Oyster Shell Powder Research Articles

Enhancing compost quality through biochar and oyster shell amendments in the co-composting of seaweed and sugar residue

Aquaculture and agricultural production generate substantial amounts of waste, including seaweed (which has plant-stimulating properties), oyster shells, and sugar residues. Through composting and appropriate management, these wastes have the potential to be converted into beneficial soil amendments. However, there is a lack of research exploring the potential of composting in promoting the conversion of seaweed into more stable humified forms, as well as in assessing whether composted seaweed retains its beneficial effects on plant growth. Additionally, studies on using oyster shells as additives to reduce waste pressure and comparing their effectiveness with biochar are relatively scarce. This study examines the impact of incorporating 5% corn stover biochar (T1), 10% biochar (T2), and 10% oyster shell powder (T3) on key physicochemical properties, product quality, and microbial community dynamics during the co-composting of seaweed and sugar residues. Results indicate that organic matter (OM) loss in T1 and T2 increased by 31.2% and 26.4%, respectively, compared to the control (CK). Moreover, Excitation-emission matrix (EEM) fluorescence spectroscopy revealed that humic substances in T1 and T2 surged by 434% and 423%, respectively, far exceeding the 289% increase in CK. The 10% biochar treatment also improved alginate degradation and seed germination index, due to the presence of biostimulants in seaweed and an increased abundance of Cobetia. Microbial analysis post-composting showed that T2 and T3 significantly enhanced the diversity and richness of bacterial communities. Notably, although oyster shell powder did not improve the humification degree of compost as significantly as biochar, it achieved effective weight reduction of waste (OM loss of 43.57%, far exceeding CK's 35.34%) without hindering the composting process. All four compost treatments retained the plant-stimulating effects of seaweed and facilitated alginate degradation. These results underscore the potential of biochar to enhance composting efficiency and utilize composting to process large quantities of oyster shell waste.

Ternary blended concrete strength evaluation: experimental and artificial intelligence techniques

Purpose The purpose of this study is to forecast the mechanical properties of ternary blended concrete (TBC) modified with oyster shell powder (OSP) and shea nutshell ash (SNA) using deep neural network (DNN) models. Design/methodology/approach DNN models with three hidden layers, each layer containing 5–30 nodes, were used to predict the target variables (compressive strength [CS], flexural strength [FS] and split tensile strength [STS]) for the eight input variables of concrete classes 25 and 30 MPa. The concrete samples were cured for 3–120 days. Levenberg−Marquardt's backpropagation learning technique trained the networks, and the model's precision was confirmed using the experimental data set. Findings The DNN model with a 25-node structure yielded a strong relation for training, validating and testing the input and output variables with the lowest mean squared error (MSE) and the highest correlation coefficient (R) values of 0.0099 and 99.91% for CS and 0.010 and 98.42% for FS compared to other architectures. However, the DNN model with a 20-node architecture yielded a strong correlation for STS, with the lowest MSE and the highest R values of 0.013 and 97.26%. Strong relationships were found between the developed models and raw experimental data sets, with R2 values of 99.58%, 97.85% and 97.58% for CS, FS and STS, respectively. Originality/value To the best of the authors’ knowledge, this novel research establishes the prospects of replacing SNA and OSP with Portland limestone cement (PLC) to produce TBC. In addition, predicting the CS, FS and STS of TBC modified with OSP and SNA using DNN models is original, optimizing the time, cost and quality of concrete.

Nitrogen fixation and calcium activation of oyster shell during composting and its performance on acidic soil amendment

