Metal Sulfates Research Articles

Deep-Ultraviolet Bialkali-Rare Earth Metal Anhydrous Sulfate Birefringent Crystal.

Birefringence is an important linear optical property of anisotropic crystals that plays a significant role in regulating light polarization. A new bialkali-rare earth metal sulfate, NaRbY2(SO4)4 compound, consisting of non-π-conjugated alkali metals and rare earth metal-centered dodecahedral YO8 has been synthesized. The structure analysis suggests that the three-dimensional (3D) structure of the compound is found to be attributable to the combination of dodecahedral YO8 and tetrahedral SO4 groups with Na+ and Rb+ located in the cavities. The ultraviolet, visible, and near-infrared (UV-vis-NIR) spectra reveal that the compound exhibits transparency at a wavelength of less than 200 nm. The observed birefringence of the compound is 0.045@550 nm, which is comparatively larger than that of most deep-ultraviolet (DUV) birefringent crystals. The birefringence mainly originated from the YO8 dodecahedron, which is suggested by first-principles calculations. This research work can provide a useful perspective to explore new DUV sulfates with excellent birefringence.

Selective Solid-Liquid Extraction of Lithium Cation Using Tripodal Sulfate-Binding Receptors Driven by Electrostatic Interactions.

Owing to the important role of and increasing demand for lithium resources, lithium extraction is crucial. The use of molecular extractants is a promising strategy for selective lithium recovery, in which the interaction between lithium and the designed extractant can be manipulated at the molecular level. Herein, we demonstrate that anion receptors of tripodal hexaureas can selectively extract Li2SO4 solids into water containing DMSO (0.8% water) compared to other alkali metal sulfates. The hexaurea receptor with terminal hexyl chains displays the best Li+ extraction selectivity at 2-fold over Na+ and 12.5-fold over K+. The driving force underpinning selective lithium extraction is due to the combined interactions of Li+-SO42- electrostatics and the ion-dipole interaction of the lithium-receptor (carbonyl groups and N atoms); the latter was found to be cation size dependent, as supported by computational calculations. This work indicates that anion binding receptors could drive selective cation extraction, thus providing new insights into the design of receptors for ion recognition and separation.

Metal mobilization from thawing permafrost to aquatic ecosystems is driving rusting of Arctic streams

Climate change in the Arctic is altering watershed hydrologic processes and biogeochemistry. Here, we present an emergent threat to Arctic watersheds based on observations from 75 streams in Alaska’s Brooks Range that recently turned orange, reflecting increased loading of iron and toxic metals. Using remote sensing, we constrain the timing of stream discoloration to the last 10 years, a period of rapid warming and snowfall, suggesting impairment is likely due to permafrost thaw. Thawing permafrost can foster chemical weathering of minerals, microbial reduction of soil iron, and groundwater transport of metals to streams. Compared to clear reference streams, orange streams have lower pH, higher turbidity, and higher sulfate, iron, and trace metal concentrations, supporting sulfide mineral weathering as a primary mobilization process. Stream discoloration was associated with dramatic declines in macroinvertebrate diversity and fish abundance. These findings have considerable implications for drinking water supplies and subsistence fisheries in rural Alaska.

Thermogravimetry as a research tool for the development of an ammonium sulphate roasting process for selective metal extraction from minerals

AbstractThe ammonium sulphate roasting process involves reacting mineral-bearing materials with ammonium sulphate via a solid–solid roasting process and subjecting the resulting roast residue to aqueous leaching. This process enables the simultaneous, non-selective co-extraction of strategic metals from the starting materials. However, effective separation of the extracted metals is often mandatory to produce quality products of high purity. In this study, the combined application of thermogravimetric analysis, X-ray powder diffraction and inductively coupled plasma optical emission spectrometry confirmed the non-selectivity of the process when applied to a South African diamond mine residue residue roasted with ammonium sulphate in a 1:2 mass ratio (m/m) at 450 °C for 2 h, with magnesium, iron and aluminium being co-extracted into water-soluble metal sulphates. Thermogravimetry was then applied to develop a multi-step, multi-temperature selective roasting process using mixtures of pure commercial metal sulphate salts. The first step of the modified process successfully separated iron and aluminium sulphates from magnesium-sulphates in the roast residues by thermally decomposing soluble iron and aluminium sulphates into insoluble oxides via calcination at 750 °C for 2 h. This temperature was lower than the one at which magnesium sulphates convert into magnesium oxide. In the second and final step, iron and aluminium were recovered from the oxide minerals via solid–solid re-roasting with ammonium sulphate at 450 °C for 1 h, causing the oxides to revert back to their water-soluble sulphate forms. The effectiveness of the modified process was subsequently verified using a diamond mine residue, showing that the soluble iron and aluminium contents in the magnesium-bearing leachate could be reduced by over 90%.

