Alkali Fusion Method Research Articles

Effect of Temperature on Zirconia Powder Synthesized from Amang Zirconium Oxychloride Precursor

Polymorphic zirconia is economically attractive in various applications due to its low reactivity, high strength, and stability. Zirconia can be synthesized from locally available Amang zircon sand as an inexpensive green alternative as it has a high zirconium content as reported by previous report. Unfortunately, the study was only focused on the formation of zirconium oxychloride despite of high zirconium content from the improved alkali fusion method proposed. Therefore, a further study on zirconia powder calcined in varied temperatures from Amang zirconium oxychloride precursor was done. Amang zirconia powder was then characterized in order to study the effect of temperature on Amang zirconia powder. Elemental analysis showed that zirconium composition was affected by temperature and increased as the temperature increased with the highest zirconium content of 81.28 wt.% with low impurities after calcined at 800 °C for 4 hours. The phase analysis satisfied monoclinic zirconia with minor tetragonal and cubic phase with sharper peaks as calcined temperature increased. Increased tetragonal and cubic phase was observed as the temperature was increased. Morphology analysis showed zirconia powder was angular and pyramidal with large crystal size which led to high tendency of monoclinic phase. Calcination temperature of 800 °C was determined to be the most suitable temperature to calcine high purity zirconia powder using Amang zirconium oxychloride precursor.

The effects of calcination heating rate on phase formation and structure of zircon sand-derived zirconia

Abstract Phase formation and structure examination has been conducted to study the effects of thermal treatment and heating rates on zircon (ZrSiO4) sand-derived zirconia (ZrO2). A preliminary investigation of the elements present in the sand using XRF revealed that Zr was the major element, corresponding to 92.4% of the sample. The zirconia precursor was synthesized through a three-stage process that involves purifying zircon powder, alkali fusion, and co-precipitation method. The zirconia crystal was obtained by heating the sample to 700, 800 and 900 °C with heating rates of 5 and 10 °C/min, respectively. The formation of tetragonal zirconia (t-ZrO2) with space group P42/nmc is shown in a qualitative study of all sample XRD patterns. Furthermore, Rietveld analysis was used to determine crystal structure parameters including lattice parameters and tetragonality. The calcination temperature and heating rate decide the phase, t-ZrO2 crystallite size, and tetragonality. Furthermore, calcining to 700 and 800 °C created t-ZrO2, however, elevated temperature to 900 °C lead to t→m transformation. The t-ZrO2 size increases with temperature between 700 and 900 °C, range of 9 and 15 nm. Meanwhile, the tetragonality of t-ZrO2 tends to decrease due to m-ZrO2 being present.

CO2 adsorption by coal fly ash zeolite and modified zeolite-templated carbon

Coal fly ash (CFA), as the main by-product of coal-fired power plants, has a high content of silica-aluminium elements that can be used to prepare zeolite by the alkali fusion method with sound CO2 adsorption capacity. Among the four effect factors of Si/Al, NaOH/CFA, H2O/AFP(alkali fusion product), and crystallisation time, NaOH/CFA had the greatest effect on the CO2 adsorption performance of coal fly ash zeolite (CFAZ), followed by Si/Al and H2O/AFP, and crystallisation time had the least effect. The CO2 adsorption performance of the samples was tested and analysed using the thermal analysis method, the CO2 adsorption amount of CFAZ reached 4.23 mmol g–1 (30 °C, 101 kPa). In addition, the CFAZ and the zeolite-templated carbon (ZTC) adsorption performance is poor at high temperatures. The co-precipitation method modification of CFAZ and ZTC can produce layered double hydroxide derived material, which can adsorb CO2 at high temperatures reached at 3.35 mmol/g (650 °C, 101 kPa). Moreover, ZTC modified with polydivinylbenzene as the hydrophobic material has a sound CO2 adsorption effect in high-humidity environments. Thus, different adsorbents also could be produced using CFA to capture CO2 with a wide temperature range between 25 and 650 °C.

