Aluminum Sulfate Research Articles

Effect of aluminium sulfate on carbothermal reduction of phosphorite in a fluidized bed

Aluminium sulfate was combined with the raw material pretreatment in a fluidized-bed reactor to reduce the phosphorite by coal, so as to improve the separation of P2 from phosphorite. The optimum reaction conditions for phosphorite reduction in a fluidized bed is found to be 1523 K, 40 min, Si/Ca mole ratio of 2, carbon excess coefficient of 1.6, and nitrogen flow of 0.11 m⋅s−1. Sensitivity analysis reveals that the five influencing factors on the conversion ratio of phosphorite, in descending order of importance, are the reaction temperature, the nitrogen flow, the reaction time, and the excess of carbon and the mole ratio of Si/Ca. The influence of adding aluminium sulfate on the reaction system and pretreating the raw material was investigated. The results show that by speeding up defluorination while decreasing the activation energy, adding aluminium sulfate and pretreatment could improve the conversion ratio of phosphorite by about 10 %.

Preparation of complex titanium-containing coagulants from large-scale mineral concentrates and their use in wastewater treatment

Relevance. Development of new, highly effective reagents for treatment of wastewater of various origins is a complex and extremely important task. An equally pressing issue remains the development of technologies for processing large-scale mineral products, which currently have not found an economically feasible technology for their processing and have received the status of “waste”. The development of a technology for producing reagents using waste as a raw material will not only have an economic effect but will also significantly minimize the level of negative impact on the environment and take a step towards the implementation of the Zero Waste concept. Aim. Development of technology for processing large-scale titanium-containing raw materials to obtain complex titanium-containing reagents and study of their effectiveness in wastewater treatment from various industries. Methods. To study the phase composition of the samples, the X-ray diffraction method was used, and the determination of metal content in acidic solutions and wastewater was carried out by atomic emission spectroscopy. Results and conclusions. The authors have proposed the technology for production of complex titanium-containing coagulants, which includes hydrometallurgical technology for sulfuric acid processing of large-capacity mineral raw materials – titanite. Aluminum hydroxide was introduced into the resulting solutions to adjust the chemical composition and neutralize free sulfuric acid. The resulting aluminum sulfate transforms into the most stable form of 18-aqueous crystalline hydrate, absorbing moisture from the solution, realizing chemical dehydration. The study of the composition of solid samples of coagulants showed that the predominant phase in the composition of the complex coagulant is aluminum sulfate, and the content of titanium compounds ranges from 1 to 14 wt %. It was established that by varying the ratio of mineral raw materials:sulfuric acid it is possible to vary the amount of modifying additive titanium compounds in the complex reagent. It was proven that the use of complex titanium-containing coagulants in wastewater treatment allows reducing the consumption of coagulants by 25–35%, increasing the efficiency of water purification, minimizing residual concentrations of pollutants, and also significantly increasing the rate of sedimentation of coagulation sludge in comparison with traditional sulfate aluminum.

Experimental and statistical models moisture release of the mixture treated with reagents raw sludge and compacted active sludge

The technology of changing the resistivity of a mixture of raw sludge and compacted activated sludge taken after the sludge pumping station of urban sewage treatment plants by treating the sludge with aluminum sulfate and polyacrylamide (PAA) in doses from 0 to 300 mg/dm3 has been tested. The degree of influence of each reagent on the process of dehydration of the sediment under study has been established. It has been shown that PAA has about 2.0 times greater effect on the process of moisture loss than Al2(SO4)3 at reagent doses from 0 to 200 mg/dm3 and about 1.5 times – at doses from 100 to 300 mg/dm3. Mathematical models of the dependence of the change in the resistivity of the sediment on the amount of Al2(SO4)3 and PAA introduced into it are obtained. Mathematical models are also presented in graphical form (isolines). The optimal doses of coagulant and flocculant for chemical treatment of the studied sewage sludge were determined.