Chicken manure, corn straw and oyster shell powder (OSP) were used as raw materials for organic-inorganic combined composting. Experiments were designed by adding different amounts of OSP (0 %, 20 %, and 40 %), designed as CK, T1, and T2, respectively. In final composts, the pH value increased to 8.72–9.08, and the electrical conductivity ranged from 2.08–3.82 mS·cm−1. The co-composting could effectively reduce ammonia emissions by 54.65 % and could activate the calcium component by 37.5 %. Addition of OSP promoted the humification and the humic acid could increased 86.1 %. This calcium-based compost of oyster shells (OSs) activated by composting was used to plant Brassica napus by pot experiment. Compared with the addition of OSP after composting, the calcium-based compost activated by composting significantly promoted the growth of Brassica napus because of more nitrogen, humus and available calcium in the calcium-based compost. In addition, this calcium-based compost significantly increased pH, organic matter (OM) and exchangeable calcium content in the acidic soil. In general, composting is an effective method to realize the fertilizer utilization of OSs. This composting process could make full use of calcium in oyster shells to achieve nitrogen retention and humification enhancement during composting, meanwhile calcium morphology in oyster shells can be activated and high-quality acidic soil conditioner can be obtained.

Effect of waste oyster shell powder as additive on properties and sulfate attack resistance of mortar

In this study, the waste oyster shell powder was added in mix design to investigate the properties, sulfate attack resistance and sulfide bacterial of concrete. Add 0%, 1%, 3%, 6% and 9% oyster shell powder to the concrete to replace part of the sand. The study conducted flow tests, compressive strength tests, sulfate corrosion resistance and antibacterial tests. From the results, it was found that adding oyster shell powder improved the resistance to sulfate corrosion and antibacterial properties and became more effective as the substitution ratio increased. In addition, the sulfate attack resistance and antibacterial have a linear relationship of mortar with oyster shell powders.

Design of an Intermittent Biosand Filter Amended with Oyster Shell Powders for the Improvement of Household Water Quality in Sub-Saharan Africa and Madagascar

Access to safe drinking water and the wide spread of water-borne diseases are major challenges in Sub-Saharan Africa and Madagascar. Based on this, a water purification models has been developed which can use on a local scale. It consists of an intermittent biosand filter amended with oyster shell powders designed from local materials. The performance of the filter was evaluated through physicochemical and bacteriological analyses using standardized methods on raw polluted well water with previously determined initial D0 characteristics. The effectiveness of the designed filter was assessed and a filtration operation was carried out over a monitoring period of 13 days (D13) prior to 7 days of acclimatization of the system. With a filtration rate of 0.75l/h-1, there is a very strong reduction in turbidity from 35.59NTU to 0 NTU and in BOD5 from 125mg/l to 2mg/l. More so, bacteriological analyses reveal a progressive and complete decrease from D0 to D13 of fecal coliforms from 9000 CFU/100ml to 0 CFU/100ml; total coliforms from 6,000 CFU/100 ml to 0 CFU/100 ml and fecal streptococci from 10,800 CFU/100 ml to 0 CFU/100 ml. Compared to the classic ceramic filter, no significant difference in the Duncan test is reported for the highlighted parameters. This filter presents potential among other water treatment methods at the local scale for reducing the risks of water-borne diseases and achieving Sustainable Development Goal 6 in developing countries.

Fabrication and properties of biodegradable poly (butylene succinate) composites by regulating the dispersed oyster shell powder with the silane coupling agent

Fabrication and properties of biodegradable poly (butylene succinate) composites by regulating the dispersed oyster shell powder with the silane coupling agent

Pemanfaatan Limbah Kulit Tiram Sebagai Substitusi Semen pada Campuran Bata Ringan

Indonesian coastal areas of tourist spots that cause large amounts of seafood waste, such as oyster shells, led to the idea of reducing beach pollution by using oyster shells as a partial substitute for lightweight bricks as construction material. Lightweight bricks require high costs and have a heavy mass as walls, so oyster shell powder, which contains calcium carbonate and has a smaller specific gravity, is expected to qualify the Indonesian National Standard (SNI) requirements for lightweight bricks. The research method is quantitative experimental, which observes the effect of variables based on SNI. The composite of the lightweight brick combination is 0.35 Water Cement Ratio (FAS): 1 cement: 2 sand: 1 foam agent: 50 water, and the variable of oyster shell powder added to the cement is 0%, 3%, 6%, 9%, and 12% of cement. The quality test for oyster shell powder for making lightweight bricks based on SNI 8640, 2018, includes density, water absorption (porosity), and compressive strength tests. The result of average density analysis for 0% = 986 kg/m³, 3% = 954 kg/m³, 6% = 978 kg/m³, 9% = 920 kg/m³, and 12% = 903 kg /m³. According to the Indonesian National Standard (SNI), the porosity test results maximum is 25%, the result of average porosity analysis at 0% = 21.2%, 3% = 19.2%, 6% = 17.2%, 9% = 23%, and 12% = 24.6%. Compressive strength analysis results at 0% = 2.3 MPa, 3% = 1.9 MPa, 6% = 2.1 MPa, 9% = 1.7 MPa, and 12% = 1.6 MPa. In conclusion, oyster shell powder waste can reduce density, reduce porosity to the optimum point, increase the porosity afterward, increase compressive strength to the optimum point, and reduce compressive strength after passing the optimum point.

