Elemental Sulfur Research Articles

Multicomponent Tandem Cyclization/Aromatization Reaction: Access to 2‐Substituted Naphthothiazoles and Benzothiazoles

A straightforward, metal‐free multicomponent tandem cyclization/aromatization approach for the synthesis of naphthothiazoles and benzothiazoles has been described. This method employs α‐tetralone and cyclohexenones as the starting materials, styrene derivatives as a one‐carbon synthon, ammonium salt as the N source, elemental sulfur as the S source, and an oxidant. This approach offers a broad substrate scope, including α‐tetralone and cyclohexenones adorned with different functional groups, resulting in moderate to high yields of the desired products.

Autotrophic denitrification by sulfur-based immobilized electron donor for enhanced nitrogen removal: Denitrification performance, microbial interspecific interaction and functional traits

Sulfur-driven autotrophic denitrification (SdAD) is a promising nitrogen removing process, but its applications were generally constrained by conventional electron donors (i.e., thiosulfate (Na2S2O3)) with high valence and limited bioavailability. Herein, an immobilized electron donor by loading elemental sulfur on the surface of polyurethane foam (PFSF) was developed, and its feasibility for SdAD was investigated. The denitrification efficiency of PFSF was 97.3%, higher than that of Na2S2O3 (91.1%). Functional microorganisms (i.e., Thiobacillus and Sulfurimonas) and their metabolic activities (i.e., nir and nor) were substantially enhanced by PFSF. PFSF resulted in the enrichment of sulfate-reducing bacteria, which can reduce sulfate (SO42−). It attenuated the inhibitory effect of SO42−, whereas the generated product (hydrogen sulfide) also served as an electron donor for SdAD. According to the economic evaluation, PFSF exhibited strong market potential. This study proposes an efficient and low-cost immobilized electron donor for SdAD and provides theoretical support to its practical applications.

Selective Removal of Arsenic and Antimony from Pb-Ag Sulfide Concentrates by Alkaline Leaching: Thermodynamic and Kinetic Studies

Arsenic and antimony are impurities that reduce the economic value of concentrates due to the environmental problems they cause. The removal of these impurities by hydrometallurgical means has been highly studied for sulfide copper concentrates using different leaching agents in an alkaline medium (NaClO, H2O2, NaOH, Na2S, NaHS, and S). For a lead–silver concentrate consisting of galena, sphalerite, and pyrite, it was possible to selectively reduce the arsenic content from 1.10% to 0.55% and antimony from 2.41 to 1.04% through the digestion-leaching technique that uses elemental sulfur as a leaching agent in alkaline medium. The adequate powdered sulfur and sodium hydroxide dosage were 336 and 342 kg/t, respectively. The process was carried out at 120 °C with a liquid/solid ratio of 2 in digestion and 5.67 in leaching; the appropriate digestion and leaching time were 20 and 30 min, respectively. The thermodynamics and kinetics of this process turned out to be very complex due to the great variety of simultaneous leaching and precipitation reactions. The digestion process exhibited a mixed kinetic control, where diffusion through the boundary layer and the chemical reaction were the controlling steps with an activation energy of 11.05 kcal/mol.

Continuous and controllable synthesis of MnO2 adsorbents for H2S removal at low temperature

H2S is an extremely noxious impurity generated from nature and chemical industrial processes. High performing H2S adsorbents are required for chemical industry and environmental engineering. Herein, α-, γ-, and δ-MnO2 adsorbents with high sulfur capacity were synthesized through a continuous-flow approach with a microreactor system, achieving much higher efficiency than hydrothermal methods. The relationship between crystal structure and synthesis conditions such as residence time, reaction temperature, concentration of K+ in solution and reactant ratio is discussed. According to the H2S breakthrough tests at 150 °C, continuously prepared α-, γ-, and δ-MnO2 exhibited sulfur capacities of 669.5, 193.8 and 607.6 mg S/g sorbent, respectively, which was at a high level among the reported adsorbents. Such enhanced performance is related to the large surface area and mesopore volume, high reducibility, and a large number of oxygen species with high reactivity and mobility. Manganese sulfide and elemental sulfur were formed after desulfurization, which indicated the reaction consisted of two steps: redox and sulfidation of the sorbents. This study provides an innovative design strategy for the construction of nanomaterials with high H2S adsorption performances.

Solubility evolution of elemental sulfur in natural gas with a varying H2S content.

