This research aimed to find an eco-friendly way to neutralize water recovered from ready-mixed concrete by dissolving carbon dioxide in it, and to verify the potential use of such water for mixing concrete. Carbon dioxide was injected using nanobubble technology into recovered water, and the optimized conditions for dissolution were established by analyzing the carbon dioxide concentration in the water and measuring pH over time. Mortar was manufactured using this recovered water following carbon dioxide nanobubbles treatment, and measurements of compressive strength and thermogravimetric analysis (TGA) were conducted to verify the formation of calcium carbonate. 2,464 mg/L of carbon dioxide was dissolved in the recovered water, and the pH was measured to be 6.34. The compressive strength of the manufactured mortar was found to be 32.02 % stronger than mortar manufactured with normal tap water. According to the thermogravimetric analysis results, the amount of calcium hydroxide produced in the mortar manufactured with recovered water from ready-mixed concrete was 8.10 %, and the production amount of calcium carbonate was 6.49 %. This means that the amount of calcium carbonate produced was greater than that in mortar manufactured with normal tap water, as well as tap water containing nanobubble carbon dioxide. The carbon dioxide was stably dissolved in water recovered from ready-mixed concrete using nanobubbles, enabling environmentally friendly neutralization without the use of chemicals. Also, when the recovered water from ready-mixed concrete containing dissolved carbon dioxide was used for mixing concrete, it was determined that the carbonation reaction influenced the formation of calcium carbonate, which contributed to the improvement in concrete strength.

This study is to manufacture a titanium dioxide (TiO2) photocatalyst by recycling sludge generated using titanium tetrachloride (TiCl4 ) as a coagulant. Compared to general sewage, a TiCl4 coagulant was applied to dyeing wastewater containing a large amount of non -degradable organic compounds to evaluate its performance. Then the generated sludge was dried and fired to prepare a photocatalyst (TFS). Scanning electron microscope -energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), and nitrogen oxide reduction experiments were conducted to analyze the surface properties and evaluate the photoactive ability of the prepared TFS. After using titanium tetrachloride (TiCl4 ) as a coagulant in the dyeing wastewater, the water quality characteristics were measured at 84 mg/L of chemical oxygen demand (COD), 10 mg/L of T -N, and 0.9 mg/L of T -P to satisfy the discharge water quality standards. The surface properties of the TFS were investigated and the anatase crystal structure was observed. It was confirmed that the ratio of Ti and O, the main components of TiO2 , accounted for more than 90 %. As a result of the nitric oxide (NO) reduction experiment, 1.56 uMol of NO was reduced to confirm a removal rate of 20.60 %. This is judged to be a photocatalytic performance similar to that of the existing P-25. Therefore, by applying TiCl4 to the dyeing wastewater, it is possible to solve the problems of the existing coagulant and to reduce the amount of carbon dioxide generated, using an eco-friendly sludge treatment method. In addition, it is believed that environmental and economic advantages can be obtained by manufacturing TiO2 at an eco-friendly and lower cost than before.

Carbon consuming concrete (CCC) represents an advanced sustainable concrete designed to optimize carbon sequestration efficiency. This study conducted preliminary tests on curing conditions to evaluate the effects of nanobubble water on the strength and carbon sequestration efficiency of concrete cured under various conditions. The curing conditions were characterized by temperature, duration, and the type of curing water utilized. The precipitation method was employed to validate the variation in the CO2-capturing capacity of nanobubble water (NBW), essential for carbon fixation within cementitious composites, as temperatures increased. Subsequently, compressive strength test and chemical analyses were performed on CCC manufactured under different curing conditions. Analysis techniques comprise differential thermogravimetry (DTG) and Fourier transform infrared spectroscopy (FT-IR). The carbon sequestration efficiency of CCC was observed to increase with shorter curing durations, and high temperatures could boost both the strength and carbon sequestration efficiency of CCC.