Particle and bulk media characteristics of food waste compost-based biomedia by dynamic high-temperature aerobic composting process

The dynamic high-temperature aerobic composting (DHAC) process, as a decentralized system, is considered a sustainable strategy for renewable resource-based raw materials. The food waste compost-based biomedia (BMFWCs) produced within five days of the DHAC process exhibited the physical properties of peaty topsoil with acceptable maturity under the meso-thermophilic phase. To understand the particle and bulk media characteristics of the BMFWCs, organic matter (OM) fraction–density–porosity parameters, particle size distribution, and uniformity coefficient were considered. Operating the DHAC process produced end products characteristics of relatively high total porosity (φb,T) and low dry bulk density (ρb) compared to the conservative mixture theory due to binary mixing and shape effects. A significant change in total porosity was estimated as an increase in non-spherical fibrous particles within the OM fraction of 0.4. Appropriate organic–mineral additives led to the effective arrangement of the variable porosity structure and improvement of aggregate stability (fom,spent coffee grounds≥0.2, fm,oyster shell powder≤0.4). The Forced aeration supply contributed to the expansion of the open space and macropore structures that serve as gas passages in the BMFWCs, while the introduction of microbes (Bacillus subtilis) promoted the biodegradation of medium and small macroaggregates (0.25–2 mm). The BMFWCs produced by the DHAC process was expected to have application potential in sustainable nature-based solution technology, due to appropriate particle properties, uniformity, and maturity.

Low-carbon UHPC with glass powder and shell powder: Deformation, compressive strength, microstructure and ecological evaluation

Waste glass and shells are by-products generated in the production process of the construction industry and aquaculture respectively. The high-value treatment of these materials presents a global challenge. Converting waste glass and shells into solid waste-based ultra-high performance concrete (UHPC) mixtures is an eco-friendly strategy. In this study, glass powder (GP) and oyster shell powder (OSP) were mixed to prepare composite supplementary cementitious materials (GOS) and partially replace cement. The compressive strength, drying shrinkage, microstructure, and environmental impact of GOS-containing UHPC were investigated. Results indicate that adding GOS reduces the fluidity of UHPC mixtures, with further decreases as GOS content increases. Replacing cement with an appropriate amount of GOS (10 wt%-20 wt%) enhances the compressive strength of UHPC, though higher GOS levels reduce its strength. Meanwhile, the drying shrinkage deformation of UHPC decreases significantly as the GOS substitution level increases. The 28-d drying shrinkage deformation of the specimen added with 20 wt% GOS is 574 μm/m, which is 61.96 % lower than the control group. Additionally, the specimen added with 20 wt% GOS shows significantly improved compactness and enhanced bonding at the interfacial transition zone. Compared with traditional UHPC, GOS-containing UHPC has lower carbon emissions and costs, effectively utilizes waste, and promotes sustainable development.

