| | | | | |
| Entity Name | State or Country of Organization |
| ACS Land Company, LLC | Delaware |
| ADA Analytics, LLC | Delaware |
| ADA Analytics Israel Ltd. | Israel |
| Arq Solutions, LLC | Delaware |
| Arq Solutions (Operations), LLC | Delaware |
| Arq Solutions (Red River), LLC | Delaware |
| Arq Solutions (Vortex IP), LLC | Delaware |
| Arq Solutions (Vortex Operations), LLC | Delaware |
| Arq Solutions (ES), Inc. | Colorado |
| ADEquity, LLC | Delaware |
| Arq Purification, LLC | Delaware |
| Crowfoot Supply Company, LLC | Delaware |
| Five Forks Mining, LLC | Delaware |
| FluxSorb Technologies, LLC | Delaware |
| Arq Series B, LLC | Delaware |
| Arq IP Limited | UK |
| Arq International Limited | UK |
| Arq UK Management Ltd | UK |
| Wharnecliffe Asset Management LLC | Delaware |
| Mine Four LLC | Delaware |
| Arq LLC | Delaware |
| Arq Projects Holding Company LLC | Delaware |
| Corbin Project LLC | Delaware |
| Arq Corbin Land LLC | Delaware |
| Arq Corbin LLC | Delaware |