The solubility variations of elemental sulfur are of great importance in the prevention of sulfur deposition during the development of high-sulfur gas formations. It has been observed that the solubility varies with H2S content, which is the main solvent of elemental sulfur in natural gas. Moreover, the addition of small amounts of CH4 and/or CO2 in H2S leads to a dramatic solubility reduction of which the mechanism remains unclear. Using a modified direct coexistence method, molecular dynamics simulations are conducted to uncover the molecular mechanism of the solubility reduction. The observed solubility variations with H2S content are reproduced, and the solubility reduction is interpreted by the antisolvent effect of CH4 and CO2. While the H2S content varies in a wide range in the known high-sulfur gas formation, our simulations provide useful information for controlling the sulfur deposition in gas development. Molecular dynamics simulations are carried out using the LAMMPS package. The initial models are constructed with the Packmol software. The Ballone and Jones' potential is used for S8, the Galliero's potential for H2S and CO2, and the transferable potentials for phase equilibria-united atom (TraPPE-UA) force field for CH4. The time step is set to 1fs, and the molecular trajectories of additional 2ns after equilibrium are collected for analysis.

Ferrocene-Based N-Heterocyclic Silylenes: Monomeric Silanechalcogenones, Silanimines, Silirenes, and Insertion Products with P4.

The stable ferrocene-based N-heterocyclic silylenes fc[(N{B})2Si] (A; fc = 1,1'-ferrocenylene, {B} = (HCNDipp)2B, Dipp = 2,6-diisopropylphenyl) and fc[(NDipp)2Si] (B) are compared in a study focussing on their reactivity towards a range of small to moderately sized molecular substrates, viz. P4, S8, Se8, MesN3 (Mes = mesityl), RC≡CH, and RC≡CR (R = Ph, SiMe3). The Dipp-substituted congener B exhibits a more pronounced ambiphilicity and is sterically less congested than its 1,3,2-diazaborolyl-substituted relative A, in line with the higher reactivity of the former. The difference in reactivity is obviously due more to electronic than to steric reasons, as is illustrated by the fact that both A and B react with the comparatively bulky substrate MesN3 under mild conditions to afford the corresponding silanimine fc[(N{B})2Si=NMes] and fc[(NDipp)2Si=NMes], respectively. The heavier ketone analogues fc[(N{B})2Si=E] (E = S, Se, Te) are readily available from A and the corresponding chalcogen. In contrast, the reaction of the more reactive silylene B with elemental sulfur or selenium is unspecific, affording product mixtures. However, fc[(NDipp)2Si=Se] is selectively prepared from B and (Et2N)3PSe; the Te analogue is also accessible, but crystallises as head-to-tail dimer.

Biochar pH reduction using elemental sulfur and biological activation using compost or vermicompost

This study aimed to improve biochar’s quality for arid land applications by using elemental sulfur as a pH reducer agent co-applied with compost or vermicompost as biological activators. Biochar pH was decreased by the addition of elemental sulfur, with the highest reduction from 8.1 to 7.2 occurring when co-amended with vermicompost. Elemental sulfur increased the water-soluble concentrations of calcium, magnesium, and many other elements, and stimulated substrate-induced respiration, especially when co-amended with vermicompost. The bacterial diversity community structure were significantly affected by all treatments. The Shannon index significantly increased in response to compost and sulfur treatments, while the vermicompost treatments showed higher microbial evenness and equitability diversity indices. Multivariate analyses indicated that elemental sulfur oxidation was associated with specific sulfur-oxidizing bacterial clusters. Integrating biochar with sulfur and (vermi)compost was found to be a promising sustainable technology for managing excessive biochar alkalinity, increasing its fertility and potential for application in aridlands.

Direct Synthesis of Monofluoromethylthioesters from Acyl Chlorides with Elemental Sulfur and Fluoroiodomethane

We report an unprecedented Ni‐catalyzed direct monofluoromethylthiolation of acyl chlorides, in situ generated from carboxylic acids, with elemental sulfur (S8) as the S source and fluoroiodomethane (ICH2F) as the CH2F radical source to produce a series of monofluoromethylthioesters in moderate to good yields. This approach features excellent functional group tolerance and broad substrate scope. Additionally, the late‐stage monofluoromethylthiolation of complex bioactive molecules can also be accomplished using this method.