Physicochemical Characterization of Zeolite Materials Produced from Selected Low-Cost Agricultural Wastes

Zeolites play a crucial role in adsorption processes for eliminating pollutants from industrial effluents and are extensively utilized in catalytic activities across diverse syntheses. This study focused on the conversion of three agricultural wastes—corncob, groundnut shell, and sugarcane bagasse—into zeolitic materials through three analytical methods: hydrothermal, microwave sintering, and alkali fusion, respectively. Standard methods were employed to assess the physicochemical parameters of the resulting zeolites. Generally, the produced zeolites had excellent surface areas and porosities. However, zeolites synthesized from sugarcane bagasse via the alkali fusion method exhibited highest porosity (80.9%), whereas that derived from corncob demonstrated highest surface area (1335 m2/g). Point of zero charge for the produced zeolites was within the range of 7.9-9.8, with zeolite produced from groundnut shells via alkali fusion having the highest value (9.8). The elevated porosities and surface areas, and point of zero charge of the synthesized zeolites signify their enhanced adsorptive capacity, implying their suitability for application as adsorbents for the removal of organic and inorganic pollutants. These findings underscore the effectiveness of synthesized zeolites in reducing or completely removing pollutants such as phenols, dyes, pesticides, heavy metals, and inorganic anions from wastewater.

Preparation of one-part geopolymers using coal gasification slag: Effect of alkali fusion product additive and liquid/solid ratio

In this work, one-part geopolymers were synthesized through the alkali fusion and component additive method (AFCAM), utilizing coal gasification slag as the primary raw material. The investigation delved into the influence of varying fusion product contents and liquid/solid (L/S) ratios on the geopolymer properties. The experimental results demonstrated a non-linear correlation between the increase in fusion product content and the compressive strength of geopolymers, revealing an initial ascent followed by a subsequent decline. Additionally, a lower L/S ratio of 0.3 was observed to enhance compressive strength compared to the L/S ratio of 0.4. Notably, the optimal combination of an L/S ratio of 0.3 and a fusion product percentage of 30 % resulted in a remarkable compressive strength of 25.2 MPa. The comprehensive strength analysis suggested that an adequate amount of fusion product enhances the geopolymerization reaction, evidenced by the transformation of aluminum coordination states. Specifically, the conversion of five-coordinated and six-coordinated aluminum in slag to four-coordinated aluminum in geopolymers was observed. Concurrently, increased silicon and aluminum reactivity led to the formation of a robust Q4(4Al) network in the geopolymer gel. The impact of L/S ratios was attributed to the accelerated dissolution and hydrolysis of aluminosilicates at an elevated L/S ratio of 0.4, hindering polycondensation. These outcomes underscore the pivotal role of fusion product content and L/S ratio in governing the strength development of one-part geopolymers.

Sintesis dan Karakterisasi Nanosilika dari Limbah Silica Scaling PLTP Dieng Melalui Metode Alkali Fusion NaOH

Silica scaling is the main problem that arises in the operation of geothermal power plants (PLTP) in Dieng. Silica scaling can disrupt electricity production and cause a buildup of waste in the environment. Silica scaling has a high silica (SiO2) content so it has the potential to be used as a value-added material, namely nanosilica. One method to obtain nanosilica is alkali fusion. This research aims to obtain nanosilica from silica scaling waste from PLTP Dieng using the alkali fusion method as well as knowing the characteristics of the nanosilica produced. The alkali fusion process is carried out using NaOH as an alkali source. Then mixing silica scaling powder and NaOH at varying temperatures of 600°C, 650°C and 700°C to produce nanosilica. The resulting nanosilica was then characterized to confirm the success of the synthesis process in producing nanosilica particles. The characterization carried out included x-ray diffraction (XRD) to characterize crystallinity, Fourier transform infrared (FTIR) to characterize functional groups, transmission electron microscope (TEM) and particle size analyzer (PSA) to determine particle size. The results of this research showed that amorphous nanosilica was successfully synthesized from silica scaling using the NaOH alkali fusion method. It was found from the results of TEM and PSA characterization that the smallest particle size was produced at a fusion temperature of 650°C. Furthermore, FTIR data also confirms the existence of functional groups at wave numbers identical to silica.

