Publications by authors named "Chang-Gu Lee"

Oxidative polymerization of phenolic pollutants by the heterogeneous Fenton-like reaction is a sustainable strategy for wastewater decontamination and recovery of carbonaceous resources. However, controlling the reaction pathway to selectively polymerize the phenolic pollutants is challenging. Herein, we used visible light to shift the reaction pathway from phenolic pollutants degradation (which often results in incomplete mineralization) to polymerization over a g-C₃N₄ catalyst deposited on a Cu₂O nanowire.

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The piezoelectric catalyst process has emerged as a promising technology for energy harvesting, effectively converting natural mechanical energies, such as wind, water flow, and waves, into usable electrical energy using piezoelectric materials. In recent years, there has been a growing interest in applying this technology to water treatment to address environmental challenges. Concurrently, research efforts have focused on enhancing the efficiency of piezoelectric catalysis by integrating it with advanced oxidation processes (AOPs).

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This study investigated the potential of machine learning (ML) as a substitute for polynomial regression in conventional response surface methodology (RSM) for decolorizing textile wastewater via a UV/HO process. While polynomial regression offers limited adaptability, ML models provide superior flexibility in capturing nonlinear responses but are prone to overfitting, particularly with constrained RSM datasets. In this study, we evaluated decision tree (DT), random forest (RF), multilayer perceptron (MLP), and extreme gradient boosting (XGBoost) models with respect to a quadratic regression model.

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The doping or co-doping of graphitic carbon nitride (g-CN) with other elements is a useful modification technique that overcomes the disadvantages of the base material and enhances its photocatalytic performance. In this study, K and P were successfully incorporated into g-CN using a one-step, single-precursor (KHPO) synthesis method. The incorporation of K and P was confirmed using energy-dispersive X-ray spectrometry and wavelength-dispersive X-ray fluorescence spectrometry.

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Cadmium (Cd), a carcinogen, is released from industrial activities like metal refineries and battery runoff, with significant contamination reported near zinc smelters in Korea. This study addresses the issue using an efficient, economical adsorption process with waste-derived biochar-based adsorbents known for high Cd removal. Poultry manure (PM), typically used as fertilizer, can lead to environmental pollution if mismanaged; therefore, it was pyrolyzed to produce biochar.

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This study explored the innovative application of wood bottom ash (WBA) as an adsorbent for arsenic (As) removal from wastewater, focusing on the adsorption mechanism and optimisation of the operational conditions. Comprehensive spectroscopic analyses, including FE-SEM/EDS, BET, XRF, XRD, FT-IR, and XPS, were performed to examine the elemental and mineralogical changes in WBA before and after As adsorption. The study assessed the adsorption kinetics and isotherms, revealing that As adsorption reached equilibrium within 48 h, with a maximum capacity of 121.

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The effective treatment of cadmium (Cd) in smelting wastewater is of great industrial importance. This study investigates the efficient removal of Cd from real industrial smelting wastewater via chemical precipitation using a series of experiments. In particular, the effects of different precipitants, agitation conditions, and the addition of NaOCl on Cd removal and pH variation are investigated.

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In the face of increasing nitrogen demand for crop cultivation driven by population growth, this study presents a sustainable solution to address both the heightened demand and the energy-intensive process of nitrogen removal from wastewater. Our approach involves the removal of nitrogen from wastewater and its subsequent return to the soil as a fertilizer. Using biochar derived from Aesculus turbinata fruit shells (ATFS), a by-product of post-medical use, we investigated the effect of pyrolysis temperature on the NH-N adsorption capacity of ATFS biochar (ATFS-BC).

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Article Synopsis
  • Algal blooms can harm water quality and lead to various issues, especially in a region of Korea known for high nitrogen and phosphorus levels from a sewage treatment plant.
  • Researchers used four machine learning models to predict chlorophyll-a (Chl-a) concentrations and found that discharge flow rate (D-Flow) and water temperature were the main factors influencing algal blooms.
  • The study revealed that maintaining a specific D-Flow is crucial for controlling Chl-a levels, with different seasonal demands indicating that adjusting D-Flow strategically can help mitigate algal bloom problems effectively.
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The surface hydrophilicity of a photocatalyst is an important factor that directly influences its interactions with organic pollutants and significantly impacts its degradation. In this study, we investigated the impact of increased hydrophilicity of g-CN (CN) by alkaline solvothermal treatment on the degradations of three antibiotics (oxytetracycline (OTC), oxolinic acid (OA), and sulfamethoxazole (SMX)) with different log K values. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and Fourier-transform infrared (FT-IR) spectroscopy showed no significant differences in the morphology, crystalline structure, and surface functional groups of CN after alkaline solvothermal treatment (Nv-HPCN).

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  • The study investigates the use of floating photocatalysts in continuous stirred tank reactor (CSTR) systems for effective water treatment, focusing on removing the pollutant methylene blue (MB).
  • A synthesized expanded polystyrene (EPS)-TiO composite showed greater pollutant degradation rates in the CSTR system compared to batch systems, with a degradation rate constant of 0.0126-0.0172/min versus 0.0113/min.
  • The research highlights the efficiency of the EPS-TiO/UV CSTR setup in using light and energy, offering insights for sustainable water treatment technologies in large-scale applications.
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Fenton sludge is a byproduct of the Fenton process that contains large amounts of Fe and Ca. Because of the secondary contamination generated during the disposal of this byproduct, ecofriendly treatment methods are needed. In this study, we used Fenton sludge to remove the Cd discharged from a zinc smelter factory, using thermal activation to enhance the Cd adsorption capacity.