Study of the Effect of the Surfactant Linear Alkylbenzene Sulfonate (LAS) on the Coagulation of Aged Microplastic

Objective: Evaluate the effect of linear alkylbenzene sulfonate (LAS) surfactant on the coagulation of aged microplastic. Theoretical Framework: Chemical coagulation is one of the steps adopted in water treatment that can help remove microplastics. During coagulation, suspended particles agglomerate, increasing the efficiency of removing these particles in the sedimentation stage. However, when coagulation occurs in the presence of surfactants, evidence points to deficits in removal capacity. Method: Using Jar Test tests, the optimal parameters for microplastic removal were determined with aluminum sulfate as a coagulating agent in the presence and absence of the surfactant linear alkyl benzene sulfonate (LAS). The LAS concentrations studied were in the range of 20 mg/L to 300 mg/L. Microplastic removal efficiency was evaluated by measuring turbidity. Results and Discussions: The combination of pH and coagulant concentration values that best suited the system were 5.0 and 4.25 mg/L, respectively. Due to the addition of surfactants, a decrease in removal efficiency was observed, with an average value ranging from 94.79% to 76.50% due to the interaction of polyethylene spheres with the surfactant. Research Implications: As explained, due to the coexistence of microplastics and surfactants in the aqueous environment, studies that describe chemical coagulation under these conditions have great value for optimizing treatment systems and technologies. Research Originality/Value: The use of aged microplastics aims to approximate their natural occurrence.

Effect of Sempervivum tectorum Extract on Some Biomarkers of Reproductive Function and Levels of Some Trace Elements in Male Rats Exposed to Aluminum.

Aluminum, a contentious trace element found in the environment, has been demonstrated to have harmful effects on both humans and animals. In contrast, Sempervivum tectorum, an evergreen plant, has been found to offer numerous beneficial effects for both humans and animals. Therefore, this study aims to assess the protective effect of S. tectorum on certain reproductive biomarkers in male rats exposed to aluminum. Thirty-five Wistar rats were randomly divided into five groups: NTC (no-treatment control) received distilled water; NC (negative control) received drinking water containing 1 mg/L aluminum sulfate (AS); E1 received 1 mg/L AS along with an 8% S. tectorum extract; PC (positive control) received only 8% S. tectorum extract; E2 received 1 mg/L AS for three months followed by 8% extract for one month. The study analyzed testosterone, LH, FSH, body weight, and the histological structure of the testis, epididymis, and prostate, as well as the levels of zinc, manganese, copper, and iron in these organs. Significant decreases in body weight, testis, and epididymis size were observed in the aluminum-exposed groups compared to the control, whereas these decreases were not significant in the S. tectorum-treated groups compared to the control. Aluminum exposure led to significant decreases in testosterone and LH levels, with FSH levels showing a nonsignificant decrease in males, which were mitigated significantly by the administration of the plant extract. Histological analysis revealed alterations in the testis, epididymis, and prostate of the AS-exposed groups, including necrosis of seminiferous tubule epithelium and Leydig cells in the testis, and basal epithelial necrosis in the epididymis and prostate. Aluminum levels increased in all organs studied, while levels of zinc, copper, iron, and manganese decreased, showing a negative and significant correlation with aluminum levels. The aqueous extract of S. tectorum demonstrated a protective effect on certain studied biomarkers in male rats affected by aluminum exposure.

Development of toxic gas sensor from anthocyanin-embedded polycaprolactone-co-polylactic acid nanofibrous mat

The colorless ammonia gas has been a significant intermediate in the industrial sector. However, prolonged exposure to ammonia causes harmful effects to organs or even death. Herein, an environmentally friendly solid-state ammonia sensor was developed utilizing colorimetric polycaprolactone-co-polylactic acid nanofibrous membrane. Pomegranate (Punica granatum L.) peel contains anthocyanin (ACN) as a naturally occurring spectroscopic probe. A mordant (potassium aluminum sulfate) is used to immobilize the anthocyanin direct dyestuff inside nanofibers, generating mordant/anthocyanin (M/ACN) coordinated complex nanoparticles. When exposed to ammonia, the color change of anthocyanin-encapsulated polycaprolactone-co-polylactic acid nanofibrous membrane from purple to transparent was examined by absorbance spectra and CIE Lab color parameters. With a quick colorimetric shift, the polycaprolactone-co-polylactic acid fabric exhibits a detection limit of 5–150 mg/L. The absorbance spectra showed a hypsochromic shift when exposed to ammonia, displaying an absorption shift from 559 nm to 391 nm with an isosbestic point of 448 nm. Scanning electron microscopy (SEM) images revealed that the polycaprolactone-co-polylactic acid nanofibers had a diameter of 75–125 nm, whereas transmission electron microscopy (TEM) images revealed that M/ACN nanoparticles exhibited diameters of 10–20 nm.