Analisis Ukuran Partikel Nanosilica Pada Proses Alkali Fusion Silica Scaling Geotermal Dieng Menggunakan KOH

One of the characteristics of the Dieng geothermal field is the high silica content in the production fluid which causes the appearance of silica scaling. The presence of silica scaling inhibits the energy extraction process and becomes waste that disturbs the environment. The silica scaling can be utilized as a nanosilica product for use as a reinforcing filler. Nano-sized powder is expected to improve the mechanical properties of a product with denser results. This research aims to synthesize nanosilica from geothermal scaling silica using the alkali fusion method. Nanosilica is obtained by reacting alkali KOH with silica scaling which has been reduced in size using ball milling. The fusion process is carried out using heat treatment at varying temperatures of 400, 450 and 500ºC. The fusion results were dissolved in distilled water for titration using 2M HCl with stirring using a magnetic stirrer until gelation was formed which was dried into silica nanoparticles. Characterization of the size of nanosilica powder using the Particle Size Analyzer (PSA) obtained the smallest size data at a fusion temperature of 400ºC with the size tending to increase as the fusion temperature increased, where these results were in line with the analysis of nanosilica images from Transmission Electron Microscopy (TEM) testing using ImageJ software. Compound analysis using Fourier Transform Infra-Red (FTIR) shows the presence of characteristic silica bonds. The results of X-Ray Diffraction (XRD) do not show sharp peaks so the compound has an amorphous phase.

Influence of liquid-to-solid ratios on properties and microstructure of coal gasification slag-based one-part geopolymer

Limited studies have been conducted on the synthesis of one-part geopolymer involving coal gasification slag by alkali fusion and component additive method (AFCAM). The ratio of liquid-to-solid (L/S) is the key aspect that has a major impact on the one-part geopolymer's compressive strength (UCS). Our research aims to determine how different L/S ratios affect the microstructure and characteristics of one-part geopolymers. MIP analysis and hydration heat test were conducted to analyze the influence caused by different L/S ratios. The results showed that as the L/S ratio increased, the UCS of geopolymers decreased, and the setting time of fresh slurry increased steadily. Additionally, geopolymer with 0.25 as an L/S ratio (G-L/S-0.25) achieved a higher UCS at 48.31 MPa, whereas the total setting time was more than 23 h. The low L/S ratio produced more gel pores and less total porosity in the geopolymer matrix, which improved the UCS. Moreover, lower porosity suggested that the geopolymer sample had higher compactness and a better internal structure. It is found that the dissolution of the fusion product released heat in the first hour, and no coal gasification slag dissolution heat was detected after one hour. This suggested coal gasification slag showed low reactivity as the additive and was embedded in the geopolymer matrix after 28-day curing. The tested results showed that G-L/S-0.25 had a greater reaction degree. This study illustrated the effects of the L/S ratio on one-part geopolymer and provided a new thought to enhance the UCS of coal gasification slag-based geopolymer.

Eco-Friendly Methods of Silica Extraction from Pyrophyllite Rocks Using Sol-Gel versus Alkali Fusion Method

Silica is the most abundant compound on the Earth’s surface. The content of silica can be found in agricultural waste ash and mineral rocks. Extracting silica from natural sources is advantageous due to its economic feasibility and easily obtained. Silica has a wide range of applications, such as in fertilizers, adsorbents, organic reaction catalysis, biofuels/alternative energy production, and as an antimicrobial agent. One type of rock that contains the highest amount of silica is Pyrophyllite. Recent research trends have focused on various methods and sources for silica extraction, yet extracting silica from mineral rocks presents its own challenges. Pyrophyllite rock contains a high amount of silica, but its extraction is quite difficult due to the presence of crystalline silicate mineral phases. This study aims to compare the silica extraction process on Pyrophyllite rocks from Malang using the sol-gel method versus the alkali fusion method.

