgate.net/topics

https://www.sciencegate.app/keyword/16457

https://pubs.rsc.org/en/content/articlehtml/2024/ra/d4ra01796j

---

These methods are backed by cutting-edge research and have diverse applications ranging from municipal water treatment to industrial processes.

Here are some recent studies and references on chloride ion removal methods:

1. **Electrocoagulation**: A study published in *Environmental Science and Pollution Research* (2023) investigated the use of aluminum electrodes for chloride ion removal. The research highlighted the role of coexisting ions like magnesium and calcium, and optimized parameters such as current density and plate spacing.

Article Removal of high concentration of chloride ions by electrocoa...

2. **Precipitation**: Research in *Minerals* (2025) explored chloride ion removal from magnesium hydroxide using sodium hydroxide and ethanol. The study demonstrated a removal efficiency of 68.9% under optimized conditions 2 Using NaOH with Ethanol - MDPI](https://www.mdpi.com/2075-163X/15/4/364/xml).

https://www.mdpi.com/2075-163X/15/4/364/xml

3. **Advanced Oxidation Processes (AOPs)**: A review in *Environmental Science: Water Research & Technology* (2023) discussed oxidation methods for chloride removal, including UV-induced and electrolysis techniques. These methods showed high efficiency but require further optimization to reduce energy consumption from acidic industrial wastewater through oxidation ...](https://pubs.rsc.org/en/content/articlehtml/2023/ew/d2ew00628f).

These references provide insights into cutting-edge techniques for chloride ion removal. Good luck