Fractal Characteristics and Microstructure of Coal with Impact of Starch-Polymerized Aluminum Sulfate Fracturing Fluids

The degree of irregularity and complexity of the pore structure are comprehensively reflected in the fractal dimension. The porosity of coal was determined by its fractal dimension, where a larger dimension indicates a lower porosity. Fractal theory and the Frenkel–Halsey–Hill (FHH) model were applied to explore the variation rules of concentration on functional groups and pore structure in this study. Combined with infrared spectroscopy (FTIR) and low-temperature nitrogen adsorption, a starch-polymerized aluminum sulfate composite fracturing fluid was prepared, which plays an important role in methane adsorption and permeability of coal samples. The test results showed that, compared with the original coal, the pore volume and specific surface area of each group of coal samples were reduced, the average pore diameter was initially enlarged and then declined, and fractal dimension D1 dropped by 5.4% to 15.4%, while fractal dimension D2 gained 1.2% to 7.9%. Moreover, the nitrogen adsorption of each group of coal samples was obviously lower than the original coal, and the concentration of starch-polymerized aluminum sulfate solution existed at a critical optimal concentration for the modification of the coal samples, and the nitrogen adsorption reached a minimum value of 0.6814 cm3/g at a concentration of 10%. The novel composite solution prepared by the combination of starch and flocculant in this paper enhanced the permeability of the coal seam, which is of great significance in improving the efficiency of coalbed methane mining.

Adsorption of methyl blue, dichromate, and copper on ettringite under various pH values

Ettringite is a hydrous calcium aluminum sulfate mineral present in cement. In this study, ettringite was synthesized via co-precipitation to remove methyl blue, dichromate, and copper ions from solutions with various pH values. The synthesized ettringite was characterized using scanning electron microscopy, X-ray photoelectron spectrometry, Fourier transform infrared spectroscopy, zeta potential analysis, and the Brunauer–Emmett–Teller method. Equilibrium adsorption experiments were performed using methyl blue and dichromate at pH values ranging from 5 to 11. To avoid precipitation, equilibrium adsorption experiments were performed on copper ions in solutions with pH values of 3, 4, and 5. The adsorption kinetics experiments for each contaminant were performed at pH 5. The results showed that ettringite was successfully synthesized, and calcite might have precipitated during the synthesis process. The point of zero charge was at pH 8.6. The maximum adsorption capacities for methyl blue, dichromate, and copper ions at pH 5 were 406, 321, and 365 mg/g, respectively. The adsorption kinetics fitted the pseudo-second-order model well. The properties of the contaminants affect their equilibrium and rate constants. Ion exchange is regarded as the primary adsorption mechanism, whereas the other mechanisms include complexation, hydrogen bonding, surface precipitation, π-interaction, and van der Waals forces. This study revealed a new adsorbent, ettringite, for the removal of contaminants from wastewater, which is a promising alternative adsorbent that can be used under specific conditions.

Remediation of sediments contaminated by harmful heavy metals using aluminum sulfate: Sustainable approach for practical applications

Chemical washing could be suitable for the remediation of marine sediments contaminated with harmful heavy metals. Considering green and sustainable remediation (GSR), the application of aluminum sulfate (AS) is intended to reduce the costs and environmental impacts. We extracted harmful heavy metals from manganese nodules using an ion exchange mechanism that occurs when AS dissociates in water. AS in the range from 2 % to 5 % was used. The remediation efficiencies using 5 % AS were found to be the highest, at 91.8 % for Ni and ≥ 100 % for other harmful heavy metals. The Pearson's coefficient evaluation showed that increasing elapsed time did not significantly affect the extraction of harmful heavy metals. Pollutants in post-processing products may not cause secondary pollutions if solidification/stabilization and additional treatments are used. Our results can serve as fundamental data for the actual remediation processes using AS not only for deep-sea mining tailings but also contaminated marine sediments.