Mechanical activation of coal gasification slag for one-part geopolymer synthesis by alkali fusion and component additive method

Coal gasification slag is an industrial by-product obtained after valuable gas production from coal gasification. There is little research concentrating on geopolymer synthesis using coal gasification slag. In this study, the suitability of mechanical activation for coal gasification slag-based one-part geopolymer synthesis has been investigated by alkali fusion and component additive method. The results showed that coal gasification slag ground at 20 min (S-20) presented the finest particle size, and the corresponding geopolymer (G-20) had the highest compressive strength. The reaction degree test proved that mechanical activation improved the reaction degree of geopolymers. However, different mechanical activation times had little influence on the reaction degree of geopolymers. It can be concluded that the particle size of the coal gasification slag was the primary reason for the compressive strength in geopolymers, and finer coal gasification slag led to higher compressive strength. Fine coal gasification slag additive particles could fill the pores of the geopolymer or be connected by the newly formed hydration products. This helped to form a dense, uniform, and compact matrix and increased the compressive strength of the geopolymers. As the mechanical activation time went up, the coal gasification slag particles got bigger, and the coal gasification slag additive's filling effect got weaker, which decreased the compressive strength of geopolymers. Furthermore, this study gave a new explanation of the role of the coal gasification slag additive in one-part geopolymer, which improved the feasibility of the other materials for one-part geopolymer synthesis by the alkali fusion and component additive method.

Simultaneous removal of Methylene blue and Cadmium from aqueous solution by a novel sulfonated material: Characterization, mechanism and application

Remediation of water bodies contaminated by organic or inorganic pollution has attracted widespread attention, only a few research focused on the remediation of organic-inorganic combined water pollution. In this study, a novel sulfonated material (HMFA), modified from coal fly ash (CFA) through alkali fusion and hydrothermal methods, was synthesized for the simultaneous removal of Methylene blue (MB) and Cadmium (Cd(II)) from wastewater, achieving the waste-control-waste strategy. Characterization results showed that functional groups such as hydroxyl and sulfonic acid groups are favorable for adsorption. The environmental factors exerted influence on the adsorption, with the presence of competing ions producing the most significant inhibitory effect. Under optimal conditions, the adsorption amounts of MB and Cd(II) were 116.69 and 93.53 mg g-1 in single system and 100.23 and 85.49 mg g-1 in binary system, respectively. The results of model fitting showed that the removal of MB and Cd(II) by HMFA in single system was consistent with pseudo-second-order kinetic model and Langmuir model. Apart from electrostatic attraction, the primary adsorption mechanisms on HMFA include hydrogen bonding for MB, as well as ion exchange and complexation for Cd(II), quantitative calculations have been carried out. HMFA remained favorable recyclability, and had higher selectivity on MB in natural water bodies. In conclusion, as a low-cost and efficient adsorbent material, HMFA has great potential for dye and heavy metal pollution control, which can provide more reference and theoretical support for solid waste resource utilization and dye/heavy metal removal in wastewater.

Effect of Alkali Fusion Methods on the Preparation of One-Part Geopolymer From Coal Gasification Slag.

This study investigated the one-part geopolymer synthesis by coal gasification slag through a calcination treatment. Two preparation methods, the traditional alkali fusion method (M-I) and the alkali fusion and modification method (M-II), were compared to illustrate the more suitable way for coal gasification slag-based one-part geopolymer (CGS-based geopolymer) synthesis. The reaction products and structure of the geopolymer were tested by XRD, FTIR, TG-DTG, and SEM. The results showed that the compressive strength of geopolymers prepared by M-I was raised as the NaOH amount increased, and the maximum compressive strength of geopolymers was achieved at 8.44 MPa. The low compressive strength suggested that M-I failed to be used for CGS-based geopolymer synthesis. When solid NaOH was selected for one-part geopolymer synthesis by M-II, the geopolymer possessed a compressive strength of 25.52 MPa and exhibited a well-combined and dense matrix. More Si and Al species in F-SH could be released for geopolymerization, and the coal gasification slag additive could be partially dissolved and act as the filler in the geopolymer matrix, which enhanced the geopolymerization degree. The M-II has been proven to be more suitable for preparing CGS-based geopolymers than the M-I.