Growth Attributes of Maize (Zea Mays L) Crop and Nutrient Uptake as impacted by Sulphur and Micronutrients Application

Maize, also known as the "queen of cereals," is a highly nutritious crop that requires a significant amount of nutrients to grow. It is particularly sensitive to deficiency of sulphur. It plays a significant role in the synthesis of chlorophyll, oil, and protein. A field experiment was conducted at Rashtriya Chemicals and Fertilizers Limited in Mumbai, Maharashtra, during the Kharif season 2023, to assess the impact of elemental sulphur application and foliar spray of multi micronutrient on maize plant growth and uptake of nutrients by maize as well as the post-harvest status of soil. The experiment was laid out in Randomized Block Design (RBD) with five treatments that were replicated six times each. T1 is the absolute control, T2 is 100% RDF, T3 is the RDF NPK with 45 kg/ha of elemental S, T4 is the RDF NPK with 45 kg/ha coupled with foliar spray of multi micronutrient, and T5 is the RDF NPK with foliar spray of multi micronutrient. The results indicated that application of 45 kg of S per hectare, in combination with a foliar spray of multi micronutrients, resulted in remarkable growth parameters of maize crops. These included plant height, cob height, yield (in kg/ha), dry weight per plant and also the uptake of essential nutrients. This was markedly higher when compared to the other treatments. Except 100 grain weight which was at par with other treatments. While girth of cob and protein content were found non-significant. The study reports suggest that the combined use of S and multimicronutrient in maize crop positively impact the uptake of nutrients and growth attributes.

An investigation of a process for selective biogas desulfurization and autotrophic denitrification in a membrane supported reactor

A lab-scale dense polydimethylsiloxane (PDMS) membrane bioscrubber (MBS) was used for selective removal of highly toxic H2S from biogas under autotrophic conditions for the first time. The performance of MBS was evaluated under the effects of sulfide loadings, pH, and hydraulic retention time (HRT). The results showed that gradual increase in sulfide loading rate from 131 to 316 g/m3.d boost S/N ratios 1.9–4.0, on average sulfide oxidation efficiencies higher than 95% were achieved. The S/N ratios were determinant on the formation of oxidation products, but not on the H2S gas removal efficiency. The transition of HRT significantly affected the denitrification rather than the sulfide oxidation, when HRT reduced from 24 to 12 h the nitrate removal efficiency suddenly dropped from 98% to 70%. Increasing the pH values from 7.0 to 9.0 also decreased the sulfide oxidation efficiency from 97±0.5–92±1.1%. Denitrification efficiency > 96% was observed between pH value of 7.0 and 8.0, whereas at pH 9.0 dropped rapidly to 82%. In the whole experiment time there was no membrane-induced problem that adversely affected the system performance. Over-all the developed anoxic dense MBS successfully employed for selective removal of 10,000 ppm H2S and nitrate concurrently with low chemical consumption, possibility for recovery of elemental sulfur, enhanced CH4 calorific value and eliminating the risks of explosion and dilution of biogas. The current work showed the PDMS MBS system is a promising alternative way in biological nitrogen removal and biogas desulfurization under anoxic conditions. Its application in real scale would have high economic importance.

Multimodal Acridine Photocatalysis Enables Direct Access to Thiols from Carboxylic Acids and Elemental Sulfur.

Development of photocatalytic systems that facilitate mechanistically divergent steps in complex catalytic manifolds by distinct activation modes can enable previously inaccessible synthetic transformations. However, multimodal photocatalytic systems remain understudied, impeding their implementation in catalytic methodology. We report herein a photocatalytic access to thiols that directly merges the structural diversity of carboxylic acids with the ready availability of elemental sulfur without substrate preactivation. The photocatalytic transformation provides a direct radical-mediated segue to one of the most biologically important and synthetically versatile organosulfur functionalities, whose synthetic accessibility remains largely dominated by two-electron-mediated processes based on toxic and uneconomical reagents and precursors. The two-phase radical process is facilitated by a multimodal catalytic reactivity of acridine photocatalysis that enables both the singlet excited state PCET-mediated decarboxylative carbon-sulfur bond formation and the previously unknown radical reductive disulfur bond cleavage by a photoinduced HAT process in the silane-triplet acridine system. The study points to a significant potential of multimodal photocatalytic systems in providing unexplored directions to previously inaccessible transformations.