Regulating the electronic property of iron catalysts for higher alcohols synthesis from CO2 hydrogenation

The electronic property of a catalyst is crucial to the generation of key reaction intermediates for targeted synthesis. Herein, we reported a strategy by modifying iron catalysts with sulfate and alkali metal (Li, Na, or K) to regulate the electronic property and optimize the reaction pathways for CO2 hydrogenation to higher alcohols. The characterizations demonstrated the influencing relationship between the electronic property of iron catalysts and the catalytic capabilities for CO dissociation, non-dissociated CO activation and catalytic hydrogenation, which were critical to selective synthesis of higher alcohols. Na-S modification was proven more effective to balance the multiple capabilities required for higher alcohols synthesis and the NaS-Fe catalyst gave a higher C2+OH yield in CO2 hydrogenation. DFT calculations further validated the advantage of Na-S modification from the aspects of CO adsorption and C−C coupling. This strategy provides more flexibility in site regulation and applies to catalyst design for many reactions.

Potentially Harmful Elements (As, Sb, Cd, Pb) in Soil Polluted by Historical Smelting Operation in the Upper Silesian Area (Southern Poland)

This study aimed at determining the concentration and possibility of migration of potentially harmful elements (PHEs) in soils and mining and metallurgical waste in the Silesian-Cracow region. Our research was carried out in selected locations of Ruda Śląska, Świętochłowice, Bytom, and in the Olkusz region (Bukowno) in southern Poland. The concentrations of metals (e.g., Ag, Ba, Ca, Cd, Cu, Fe, Mg, Mn, Pb, Sr, Zn), metalloids (As, Sb), and sulphur were determined in 33 soil samples (with a depth range of 0.0–0.3 m) and 12 slag samples. These studies show an increased concentration of metals, metalloids, and sulphur, exceeding the level of regional geochemical background. The research results indicate that the degree of the chemical transformation of soils in the analysed regions of Ruda Śląska, Bytom, and Bukowno is advanced. This highlights the high concentrations of most metals, i.e., arsenic, antimony, and sulphur, in the surface layer of soils (topsoil) due to historic Zn-Pb ore mining and Zn and Fe metallurgy. The presence of both primary and secondary metal sulphides, sulphates, carbonates, oxides/hydroxides, silicates, and aluminosilicates was found in the mineral composition of soils and slags.

Mycoremediation of polyaromatic hydrocarbon contaminated anoxic ecosystem by <i>Trichoderma</i> species in synergy with <i>Bacillus</i> species

Fungi-base remediation is a cheap, effective and ecofriendly procedure for the cleanup of crude oil contaminated ecosystem. The study investigated the reduction of lag in crude oil degradation by Trichoderma in synergy with Bacillus in biofilm mode Sediment samples were collected from Bodo Ogoni River State using random stratified method.at depth 0 – 15 cm and 15 – 30 cm. The experimental setup consists of consortium of 1 % and 50 % crude oil (bonny light) with Trichoderma inoculum alone and/or Trichoderma and Bacillus inoculum for sixty (60) days. Microbiological test, Biochemical test, Physiochemical test (pH, conductivity) salt (nitrate, phosphate, sulphate) metal (lead, nickel, chromium, vanadium, iron) and total petroleum hydrocarbon and polyaromatic hydrocarbon using Gas chromatography flame ionization detector. Trichoderma koningopsis strain (MT111912.1): accession no (ON564694) and Bacillus velezensis strain (ON287164.1) accession no. (ON584354) were molecularly identified. 1 % crude oil Trichoderma only setup recorded 33.3 % reduction of PAHs while Trichoderma and Bacillus 1 % crude oil setup recorded 78.8 %. The 50 % crude oil Trichoderma only setup recorded 57.5 % reduction of PAHs while Trichoderma and Bacillus 50 % crude oil setup recorded 90.8 %. For TPH 1 % crude oil Trichoderma only setup recorded 29.9 % reduction while Trichoderma and Bacillus recorded 71.9 %. The 50 % crude oil Trichoderma only setup recorded 49.2 % reduction of while Trichoderma and Bacillus 50 % crude oil setup recorded 85.8 %. The study revealed that Trichoderma species can degrade polyaromatic hydrocarbon and total petroleum hydrocarbon faster in synergy with Bacillus.

