Remediation of cobalt from semiconductor wastewater in the frame of fluidized-bed homogeneous granulation process

Lester Lee E. Bayon, Florencio C. Ballesteros, Angelo Earvin Sy Choi, Sergi Garcia-Segura, Ming Chun Lu

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Green and sustainable strategies aim for the development of manufacturing processes that maximize the use of resources, instigating the semiconductor industry to adopt zero-liquid discharge policies. Complexity and variations in semiconductor wastewater effluents open an opportunity for resource recovery. One such opportunity is the potential recovery of heavy metals such as cobalt and/or copper in chemical-mechanical polishing wastewater, and inorganic anions such as phosphate from etching and acid cleaning. The present work demonstrates the capabilities of homogeneous crystallization in fluidized-bed reactor as treatment technology to process water effluents for industrial reuse while simultaneously recovering precious resources such as copper, cobalt and phosphate. Experimental results revealed that the optimum conditions were achieved at effluent pH of 7.75 – 8.0 and [PO4−3]/[Co2+] of 2.0. Uniform crystal growth was attained due to appropriate fluidization and proper collision of the particles at up flow velocity 40.11 m h−1 with 1.18 kg Co2+ m−2 h−1 loading. Performance was based on the removal/recovery capabilities of cobalt as heavy metal pollutant. The percentage of total cobalt recovered by granulation was 98.8%, whereas 99% cobalt removal was attained at optimal parameters. Coexistence of EDTA and citrate inhibits crystal growth, decreasing the metal granulation capability ~35%. Mixing of copper and cobalt ions in fluidized-bed homogeneous crystallization process was also investigated in which the highest granulation of 95.9% was attained at effluent pH of 6.50 for copper, and 96.8% at effluent pH of 7.50 for cobalt with an equimolar metal concentration of 7.0 mM and phosphate-metal molar ratio of 1.60. The granules recovered were analyzed using XRD and SEM-EDS. The recovered crystals were identified as mineral libethenite (Cu2(PO4)OH) and cobalt phosphate hydrate (Co3(PO4)2.8H2O).

Original languageEnglish (US)
Article number105936
JournalJournal of Environmental Chemical Engineering
Volume9
Issue number5
DOIs
StatePublished - Oct 2021

Keywords

  • Cobalt
  • Copper
  • Fluidized-bed homogeneous granulation process
  • Nucleation
  • Semiconductor wastewater

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Waste Management and Disposal
  • Pollution
  • Process Chemistry and Technology

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