Novel Agglomeration Strategy for Elemental Sulfur Produced during Biological Gas Desulfurization

Abstract

This article presents a novel crystal agglomeration strategy for elemental sulfur (S) produced during biological desulfurization (BD).A key element is the nucleophilic dissolution of S by sulfide (HS − ) to polysulfides (S x 2− ), which was enhanced by a sulfide-rich, anoxic reactor. This study demonstrates that with enhanced S x 2− formation, crystal agglomerates are formed with a uniform size (14.7 ± 3.1 μm). In contrast, with minimal S x 2− formation, particle size fluctuates markedly (5.6 ± 5.9 μm) due to the presence of agglomerates and single crystals. Microscopic analysis showed that the uniformly sized agglomerates had an irregular structure, whereas the loose particles and agglomerates were more defined and bipyramidal. The irregular agglomerates are explained by dissolution of S by (poly)sulfides, which likely changed the crystal surface structure and disrupted crystal growth. Furthermore, S from S x 2− appeared to form at least 5× faster than from HS − based on the average S x 2− chain length of x ≈ 5, thereby stimulating particle agglomeration. In addition, microscopy suggested that S crystal growth proceeded via amorphous S globules. Our findings imply that the crystallization product is controlled by the balance between dissolution and formation of S. This new insight has a strong potential to prevent poor S settleability in BD.

Insights into the Superior Bioavailability of Biogenic Sulfur from the View of Its Unique Properties: The Key Role of Trace Organic Substances

“…Most bio-S 0 particles took on a bipyramidal shape (Figure A,B). These bio-S 0 particles were identified as orthorhombic sulfur particles since the bipyramidal shape is recognized as the typical morphology of orthorhombic sulfur particles. , The XRD results in Figure C confirmed the orthorhombic structure of bio-S 0 (α-S 8 ) with a crystalline structure. In addition, bio-S 0 was detected to have a binding energy of 164.0 eV, indicating a zero-valence state according to standard XPS (Figure D) .…”