Fabrication of one-part geopolymer from coal gasification slag via alkali fusion and component additive method: Effect of different alkali-to-slag ratios

This research aims to explore using coal gasification slag (slag) to synthesize one-part geopolymer by alkali fusion and component additive method. The effect of various alkali-to-slag (A/S) ratios on the synthetic one-part geopolymer was studied. The geopolymer reaction products were analyzed using XRD, FTIR, TG-DTG, SEM, and XPS. The dissolution test, reaction degree experiment, and alkalinity of the pore structure were conducted to study the reaction process of the one-part geopolymer. The results demonstrated that the dissolution amount of Si and Al elements in the fusion product was raised with the increase of A/S ratio, and the fusion product with a high A/S ratio possessed high activity. In addition, as the A/S ratio was raised, the compressive strength of geopolymers increased initially before falling off, and geopolymer with an alkali-to-slag ratio of 1.2 (G-1.2) exhibited the highest compressive strength of 26.52 MPa. SEM images showed that geopolymers with a high A/S ratio had a relatively less porous matrix. Furthermore, the reaction degree of geopolymers and dissolution amount of the fusion product was raised as the A/S ratio increased, demonstrating that the fusion product was the primary reactant to provide active Si and Al species for geopolymerization. Moreover, the geopolymer with a low A/S ratio had a low reaction degree, and the slag additive could not be dissolved efficiently. The high A/S ratio of fusion product produced more Q4(mAl) structure in geopolymers, which reflected a relatively complete geopolymerization reaction. Additionally, a high A/S ratio improved the reactivity of the fusion product and led to the consumption of newly formed products in geopolymer, which destroyed the microstructure of geopolymer. An appropriate A/S ratio in the fusion product ensured the integrity of the geopolymer structure. The obtained results provide a new idea for the utilization of slag via alkali fusion and component additive method.

Analysis of Rare Earth Elements in Pteridophytes from the Historical Mining Area, Southwestern Japan

Recent studies have shown that various fern species can accumulate REEs in the soil and may be utilized as indicator plants. Athyrium yokoscense, commonly called hebino negoza in Japan, is a pteridophyte that is used as an indicator of metal-contaminated soils in Japan. Mining and mineral processing increase the potential of mine minerals to oxidize and change their chemical form. A study on the biogeochemical behavior of REEs in the mine area needs to be conducted due to the significant use of REEs as an essential material for various applications in the world. The REE content in sediment and pteridophytes under different mining areas was analyzed by inductively coupled plasma-mass spectrometry. The concentration of REEs contained in Athyrium yokoscense was analyzed and then compared to sediment to determine the ability of the plant to absorb and accumulate rare earth elements in the mine area. Sediment and plant samples were collected from three mining areas: Ikuno mine, Akenobe mine, and Tada mine. Athyrium yokoscense plants were collected and digested with hydrogen peroxide (H2O2) and nitric acid (HNO3) at a ratio of 2:5. Sediment samples were taken and digested by the alkali fusion method using lithium tetraborate and then processed using the conventional column method. The present study determined that the concentration of REEs varies in every location, and light REEs tend to be more abundant in sediments than heavy REEs. The amount that can be transferred to ferns also varies. Athyrium yokoscense in the ex-mining area accumulates proportionately more LREEs than HREEs, specifically in the Athyrium yokoscense leaves. The characteristic of the element significantly contributes to the accumulation of REEs in pteridophytes.

Facile Extraction and Characterization of Silica Nanopowder from Marine National Park beach sand via Alkali Fusion Route

The current study showed utilization of locally available beach sand from Marine National Park in facile extraction of highly amorphous silica via a simple alkali fusion method. The purification of the silica sand was done using 6 N HCl solution to increase its purity. The method entailed formation of sodium silicate (Na2SiO3) solution from silica sand, precipitation using HCl acid to form tetraortosilicate acid, Si(OH)4 (silica gel) which is then heated to form amorphous silica (SiO2). The percentage yield of the extracted silica was 35.0139±0.11%. The extracted silica was characterized using X-Ray Fluorescence Spectrometer (XRF), X-Ray Diffractometer (XRD) and Fourier Transform Infrared Spectrophotometer (FT-IR). The XRF characterization revealed that the extracted silica content was 94.16±0.47 % which increased from 81.32±0.81% (Silica sand). The XRD results revealed a highly crystalline quartz as the main component of silica sand. The XRD spectra of extracted silica showed a broad diffraction peak at 2θ = 21.76o revealing its amorphous nature. The average particle size of the extracted silica was 45.15nm. The FT-IR characterization of the extracted silica showed hydroxyl (-OH) in silanol (Si-OH) and siloxane (Si-O-Si) as important functional groups. The results showed a low cost technique for the production of highly pure amorphous nanosized silica as a potential mineral that can be employed in vast industrial fields.