Using Oyster shell for production of greener building mortars: exploring mechanical and microscale characteristics

In the pursuit of greener and sustainable materials for developimg cementitious composites, several agricultural and undustrial wastes are continually explored for use in the process. The current study focused on the use of 20%, 25% and 30% Oyster shell powder (OSP) as a partial substitute for Ordinary Portland cement, and 100% Oyster shell aggregate (OSA) and 100% recycled concrete aggregate (RCA) (OPC) as total replacement for fine aggregate in mortar production. The mechanical properties of the mortars such as compressive strength, flexural stremntgh and water abosprion were determined. Also, microscale analysis using SEM-EDX was conducted on selected mortars. The results showed that the control mortar demonstrated the maximum compressive strength, however, OSP is adequate as binder at upto 25% replacement level, producing strength somewhat close to that of the control mortar. Results obviously showed that the replacement amounts of OSP, RCA and OSA greatly influence the hydration process of the mortar matrix, and the overall performance.

Effect of waste oyster shell powder on the micro- and macroproperties and sustainable performance of cement-based materials

A large amount of oyster shell waste is generated globally every year. Proper disposal of discarded oyster shells is crucial for reducing environmental pollution and achieving sustainable development. The aim of this paper was to study the feasibility of using waste oyster shells as a cementitious material to replace cement. The effects of waste oyster shell powder (OSP) with different water–binder ratios (w/b = 0.5, w/b = 0.2) and different substitution rates (10 %, 20 %) on the properties of cement-based materials were studied. The experimental results are as follows: The addition of oyster shell powder reduces the compressive strength, ultrasonic pulse velocity (UPV), surface electrical resistivity and cumulative heat of hydration of the mortar, but the strength loss is smaller for a water-to-binder ratio of 0.2 than for a water-to-binder ratio of 0.5. A good linear relationship between the compressive strength and UPV was also found. A good exponential relationship exists between the surface electrical resistivity and compressive strength. The heat of hydration results show that when the water–binder ratio is 0.5, replacing cement with waste OSP promotes aluminate phase hydration and advances the acceleration period. Finally, the carbon emissions of the mortar were normalized according to the compressive strength, and using OSP instead of cement at a low water–binder ratio was more conducive to reducing CO2 emissions.

Effects of oyster shell derivatives on performance enhancement of biomass-based 3D printed concrete

In this research, sustainable oyster shell derivatives were used as partial replacement of Portland cement-sulfate aluminate cement composite (OPC-SAC) composites to investigate the potential application in the mix-stir-extrusion integrated 3D concrete printing. Calcined oyster shell powder (CS) was added into OPC-SAC concrete at 0–15 wt% to prepare a new 3D printed concrete. Additionally, oyster shell particles (CSS) were substituted for river sand at 0–41.7 wt% as another new material. The effects of oyster shell derivatives on the forming mechanism and performance of 3D printed concrete were studied by macro and micro tests. The results demonstrate that the two new materials, which can be printed with an initial setting time within 15–36 min, exhibit superior overall performance compared to OPC-SAC, achieving an efficiency improvement of up to 75%. When the CS content was 15%, the formability of 3D printed concrete reached the best. The optimized compressive strength and flexural strength at 28 days surpassed 40 MPa, and 10 MPa, respectively. Micro-morphological analysis showed that CaO in CS facilitated the hydration reaction of concrete and generated more C-S-H gels and Aft crystals, which resulted in a denser bond between the substances and enhanced the mechanical strength. The above results indicated that both CS and CSS could improve the mechanical properties of OPC-SAC.

A Hydration-Based Integrated Model to Evaluate Properties Development and Sustainability of Oyster Shell Powder–Cement Binary Composites