Developing energy-efficient and multifunctional wearable electronic textiles (E-textiles) is a significant challenge. This study investigates MXene-coated cellulose hybrid fibers, focusing on their electrical properties, heating performance, and thermal stability. The fabrication process involves continuous dipping of cellulose fibers into an aqueous MXene solution, resulting in the creation of MXene-coated cellulose hybrid fibers. We confirm the uniform coating of MXene sheets on the cellulose fiber surfaces, with increasing content throughout the dip coating cycle, as evidenced by X-ray diffraction and scanning electron microscopy analysis. The high thermal conductivity of MXene acts as a heat source, impacting the thermal stability of cellulose fibers at lower temperatures. Additionally, the electrical properties of MXene/cellulose hybrid fiber composites are influenced at elevated temperatures. Remarkably, the longitudinal electrical conductivity of the MXene-coated cellulose fiber composites exhibits a notable increase of 0.06 S/cm after the final coating cycle, demonstrating the effective and conductive nature of the layer-by-layer MXene network formed on the cellulose fibers.

In this study, a new type of composite material combined with carbonyl iron, a relatively strong ferromagnetic material, was prepared to overcome the current application limitations of Prussian blue, which is effective in removing radioactive cesium. The surface of the prepared composite was analyzed using SEM and XRD, and it was confirmed that nano-sized Prussian Blue was synthesized on the particle surface. In order to evaluate the cesium removal ability, 0.2 g of the composite prepared for raw cesium aquatic solution at a concentration of 5 & mu;g was added and reacted, resulting in a cesium removal rate of 99.5 %. The complex follows Langmuir's adsorption model and has a maximum adsorption amount (qe) of 79.3 mg/g. The Central Composite Design (CCD) of the Response Surface Method (RSM) was used to derive the optimal application conditions of the prepared composite. The optimal application conditions achieved using Response optimization appeared at a stirring speed of pH 7, 17.6 RPM. The composite manufactured through this research is a material that overcomes the Prussian Blue limit in powder form and is considered to be excellent economically and environmentally when applied to a cesium removal site.

Air quality in Seoul is significantly worse than in major OECD countries, with 1.2-3.5 times higher levels of fine dust and nitrogen dioxide. Photocatalytic reaction with Ca-bound catalyst efficiently removes nitrogen oxides (NOx), especially in building materials, promising solutions for NOx removal in urban air purification. This study therefore investigates the effect of various forms of titanium dioxide (TiO2) on the mechanical properties and NOx removal capability of foam concrete. To produce foam concrete, the type and amount of air foaming agent were optimized. Two types of commercially available TiO2 (P25 and NP600) were incorporated into the foam concrete, alongside synthesized TiO2-mayenite (as an intermixing powder or a coating material). Test results indicated that the incorporation of P25 and NP600 led to increased compressive strength and decreased porosity. The strength increased and porosity decreased, as the amount of TiO2 powders was increased. P25 outperformed NP600 in terms of the NOx removal capacity of foam concrete, with the peak NOx removal capacity (6.07 mu mol/50 cm2.5 h) observed at a P25 content of 3%. An even higher NOx removal amount of 6.19 mu mol/50 cm2.5 h was achieved by triple-coating the foam concrete surface with 10 wt% TiO2-mayenite. Consid-ering the thickness of the coated TiO2-mayenite and economic feasibility, an approach with dual -coating emerged as the most suitable.

A porous photocatalyst concrete filter was successfully produced to remove NOx, by mixing TiO(2 )photocatalyst with lightweight aerated concrete. Ultra Fine Bubbles were used to form continuous pores inside the porous photocatalytic concrete filter, which was mixed via a bubble generation experiment. The optimal mixing condition was determined to be with 4 % of the bubble generation agent B. NO removal specimens were prepared for various photocatalytic loading conditions, and the specimen containing 3 % P-25 removed NO at a concentration of 1.03 mu mol in 1 h. The NO removal rate of the porous photocatalytic concrete filter prepared in this study was 10.99 %. This photocatalytic filter performance was more than 9 times the amount of NO removed by a general photocatalytic filter. The porous photocatalyst concrete filter for removing NOx developed in this study can be applied to various construction sites and the air quality can be solved by reducing NOx contributing to the formation of fine particles.