Influence of the use of remediated soil and agricultural drainage water on the safety of tomato fruits

The objective of this study is to assess the effectiveness of different techniques employed in remediating contaminated soil and wastewater ecosystems to ensure the safety of tomato fruits (Solanum lycopersicum L. var. cerasiforme) cultivated in these environments. Three biochemical techniques T1–T3, besides two controls CCU and CCT, were used to remediate contaminated soil ecosystems using rock phosphate, elemental sulfur, bentonite, phosphate-dissolving bacteria, and Thiobacillus sp. The contaminated agricultural drainage water was remediated by a down-flow hanging sponge (DHS) system. Two experiments were conducted: a pot experiment took place in the greenhouse at the National Research Center of Cairo (Egypt) and a field experiment was carried out at the basin site in the village of El-Rahawy, applying the optimal treatment(s) identified from the greenhouse experiment. The health risk assessment for potentially toxic elements (PTEs) in the harvested tomato fruits was conducted by calculating estimated daily intake (EDI) and target risk quotient (THQ) values. Results from the greenhouse experiment indicated the high effectiveness of the DHS technique in remediating El-Rahawy agricultural drainage water. The content of PTEs after remediation was significantly reduced by 100%, 93.3%, 97.8, and 77.8% for cadmium, copper, manganese, and zinc, respectively. The application of treated drainage water in employed reclaimed soil ecosystems led to a remarkable decrease in PTE levels, especially under T3 treatment; the reduction reached 89.4%, 89.5%, and 78.4% for nickel, copper, and zinc, respectively. The bioremediation technique also reduced the content of PTEs in tomato fruits harvested from both greenhouse and field experiments; the cadmium content, for example, was below detection limits in all treatments. The T3 treatment applied in the greenhouse experiment caused the highest percentage decrease among the employed PTEs in tomato fruits grown in the greenhouse. The same trend was also reached in the field experiment. Microbiological analyses of tomato fruits revealed that E. coli, Salmonella, or S. aureus bacteria were identified on tomato fruits harvested from either greenhouses or field experiments, showing that the counted total bacteria were higher under the field experiment compared to the greenhouse experiment. The health risk assessment parameter THQ was below 1.0 for all tested metals under all treatments. This means that no potential health risk is expected from consuming tomato products produced under the different employed remediation treatments. In conclusion, the employed bioremediation techniques successfully reduced the PTE content and microbial load in both soil and drainage water ecosystems and in harvested tomato fruits. Henceforth, no health risks are expected from the consumption of this product.

Characteristics and mechanisms of phosphine production in sulfur-based constructed wetlands

Phosphine (PH3) is an important contributor to the phosphorus cycle and is widespread in various environments. However, there are few studies on PH3 in constructed wetlands (CWs). In this study, lab-scale CWs and batch experiments were conducted to explore the characteristics and mechanisms of PH3 production in sulfur-based CWs. The results showed that the PH3 release flux of sulfur-based CWs varied from 0.86±0.04 ng·m−2·h−1 to 1.88±0.09 ng·m−2·h−1. The dissolved PH3 was the main PH3 form in CWs and varied from 2.73 μg·L−1 to 4.08 μg·L−1. The matrix-bound PH3 was a staging reservoir for PH3 and increased with substrate depth. In addition, the sulfur-based substrates had a significant improvement on PH3 production. Elemental sulfur is more conducive to PH3 production than pyrite. Moreover, there was a significant positive correlation between PH3 production, the dsrB gene, and nicotinamide adenine dinucleotide (NADH). NADH might catalyze the phosphate reduction process. And the final stage of the dissimilatory sulfate reduction pathway driven by the dsrB gene might also provide energy for phosphate reduction. The migration and transformation of PH3 increased the available P (Resin-P and NaHCO3-P) from 35 % to 56 % in sulfur-based CW, and the P adsorption capacity was improved by 12 %. The higher proportion of available P increased the plant uptake rate of P by 17 %. This study improves the understanding of the phosphorus cycle in sulfur-based CW and provides new insight into the long-term stable operation of CWs.

Hydrogen Sulfide Splitting into Hydrogen and Sulfur through Off-Field Electrocatalysis.

Hydrogen sulfide (H2S), a toxic gas abundant in natural gas fields and refineries, is currently being removed mainly via the Claus process. However, the emission of sulfur-containing pollutants is hard to be prevented and the hydrogen element is combined to water. Herein, we report an electron-mediated off-field electrocatalysis approach (OFEC) for complete splitting of H2S into H2 and S under ambient conditions. Fe(III)/Fe(II) and V(II)/V(III) redox mediators are used to fulfill the cycles for H2S oxidation and H2 production, respectively. Fe(III) effectively removes H2S with almost 100% conversion during its oxidation process. The H+ ions are reduced by V(II) on a nonprecious metal catalyst, tungsten carbide. The mediators are regenerated in an electrolyzer at a cell voltage of 1.05 V, close to the theoretical potential difference (1.02 V) between Fe(III)/Fe(II) and V(II)/V(III). In a laboratory bench-scale plant, the energy consumption for the production of H2 from H2S is estimated to be 2.8 kWh Nm-3 H2 using Fe(III)/Fe(II) and V(II)/V(III) mediators and further reduced to about 0.5 kWh Nm-3 H2 when employing well-designed heteropolyacid/quinone mediators. OFEC presents a cost-effective approach for the simultaneous production of H2 and elemental sulfur from H2S, along with the complete removal of H2S from industrial processes. It also provides a practical platform for electrochemical reactions involving solid precipitation and organic synthesis.