Currently, oyster shell powder (OSP) is becoming more widely used in the production of cement-based materials. The purpose of this study is to propose a predictive model that can predict the properties of concrete materials incorporating oyster shell powder. The methods of this prediction model are given as follows. First, based on the measurement results of the heat of hydration in the first 7 days, the prediction parameters of the hydration model are obtained. Secondly, based on the hydration model, the measured results of the heat of hydration were extrapolated, and the heat of hydration from the start of stirring to day 28 was calculated. From the calculation results, the developments of compressive strength, ultrasonic velocity, and surface electrical resistivity were estimated. Finally, we evaluated the CO2 emissions of concrete incorporating oyster shell powder. The CO2 emissions corresponding to unit compressive strength and unit surface electrical resistivity were calculated. The important conclusions of the prediction model are given as follows. First, for different substitution amounts of oyster shell powder, the model result shows that the ultimate value of the heat of hydration corresponding to the unit cement mass is the same, i.e., 454.27 J/g. While the substitution amount of oyster shell powder increases from 0% to 30%, the model result shows that the cumulative 28-day hydration heat for 1 g cement increases the powder amount from 405.7 J/g to 419.3 J/g. Secondly, as the amount of substituted oyster shell powder increases from 0% to 30%, the model result shows that the cumulative 28-day heat of hydration per gram of cementitious material decreases this amount from 405.7 J/g to 293.4 J/g. Compressive strength, ultrasonic pulse velocity, and surface electrical resistivity can all be expressed as exponential functions of the heat of hydration. For compressive strength, ultrasonic pulse velocity, and surface electrical resistivity, the coefficients of determination for the simulation results and experimental results are 0.8396, 0.7195, and 0.9408, respectively. Finally, as the amount of substituted oyster shell powder increases from 0% to 30%, the model result shows that the CO2 emission per unit of compressive strength increases from 10.18 kg/MPa to 16.51 kg/MPa. As the amount increases from 0% to 30%, the model result shows that the CO2 emission corresponding to the unit surface electrical resistivity does not change significantly. In summary, the importance of this model is that it can predict various properties of concrete mixed with oyster shell powder, reduce the number of experiments, and promote the engineering application of oyster shell powder concrete.

Biosynthesis of Iron Nanoparticles (Fe NPs), and their Antibacterial Activity

Our ongoing research involves the synthesis of iron nanoparticles through a multi-step procedure that includes intricate processes resulting in the disruption of the bonds between the fundamental components of the oyster shell. As a result, we successfully extract iron nanoparticles from oyster shell powder. The obtained iron nanoparticles were characterized using X-ray Diffraction Analysis (XRD), Scanning Electron Microscopy (SEM), and FTIR-Based Analysis. These techniques confirmed that the nanoparticles possess the standard properties and meet the optimal specifications necessary for their function as an antibiotic to suppress bacterial action. Objective: Our research aims to biologically generate iron nanoparticles from oyster shells, meeting conventional standards that enable them to function as antibiotics. Methods: Our research employs a method for producing iron nanoparticles that involves a series of processes combined with the addition of chemicals that disrupt the bonds between the fundamental constituents of the oyster shell. This shell is first purified and then ground into a powder. Results And Characterization: The results were obtained using the SPSS statistical program, and the size of the iron particles was determined using the XRD crystallite (grain) calculator, specifically the Scherrer Equation. The characteristics acquired from the steps involving Fe NPs in our ongoing study are confirmed based on the measurements conducted using X-ray Diffraction Analysis (XRD), Scanning Electron Microscopy (SEM), and FTIR-Based Analysis. These measurements indicate that the particles have a satisfactory size range of 30-100 nanometers.Conclusion: We conclude from our current study that there are no significant differences between the number of patients and the three stages type that recorded through this periodic time, even if there is a difference in age and gender.

Biosynthesis of Iron Nanoparticles (Fe NPs), and their Antibacterial Activity

Our ongoing research involves the synthesis of iron nanoparticles through a multi-step procedure that includes intricate processes resulting in the disruption of the bonds between the fundamental components of the oyster shell. As a result, we successfully extract iron nanoparticles from oyster shell powder. The obtained iron nanoparticles were characterized using X-ray Diffraction Analysis (XRD), Scanning Electron Microscopy (SEM), and FTIR-Based Analysis. These techniques confirmed that the nanoparticles possess the standard properties and meet the optimal specifications necessary for their function as an antibiotic to suppress bacterial action. Objective: Our research aims to biologically generate iron nanoparticles from oyster shells, meeting conventional standards that enable them to function as antibiotics. Methods: Our research employs a method for producing iron nanoparticles that involves a series of processes combined with the addition of chemicals that disrupt the bonds between the fundamental constituents of the oyster shell. This shell is first purified and then ground into a powder. Results And Characterization: The results were obtained using the SPSS statistical program, and the size of the iron particles was determined using the XRD crystallite (grain) calculator, specifically the Scherrer Equation. The characteristics acquired from the steps involving Fe NPs in our ongoing study are confirmed based on the measurements conducted using X-ray Diffraction Analysis (XRD), Scanning Electron Microscopy (SEM), and FTIR-Based Analysis. These measurements indicate that the particles have a satisfactory size range of 30-100 nanometers.Conclusion: We conclude from our current study that there are no significant differences between the number of patients and the three stages type that recorded through this periodic time, even if there is a difference in age and gender.