A porous photocatalyst concrete filter (deNOx PCF) is successfully manufactured to reduce NOx by mixing TiO 2 photocatalyst with lightweight aerated concrete. From the results, 4% infusion rate of each foaming agent provided the smallest change of the height, and the optimal quality of the air bubbles can be produced by using foaming agent B with 4% of infusion rate. When 3% of TiO 2 photocatalyst was mixed, less irregular and relatively homogeneous pores were formed on the surface with white color due to the proper amount of photocatalyst applied. For 3% of photocatalyst mixed with deNOx PCF, 1.03  μ mol/hr of NO was reduced equivalent to 10.99% of NO reduction, suggesting that the TiO 2 photocatalyst dispersed in the continuous and well-developed pores inside the specimen successfully performed the removal of NO flowing through deNOx PCF using synergistic effects of adsorption and photodegradation reaction. Finally, the specimen of porous deNOx PCF for reducing NOx developed in this study can be applied to various construction sites and the air quality can be solved by reducing NOx contributing to the formation of fine particles.

Two immobilization methods (i.e., ice water-soaked using a digital temperature controller vs. freeze-dried using liquid nitrogen) were applied for mass production techniques of TiO₂-embedded expanded polystyrene (TiEPS) balls with nanoscale TiO₂ particles embedded on EPS balls. No significant changes in crystalline structure of TiO₂ nanoparticles embedded on the TiEPS balls were observed during the mass production of TiEPS balls. Greater residuals of freeze-dried TiEPS balls suggested the improved immobilization methods for mass production procedures of TiEPS balls. Although similar growth inhibition between TiEPS balls using two immobilization methods was observed within 10 hrs, both growth and reproduction of M. aeruginosa can be more significantly inhibited by applying the freeze-dried TiEPS balls after 10 hrs. These results were mainly attributed to the difference in exposed surface area of embedded TiO₂ nanoparticles which generated various reactive oxygen species peroxidizing and leading to the inactivation and degradation of M. aeruginosa. Relatively greater k value (0.207 day-1) was estimated from freeze-dried TiEPS balls than that (0.089 day-1) from ice water-soaked TiEPS balls, suggesting that both growth and reproduction of M. aeruginosa were effectively inhibited with greater amounts of reactive oxygen species generated from freeze-dried TiEPS balls. Consequently, self-floating freeze-dried TiEPS balls can be readily applied to inhibit the excessive growth of harmful algae in the stagnant water body without the recovery process for long time.

Titanium tetrachloride (TiCl₄) as an alternative coagulant to remove organic matters and nutrients from the effluent of the secondary wastewater treatment was evaluated by comparison of removal efficiency of total phosphorous to Al- and Fe-based coagulants. Also, the surface characteristics, elemental contents, and crystallinity of the TiO₂ produced from wastewater sludge flocculated with TiCl₄ coagulant were investigated depending on the calcination temperatures. The more dosages of coagulants were injected, the greater concentrations of the cations (Al+3, Fe+3, Ti+4) and hydrogen ions (H+) resulted in the lower pH. Also, TiCl₄ formed larger and heavier flocs than other coagulants and resulted in greater T-P removal efficiencies with reduced amounts of dosage. The phase change of anatase and rutile crystalline structures of TiO₂ incinerated from wastewater sludges of TiCl₄ coagulant was observed at relatively high calcination temperatures due to the existence of mixtures of organic matters, nutrients, and various impurities in the wastewater sludges of TiCl₄ coagulant. Both C and P atoms were found to be mainly doped in/on TiO₂ and the C and P atom originated from residual carbon of the settled organic matters and phosphorus nutrients present in effluents from sewage treatment plant, respectively. Therefore, 600-800 °C is the optimal calcination temperatures for TiO₂ produced from TiCl₄ coagulant flocculated with effluents from sewage treatment plant.

In this study, nano-sized low cost titanium dioxide (TFS) was prepared using sludge from sewage treatment and performance was verified. To remove air pollutants, the photocatalytic degradation of methylene blue and efflorescence characteristics is assessed according to the mixing ratio of the nano-sized TFS by applying them to concrete sidewalk blocks. The photocatalytic degradation performance of concrete sidewalk blocks shows that the methylene blue removal rate of specimens containing 2.5%, 5%, and 10% of nano-sized TFS is 29%, 27%, and 38%, respectively. When the nano-sized TFS is mingled on the surface of the sidewalk block, the performance of anti-corrosion and antifouling showed excellency mainly due to the moisture blocking derived by the antifouling function of photocatalysts.

