Organic wastewater causes serious environmental pollution, and catalytic oxidation is promising technique for wastewater treatment. Developing green and effective catalysts is currently challenging. In this work, green synthesis of nano zerovalent iron loaded onto porous biochar derived from popcorn is conducted, and catalytic oxidation of Rhodamine B (RhB) is evaluated in the presence of H2O2. Effect of process factors is examined on catalytic performance for RhB removal. The mechanism of RhB removal is discussed by characterizations (Fourier transform infrared spectra and Raman) and UV–vis spectra. RhB removal is improved with high catalyst dosage, low initial RhB concentration, and high reaction temperature, while it is slightly influenced by carbonization temperature of biochar, H2O2 dosage and pH value. Under conditions of BC-250 1.0 g/L, H2O2 0.01 mol/L, pH 6.1, and temperature 30 °C, the removal rate of RhB is 92.27% at 50 min. Pseudo first-order kinetics is used to fitting experimental data, and the activation energy for RhB removal in BC-250/H2O2 system is 39 kJ/mol. RhB removal in BC-250/H2O2 system can be attributed to adsorption effect and catalytic oxidation with the dominant role of hydroxyl radical. This work gives insights into catalytic oxidation of organic wastewater using green catalyst.

Selenium (Se), a vital trace element found naturally, plays a pivotal role for human being in low concentrations. Notably, within the spectrum of essential elements, Se possesses the most restricted range between the dietary deficiency (< 40 μg day-1) and the acute toxicity (> 400 μg day-1). Therefore, it is of paramount importance to maintain bioavailable Se levels within permissible limits in our drinking water sources. Among the various Se species, inorganic variants such as selenite (SeO3 2-) and selenate (SeO4 2-) are highly water-soluble, with SeO3 2- being notably more toxic than SeO4 2-. Consequently, the primary focus lies in effectively sequestering SeO3 2- from aquatic environments. Numerous methods have been investigated for SeO3 2- adsorption, including the use of metal oxides and carbon-based materials. Especially, iron oxides have garnered extensive attention due to their water stability and environmentally friendly properties. Nevertheless, their limited surface area and insufficient adsorption sites impose constraints on their efficacy as materials for SeO3 2- removal. Recently, metal–organic frameworks (MOFs), composed of metal centers bridged by organic linkers have increasingly focused as promising adsorbents for SeO3 2- removal, offering significant advantages such as large surface areas, high porosities, and structural versatility. Furthermore, there is a growing interest in defective MOFs, where intentional defects are introduced into the MOF structure. This deliberate introduction of defects aims to enhance the adsorption capacity by increasing the number of available adsorption sites. In this context, herein, we present the Fe-BTC (BTC = 1,3,5-benzenetricarboxylic acid) synthesized via a post-synthetic metal-ion metathesis (PSMM) approach, which is one of the defect engineering methods applied to metal sites. We employ the well-established MOF, HKUST-1, known for its substantial surface area, as the pristine MOF. While the pristine MOF has a crystalline phase, during the PSMM process, Fe-BTC is transformed into an amorphous phase by allowing the introduction of numerous metal defect sites. These introduced metal defect sites serve as Lewis acidic sites, enhancing the adsorption capability for selenite. Furthermore, despite its amorphous nature, Fe-BTC exhibits a substantial surface area and porosity comparable to that of the crystalline pristine MOF. Consequently, Fe-BTC, distinguished by its numerous adsorption sites and its high porosity, demonstrates a remarkable capacity for selenite adsorption.