Enhanced biomass production and harvesting efficiency of Chlamydomonas reinhardtii under high-ammonium conditions by powdered oyster shell

Chlamydomonas reinhardtii prefers ammonium (NH4+) as a nitrogen source, but its late-stage growth under high-NH4+ concentrations (0.5 ∼ 1 g/L) is retarded due to medium acidification. In this study, oyster shell powders were shown to increase the tolerance of C. reinhardtii to NH4+ supplementation at 0.7 g/L in TAP medium in 1-L bubble-column bioreactors, resulting in a 22.9 % increase in biomass production, 62.1 % rise in unsaturated fatty acid accumulation, and 19.2 % improvement in harvesting efficiency. Powdered oyster shell mitigated medium acidification (pH 7.2–7.8) and provided dissolved inorganic carbon up to 8.02 × 103 μmol/L, facilitating a 76.3 % NH4+ consumption, release of up to 189 mg/L of Ca2+, a 42.1 % reduction in ζ-potential and 27.7 % increase in flocculation activity of microalgae cells. This study highlights a promising approach to utilize powdered oyster shell as a liming agent, supplement carbon source, and bio-flocculant for enhancing biomass production and microalgae harvesting in NH4+-rich environments.

Effects of calcined oyster shell powder composited with iron salt on the simultaneous removal of phosphorus and arsenic during algal bloom control process

Calcined oyster shell powder (COS) has the potential to serve as an efficient coagulant aid in water treatment for iron salt (IS) due to its potentially high aid capacity in alkalinity recovery and the simultaneous removal effects on algae, arsenic, phosphorus, and organic substances. However, little information is available on the specific effects and environmental impacts of COS composited with IS in coagulation for algal bloom removal. Hence, the COS was used as a coagulant aid to investigate the simultaneous removal effects on phosphorus and arsenic as well as the water environment changes during the bloom control of Microcystis aeruginosa using ferric chloride as a coagulant impacted by different hydraulic disturbances. Results showed that compared to the single IS coagulation with a pH value of about 3.1, the pH value significantly increased and stabilized at 7.5 from the 3rd day with the COS as the coagulant aid condition. Meanwhile, the removal rates of arsenic and phosphorus also improved by 14.4 % and 50.6 %, respectively, within 12 h, achieving near complete removal with little re-release risk, demonstrating excellent alkalinity adjustment and persistently simultaneous removal effects on phosphorus and arsenic. Furthermore, the coagulation aid of COS effectively inhibited the release of fulvic acid-like substances from algal cells on the 7th day. Meanwhile, it promoted the secretion of humic acid-like substances and microcystins production, as well as the release of fluorescent substances under hydraulic disturbance conditions. From the structural information presented by X-ray photoelectron spectroscopy (XPS), the precipitates mainly consisted of proteins and lipids derived from algal cells, calcium carbonate, ferric hydroxide, and trace amounts of arsenite, further confirming their precipitated mechanism of algal cell combined through COS and IS. The results provide scientific support for the practical application of COS in algal blooms and its subsequent environmental risk control.