Preparation and thermal conductivity enhancement of binary non-eutectic phase change materials based on alum-urea for solar heat storage system

Heat accumulators using latent heat storage are commonly used in solar energy storage systems. Potassium aluminum sulfate dodecahydrate (Alum) is an inexpensive phase change material, but the high phase change temperature limits its application in heat accumulator. To address this limitation is controlling the melting temperature of Alum. In this study, Alum-urea mixtures were first developed by adding 10 wt% urea. Modified phase change materials (MPCM) without phase separation and supercooling were developed by adding NiSO4·6H2O and xanthan gum to the Alum-urea mixture. Composite phase change materials (CPCM) with high thermal conductivity were developed by loading MPCM in expanded graphite. The melting temperature of the Alum-urea mixture was 72.52 °C with 10 wt% urea content, which was 21.4% lower compared to the Alum. The MPCM still has a high phase change enthalpy (157.7 J·g−1) and ignorable subcooling degree (0.8 °C). The thermal conductivity of CPCM is increased by 16 times, and it has good photothermal conversion ability. The CPCM holds significant promise for applications in latent heat energy storage.

Treatment of olive mill wastewater by coagulation–flocculation with aluminum sulphate / aluminum polyhydroxichlorosulfate and effect on phytotoxicity

In the present study, coagulation floculation was examined using two different coagulants: aluminum sulphate (Al2(SO4)3) which is widely used on an industrial scale for olive mill wastewater (OMW) treatment, and polyhydroxichlorosulfate aluminum (Aln OHm Cl3n-m-2k (SO4)k) popularly known as WAC. The coagulant WAC is already used in the treatment and purification of water, but it has never been tested for the treatment of OMW. The phytotoxicity study of OMW (before and after treatment) to wheat seeds showed that the toxic compounds of this effluent affect both the seed germination and the seedling growth. The root length was more sensitive to OMW than the shoot length. However, the toxicity of this effluent has been greatly reduced after treatment with WAC (growth was inhibited at concentration of 80 %) compared to another OMW treated with aluminum sulfate. The highest percentages of germination have been observed in the seeds irrigated by OMW treated with WAC. This study also showed that the phytotoxicity decreased with dilution (5–40 % for raw OMW, 5–50 % for OMW treated with aluminum sulfate, and 5–60 % for OMW treated with WAC). Finally, the experimental results obtained show that the dilution and the treatment by the WAC coagulant (2.50 g; pH between 6.50 and 7.50) are two important processes to reduce the phytotoxicity effect of OMW.

Comparing the effects of Al-based coagulants in waste activated sludge anaerobic digestion: Methane yield, kinetics and sludge implications

Due to its effectiveness and ease of application, the process of flocculation and coagulation is often used for pollution removal in wastewater treatment. Most of these coagulants precipitate and accumulate in waste activated sludge (WAS), and could negatively affect sludge treatments, as observed for anaerobic digestion. Nowadays, wastewater treatment plants (WWTPs) are widely discussed because of the current paradigm shift from linear to circular economy, and the treatments performed at the facility should be planned to avoid or reduce adverse effects on other processes. The aim of this study was to compare the impact of poly aluminum chloride (PAC) and aluminum sulfate (AS) on WAS anaerobic digestion, by feeding replicate serum reactors with different levels of coagulant (5, 10 and 20 mg Al/g TS). Reactors without the addition of any coagulants represented the control group. Results revealed that Al-based coagulants inhibited methane production, which decreased as the coagulant addition increased. The inhibition was much more severe in AS-conditioned reactors, showing average reductions in methane yield from 14.4 to 31.7%, compared to the control (167.76 ± 1.88 mL CH4/g VS). Analytical analysis, FTIR and SEM investigations revealed that the addition of coagulants affected the initial conditions of the anaerobic reactors, penalizing the solubilization, hydrolysis and acidogenesis phases. Furthermore, the massive formation of H2S in AS-conditioned reactors played a key role in the suppression of methane phase. On the other hand, the use of coagulant can promote the accumulation and recovery of nutrient in WAS, especially in terms of phosphorus. Our findings will expand research knowledge in this field and guide stakeholders in the choice of coagulants at full scale plant. Future research should focus on reducing the effect of coagulants on methane production by modifying or testing new types of flocculants.

