Sodium Silicate Concentration Research Articles

Research on the Rheological Properties and Diffusion Law of Coal-Based Solid Waste Geopolymer Grouting Material.

The rheological properties and diffusion law of coal-based solid waste geopolymer grouting material (CGGM) slurry were investigated by rheological property test and diffusion theory model derivation. Based on the power-law fluid constitutive equation, a theoretical model of slurry diffusion in an inclined fissure aquifer was established, and the effect of slurry grouting time on the slurry diffusion distance under different fissure widths, fissure inclination angles, and grouting pressures were analyzed. The results show that when coal gangue:cement:fly ash = 5:4:1, sodium silicate modulus 2.0, sodium silicate content is 10%, CGGM slurry's bleeding rate of 1%, the liquidity of 227 mm, the initial and final setting time is 412 min and 825 min, respectively, to meet the requirements of the grouting project. CGGM slurry is a typical viscosity time-varying power-law type fluid, and the slurry diffusion distance is positively correlated with the grouting pressure, fissure width, fissure inclination angle, and negatively correlated with the rheological index. The established theoretical model can provide a reference for the parameter design of CGGM slurry in grouting construction.

Pre-treated municipal solid waste bottom ash as alkali-activated mortar precursor

Pre-treated incinerator bottom ash was used as a precursor of alkali-activated mortars. Control mortars were produced using coal fly ash. Different combinations of alkaline activator were tested (sodium oxide/binder ratio (4%, 6%, 8%, 10% and 15%) and silicon dioxide/sodium oxide ratio (0, 0.5, 1.0, 1.5 and 2.0)) and the influence of these on the mortar's mechanical performance was evaluated. The mortars were tested in both fresh (for density and workability) and hardened states (for dry density, compressive and flexural strengths and modulus of elasticity) after 7, 28, 91 and 182 days. The first stage of work was precursor pre-treatment in a sodium hydroxide solution to prevent the expansion of fresh specimens due to the reaction of aluminium with the alkaline activator. The pre-treatment was effective in preventing excessive hydrogen gas generation during setting, leading to dimensional stability and improved strength. Different optimum sodium oxide contents were observed after 28 days (i.e. 15% for fly ash specimens and 8% for bottom ash specimens). The results of a simplified life-cycle assessment showed that such mixes exhibited lower overall carbon dioxide emissions when compared with cement-based counterparts. However, this trend was reversed with increasing contents of sodium hydroxide and sodium silicate.

A comprehensive electrochemical evaluation of the corrosion inhibition by sodium silicate on carbon steel

Sodium silicate (SS) is investigated as a sustainable green corrosion inhibitor for carbon steel in saline environment under both static and dynamic flow conditions. Potentiodynamic scans and Electrochemical Impedance Spectroscopy revealed that silica is both highly efficient in static and flowing water conditions (up to 98 and 99% resp.). An increased inhibition efficiency (IE) is seen as a function of silica concentration as a result of decreased defects in the resulting silica film (Mott–Schottky). The film forming behaviour changes at increasing flow speed, producing a more defect-rich structure at both low and high silica concentration, although showing improved IE at intermediate flow speed for low SS concentrations.

Study of nanosilica coated and polyaniline grafted cotton fabric

Valuable biomass product nanosilica obtained from rice husk has been hybridized with polyaniline through grafting and was used as coating material over cotton fabric using 3-aminopropyltriethoxysilane as crosslinking agent. In order to optimize the coating percentages of nanosilica and polyaniline, different weight concentration of both sodium silicate and aniline were used to develop the nanosilica coated and polyaniline grafted cotton fabric. The resulting cotton fabrics were studied for their UV shielding property, thermal and basic fabric properties. Cotton fabric coated with 50% of aniline and 0.75% of silica (S0.75A50C) affords the highest Ultraviolet Protection Factor (UPF) as 46.2. The result shows that the nanosilica coated and polyaniline grafted cotton fabric possess higher UV shielding when compared with that of neat cotton fabric.