Research on and application of low-temperature calcination on waste Taiwanese hard clam shell during Taiwanese hard clam aquaculture

This study uses a circular economy-regenerative value addition approach. Pre-treated waste clam shells were calcined at a low temperature (about 300 °C) and then crushed into clamshell powder. Taiwanese hard clam shell (THCS) powder and commercially available calcium carbonate products, such as low-temperature calcined oyster shell (OS) powder, slaked lime, and calcium carbonate, were compared experimentally, and the safety of THCS powder was determined. In the safety evaluation, the Vibrio-like bacteria test results showed that no colony growth was found for the low-temperature-calcined THCS powder, indicating that it did not contain Vibrio-like bacteria. Tolerance test results showed that high-dose slaked lime will cause high Taiwanese hard clam mortality, and the survival rates of other groups were all 100%. In addition, slaked lime had the most significant effect on increasing the water pH. OS powder had the greatest effect on increasing the calcium ion concentration in the water, followed by THCS power. The aquaculture benefit-related experimental results showed that the low-temperature calcined OS powder and THCS powder groups had the most favorable performance in terms of Taiwanese hard clam growth rate, shell weight, and shell thickness. This study used different calcium carbonate products as additives in Taiwanese hard clam aquaculture ponds and observed growth differences between the different groups. These results indicated that the low-temperature calcination of THCS in Taiwanese hard clam aquaculture can effectively replace the commonly used OS powder, slaked lime, and calcium carbonate products in traditional aquaculture. Furthermore, it can effectively solve the problem of THCS waste accumulation, promote environmental beautification, create a circular economy and aquaculture application value, and conform to the economic benefits of aquaculture.

Potential use of silane-modified oyster shell powder in hydrophobic concrete

This article describes the laboratory-scale manufacture of hydrophobically modified oyster shell powder (mOSP) via a silane coupling agent and used as cement substitutes at 0% to 2.5%. Hydrophobic chemicals have been used in concrete to minimise capillary action by researchers. Although hydrophobic fillers improve concrete’s water repellency, replacing fine particles with them in higher proportions has a negative effect. We can use hydrophobically modified fillers in smaller amounts to replace cement while maintaining its critical properties. When mOSP is added in various quantities to binary and ternary mixes with natural zeolite, concrete hydration, mechanical strength, and durability are examined. At a 1.5% replacement ratio, mOSP improved concrete characteristics and durability. With free water and the hydrophobic modified nOSP, concrete mixes were consistently more workable. A gliding effect on the cementitious matrix caused by the surface roughness and hydrophobicity of the developed silane-coated nOSP increases the slump value. The 28-day compressive strength of concrete containing modified nOSP ranged from 39 to 42 MPa without zeolite and 43 to 46 MPa with it. Compressive strength increased more when 10% natural zeolite (NZ) was added with different amounts of mOSP. The RCPT values of the concrete series without zeolite dropped until 1% mOSP replacement (mOSCII), while the 1.5% mix (mOSZIII) had the lowest value. The angularly modified nOSP aggregates interlocked, improving the migration coefficient of mOSP concrete.

Preparation of a novel ZnFe2O4 /oyster shell powder composite photocatalyst for visible-light-driven photocatalytic degradation of ammonia nitrogen wastewater

In this study, ZnFe2O4/oyster shell powder (ZF-OSP) composite photocatalyst was successfully synthesized via sol-gel method for the purpose of removing ammonia nitrogen (NH4+-N) from wastewater. The NH4+-N degradation rate by ZF at pH of 6.2 in 210 min was observed to be 19.5%. To improve the NH4+-N treatment efficiency of ZF, a high pH level of 11 was required by adding NaOH. In comparison, the ZF-OSP composite photocatalyst with a mass ratio of 1:1 achieved an impressive 91.8% elimination of NH4+-N at pH of 6.2 in 210 min without the requirement for additional pH adjustment and pH was stably maintained at 9.5–10.0. In addition, NO3--N and NO2--N were barely accumulated during the NH4+-N degradation process. Quenching experiments demonstrated that the degradation of NH4+-N in wastewater was significantly mediated by the participation of h+, •OH and •O2-. Moreover, NH4+-N removal rate of recovered ZF-OSP/1:1 composite photocatalyst by magnetic force after the first reuse cycle remained above 80.8%. Overall, the ZF-OSP/1:1 composite photocatalyst could not only address the challenge of recovery for non-magnetic powder photocatalysts, but also reduce the use of NaOH and offer a potentially effective and environmentally friendly solution for water treatment.