Selective arsenic precipitation from acidic boron waters using sodium sulfide (Na2S)
HYDROMETALLURGY, cilt.244, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 244
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.hydromet.2026.106790
- Dergi Adı: HYDROMETALLURGY
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, INSPEC
- Karadeniz Teknik Üniversitesi Adresli: Evet
Özet
The presence of arsenic in acidic mine wastewater poses serious environmental and regulatory challenges due to its toxicity and high mobility under acidic conditions. In conventional boric acid production processes, arsenic is typically removed by lime-based treatment, which leads to the generation of large volumes of secondary waste. In this study, sodium sulfide (Na2S) was evaluated as a selective precipitating agent for arsenic removal from both synthetic and barren solution (BS), derived mainly from colemanite ores processed with sulfuric acid. The precipitation experiments were performed under controlled laboratory conditions, and the resulting arsenic sulfide precipitates were characterized using XRD, SEM-EDS, and ICP-OES techniques. The results demonstrated that Na2S effectively removed arsenic in the form of orpiment (As2S3), achieving efficiencies above 95% under optimized pH and dosage conditions. The effects of temperature, Na2S /As molar ratio, and reaction time were systematically studied. The influence of boron and sulfate ions on arsenic precipitation was also assessed. In addition, the potential applicability of the proposed method within the leaching process and its effect on boric acid quality were evaluated. Although the generated precipitates exhibited low environmental stability and high leaching potential during standardized leaching tests, the findings indicate that Na2S precipitation can serve as a practical primary treatment step for arsenic removal from acidic barren solution (BS). However, post-treatment stabilization, such as hydrothermal processing, is recommended prior to disposal. Overall, this study demonstrates that Na2S-based precipitation offers a promising alternative to conventional lime-based treatment and provides an integrated perspective for improving process efficiency and product quality in boric acid production.