Ultrafast and highly efficient Cd(II) and Pb(II) removal by magnetic adsorbents derived from gypsum and corncob: Performances and mechanisms

The utilization of gypsum and biomass in environmental remediation has become a novel approach to promote waste recycling. Generally, raw waste materials exhibit limited adsorption capacity for heavy metal ions (HMIs) and often result in poor solid–liquid separation. In this study, through co-pyrolysis with corncob waste, titanium gypsum (TiG) was transformed into magnetic adsorbents (GCx, where x denotes the proportion of corncob in the gypsum–corncob mixture) for the removal of Cd(II) and Pb(II). GC10, the optimal adsorbent, which was composed primarily of anhydrite, calcium sulfide, and magnetic Fe3O4, exhibited significantly faster adsorption kinetics (rate constant k1 was 218 times and 9 times of raw TiG for Cd(II) and Pb(II)) and higher adsorption capacity (Qe exceeded 200 mg/g for Cd(II) and 400 mg/g for Pb(II)) than raw TiG and previous adsorbents. Cd(II) removal was more profoundly inhibited in a Cd(II) + Pb(II) binary system, suggesting that GC10 showed better selectivity for Pb(II). Moreover, GC10 could be easily separated from purified water for further recovery, due to its high saturation magnetization value (6.3 emu/g). The superior removal capabilities of GC10 were due to adsorption and surface precipitation of metal sulfides and metal sulfates on the adsorbent surface. Overall, these waste-derived magnetic adsorbents provide a novel and sustainable approach to waste recycling and the deep purification of multiple HMIs.

Differential surface modification mechanism of chalcopyrite and pyrite by Thiobacillus ferrooxidans and its response to bioflotation

Mineral processing encounters the challenge of separating chalcopyrite and pyrite, with the conventional high alkali process characterized by issues such as large dosages of reagents, complex procedures, and environmental pollution. This study addresses this challenge by isolating and enriching Thiobacillus ferrooxidans (T·f) from acidic mine drainage, employing it as a biosurfactant. The modification mechanism of T·f was thoroughly analyzed. Fe dissolution through biological oxidation formed a passivation layer (jarosite [KFe3(SO4)2(OH)6], elemental sulfur (S0), and metal sulfides (Cu/Fe–S) on the surface of minerals. Metal oxides, hydroxides, and sulfates were detected on the surface of two minerals, but the difference was that elemental sulfur (S0) and copper sulfide (Cu-S) were detected on the surface of chalcopyrite. elucidating the fundamental reason for the significant difference in surface hydrophobicity between chalcopyrite and pyrite. T·f has been successfully used as a biosurfactant to achieve copper-sulfur separation.

Luminescence and creation of electron-hole trapping centers in alkali metal sulfates activated by Pb2+ impurity

Luminescence and creation of electron-hole trapping centers in alkali metal sulfates activated by Pb2+ impurity

Сорбция ионов Cu(II) и Fe(II) хлопковой целлюлозой, модифицированной диэтилентриамином

The authors have developed new effective sorbent based on chemically modified cotton cellulose. The modification process consists of two stages, including sequential treatment of cellulose with epichlorohydrin and diethylene triamine. The authors present 
 the optimal modification conditions for the obtained sorbent. It allows ones’ to achieve the highest values of sorption capacity for the extraction of iron(II) and copper(II) ions from aqueous solutions. The authors investigated the kinetics and equilibrium of heavy metal ion sorption in the system "cellulose sorbent - aqueous solution of metal sulphate" for original and modified cotton cellulose. Processing of the kinetic experiment results indicates that the kinetics of metal ion sorption is described most correctly in the framework of the pseudo-second-order kinetics model. Isotherms of heavy metal ions sorption clearly indicate the growth of sorption capacity for the modified sorbent in comparison with the original one. Processing of experimental isotherms within the Langmuir model made it possible to determine the values of the maximum sorption capacity (A∞) of original and modified with diethylenetriamine cotton cellulose with respect to Cu(II) and FE(II) ions. It was found that the A∞ of the modified sorbent was about 3 times higher than the ultimate sorption capacity of original cotton cellulose towards iron(II) and Cu(II) IONS. Comparison of IR spectra of the original cellulose samples and cellulose treated with diethylenetriamine indicates the changes that occurred during chemical modification. The paper presents SEM images showing the changes in the surface structure of the modified sorbent compared to the original one.