Effect of Annealing Temperature on the Structural Properties of Dual Solution Synthesized AlS: ZnS Thin Films

Using two solution-based techniques—solution growth technique (SGT) and sequential ionic layer adsorption and reaction (SILAR) AlS: ZnS alloyed thin films were successfully produced on glass substrates. The sources of Al, Zn, and S were aluminum sulphate (AlSO4.7H20), zinc sulphaate (ZnSO4.7H20), and sodium thiosulphate (Na2S2S03). The complexing agent that was utilized was ethylene diamine tetraacetic acid (EDTA). Using a Master Chef Annealing Machine, the deposited alloyed samples were annealed between 373K and 523K. The scanning electron microscope (SEM) and X-ray diffractometer (XRD) were used for the crystallographic investigations. Samples R1 and R6 AlS: ZnS alloyed thin films exhibit well-defined peaks in their XRD pattern, indicating that they are polycrystalline in nature. We computed their grain sizes. Spectroscopy using Rutherford backscattering (RBS). Analysis using Rutherford backscattering spectroscopy (RBS) verified the composition of aluminum, zinc, and sulfur in the alloyed thin films. The microstructure of the deposited alloyed thin films is revealed by the results of surface electron microscopy. Two significant semiconductor materials that have potential uses in optoelectronics, photovoltaics, and sensing devices are aluminum sulfide (AlS) and zinc sulfide (ZnS). Depositing these materials in thin films at a reasonable cost and with good efficiency is possible with dual solution synthesis. However, the annealing temperature, a crucial factor in establishing the crystal structure, morphology, and optical properties of these films, can have an impact on their structural characteristics. Prior studies have examined how the annealing temperature affects the structural characteristics of AlS and ZnS thin films separately; however, the dual solution-produced AlS: ZnS thin films have not received as much attention. The purpose of this work is to examine how the annealing temperature affects the crystal structure and surface morphology of AlS: ZnS thin films. The results of this investigation can offer significant understanding regarding the refinement of the annealing temperature to produce superior AlS: ZnS thin films for a range of uses. Based on their properties, sulphide alloyed thin films could find applications in microelectronics, window coating, and antireflection coating. They work well as coatings for eyeglasses and as absorber layers for photocells, among other applications.

Evaluation of Anticoagulant Effect of Alum in Rats

Potassium aluminium sulfate, KAl(SO4)2, also called Alum, is an acidic white chemical substance. The role of alum in bleeding and clotting is not fully understood. Objective: To determine the effects of alum on clotting time, D-dimer levels, fasting blood glucose level, and lipid profile. Methods: The study was conducted on 24 male Wistar rats, which were randomly divided into six groups. Four groups were given different concentrations of alum solutions. The remaining two groups received warfarin, and distilled water, which are control, and placebo groups, respectively. Blood tests such as fasting blood sugar (FBS), D-dimers, clotting time, and lipid profile were performed. Results: The study found that the administration of alum prolonged the time it took for blood to coagulate. Alum showed a dose dependent increase in clotting time when compared to the warfarin-control group and group 4 (100 mg/kg alum dose) showed the most significant effect. Similarly, in the case of D-dimers, a dose dependent decrease in the level of D-dimers was seen and the most significant effect was found for high concentration. The plasma blood glucose and lipid level of animals treated with alum did not show any significant effect as compared to placebo. Conclusions: The efficacy of alum as an anticoagulant drug was investigated, and it was found to significantly prolong clotting time while simultaneously reducing the level of D-dimers. Furthermore, it was deemed safe and showed no effects on fasting plasma glucose and lipid profile. The safety profile of alum was assessed to be favorable, thus highlighting its potential as an anticoagulant drug of the future

Life Cycle Assessment of a Vegetable Tannin-Based Agent Production for Waters Treatment