Improving the scour-resistance performance of for offshore wind turbines: Experimental and computational fluid dynamics studies on macro and micro characteristics

To enhance the resistance to local scour around offshore wind turbine monopiles, 15 mixtures were designed based on Response Surface Methodology (RSM). Cement content, sodium silicate content, and rubber powder content were selected as independent variables. After determining their flowability, the compressive strength and shear strength were measured after curing in pure water and artificial seawater for 3 days, 7 days, 14 days, and 28 days. Experimental results indicate significant improvement in the mechanical properties of the modified soil, including increased Unconfined Compressive Strength (UCS), internal friction angle, and cohesion. The optimal mix ratio is identified as CSR40–10–15, consisting of 40 % cement, 10 % sodium silicate, and 15 % rubber powder. The strength variation mechanism is elucidated from both macroscopic and microscopic perspectives. Finally, numerical simulations using Computational Fluid Dynamics (CFD) software validate the scour resistance performance based on the optimal mix ratio of flowable solidified soil, offering a new approach for local scour protection around offshore wind turbine monopile.

Mechanical and microstructural characterization of one-part binder incorporated with alkali-thermal activated red mud

The traditional production of silicate cement is associated with substantial carbon emissions and environmental degradation. In contrast, cementless alkali-activated binders, derived from solid waste and industrial byproducts, have garnered significant interest for their reduced material costs, energy efficiency, and environmental benefits. This research investigates the application potential of an advanced mixture of anhydrous sodium silicate and red mud in one-part alkali-activated binders. It is assessed through various analytical techniques, including compressive strength, X-ray diffraction, fourier transform infrared, thermogravimetric analysis, digital image correlation, and scanning electron microscopy with energy dispersive spectroscopy. Findings demonstrate that the synergy between red mud and anhydrous sodium silicate markedly enhances the early strength of one-part alkali-activated binders incorporated with alkali-thermal activation. The increment in sodium silicate content is pivotal for bolstering binder performance. A 40 % red mud admixture results in a compressive strength of 40 MPa, achieving an optimal carbon-to-strength ratio. The inclusion of polypropylene fiber significantly influences the mode of compression failure in alkali-activated binders. Alkali-thermal activation of red mud elevates the levels of active silicon and aluminum, markedly augmenting the reactive silica and aluminum content. This modification fosters the disintegration and reorganization of Si-O and Al-O bonds in silica-aluminum materials, culminating in a denser structure. This structure is characterized by the generation of amorphous ((N, C)-A-S-H) gels, contributing to the material's enhanced properties.

Utilization of silicon dioxide nanoparticles and silicon salts to enhance astaxanthin production in Haematococcus Pluvialis

Haematococcus pluvialis is a type of microalgae that is commercially important as it is the primary source of natural astaxanthin - a potent antioxidant used in nutraceuticals, cosmetics, food, and aquaculture industries. Various nanoparticles and chemicals have been used to stimulate the growth of H. pluvialis to increase astaxanthin production. In this study, silicon nanoparticles were synthesized from tetraethyl orthosilicate (TEOS) and characterized to ensure the pure synthesis of uniform nanocrystals of silicon dioxide. The microalgae were cultivated in optimal Haematococcus medium (OHM) under specific conditions, including a temperature of 25 °C, a pH of 7, and a light intensity of 50 μmol. s−1.m−2 for 12 h of light and 12 h of darkness. To study the amount of viability and astaxanthin production, the microalgae were exposed to different concentrations of silicon, sodium silicate, calcium silicate, and potassium silicate. The highest astaxanthin production (194 mg/g) was obtained after stimulation at 200 μg/ml of silicon compared to the control after 15 days by high-performance liquid chromatography (HPLC) technique. Therefore, it can be concluded that certain concentrations of silicon and silicon salts can be considered a suitable stimulus to produce astaxanthin in the H. pluvialis microalgae. This study highlights the potential of using silicon nanoparticles as a stimulant for astaxanthin production in H. pluvialis, which could have significant implications for the nutraceuticals, cosmetics, food, and aquaculture industries.

AI-driven design for the compressive strength of ultra-high performance geopolymer concrete (UHPGC): From explainable ensemble models to the graphical user interface

Ultra-high performance geopolymer concrete (UHPGC) has become of interest in recent years as a more economical and sustainable alternative while offering similar mechanical performance to ordinary ultra-high performance concrete (UHPC). The lack of an effective mix design methodology has inhibited the widespread use of UHPGC, despite its potential. This paper adopted an artificial intelligence (AI)-based approach to accurately model the compressive strength (CS) of UHPGC, a critical parameter to ensure structural integrity and reliability. Ensemble machine learning (ML) models such as RF, XGBoost, LightGBM and AdaBoost, which have been very popular lately, were selected as AI algorithms. For the establishment of these models, a comprehensive and reliable dataset of 181 test results was used, including 13 input features. Additionally, feature importance and Shapley additive explanations (SHAP) analyses were used to ensure the explainability of the prediction models and tackle the "black box" challenge of ML models. The results obtained revealed that all ensemble models successfully predicted the CS of UHPGC; in particular, the XGBoost model consistently exhibited the best overall performance in terms of higher R2 (0.948) and lower RMSE (6.68), MAE (4.73), MAPE (4 %), and mean error value (1.095), in the test phase. Moreover, feature importance and SHAP analyses revealed that the most influential features on the CS of UHPGC were age, fiber and silica fume, sodium silicate (Na2SiO3), and water content. Lastly, a graphical user interface (GUI) was developed to easily predict the CS of UHPGC in practical applications.