Cu(II) AND Fe(II) ION SORPTION BY COTTON CELLULOSE MODIFIED WITH DIETHYLENETRIAMINE

The authors have developed new effective sorbent based on chemically modified cotton cellulose. The modification process consists of two stages, including sequential treatment of cellulose with epichlorohydrin and diethylene triamine. The authors present 
 the optimal modification conditions for the obtained sorbent. It allows ones’ to achieve the highest values of sorption capacity for the extraction of iron(II) and copper(II) ions from aqueous solutions. The authors investigated the kinetics and equilibrium of heavy metal ion sorption in the system "cellulose sorbent - aqueous solution of metal sulphate" for original and modified cotton cellulose. Processing of the kinetic experiment results indicates that the kinetics of metal ion sorption is described most correctly in the framework of the pseudo-second-order kinetics model. Isotherms of heavy metal ions sorption clearly indicate the growth of sorption capacity for the modified sorbent in comparison with the original one. Processing of experimental isotherms within the Langmuir model made it possible to determine the values of the maximum sorption capacity (A∞) of original and modified with diethylenetriamine cotton cellulose with respect to Cu(II) and FE(II) ions. It was found that the A∞ of the modified sorbent was about 3 times higher than the ultimate sorption capacity of original cotton cellulose towards iron(II) and Cu(II) IONS. Comparison of IR spectra of the original cellulose samples and cellulose treated with diethylenetriamine indicates the changes that occurred during chemical modification. The paper presents SEM images showing the changes in the surface structure of the modified sorbent compared to the original one.

Research on the recycling of waste lithium battery electrode materials using ammonium sulfate roasting

Owing to resource limitations, environmental pollution concerns, and the increasing global demand for lithium-ion battery raw materials, the recycling of discarded electrode materials from lithium-ion batteries has emerged as a prominent research area. Nevertheless, among various types of discarded lithium battery electrode materials, limited research has been conducted on the recycling of ternary electrode materials (LiNixCoyMn1-x-yO2). This study proposes an eco-friendly process for the efficient recovery of valuable metals and carbon from mixed materials of discarded ternary lithium-ion battery electrodes. This study investigated the influence of various roasting using ammonium sulfate and leaching conditions on the conversion and extraction rates of valuable metals. Under the condition of a 3:1 mass ratio of ammonium sulfate to lithium battery electrode mixed material, roasting temperature of 450 °C, roasting time of 30 min, liquid-solid ratio of 20:1, leaching time of 20 min, and leaching temperature of 60 °C, the recovery rates of various valuable metals including Li, Ni, Co, and Mn reached 99.99%. For the above process, the chemical control reaction prevailed in the initial 10 min of the roasting reaction, succeeded by the dominance of diffusion control reaction in the subsequent 20 min. In the leaching process, the chemical control reaction governed the first 2 min, succeeded by diffusion control reaction for the next 18 min. Analysis of the reaction's macroscopic and microscopic mechanisms reveals that ammonium sulfate roasting of waste ternary lithium-ion batteries constitutes a typical liquid-solid reaction. In the molten state, NH4+ decomposition releases high-energy H+ ions that break the bonds between metals and oxygen. Consequently, metal atoms from the waste battery's crystal structure combine with ammonium sulfate's sulfate groups, forming various metal sulfates. This paper establishes an eco-friendly process for the efficient recovery of valuable metals by employing the ammonium sulfate roasting method to convert valuable metals in discarded electrode mixed materials into water-soluble sulfates.

Biogeochemical impact of historical submarine mine tailings on benthic ecosystems in the Repparfjord (Northern Norway)

Historical copper mine tailings deposited in the Repparfjord, Northern Norway, provided new insight into the biogeochemical impact of submarine tailings disposals on high-latitude coastal ecosystems. The submarine tailings disposal in the Repparfjord represents a product of mining activities between 1972 and 1979. Their environmental impact has been extensively studied during the last decade, but geochemistry of the sediment pore water, which is crucial to assess and monitor the in-situ metal leaching and bioavailability, has never been analysed. The actual impact on the benthic fauna remains poorly known. Therefore, this study couples the pore water chemistry and the foraminiferal analysis obtained from selected sediment cores (gravity core, multicore, box cores) to examine metal stability and the past and current status of the foraminifera community. We measured down-core sulfate and trace metal concentrations and Eh-Ph and applied the Shannon index, the AZTI's Marine Biotic Index (F-AMBI) index and the foraminiferal abnormality index. This study confirms the ongoing leaching of Cu from the underlying mine tailings and release across the sediment-water interface. Leaching of Ni, Zn and Pb have been attributed to weathering of natural bedrock lithologies. The original benthic foraminiferal community disappeared almost entirely during the disposal period, and now it is dominated by stress-tolerant and opportunistic species like Bulimina marginata and Spiroplectammina biformis. Anyhow, against previous assumptions, the community composition changed, while the overall diversity and abnormalities (FAI) shell formation is unaffected by elevated Cu concentrations.