In this study, nano bubbles (NBs) of around 100 nm size were generated by using GoodSam-NB generator (made by S company) which utilizes cavitation technique. The generated NBs were directly applied to the strawberry cultivation process to monitor the productivity of strawberry. When the aqueous nutrient solution with NBs was supplied to the strawberry culture medium, it had a slightly higher initial concentration of dissolved oxygen (DO) compared to the nutrient solution prepared with ordinary groundwater at a concentration of about 9 mg/L and did not decrease over time. In other words, NBs helped to supply DO to support the development of roots in the early stage of strawberry’s growth, thereby promoting the overall growth of strawberries. After feeding the NBs nutrient solution, the nitrate concentration of the discharged solution was analyzed. The concentration of the nitrate in the effluent was reduced, hence the growth of strawberry was promoted. It can be concluded that the DO contained in aqueous nutrient solution with NBs helped the nitrate to be smoothly taken from the soil.

Among the various radioactive materials, Cesium is a major source of radioactive contamination and known to be the most dangerous radioactive material, can cause enormous damage to the ecosystem environment when released into the environment. Prussian Blue (PB) has been used as an adsorbent to effectively remove cesium, however it has the problem of being difficult to separate in water. In this study, carbonyl iron (CI) which is known as ferromagnetic synthesized with precursor of PB (FeCl3 and potassium ferricyanide) to solve the problem of PB particles. Adsorption isotherm experiments were also conducted to evaluate the cesium removal ability of the manufactured novel composites. The results obtained in the present study indicate that the novel composite has a cesium removal rate of 99.88% and a distribution coefficient value of 124,900 mL/g. Adsorption behavior follows Langmuir isotherms and the maximum adsorption amount is (q(m)) 79.3 mg/g. In conclusion, Nano-sized Prussian blue with carbonyl Iron prepared through this study has excellent cesium removal capacity, and it can be completely separated from water when used directly in the cesium treatment field.

Wastewater treatment plants (WWTPs) have been identified as main contributors to releasing microfibres into the environment, however, WWTPs do not have microfibre-targeting technologies. In this study, photocatalysis is evaluated as a potential technology to treat microfibres in WWTPs by studying the degradation of polyamide 66 (PA66) microfibres using ultraviolet (UV) and titanium dioxide (TiO2). PA66 microfibres suspended in deionised water were exposed to different combinations of UV and TiO2. The degradation of the PA66 microfibres was monitored by changes in mass, carbonyl index and morphology using microbalance, infrared spectroscopy, and scanning electron microscopy. The formation of by-products from the degradation of the fibres was evaluated by measuring the chemical oxygen demand (COD) of the treated water. The degradation efficiency was optimised under UVC with a dose of 100 mg TiO2/L. Under these conditions, the PA66 microfibres presented a 97% mass loss within 48 h. The photocatalytic conditions applied generated a relatively low level of by-products (<10 mg/L of COD). Therefore, photocatalysis with TiO2 an UVC could potentially be a feasible technology to treat microfibres in WWTPs, although more investigation is required to establish if this treatment leads to the formation of nanofibres. Further work is needed to translate the present optimised conditions to WWTPs.

Metaldehyde has been detected in drinking water system in relatively high concentration exceeding European water quality standard. In order to address this problem, the aim of this project was to treat metaldehyde aqueous solution by advanced oxidation processes (AOPs) and granular activated carbon (GAC) column. Ten novel materials were tested for degradation rates of metaldehyde under ultraviolet light irradiation (UVC). For treatment of 1 mg/L metaldehyde solution by AOPs, the highest degradation rate is 16.59% under UVC light with the aid of nitrogen doped titanium dioxide coated graphene (NTiO₂/Gr). Furthermore, 0.5 mg/L is the optimal concentration for degradation of metaldehyde with N-TiO₂/Gr under UVC light. Apart from that, the lifetime of GAC column could be elongated on condition that metaldehyde has been treated by AOPs previously. Hence, combination of AOPs and GAC column is promising in treating water containing metaldehyde.