The scarcity of natural resources makes it essential to develop products that meet environmental requirements. This is also true for the water and wastewater treatment business, where even consolidated processes, such as coagulation and flocculation, must be improved, opening opportunities for searching for alternative options to conventional processes. Among the existing options, tannin-based agents (TBAs) have been highlighted in recent years due to their biodegradability and proven efficiency. However, little is known about the impacts of the production process of these agents on an operational/industrial scale. In this study, an examination of the environmental impacts of the full-scale production (more than 500 tons yearly) of a TBA from Acacia spp. (known as black acacia or mimosa) was carried out. To accomplish this, a life cycle assessment (LCA) was developed using openLCA version 2.0.0 to assess a cradle-to-gate system of 1 kg of packed TBA produced. Additionally, a comparison was made between the impacts of the production of TBA and a conventional water treatment agent, aluminum sulfate, to verify the benefits of producing the former. The most relevant impacts resulting from the production of 1 kg of TBA are observed in the following categories: global warming (1.52 kgCO2-eq); terrestrial (7.67 kg1.4-DCB-eq), freshwater (0.06 kg1.4-DCB-eq), and marine (0.08 kg1.4-DCB-eq) ecotoxicities; carcinogenic (0.10 kg1.4-DCB-eq) and non-carcinogenic (1.36 kg1.4-DCB-eq) human toxicities; and water use (0.02 m3). The main contributors to the impacts were the chemicals ammonium chloride and formaldehyde used, the transport of inputs, and the energy used. The aluminum sulfate showed better performance than the TBA for a greater number of categories; however, the normalization of the impacts showed the TBA as a very interesting option. The results obtained here can be used by TBA producers to act on the most impactful categories so that the production process becomes increasingly sustainable.

Utilisation of Waste Sludge from Drinking Water Treatment as a Filler Material in Hot Mix Asphalt.

This research investigated the suitability of using sludge from the treatment of drinking water in hot mix asphalt (HMA) as a filler material. The storage and environmental impact of sludge is an enormous problem, especially for countries with large populations. Two different types of sludges, ferric chloride (FC) and aluminium sulphate (AS), were used as a filler material in HMA. The Hamburg Wheel Tracking (HWT) test, which correlates with rutting, and the Indirect Tensile Strength (ITS) test, which indicates the moisture sensitivity of HMA, were carried out at the optimum bitumen content of the mixes to investigate the usability of sludge in HMA. The test results indicate the usability of FC and AS in HMA compared to the reference mixes. However, the AS type of sludge has better rutting resistance than the FC type. Although the results support the usability of both sludges in HMA, it should be noted that the increased cost of the mix containing sludges due to the combustion process and the increased bitumen content during application should be considered.

Organic-inorganic core-shell materials as reinforced fillers of UHMWPE to improve its tribological and mechanical properties

Generally, modification of materials by adding multiple types of nano particles could cause dispersion problems, generally limited the performance improvement effect. Herein, we report the modification of UHMWPE materials by organic-inorganic core-shell particles with PTFE as the core and Al(OH)3 as the shell, which prepared by in-situ polymerization of sodium bicarbonate and aluminum sulfate solution. Core-shell particles were filled in UHMWPE matrix and sintered into composite by spark plasma sintering (SPS). The mechanical and tribological properties of the composites were characterized by tensile compression testing machine, universal micro tribometer (UMT-5), three-dimensional white light interferometer and scanning electron microscope (SEM). The results showed that the addition of core-shell structural materials effectively improved the tribological properties (friction coefficient decreased by 40%, wear rate decreased by 30%) and mechanical properties (compression strength increased by 2.4 times) of the composites. It was demonstrated that the inorganic framework provided strength to improve the mechanical properties and wear resistance of materials, and the organic phase was used as a lubricating phase to reduce the friction coefficient of materials. Surface treatment of core-shell particles both improved the binding between particles and matrix and decreased the formation of agglomerations, thus significantly reducing ploughing phenomena’s effect produced by abrasive wear of agglomeration

Recovery of aluminum oxide and iron oxide from aluminum electrolysis iron-rich cover material and preparation of aluminum fluoride.