Heavy metal wastewater containing cobalt (Co2+) has received more attention as an environment issue, which is released from electroplating processes, battery materials industries, nuclear power plants, etc. Especially, cobalt exposed to high-temperature and high-pressure environment during the operation of a nuclear power plant to form corrosion products and forming a chalk river unidentified deposit (CURD) along with radioactive materials generated in cooling water pipes. Cobalt present in the oxide film is mainly Co-60, which emits radiation and causes increased radiation exposure to workers, and efficient management is essential. In this study, we demonstrated the performance of copper hexacyanoferrate (CuHCF) electrodes in a capacitive deionization (CDI) system for Co2+ ions removal. The structure and chemical status of CuHCF used as an electrode material were characterized, and electrochemical properties were evaluated. This study showed that Co2+ ions could be efficiently removed in aqueous solutions using CuHCF electrodes. It has been experimentally shown that the ion removal mechanism is driven by the insertion of Co2+ ions within the CuHCF lattice channels. The deionization capacities in 20 and 50 mg-Co2+ L-1 aqueous solutions were 141.62 and 156.85 mg g-1, respectively, and the corresponding charge efficiencies (Λ) were 0.55 and 0.68, respectively. Thus, we suggest that an electrochemically driven process using CuHCF can usefully remove Co2+ ions from wastewater.

To address the pressing societal concern in Korea, characterized by the imminent saturation of spent nuclear fuel storage, this study was undertaken to validate the fundamental reprocessing process capable of substantially mitigating the accumulation of spent nuclear fuel. Reprocessing is divided into dry processing (pyro-processing) and wet reprocessing (PUREX). Within this context, the primary focus of this research is to elucidate the foundational principles of PUREX (Plutonium Uranium Redox Extraction). Specifically, the central objective is to elucidate the interaction between uranium (U) and plutonium (Pu) utilizing an organic phase consisting of tributyl phosphate (TBP) and dodecane. The objective was to comprehensively understand the role of HNO3 in the PUREX (Plutonium Uranium Redox Extraction) process by subjecting organic phases mixed with TBPdodecane to various HNO3 concentrations (0.1 M, 1.0 M, 5.0 M). Subsequently, the introduction of Strontium (Sr-85) and Europium (Eu-152) stock solutions was carried out to simulate the presence of fission products typically contented in the spent nuclear fuel. When the operation proceeds, the complex structure takes the following form. 􀜷􀜱􀬶 􀬶􀬾(􀜽􀝍) + 2􀜰􀜱􀬷 􀬿(􀜽􀝍) + 2􀜶􀜤􀜲(􀝋􀝎􀝃) ↔ 􀜷􀜱􀬶(􀜰􀜱􀬷)􀬶 ∙ 2􀜶􀜤􀜲(􀝋􀝎􀝃) Subsequently, separate samples were gathered from both the organic and aqueous phases for the quantification of gamma-rays and alpha particles. Alpha particle measurements were conducted utilizing the Liquid Scintillation Counter (LSC) system, while gamma-ray measurements were carried out using the High-Purity Germanium Detector (HPGe). The distribution ratio for U, Eu (Eu-152), and Sr (Sr-84) was ascertained by quantifying their activity through LSC and HPGe. Through the experiments conducted within this program, we have gained a comprehensive understanding of the selective solvent extraction of actinides. Specifically, uranium has been effectively separated from the aqueous phase into the organic phase using a combination of tributyl phosphate (TBP) and dodecane. Subsequently, samples containing U(VI), Eu(III), and Sr(II) underwent thorough analysis utilizing LSC and HPGe detectors. Our radiation measurements have firmly established that the concentration of nitric acid enhances the selective separation of uranium within the process.

In order to extend the business viability of carbon nanotubes (CNTs), research on CNT dispersion in a solvent as well as in polymer matrix should be established. Herein, three kinds of dispersing agents, sodium deoxycholate (DOC), sodium dodecylbenzene sulfonate (NaDDBS), polyvinyl pyrrolidone (PVP), are selected and applied to quantify the dispersibility and dispersion stability of CNT aqueous dispersion. The dispersibility of CNT dispersion with the PVP, evaluated via viscosity and particle size analyses, are superior to those with the DOC and NaDDBS dispersing agents. CNT aqueous solution dispersed with PVP showed slightly higher viscosity and narrower particle size distribution than those with DOC and NaDDBS dispersing agents. In addition, the dispersion stability of CNT dispersion with the PVP, measured via lumisizer analyses, are superior to those with the DOC and NaDDBS dispersing agents. HR-TEM analysis verifies that the outstanding dispersibility and dispersion stability of CNTs in aqueous solution are due to the effect of the robust polymer wrapping of the PVP dispersing agent on the CNT surface. From the results of this study, the guidelines for the selection of the suitable dispersing agents and the systematic evaluation of dispersibility and dispersion stability of CNT dispersions can be suggested.