Study on the microscopic characteristics and hydration mechanism of thermo-alkali activated electrolytic manganese residue geopolymers

As a form of solid waste, electrolytic manganese residue (EMR) exhibits low reactivity, high sulfate content, and exceeds the standards for heavy metals. To address these drawbacks, a high-temperature thermal activation method was employed to enhance its reactivity and remove pollutants. The study investigated the physicochemical properties and leaching toxicity of EMR under different thermal activation conditions. Additionally, the thermally activated EMR was utilized in the preparation of geopolymer material, and the influence of EMR activation temperature, EMR content, sodium silicate content, and molar ratio on the mechanical properties, hydration mechanism, microstructure, and leaching toxicity of the EMR geopolymers was analyzed. The results indicated that after activation in the temperature range of 0–1200°C, the active content of silica-alumina in EMR increased, sulfate decomposition occurred, and the leaching of Mn2+ and NH4+-N decreased to 21.24 and 0.576 mg/L, respectively. When the activation temperature reached 1200°C, the compressive strength of the geopolymer, prepared with 50 % EMR, 50 % granulated blast furnace slag (GBFS), 30 % sodium silicate, and a molar ratio of 1.2, could reach 53.2 MPa at 28-day. Under activation in the range of 0–800°C, ettringite was abundant in the geopolymers, providing strength support. With activation in the range of 800–1200°C, the geopolymers became denser, exhibiting flaky and agglomerate gels. A diffraction peak appeared at 20°-40°(2θ) corresponding to C-(A)-S-H and N-S-A-H gels. Due to the slow depolymerization-polymerization kinetics of the EMR geopolymer and high sulfate content, the heat release rate and cumulative heat were significantly lower than ordinary portland cement (OPC). In the structure of EMR geopolymer, Mn2+ replaced Na+ and Ca2+ in the silicoaluminate structure or chemically bonded with anionic groups to the geopolymer. Simultaneously, Mn2+ participated in the formation of the EMR geopolymer gel, encapsulating within the gel. Therefore, the leaching of pollutants from EMR geopolymers met the standards of GB8978–1996.

Optimization using central composite design for continuous absorption of CO2 gas with green sodium silicate in a packed bed column

If absolutely nothing is taken to reduce carbon dioxide (CO2) emissions, atmospheric concentrations of carbon dioxide will rise to 550 parts per million by 2050, which will have disastrous effects on the world's climate and food production. An apparatus has been designed and setup to convert CO2 into a useful and vital product which was silica. The effect of different experimental factors on the compositions by weight percent of SiO2 and Na2CO3 were studied including the CO2 gas flow rate (1.037, 1.648 and 2.26 L/min), initial concentration of sodium silicate (Na2SiO3) solution (5, 7.5 and 10 %wt) and the packing size (15.95, 20.175, and 24.4 mm). An optimization process was performed using the Design Expert software program to achieve the optimum experimental conditions at which the maximum weight percent of SiO2 (main product), the minimum weight percent of (Na2CO3) (side product) and the minimum reaction time were determined. From the optimization process, the maximum weight percent of SiO2 (25.63 %), the minimum weight percent of (Na2CO3) (9.62 %) and the minimum reaction time (7.59 min) were achieved at the following optimum experimental conditions of CO2 gas flow rate = 1.648 L/min, packing size = 24.4 mm and initial concentration of sodium silicate solution = 10 %wt.

Preparation and Hydration Properties of Sodium Silicate-Activated Municipal Solid Waste Incineration Bottom Ash Composite Ground-Granulated Blast Furnace Slag Cementitious Materials.