Synthesis of ordered mesoporous silica from biomass ash and its application in CO2 adsorption

It is possible to achieve high-value utilization of solid wastes and lower the cost of mesoporous silica synthesis by synthesizing mesoporous silica from solid wastes. In this study, silica was extracted using the alkali fusion method using biomass ash as the starting material. Biomass ash based mesoporous silica was successfully prepared by hydrothermal method with silicon extract solution as silicon source. The optimum conditions for preparation were determined as follows: addition of cetyltrimethylammonium bromide was 0.45g, hydrothermal temperature was 120 °C, hydrothermal time was 24h. The prepared mesoporous silicon was systematically characterized, and the results showed that high surface area (495 m2/g) and ordered pore structure appeared in the synthesized mesoporous silica materials. The synthesized mesoporous silica showed excellent CO2 adsorption performance (0.749 mmol/g) at 25 °C and 1 bar. According to the calculation of adsorption isotherm and thermodynamics, non-linear Freundlich model can fit the adsorption isotherm better and the adsorption heat of mesoporous silica is less than 20 kJ/mol, which belongs to physical adsorption. After five cycles of CO2 adsorption, the adsorption property was still above 90%, and the CO2/N2 adsorption selectivity reached 396.6, showing good regeneration performance and adsorption selectivity. This research can provide a new possibility for the high-value exploitation of biomass ash and reducing the cost of synthetic mesoporous silica.

Kinetic, Thermodynamic, and Mechanistic Studies on the Effect of the Preparation Method on the Catalytic Activity of Synthetic Zeolite-A during the Transesterification of Waste Cooking Oil

Egyptian kaolinite was applied in the synthesis of zeolite-A by conventional hydrothermal and alkali fusion methods, resulting in two forms of zeolite-A: the hydrated phase (H.ZA) and the dehydrated phase (DH.ZA). The DH.ZA phase exhibits an enhanced surface area (488 m2/g), total basicity (7.73 mmol OH/g), high sodium content (20.2%), and a narrow particle size distribution (5 to 25 µm) as compared to the H.ZA phase (423 m2/g surface area, 5.88 mmol OH/g total basicity, 13.3% sodium content, and 10 to 45 µm particle size distribution). DH.ZA exhibits enhanced catalytic activity, achieving a biodiesel yield of 96.8% after 60 min at 60 °C, while the application of H.ZA resulted in a 95.8% yield after 120 min at 80 °C. The controlled transesterification mechanism in the presence of H.ZA and DH.ZA involved robust base-catalyzed reactions. The reactions follow the pseudo-first-order kinetics, and the rate constants (Kc) were determined at three different temperature values (40, 50 and 60 °C). The activation energies using H.ZA (35.9 kJ·mol−1) and DH.ZA (32.714 kJ·mol−1) demonstrates their efficiencies in mild conditions. The thermodynamic parameters of enthalpy (33.23 kJ·mol−1 (H.ZA) and 30.03 kJ·mol−1 (DH.ZA)), Gibb’s free energy (65.164 kJ·mol−1 (H.ZA) and 65.268 kJ·mol−1 (DH.ZA)), and entropy (−195.59 J·K−1·mol−1 (H.ZA) and −195.91 J·K−1·mol−1 (DH.ZA)) demonstrate the spontaneous and endothermic behaviours of these reactions. The obtained biodiesel matches the physical properties of the international standards, and the recyclability properties of the two zeolite phases demonstrate their suitability for commercial-scale applications.