Novel eco-friendly adsorbents were prepared through pyrolysis and acid activation of raw almond leaf (RAL) to form almond leaf biochar (ALB) and chemically activated almond leaf biochar (CAL), respectively. The prepared adsorbents were characterized using TGA, FTIR, SEM–EDX, BET and XRD techniques and their physicochemical properties investigated. RAL, ALB and CAL were utilized for adsorption of BPB dye from aqueous solution using batch technique under optimum conditions. The optimum dye adsorbed by RAL, ALB and CAL were 92.83, 93.21 and 94.89%, respectively at pH 3, dye initial conc. (100 mg/L), adsorbent dose (0.04 g/25 mL), 60 min contact time and 301 K adsorption temperature. Although, Langmuir maximum monolayer adsorption capacities were found to be 365.36, 535.62 and 730.46 mg/g for RAL, ALB and CAL, respectively, but isotherm conformed to Freundlich model. Kinetic study confirmed suitability of pseudo-second-order model with rate constant 9.33 × 10–4, 9.91 × 10–4 and 12.60 × 10−4 g mg−1 min−1 for RAL, ALB and CAL, respectively. Negative values of thermodynamic parameters (ΔG and ΔH) established sequestration process to be spontaneous and exothermic. RAL, ALB and CAL were discovered to be highly efficient adsorbents that could be used in place of expensive commercial adsorbents.

수용액에서 Sodium hyaluronate(NaHA)와 Alkanediyl-bis(dimethylalkylammonium bromide) 계면활성제의 회합성질에 관한 연구를 계면활성제의 화학적 구조와 관련하여 조사하였다. 계면장력을 측정한 결과 특정 농도에서 최소값(Cmin)을 나타내는 포물선 모양의 그래프를 보여주었다. 이 최소 농도 이상에서 계면장력의 증가는 공기와 물의 접촉면에서 NaHA사슬과 이합체 계면활성제들로 이루어진 집합체의 형성과 관계있다고 생각된다. NaHA와 계면활성제의 착물결합체에서 하나의 NaHA 음전하에 대한 계면활성제의 양전하 비율을 보면 약간 양전하가 우세하나, 전체적으로 전하의 균형은 크게 벗어나지 않았다. NaHA/이합체 계면활성제의 착물결합체에서 계면활성제 농도와 점성도의 관계가 비 선형성을 나타내는 것은 계면활성제의 화학적 구조와 관계되기 때문이다. 이 비 선형성은 착물체의 성장에 따른 크기 증가와 Cmin 농도 이상에서의 수축 현상과 밀접하게 관련된다고 볼 수 있다.

Recently, various researches have been studied, such as water treatment, water reuse, and seawater desalination using CDI (Capacitive deionization) technology. Also, applications like MCDI (Membrane capacitive deionization), FCDI (Flow-capacitive deionization), and hybrid CDI have been actively studied. This study tried to investigate various factors by an experiment on the TDS (Total dissolved solids) removal characteristics using MCDI module in aqueous solution. As a result of the TDS concentration of feed water from 500 to 2,000 mg/L, the MCDI cell broke through faster when the higher TDS concentration. In the case of TDS concentration according to the various flow rate, 100 mL/min was stable. In addition, there was no significant difference in the desorption efficiency according to the TDS concentration and method of backwash water used for desorption. As a result of using concentrated water for desorption, stable adsorption efficiency was shown. In the case of the MCDI module, the ions of the bulk solution which is escaped from the MCDI cell to the spacer during the desorption process are more important than the concentration of ions during desorption. Therefore, the MCDI process can get a larger amount of treated water than the CDI process. Also, prepare a plan that can be operated insensitive to the TDS concentration of backwash water for desorption.