The production of municipal solid waste incineration bottom ash (MSWIBA) is substantial and has the potential to replace cement, despite challenges such as complex composition, uneven particle size distribution, and low reactivity. This paper employs sodium silicate activation of MSWIBA composite Ground-granulated Blast Furnace slag (GGBS) to improve the reactivity in preparing composite cementitious materials. It explores the hydration performance of the composite cementitious materials using isothermal calorimetric analysis, Fourier-transform infrared (FTIR) spectroscopy, XRD physical diffraction analysis, and SEM tests. SEM tests were used to explore the hydration properties of the composite gelling. The results show that with an increase in MSWIBA doping, the porosity between the materials increased, the degree of hydration decreased, and the compressive strength decreased. When the sodium silicate concentration increased from 25% to 35%, excessive alkaline material occurred, impacting the alkaline effect. This inhibited particle hydration, leading to a decrease in the degree of hydration and, consequently, the compressive strength. The exothermic process of hydration can be divided into five main stages; quartz and calcite did not fully participate in the hydration reaction, while aluminum did. The vibrational peaks of Si-O-Ti (T = Si and Al) were present in the material. The vibrational peaks of XRD, FTIR, and SEM all indicate the presence of alumosilicate network structures in the hydration products, mainly N-A-S-H and C-A-S-H gels.

The Potential of Sodium Silicate from Rice Husk as Corrosion Inhibitor on Mild Steel

Study of sodium silicate from rice husks as coating material is reported. The extraction was conducted via precipitation method with sodium hydroxide, nitric acid and ethanol at pH 8. The resulting silica was tested as hydrophobic coating by coating it on a glass surface. Based on the value of the contact angle, silica has good hydrophobic properties. The highest hydrophobic properties were obtained from sample, which labeled as Si10A:Si5B with an average contact angle of 105.3 °. Investigation of the potential application of sodium silicate as an inhibitor of corrosion has been conducted by coating it on steel surfaces. The effect of the concentration of sodium silicate was conducted at 0, 10, 20 and 30 ppm and found that the morphology of steel coated with 20 ppm has the lowest corrosion rate with 81 % inhibition efficiency. HIGHLIGHTS The amorphous silica was successfully synthesized from rice husk using the precipitation method The silica from rice husk shows hydrophobic properties with a contact angle of 105.3 ° Sodium silicate from rice husk has the ability as a corrosion inhibitor and has an inhibition efficiency of 81 % for 20 ppm GRAPHICAL ABSTRACT

Upcycling of pine and sodium silicate composites through pyrolysis: Effects of pyrolysis temperature and sodium silicate content

In 3D-printing, sodium silicate (SS) can be used as an inorganic binder for wood-based composites due to its better rheological properties, high strength, and affordability. Investigating the recyclability of 3D-printed composites is necessary to understand the reusability of demolished additively manufactured construction waste. In this work, the bio-oil through pyrolysis was produced using pine and SS composites and further characterized to observe the effects of the pyrolysis temperatures and the proportion of SS in composites. Pine and SS composites with 0, 33.33, 50, and 66.67 % of the SS on a mass basis were prepared and cured to mimic the 3D-printed composites. Then, pyrolysis of cured composites was performed in a bench-scale fixed bed pyrolysis reactor at four temperatures (450–600 °C). From the pyrolysis of composites with 66 % SS at 600 ℃, a maximum condensed liquid yield of 68 % (wt.%, dry basis) was obtained. Further, it was observed that the selectivity towards hydrocarbons and alkyl phenols increased by increasing the proportion of SS in the composite, but methoxy phenols decreased, which enhanced bio-fuel production. A maximum hydroxyl concentration of 6.54 mmol g−1 was observed for the bio-oil from pyrolysis of SS-based composite at 600 ℃. This study shows the feasibility of upcycling the 3D-printed wood composites through pyrolysis to generate bio-oil that can be used for bio-based resin synthesis and bio-fuel applications.

Effect of Data Augmentation Using Deep Learning on Predictive Models for Geopolymer Compressive Strength

In recent years, machine learning models have become a potential approach in accurately predicting the concrete compressive strength, which is essential for the real-world application of geopolymer concrete. However, the precursor system of geopolymer concrete is known to be more heterogeneous compared to Ordinary Portland Cement (OPC) concrete, adversely affecting the data generated and the performance of the models. To its advantage, data enrichment through deep learning can effectively enhance the performance of prediction models. Therefore, this study investigates the capability of tabular generative adversarial networks (TGANs) to generate data on mixtures and compressive strength of geopolymer concrete. It assesses the impact of using synthetic data with various models, including tree-based, support vector machines, and neural networks. For this purpose, 930 instances with 11 variables were collected from the open literature. In particular, 10 variables including content of fly ash, slag, sodium silicate, sodium hydroxide, superplasticizer, fine aggregate, coarse aggregate, added water, curing temperature, and specimen age are considered as inputs, while compressive strength is the output of the models. A TGAN was employed to generate an additional 1000 data points based on the original dataset for training new predictive models. These models were evaluated on real data test sets and compared with models trained on the original data. The results indicate that the developed models significantly improve performance, particularly neural networks, followed by tree-based models and support vector machines. Moreover, data characteristics greatly influence model performance, both before and after data augmentation.