New insight into the intrinsic effect of sulfur dioxide on Hg0 oxidation in the absence/presence of SCR atmosphere

Collaborative control of Hg0 in selective catalytic reduction (SCR) device is considered to be feasible and cost-effective, whereas the negative impact of SO2 remains a thorny issue for industrial applications. Herein, the intrinsic effect mechanism of SO2 on Hg0 oxidation in the absence/presence of SCR atmosphere over the hollow nanotube CoMnTiOx was systematically investigated. It was demonstrated that SO2 possessed a bidirectional effect on Hg0 oxidation, the facilitating effect was attributed to the production of HgSO4 and the inhibiting effect was due to the formation of metal sulfate, which was exactly equilibrated when the deposition of sulfate on the catalyst reached 3.88 %. Interestingly, the presence of SCR atmosphere enhanced the suppression of SO2 on Hg0 oxidation, which was caused by the fact that SO2 + O2 consumed partial Hg0 to form HgSO4, upsetting the reaction equilibrium of HgO reduction induced by SCR atmosphere and ultimately aggravating the reduction process of the already generated HgO. This work provides a new and comprehensive insight into the effect of SO2 on Hg0 oxidation during the synergistic removal of Hg0 in SCR device, which is instructive in exploring strategies to mitigate the SO2 poisoning.

Role of Cooling Temperature on Impurities Precipitation of Metal Sulfate Solution Derived from Crude Ferronickel Leaching Using MgO

Nickel is used as a raw material for Nickel Manganese Cobalt (NMC) batteries as a compound of Nickel Sulphate Hexahydrate (NiSO4.6H2O). This study used nickel laterite as ore. A hydrometallurgical process carries out Ferronickel to extract nickel concentrate. The first step is leaching using 2M H2SO4 solution for 6 hours with a stirring speed of 200 rpm at 90°C. The leached solution was then neutralized using a neutralizing agent MgO 5% w/w until it reached a pH of 3.5. The neutralized filtrate was then filtered to separate the filtrate and the residue. The neutralization process produces magnesium sulfate salt (MgSO4), which is an impurity. Next, the cooling temperature method is used to precipitate MgSO4 crystals. In this study, the variation of the MgSO4 cooling temperature used was -5, 0, and 5 °C. Subsequently, crystallization was carried out to produce NiSO4.6H2O. The highest nickel recovery (59.61%) can be achieved using a cooling temperature of -5 °C. Also, by using -5 °C of cooling temperature, the nickel content of crystal product is 2.75%. The crystallization product still contains other compounds, such as MgSO4, FeSO4, and CoSO4.

Obtaining of silicon dioxide from abrasive wastes

In the production of abrasive materials from metallurgical slags, fine waste with a size of less than 40 microns is produced, which contains valuable components. Unlike slag, this waste does not need to be pulverized for processing, which greatly simplifies the process. However, without silica extraction, it is impractical to carry out waste treatment. The authors of the work considered the possibility of obtaining silicon dioxide from abrasive wastes of Rezh, Orsk and Kyshtym, containing up to 20,7 % of silicon, up to 31,7 % of iron and up to 0,7 % of the sum of nickel and copper. Sulfuric acid treatment of waste produced a solution containing magnesium and iron (II) sulfates and silicic acid. It was found that during processing of Orsk wastes the degree of components extraction is significantly lower in comparison with Rezh and Kyshtym wastes 24,5, 67,8 and 59,3, respectively. The obtained solution is used to produce silica powders by dehydrating it. The dried mixture is subjected to aqueous washing of metal sulfates. As a result, samples with high specific surface area in the range of 387,6 to 841,5 m2/g were obtained. The average pore size is 2,3–3 nm, which allows us to attribute these silicas to mesoporous silica. SiO2 content in the samples reaches up to 98 %. Samples of silicon dioxide from abrasive materials were compared with that obtained from metallurgical slag of Pechenganickel Combine and have similar parameters. The obtained insoluble leaching residue contains concentrate of non-ferrous metals and according to X-ray data it consists of calcium sulfate, so after separation of non-ferrous metals it can be used in construction industry.