양이온 계면활성제인 tetradecyltrimethylammonium bromide (TTAB)에 의한 크레졸 이성질 체의 가용화에 미치는 치환기, 온도 그리고 NaCl과 n-부탄올과 같은 첨가제의 효과를 UV-Vis법으로 측정하였다. 가용화상수(K8)값은 o-크레졸<m-크레졸<p-크레졸 순으로 증가하였으며, 온도의 증가에 따라 이들 K8값은 감소하였다. 크레졸 이성질체들의 가용화에 대하여 계산한 ΔG0값과 ΔH0값은 모두 음의 값을 나타내었다. 그러나 ΔS0값은 모두 양의 값을 나타내었다. 또한 ΔG0값은 n-부탄올의 농도가 증가할수록 증가하는 경향을 그러나 NaCl의 농도가 증가할수록 더욱 감소하는 경향을 보였다. 이러한 사실들로부터 크레졸 이성질체들의 가용화에는 엔탈피와 엔트로피가 동시에 기여하고 있으며, 또한 크레졸분자들이 가용화되는 위치는 미셀의 표면이나 palisade층에서 주로 이루어짐을 알 수 있다.

The biosorption characteristics of SRCM 120569 biomass on anionic Congo red (CR) dye. SRCM 120569 strain isolated from Korean turbid rice wine (makgeolli) was identified by 16S rRNA sequence analysis as Bacillus licheniformis. Bacillus licheniformis SRCM 120569 (Genbank Accession No. MW819861) showed superior CR dye biosorption capacity in an aqueous solution. Maximum adsorption capacities of 61.2 and 133.1 mg/g were obtained at pH 3.41 and 0.01 g/50 mL dried cell dosage, respectively. The CR dye adsorption properties by the Bacillus licheniformis SRCM120569 strain were characterized by Fourier transform infrared spectroscopy (FT-IR), point of zero charge (pHpzc) analysis, and phylogenetic analysis. The biosorption isotherm and kinetic models are well described with the Langmuir adsorption isotherm and pseudo-second-order kinetic models.

In this research, Pb (II), Co (II), and Ni (II) toxic heavy metal ions adsorption from synthetic aqueous system have been studied using the activated carbon prepared from Citrus limetta leaves. Therefore, the relationship between the adsorption parameters (solution pH, dosage of adsorbent, temperature, initial concentration of the ions, and adsorption time) and the removal percentage of the prepared adsorbent have been investigated. Additionally, the adsorbent was analyzed through BET, SEM, EDX, FTIR, and XRD analyses. According to the results, the maximal adsorption efficiencies for heavy metal ions were achieved in pH = 6, the adsorbent dosage of 1 g/L, temperature = 25 °C, the ion initial concentration of 5 mg/L, and contact time of 60 min, which were 99.53%, 98.63%, and 97.54% for Pb, Co, and Ni ions, respectively. Based on Kinetic studies, the performance of pseudo-second-order kinetic model was better than pseudo-first-order model for the description of time-dependent behavior of the process. Additionally, the equilibrium data were fitted by Langmuir and Freundlich isotherms, while the former performed better than the latter. The maximum adsorption capacity values for Pb, Co, and Ni ions were achieved equal to 69.82, 60.60, 58.139 mg/g, respectively. Considering the thermodynamic data, the studied processes were exothermic and spontaneous.

In this study, Bacillus sp. SRCM 112835 was isolated from soybean paste (Doenjang, Korean Fermented Soy Paste). Bacillus sp. SRCM 112835 showed biosorption of the Cu (II) in aqueous solution. The strain effectively absorbed 30.2% of the Cu (II) from a 52.3 mg/L within 60 min. The properties of the Bacillus sp. SRCM 112835 were investigated by Fourier transform infrared spectroscopy (FT-IR), point of zero charge (pHpzc), and phylogenetic analysis. The influence of initial pH (2.08-9.98) and biomass dosage (0.005-0.07 g) were likewise probed. Isotherm and kinetic experiment results suggested that the Langmuir isotherm and pseudo-second-order kinetic models well-fitted the experimental data, respectively.