Preparation and performance influencing factors of sludge-based non-sintering ceramsite foam concrete block

In this study, the preparation of ceramsite foam block using Sludge-based Non-sintering Ceramsite (SNSC) was investigated through orthogonal test and performance optimization test to investigate the effects of different coal fly ash addition, volume ratio of SNSC, water binder ratio and sodium silicate concentration on the performance of the concrete block, and the optimal material mixing ratios were obtained as follows: cement was 400 kg/m3, coal fly ash was 100 kg/m3, SNSC was 371 kg/m3, water binder ratio was 0.43, CaCl2 was 10 kg/m3, and Na2SO4 was 5 kg/m3. The performance of Sludge-based Non-sintering Ceramsite Foam Concrete Block under these conditions meets the specification requirements of GB/T 36534–2018 "Ceramsite Foam Concrete Block". Its compressive strength was 7.76 MPa, dry bulk density was 948.7 kg/m3, the water absorption was 20.75 %, and the softening coefficient was 0.861. XRD and SEM analyses revealed that the internal physical phase of the concrete blocks under the optimal conditions was tightly bonded, with fewer and uniformly distributed pores, and that the hydration generated C-S-H, C-A-H gel-like substances, calcium alumina (AFt), and hydrated calcium chloroaluminate generated by hydration could significantly improve the physical and mechanical properties of concrete blocks.

Research on the long-term strength development of Datça Pozzolan-based geopolymer

This study examined the influence of long-term curing duration on the properties of geopoly- mers produced through the geopolymerization reaction between Datça Pozzolan and sodium silicate and potassium hydroxide solutions. The specimens were heat cured at 90 °C, 95±5% RH for 24 h initially and then kept under ambient conditions until the tests were conducted at 7, 90, and 365 days. The results showed that applied initial heat curing was appropriate to achieve high early and long-term strength. Geopolymer mortars with 12.5 M and 2.5 activator ratios had the lowest porosity (20.90%) and the highest ultrasound pulse velocity (UPV) (3.10 km/s), compressive strength (10.57 MPa), and flexural strength (5.20 MPa) after seven days. While the porosity of the identical specimens decreased by up to 15.77%, the UPV, compres- sive strength and flexural strength increased by 3.37 km/s, 15.32 MPa, and 6.06 MPa, respectively, after 365 days. The physical and mechanical improvement in the first 90 days exceeded 90–365 days. A higher rate of improvement was obtained when the activator ratio was low, i.e., the improvement decreased inversely as the sodium silicate content of the mortar increased. An increasing trend was observed in the plot of compressive strength as a function of UPV, and the slope values presented a strongly related linear function relation.

Effects of elevated temperatures and cooling regimes on the waste andesite dust-based geopolymer mortars

In this study, the geopolymer mortar mixtures were manufactured by activating andesite stone cutting waste dust with sodium silicate. The sodium silicate content in the mixtures was determined to contain 6%, 8% and 10% Na2O by weight of waste andesite dust (WAD). The produced mixtures were subjected to thermal curing at three different temperatures (60 ºC, 75 ºC and 90 ºC), and in two different periods (8 hours and 24 hours). Flexural strength (fs) and compressive strength (fc) tests of 1, 28 and 56 days were carried out on the specimens obtained from the geopolymer mortar mixtures. The effects of Na2O content, thermal curing temperature and time on the strength values of the geopolymer mortars were investigated. Moreover, the geopolymer mortar samples produced with 8 hours of thermal curing were exposed separately to 400 ºC, 600 ºC and 800 ºC. The specimens, which were kept for 1 hour at 400 ºC, 600 ºC and 800 ºC, were exposed to three different cooling conditions (slow-cooled in air, fast-cooled in air and water-cooled). The fs and fc tests were carried out on the cooled geopolymer mortars, and the effects of high temperatures and cooling conditions on the strength properties of the geopolymer mortars were evaluated. In addition, the changes in the microstructures were examined by performing XRD and SEM/EDAX analyses on the selected geopolymer mortars. The fs and fc values of the water-cooled geopolymer mortars significantly decreased.