Influence on Ratio of NaOH/ZrSiO4 in Alkali Fusion for Amang Zircon Sand

Amang Zircon Sand from Amang Onn Sdn. Bhd. mineral company has a high composition of zirconium at 61.63 wt% and low silicon composition at 4.90 wt%. The high composition of zirconium in Amang zircon sand indicates the possibility to synthesise it into a zirconia. Zirconium was synthesised using alkali fusion method with different ratio of NaOH/ZrSiO4 to determine the optimum ratio based on the zirconium yield. Alkali fusion method is coupled with thermal treatment as it will produce a higher yield of zirconium with lower impurities. Then it will be leached with deionised water and hydrochloric acid (HCl). The synthesised zirconium was characterised through X-Ray fluorescence (XRF) spectroscopy, X-Ray diffraction (XRD) and particle size distribution (PSD) analysis. The XRF analysis after the fusion and thermal treatment shows a high composition of zirconium as well as great reduction of silicon. 1.2NaOH/ZrSiO4 is determined to be the optimum ratio as it has the lowest silicon impurity of 2.11 wt% and high yield of zirconium at 71.40 wt%. The low impurities will reduce the chance of cracking and maximising the efficiency of zirconia. It is supported by XRD patterns that are dominated by high zirconium peaks. The zirconium oxychloride obtained after acid leaching has a high zirconium composition. This shows that it is possible to use Amang zircon sand as a precursor to synthesis a zirconia using alkali fusion method with sodium hydroxide.

Spatial and Temporal Distribution of Total Phosphorus in Sediments of Shuangtai Estuary Wetland during the Period of Reed Growth

Phosphorus is an essential macronutrient that plays a crucial role in the regulation of the biological productivity and biogeochemical cycling of other biogenic elements. As a large tidal wetland dominated by reeds in Liaoning province, China, the Shuangtai estuary wetland is a unique ecosystem class. To better understand the spatial and temporal distributions of total phosphorus (TP) in the sediments of the Shuangtai estuary wetland during the period of reed growth, eight sampling sites were established within the wetland, approximately 11 to 24 km from Liaohe River. These sites were sampled once a month at multiple sediment depth intervals between April and October in 2018 and 2019, periods of time that corresponded with the reed growth period. An alkali fusion method was used to determine TP in the sediment samples. The results show that sediment TP content of wetland sediments ranged from 0.001 to 0.781 mg/kg, and decreases from southwest to northeast with the increase in sediment depth. The TP content reaches the maximum corresponding to the fastest growth stage of the reeds (June and July), while the minimum occurs in October (i.e., the maturity stage of reeds). The variation law of TP in cross-sectional sediment in the wetland is that the deeper the sediments are, the lower the content; its maximum content occurs in surface soil. The TP content of each site tends to be stable with increasing depth and has a regularly dynamic seasonal variation with the growth of reeds.

Recycling light-emitting-diode waste quartz sand and stone sludge for the synthesis of amine grafted mesoporous humidity control material

This article proposes a cost-effective development method to recycle two types of waste material (i.e., light-emitting-diode (LED) waste quartz and stone sludge) to produce mesoporous materials. The proposed method is simple yet effective. Extraction of the precursor liquid from the silicon and aluminum sources respectively contained in the waste quartz and stone sludge is based on the alkali fusion method, and the mesoporous material is synthesized after the hydrothermal reaction. The novelty of this work lies in our functionalization of Mobil Composition of Matter No. 41 (MCM-41) through amine group grafting (AGG-MCM-41). The results show that the structure of the mesoporous MCM-41 grafted by the amine functional groups remains orderly. The 29Si nuclear magnetic resonance spectrum confirmed that the supported surface of the MCM-41 features a large number of silanol groups, which verifies that modification of the amine functional group improved the effect. The results show that when the addition amount of amine functional group is 5 vol% (when relative humidity = 95%), the highest equilibrium moisture content of the material is 26.5 kg/kg. The wet performance of the material was studied, and it was proved that 5.0-AGG-MCM-41 complies with the standard of Japanese Industrial Standard (JIS A 1475) (equilibrium moisture content>5 m3/m3). The research results also show that the optimal equilibrium moisture content is more than 44 times that of metal-organic frameworks humidity pump. Therefore, the synthesized AGG-MCM-41 offers excellent humidity control performance in the practical application of building materials as it narrows the indoor humidity fluctuation spontaneously without any energy consumption. This creates new opportunities for smart indoor humidity control. The amine-group-grafted MCM-41 effectively reduces the shortcomings of high energy consumption, high costs, and insufficient space caused by mechanical dehumidifiers. In addition, the production of AGG-MCM-41 from LED waste and stone sludge achieves 100% recycling. Transformation of two problematic industrial byproducts into humidity-conditioning materials with beneficial technical and environmental properties represents a significant contribution towards the goals of sustainable development.