In aluminum electrolysis, the iron-rich cover material is formed on the cover material and the steel rod connecting the carbon anode. Due to the high iron content in the iron-rich cover material, it differs from traditional cover material and thus requires harmless recycling and treatment. A process was proposed and used in this study to recovery F, Al, and Fe elements from the iron-rich cover material. This process involved aluminum sulfate solution leaching for fluorine recovery and alkali-acid synergistic leaching for α-Al2O3 and Fe2O3 recovery were obtained. The optimal leaching rates for F, Na, Ca, Fe, and Si were 93.92, 96.25, 94.53, 4.48, and 28.87%, respectively. The leaching solution and leaching residue were obtained. The leaching solution was neutralized to obtain the aluminum hydroxide fluoride hydrate (AHFH, AlF1.5(OH)1.5·(H2O)0.375). AHFH was calcined to form a mixture of AlF3 and Al2O3 with a purity of 96.14%. The overall recovery rate of F in the entire process was 92.36%. Additionally, the leaching residue was sequentially leached with alkali and acid to obtain the acid leach residue α-Al2O3. The pH of the acid-leached solution was adjusted to produce a black-brown precipitate, which was converted to Fe2O3 under a high-temperature calcination, and the recovery rate of Fe in the whole process was 94.54%. Therefore, this study provides a new method for recovering F, Al, and Fe in iron-rich cover material, enabling the utilization of aluminum hazardous waste sources.

Development of green and sustainable ammonia sensor from xanthohumol extract-immobilized polylactic acid nanofibers

Ammonia is a significant industrial gaseous agent that is colorless. However, long exposure to ammonia gas can cause organ damages or even death. This study describes the preparation of a solid-state vapochromic sensor for gaseous and aqueous ammonia using eco-friendly smart colorimetric polylactic acid nanofibers. Xanthohumol (XMOL) is a natural spectroscopic probe that can be found in the common hop (Humulus lupulus L.) plant. Nanoparticles of mordant/xanthohumol (M/XMOL) coordinated complex were synthesized by immobilizing the xanthohumol direct dyestuff into polylactic acid nanofibers in the presence of a mordant (potassium aluminum sulfate). Xanthohumol can be described as an appropriate sensor for gaseous and aqueous ammonia due to its tiny molecular size and high water-solubility. Both of CIE Lab color parameters and absorbance spectra were used to inspect the color shift of the xanthohumol-finished polylactic acid nanofibers from yellow to colorless upon exposure to ammonia. This could be attributed to the intramolecular charge transfer caused by molecular switching of xanthohumol. In a fraction of second, the polylactic acid nanofibrous fabric showed a colorimetric change with a detection limit of 10–450 mg/L. The absorption spectra of the xanthohumol probe exhibited hypsochromic shift with a wavelength change from 465 nm to 315 nm (isosbestic point of 370 nm) in response to an aqueous solution of ammonia. Transmission electron microscopic (TEM) images showed that M/XMOL particles were 13–27 nm in diameter, whereas scanning electron microscopic (TEM) images demonstrated that the polylactic acid nanofibers were 150–450 nm in diameter. We observed no significant differences in air-permeability and bending-length of the nanofibrous fabric after immobilization of M/XMOL into polylactic acid nanofibers. In addition, the colorfastness properties of the treated polylactic acid nanofibers were investigated.

Mechanistic Study of the Influence of Reactant Type and Addition Sequence on the Microscopic Morphology of α-Al2O3

To perform an in-depth study of the crystal growth habits and phase changes of alumina and its precursors in reaction systems, this paper studied the effects of reactant type and addition order on the morphology of alumina using hydrothermal methods with different precipitants and aluminum sources as reactants. Research has shown that sodium bicarbonate and ammonium bicarbonate can be used as precipitants to prepare adhered spherical alumina and irregular short rod alumina, while potassium bicarbonate can be used as a precipitant to prepare hexagonal flake alumina. Using aluminum sulfate octahydrate, aluminum chloride hexahydrate, and aluminum nitrate, nine hydrates were prepared as aluminum sources, and agglomerated alumina, irregular short rod-shaped alumina, and fused alumina were obtained. The order of reactant addition affects the precursor phase of alumina, thereby affecting the microstructure of alumina after calcination, resulting in flake alumina with pores and short rod alumina. The results of this paper will provide theoretical guidance for the preparation of alumina with different micromorphologies.