Analysis and prevention of copper pipe corrosion

The failure of the locomotive heat exchanger due to pitting and corrosion of the T2 heat exchange copper tube is used as the engineering application background. The pitting corrosion and influencing factors of T2 copper tu were studied by weight loss method, SEM, and EDS. The optimal ratio of compound corrosion inhibitors (borax, sodium nitrite, sodium silicate, and benzotriazol) of T2 copper tube was obtained. The results show that the main reason for the pitting corrosion of T2 copper pipe is the local rupture of cuprous oxide protective film on the copper surface, resulting in the copper at the bottom of the pit as the anode and the Cu2O oxide film on the surface as the cathode to form a corrosion cell so that copper dissolves and pitting in the pit. The rupture of the Cu2O oxide film is related to excessive carbon-containing residue and the deposition of dirt (foreign matter) on the surface, mechanical attack, and defects of the material itself. The optimal ratio of compound corrosion inhibitor in 2 L pure aqueous solution is as follows: Borax content is 4.4 g, sodium silicate content is 4.23 g, sodium nitrite content is 4 g, and benzotriazole content is 0.2 g.

Developing High-Performance and Low-Cost Paint Thermoelectric Materials for Low-Midtemperature Applications.

Most thermoelectric (TE) materials used to convert heat energy into electrical energy are expensive and, to a certain degree, toxic. Moreover, due to the chemical complexity in the synthesis process, some of the TE materials are not reproducible. Similarly, the scarcity of TE materials hampers their scalability. To address the above issues, this study presents an inexpensive, nontoxic, scalable, and highly reproducible paint-based TE module for the conversion of heat energy to electrical energy. Transport properties with structural analysis indicate that the electrical conductivity of the paint TE material is controlled by the concentration of graphite and sodium silicate, while the Seebeck coefficient is dominated by the ratio of n- and p-type Bi-Sb-Te. The results indicate that the as-developed TE module can withstand an operating temperature of up to 160 °C. At a temperature of 57 °C, the highest power factors of the as-synthesized n- and p-type TE paints are 1.34 and 1.42 μW/(cm K2), respectively. It is also found that the TE module can have a higher output voltage when the cold side of the TE module is allowed to float in the air in comparison to that when it is in contact with the human body. The performance of the paint-based TE module is measured on five parts of the body, namely, the chest, palm, leg, wrist, and neck; the wrist has the highest open-circuit voltage of 1.9 mV, indicating its suitability for wearable applications. Finally, at a temperature gradient of 30 °C, a maximum output power of 6.8 μW is attained.

Alleviating Cd Stress in Sunflower (Helianthus annuus) through the Sodium Silicate Application

Sunflower has substantial potential for the remediation of heavy metals in soil, but its efficiency in Cd-contaminated soil is limited, with high concentrations of Cd causing stress in plants. Exogenous Si enhances plant tolerance to heavy metals, but the mechanism for enhancing the tolerance of oil sunflower under Cd stress is not known. In potting experiments, sunflowers were grown in soil with a Cd concentration of 11.8 mg/kg soil (the maximum value in the Zhundong coal mining area of Xinjiang) and five Si treatment levels (0, 50, 250, 500, and 1500 mg/kg soil). Exogenous Si improved sunflower development, gas exchange characteristics, and antioxidant enzyme activities in sunflower compared with the Cd-only control; exogenous Si application increased Cd concentrations in sunflower roots, stems, and leaves, and Cd was mainly concentrated in sunflower roots. Sunflower biomass increased by 13.83–114.18%, and gas exchange parameters increased by 16.95–36.03%, 30.06–66.82%, and 9.77–14.71%, respectively, as compared to the control. With the increase in sodium silicate concentrations, sunflower antioxidant enzyme activities increased by 8.81–150.28%, 91.35–351.55%, and 35.11–54.69%, respectively, and MDA content decreased by 3.34–25.14% as compared to Si0. Moreover, exogenous Si increased Cd uptake and minimized Cd stress in sunflowers at the seedling and blooming stages, and it potentially facilitated the phytoremediation of Cd-contaminated soils through enriched plants such as sunflower, as well as contributing to the achievement of sustainable development of the soil environment.