Microbial communities of acidic post-mining environments and their use in laterite bioreduction

The biogeochemistry of post-mining areas is important because of their impact on the environment and the possibility of remediating such areas. Such a hostile environment is also a source of acidophilic microorganisms that can dissolve minerals that might be applied in the extractive metallurgy of low-grade oxide ores. Therefore, the study used autochthonic microorganisms isolated from water and sediment samples taken from places affected by acid mine drainage. The acidophiles were isolated under aerobic and anaerobic conditions. Genomic analysis revealed low prokaryotic diversity. The genera with a relative abundance greater than 1% were Acidithiobacillus (39.8-84.2%), Ferrimicrobium (26.4-34.4%), Acidiphilium (8.31-28.8%), and Leptospirillum (9.6-32.1%). Aerobic bacteria were adapted to reduce iron(III) under a nitrogen atmosphere and the presence of elemental sulfur as an electron donor. It was shown that increasing the amount of sulfur (1-5 g) had little effect on the process kinetics. In anaerobic bottom sediments, Sulfobacillus (45.7%) and Acidisphaera (32.7%) predominated. Microorganisms showed the fastest reduction activity when glycerol was used as an electron donor. Four weeks of anaerobic-controlled bioreduction of laterites yielded nickel and magnesium at 33.3% and 77.3%, respectively, which could have potential applications in the processing of laterites.

Biogenic sulfur recovery from sulfate-laden antibiotic production wastewater using a single-chamber up-flow bioelectrochemical reactor

The high-concentration sulfate (SO42−) in the antibiotic production wastewater hinders the anerobic methanogenic process and also proposes possible environmental risk. In this study, a novel single-chamber up-flow anaerobic bioelectrochemical reactor (UBER) was designed to realize simultaneous SO42− removal and elemental sulfur (S0) recovery. With the carbon felt, the cathode was installed underneath and the anode above to meet the different biological niches for sulfate reducing bacteria (SRB) and sulfur oxidizing bacteria (SOB). The bio-anode UBER (B-UBER) demonstrated a much higher average SO42− removal rate (SRR) of 113.2 ± 5.7 mg SO42−−S L−1 d−1 coupled with a S0 production rate (SPR) of 54.4 ± 5.8 mg S0-S L−1 d−1 at the optimal voltage of 0.8 V than that in the abio-anode UBER (control reactor) (SRR = 86.6 ± 13.4 mg SO42−−S L−1 d−1; SPR = 25.5 ± 9.7 mg S0-S L−1 d−1) under long-term operation. A large amount of biogenic S0 (about 72.2 mg g−1 VSS) was recovered in the B-UBER. The bio-anode, dominated by Thiovirga (SOB genus) and Acinetobacter (electrochemically active bacteria genus), exhibited a higher current density, lower overpotential, and lower internal resistance. C-type cytochromes mainly served as the crucial electron transfer mediator for both direct and indirect electron transfer, so that significantly increasing electron transfer capacity and biogenic S0 recovery. The reaction pathways of the sulfur transformation in the B-UBER were hypothesized that SRB utilized acetate as the main electron donor for SO42− reduction in the cathode zone and SOB transferred electrons to the anode or oxygen to produce biogenic S0 in the anode zone. This study proved a new pathway for biogenic S0 recovery and sulfate removal from sulfate-laden antibiotic production wastewater using a well-designed single-chamber bioelectrochemical reactor.