Multi-omics insights into biogeochemical responses to organic matter addition in an acidic pit lake: Implications for bioremediation

Acidic pit lakes (APLs) emerge as reservoirs of acid mine drainage in flooded open-pit mines, representing extreme ecosystems and environmental challenges worldwide. The bioremediation of these oligotrophic waters necessitates the addition of organic matter, but the biogeochemical response of APLs to exogenous organic matter remains inadequately comprehended. This study delves into the biogeochemical impacts and remediation effects of digestate-derived organic matter within an APL, employing a multi-omics approach encompassing geochemical analyses, amplicon and metagenome sequencing, and ultra-high resolution mass spectrometry. The results indicated that digestate addition first stimulated fungal proliferation, particularly Ascomycetes and Basidiomycetes, which generated organic acids through lignocellulosic hydrolysis and fermentation. These simple compounds further supported heterotrophic growth, including Acidiphilium, Acidithrix, and Clostridium, thereby facilitating nitrate, iron, and sulfate reduction linked with acidity consumption. Nutrients derived from digestate also promoted the macroscopic development of acidophilic algae. Notably, the increased sulfate reduction-related genes primarily originated from assimilatory metabolism, thus connecting sulfate decrease to organosulfur increase. Assimilatory and dissimilatory sulfate reduction collectively contributed to sulfate removal and metal fixation. These findings yield multi-omics insights into APL biogeochemical responses to organic matter addition, enhancing the understanding of carbon-centered biogeochemical cycling in extreme ecosystems and guiding organic amendment-based bioremediation in oligotrophic polluted environments.

Enhanced bioremediation of acid mine-influenced groundwater with micro-sized emulsified corn oil droplets (MOD) and sulfate-reducing bacteria (Desulfovibrio vulgaris) in a microcosm assay

High concentrations of metals and sulfates in acid mine drainage (AMD) are the cause of the severe environmental hazard that mining operations pose to the surrounding ecosystem. Little study has been conducted on the cost-effective biological process for treating high AMD. The current research investigated the potential of the proposed carbon source and sulfate reduction bacteria (SRB) culture in achieving the bioremediation of sulfate and heavy metals. This work uses individual and combinatorial bioaugmentation and bio-stimulation methods to bioremediate acid-mine-influenced groundwater in batch microcosm experiments. Bioaugmentation and bio-stimulation methods included pure culture SRB (Desulfovibrio vulgaris) and microsized oil droplet (MOD) by emulsifying corn oil. The research tested natural attenuation (T 1), bioaugmentation (T2), biostimulation (T3), and bioaugmentation plus biostimulation (T4) for AM-contaminated groundwater remediation. Bioaugmentation and bio-stimulation showed the greatest sulfate reduction (75.3%) and metal removal (95–99%). Due to carbon supply scarcity, T1 and T2 demonstrated 15.7% and 27.8% sulfate reduction activities. Acetate concentrations in T3 and T4 increased bacterial activity by providing carbon sources. Metal bio-precipitation was substantially linked with sulfate reduction and cell growth. SEM-EDS study of precipitates in T3 and T4 microcosm spectra indicated peaks for S, Cd, Mn, Cu, Zn, and Fe, indicating metal-sulfide association for metal removal precipitates. The MOD provided a constant carbon source for indigenous bacteria, while Desulfovibrio vulgaris increased biogenic sulfide synthesis for heavy metal removal.

Utilization of Tamarind Seeds Extract as a Natural and Sustainable Fabric Dye

This research focuses on the use of tannin components in tamarind seed coats as a mordant and natural dye in cotton fabrics. Tannins were extracted from the tamarind seed coat by boiling method and then the tannin content was determined. The tannin extract was then used as a natural mordant with the addition of metallic copper sulfate (CuSO4) mordant. Tannin extract is also used as a dye on fabrics with the addition of sodium sulfate (NaSO4). The color strength of the tannins in the fabric was analyzed using a spectrophotometer from the rinse water. The results showed that the cloth that had been given the mordant had a stronger color strength than the cloth without the mordant. The use of mordant was varied at concentrations of 5, 10, 15, 20, and 25%-owf. The results of the analysis showed the most optimum tannin concentration at 15%-owf. The concentration of tannin used in the coloring process was also varied at concentrations of 5, 10, 15, 20, and 25%-owf. The results of the analysis show that the concentration of tannin used in the dye does not affect the strength of the color, but only affects the brightness of this color.