Mass production technique of nanoscale TiO₂ particle-embedded expanded polystyrene (EPS) balls with temperature-controlled melting method was developed, and the photocatalytic activity of TiO₂-embedded EPS (TiEPS) balls to suppress the excessive growth of Microcystis aeruginosa (M. aeruginosa) cultured from both indoor and outdoor experiments was verified under ultraviolet and solar light irradiation, respectively. According to the experimental results, the growth inhibition of M. aeruginosa was evidently observed by applying TiEPS balls, and increased proportionally with the surface area coverage of TiEPS balls. Based on the comparison of both specific growth rate (μ) and first-order degradation rate (k), the experimental cases using TiEPS balls with surface area coverage of 100% suppressed more significantly the growth of M. aeruginosa cultured from both indoor and outdoor experiments during the initial period of the experiment. However, through the whole experiment, both μ and k values between experimental cases using TiEPS balls and EPS balls with surface area coverage of 100% were not statistically different (p > 0.05). These results indicated that the photocatalytic degradation effect was dominant during the initial period of application, and the irradiation shading became dominant with the elapsed time. Therefore, the growth of M. aeruginosa can be suppressed due to both synergistic and combinational effects of photocatalytic degradation and irradiation shading under natural solar light. Based on the aforementioned results, self-floating TiEPS balls produced from this simple and cost-effective mass production technique can be readily applied to inhibit the excessive growth of harmful algae in the stagnant water body.

A new immobilization technique of nanoscale TiO₂ powders to expanded polystryrene (EPS) balls with temperature-controlled melting method was validated for mass production, and the photocatalytic activity of TiO₂ powder-embedded EPS (TiEPS) balls using methylene blue (MB) solution with different concentrations under ultraviolet irradiation and under the natural solar light irradiation. Whereas MB molecules were weakly adsorbed onto the surface of both TiO₂ powders and supporting polymers without any specific interactions, the photocatalytic efficiency of TiEPS balls with UV (Kapp =0.016~0.043 min-1) was greater through coupled reaction processes (adsorption, photolysis, and photocatalysis). After 5-min sonication, more TiO₂ powders on the TiEPS balls can be involved into the both adsorption and photocatalytic reactions of MB, and can increase the MB removal efficiencies. TiEPS balls can be reused for several consecutive runs without any significant decrease in photocatalytic activity until the recalcitrant contaminants were completely coated on the surface of TiEPS balls and loss of TiO₂ powders embedded on the surface of TiEPS balls was significant. Based on the aforementioned results, self-floating TiEPS balls manufactured from this simple and cost-effective melting method can be used to remove the organic contaminants and to inhibit the excessive growth of harmful algae in the stagnant water body.

The aim of this study is to evaluate a newly invented instrument, activated sludge plant controller (ASP-Con), and to optimize treatment processes by reducing energy consumption and saving costs in pursuance of achieving sustainable energy and water cycles. Although three hundred billion dollars of investment were put into the energy independence project to save energy and cost when operating wastewater treatment plant in Korea, it failed because the investments were allocated only to improvements of digester facilities, designs, and capacities. To propose a feasible optimization strategy for the wastewater treatment plant with minimal wastes, the ASP-Con was introduced and experimented in four major wastewater treatment plants in the Republic of Korea. This study identifies the optimal operating points for blower based on the oxygen uptake rate and dissolved oxygen measurement, and supported by ammonium measurements to run the plant efficiently in real time.

Novel composites with nano-sized TiO₂ synthesized on the surface of bottom ash (NTB) were prepared for treatment of spent sulfidic caustic (SSC) wastewater. The efficiency of SSC wastewater treatment was compared and evaluated by using NTBs made with organic binder and inorganic binder, respectively. The treatment efficiency of NTB composite made with organic binder was higher than that of NTB composite made with inorganic binder. Although NBT composite made with inorganic binder had many pores on the surface, the white cement used as binder was excessively applied to the surface, and amount of coated nano-sized TiO₂ was decreased. The photocatalytic activity of nano-sized TiO₂ is more effective for SSC wastewater treatment than surface adsorption ability of surface pores.