Cu-MOF-derived Cu nanoparticles decorated porous N-doped biochar for low-temperature H2S desulfurization

Hydrogen sulfide (H2S) is a highly toxic and corrosive gas that poses significant risks to human health and the environment. Therefore, the development of an adsorbent capable of efficiently purifying H2S at room temperature remains a challenging task. In this study, a novel composite adsorbent with a specific surface area of 434 m2·g−1 was fabricated by modifying porous N-doped biochar with Cu nanoparticles (Cu/NBC) derived from Cu-MOFs for low-temperature desulfurization of H2S. The effect of pyrolysis temperature and the doping ratio of Cu-MOFs to biochar on the desulfurization performance of H2S for the as-prepared Cu/NBC was comprehensively investigated. Experimental results indicated that the desulfurization capability of the optimized Cu/NBC-600-1 adsorbent (synthesized at a pyrolysis temperature of 600 °C and a doping ratio of 1:1) was significantly affected by the desulfurization conditions, and the optimal conditions were determined to be at 25 °C, with 20 % oxygen content and 70 % relative humidity. Under the optimized conditions, the Cu/NBC-600-1 adsorbent exhibited a high H2S removal capacity of 158.28 mg·g−1, which was about 3.8 times higher than that of the pristine N-doped biochar. The desulfurization mechanism of the Cu/NBC composite was demonstrated to involve reactive adsorption and catalytic oxidation, resulting in the formation of elemental sulfur and copper sulfides as the main products. This study not only provides a promising approach to modify porous biochar with MOF derivatives, but also offers an effective strategy to remove low concentration H2S at room temperature.

Pushing Boundaries: What's Next in Metal-Free C-H Functionalization for Sulfenylation?

The synthesis of thioether derivatives has been explored widely due to the potential application of these derivatives in medicinal chemistry, pharmaceutical industry and material chemistry. Within this context, there has been an increasing demand for the environmentally benign construction of C-S bonds via C-H functionalization under metal-free conditions. In the present article, we highlight recent developments in metal-free sulfenylation that have occurred in the past three years. The synthesis of organosulfur compounds via a metal-free approach using a variety of sulfur sources, including thiophenols, disulfides, sulfonyl hydrazides, sulfonyl chlorides, elemental sulfur and sulfinates, is discussed. Non-conventional strategies, which refer to the development of thioether derivatives under visible light and electrochemically mediated conditions, are also discussed. The key advantages of the reviewed methodologies include broad substrate scope and high reaction yields under environmentally benign conditions. This comprehensive review will provide chemists with a synthetic tool that will facilitate further development in this field.

Sulfuric acid leaching of a complex zinc sulfide concentrate with high copper and lead concentrations under oxygen pressure

ABSTRACT This paper presents the use of an oxygen pressure-based acid leaching process for the selective extraction of basic metals from a complex zinc ore containing high concentrations of lead (6.00%) and copper (2.47%). The effects of leaching temperature, ore particle size distribution, leaching time, liquid-to-solid ratio, and oxygen partial pressure on the leaching efficiencies of zinc and copper were investigated, and the phase transformation behaviour of lead compounds was studied. Under the optimal conditions that is, a particle size of −48/+40 μm, initial sulfuric acid concentration of 150 g/L, liquid-to-solid ratio of 6:1, leaching time of 150 min, leaching temperature of 150°C, and oxygen partial pressure of 0.8 MPa – the leaching efficiencies of zinc, copper, and iron were 98.85%, 82.69%, and 33%, respectively. The leaching residue showed that almost all of the zinc sulfide was dissolved as ZnSO4, and most of the negatively charged bivalent sulfur was converted to zero-valent element sulfur. Through the pressure leaching reaction, galena in the concentrate was converted to lead jarosite (PbFe6(SO4)4(OH)12) and elemental sulfur. The formation of lead jarosite facilitated the removal of a significant portion of iron during leaching, reducing the subsequent purification burden.

Modification of Polysulfide Surfaces with Low-Power Lasers.

The modification of polymer surfaces using laser light is important for many applications in the nano-, bio- and chemical sciences. Such capabilities have supported advances in biomedical devices, electronics, information storage, microfluidics, and other applications. In most cases, these modifications require high power lasers that are expensive and require specialized equipment and facilities to minimize risk of hazardous radiation. Additionally, polymer systems that can be easily modified by lasers are often complex and costly to prepare. In this report, these challenges are addressed with the discovery of low-cost sulfur copolymers that can be rapidly modified with lasers emitting low-power infrared and visible light. The featured copolymers are made from elemental sulfur and either cyclopentadiene or dicyclopentadiene. Using a suite of lasers with discreet wavelengths (532, 638 and 786 nm) and powers, a variety of surface modifications could be made on the polymers such as controlled swelling or etching via ablation. The facile synthesis and laser modification of these polymer systems were exploited in applications such as direct laser lithography and erasable information storage.