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Quercus wood was used for thermal energy production, and wood bottom ash (WDBA) was used as a medium for water purification and soil fertilizer in accordance with the recently proposed food-water-energy nexus concept. The wood contained a gross calorific value of 14.83 MJ kg, and the gas generated during thermal energy production has the advantage of not requiring a desulfurization unit due to its low sulfur content.

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This study addresses ways to circulate the flow of phosphorus (P) from water to soil to improve water quality and provide a sustainable supply of P into soil. Here, bottom ash (BA_CCM), the byproduct of the combustion of cattle manure, which is performed for obtaining energy, was used to remove P in wastewater. Next, the P-captured BA_CCM was used as P fertilizer for rice growth.

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Photocatalysis offers opportunities to degrade recalcitrant organic pollutants without adding treatment chemicals. Nitrogen (N) vacancy is an effective point-defect engineering strategy to mitigate electron-hole recombination and facilitate hydroxyl radical (•OH) production via superoxide radical (O) generation during photocatalytic application of graphitic carbon nitride (g-CN). Here, we report a novel strategy for fabrication of N-vacancy-rich g-CN (NvrCN) via post-solvothermal treatment of Mg-doped g-CN.

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Article Synopsis
  • Researchers synthesized ordered mesoporous carbons (OMCs) to efficiently remove methylene blue (MB) dye from water, focusing on their pore characteristics.
  • The OMCs showed varying pore sizes and lengths, optimizing the accessibility of MB, with sCMK-5 exhibiting a much faster adsorption rate compared to commercial activated carbon.
  • The adsorption process was found to be endothermic and driven by both physical adsorption and chemisorption, making OMCs effective for treating wastewater that contains dye contaminants.
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Sweat discharged as a result of exposure to sauna plays an important role in removing inorganic ions accumulated in the body, including heavy metals. In this study, inorganic ions (toxic and nutrient elements) excreted in the form of sweat from the body using a water-filtered infrared-A (wIRA) sauna were determined using inductively coupled plasma sector field mass spectrometry. The analyzed elements included eight toxic elements (Al, As, Be, Cd, Ni, Pb, Ti, and Hg) and 10 nutrient elements (Ca, Co, Cr, Cu, Fe, Mg, Mn, Se, V, and Zn), and their correlations were determined.

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In this study, we optimized and explored the effect of the conditions for synthesizing Fe-loaded food waste biochar (Fe@FWB) for Cr(VI) removal using the response surface methodology (RSM) and artificial neural network (ANN). The pyrolysis time, temperature, and Fe concentration were selected as the independent variables, and the Cr(VI) adsorption capacity of Fe@FWB was maximized. RSM analysis showed that the p-values of pyrolysis temperature and Fe concentration were less than 0.

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This work investigates the applicability of thermally treated calcium-rich minerals (CRMs), such as sepiolite (SPL), attapulgite (ATT), and dolomite (DLM) to hinder the nitrogen (N) and phosphorus (P) release from river sediments. A non-woven fabric mat (NWFM) or a sand layer were also capped as armor layers, i.e.

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Article Synopsis
  • The study examined the levels and distribution of six phthalate acid esters (PAEs) in the Pearl River's surface water and sediment, revealing that di(2-ethyl-hexyl) phthalate (DEHP) and dibutyl phthalate (DBP) were the most prevalent.
  • Overall concentrations of PAEs in water ranged from 1,797.5 to 4,968.5 ng/L, while sediment levels varied from 95.24 to 3,677.26 ng/g dw, with contamination levels highest in Xijiang River (XR) and Beijiang River (BR).
  • The research found that agricultural and industrial activities, along with seawater intrusion, likely contributed to P
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Phosphorus, a limiting element, is essential for living organisms, but the total amount available is decreasing with its increasing use. This problem can be solved by studying the methods of phosphorus recovery from waste. Phosphorus (PO, 13.

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This study investigated the solution for two environmental issues: excess of P in water and its deficiency in soil, which is restored by transferring the adsorbed P from water into the soil using eggshell as an adsorbent. The eggshells were calcined at different temperatures to improve their adsorption capacity, and evaluated for their physical/chemical properties and P adsorption capacity. The eggshells calcined at 800 °C (CES-800) had the highest P adsorption; CaCO decomposed into 23.

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Herein, pyrolysis of cattle manure was conducted to synthesize an effective material for removing heavy metals (e.g., selenium) from water environments.

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This study investigated the applicability of waste antivirus copper film (CF) as a Fenton-like catalyst. The reaction activity of HO and CF in combination was significantly enhanced by ultrasound (US) irradiation, and the synergy factor calculated from bisphenol A (BPA) degradation using CF-HO-US was 9.64 compare to that of dual factors.

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In this study, the use of eggshells was suggested as an adsorbent for fluoride removal, and their mechanism of fluoride removal was investigated. The eggshells underwent thermal treatment to improve their adsorption capacity; 800 °C was found to be the optimal temperature for treatment. Eggshells thermally treated at 800 °C (ES-800) were mainly composed of Ca (82.

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