Samples of the bimetallic-based NH₂-MIL-125(Ti) at a ratio of Mⁿ⁺/Ti⁴⁺ is 0.15 (Mⁿ⁺: Ni²⁺, Co²⁺ and Fe³⁺) were first synthesized using the solvothermal method. Their fundamental properties were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectra, scanning electron microscopy (SEM), N₂ adsorption–desorption measurements, and UV–Vis diffuse reflectance spectroscopy (UV-Vis DRS). The as-acquired materials were used as high-efficiency heterogeneous photocatalysts to remove Rhodamine B (RhB) dye under visible light. The results verified that 82.4% of the RhB (3 × 10⁻⁵ M) was degraded within 120 min by 15% Fe/Ti−MOFs. Furthermore, in the purpose of degrading Rhodamine B (RhB), the rate constant for the 15% Fe/Ti-MOFs was found to be 2.6 times as fast as that of NH₂-MIL-125(Ti). Moreover, the 15% Fe/Ti-MOFs photocatalysts remained stable after three consecutive cycles. The trapping test demonstrated that the major active species in the degradation of the RhB process were hydroxyl radicals (HO^∙) and holes (h⁺).

Recently, organic contaminants from textile and dye industry have adversely affected on human’s health and living things. Hence, the development of effective contaminated water treatment is one of the most crucial tasks. Expanded Graphite (EG) has been considered as efficient platforms to remove of organic dyes from aqueous solution due to its excellent performance. The main objective of the present work is to investigate adsorption behavior of methylene blue (MB) and Congo Red (CO) on exfoliated graphite fabricated using flake graphite from Yen Bai province. The exfoliation of graphite was carried out using potassium permanganate and perchloric acid as oxidant agent and anhydride acetic as intercalating agent via microwave-assisted technique. The properties of EG were characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy and nitrogen adsorption/desorption analysis. In batch adsorption experiments, various factors including initial dye concentration (50–600 ppm), adsorbent dosage (0.5–3 g/L), contact time (10–120 min) and pH of solution (4–10) were also studied. It is found that as-prepared EG provided high removal efficiency and fast adsorption rate for MB and CO. The maximum adsorption capacity of EG for CO and MB was found at 201.21 and 47.62 mg/g, respectively. These results demonstrate that the as-synthesized EG appears as an efficient and low-cost platform for remediation of colored effluents via adsorption route.

Co-doped Fe-MOF bimetallic organic framework materials at different ratios were synthesized based on the solvothermal method, and we evaluated their morphological characteristics by modern analytical methods such as SEM, XRD, FT-IR, and isotherm of nitrogen adsorption-desorption (BET). The specific surface area of the 0.3 CoFe-MOF sample (280.9 m²/g) is much larger than the Fe-MOF and samples at other ratios. The post-synthesized materials were evaluated for their ability to absorb various dyes, including Methylene Blue (MB), Methyl orange (MO), Congo red (CR), and Rhodamine (RhB), and evaluated for the effects of pH, the initial concentration of the dye solution, time, and dose of adsorbent. The results show that the 0.3 CoFe-MOF material has a high adsorption capacity that is superior to both the original Fe-MOF and the CoFe-MOFs at other ratios. The highest adsorption capacity of MB dye by 0.3 CoFe-MOF reaches up to 562.1 mg/g at pH 10, the initial concentration of MB of 200 mg/L, after 90 min. The charged properties of the dyes and the charged nature of the bimetallic organic frameworks are best demonstrated through the adsorption of dye mixtures. The adsorption efficiency on the mixed system of cationic (MB) and anionic (MO) dyes yielded the highest removal efficiency of 70% and 81%, respectively, after 30 min. Therefore, the research has opened up the potential application of M/Fe-MOF modified materials and CoFe-MOF in organic dyes adsorption in wastewater treatment for environmental protection.

Activated carbon is produced from Burmese grapes using NaOH as the activator under microwave irradiation. Through scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction analysis, and Brunauer–Emmett–Teller analysis methods, the activated carbon material is found to have a rough and uneven surface with the formation of pores, an amorphous structure, and possesses hydroxy, C–H, carbonyl, alkene, and ether functional groups. The surface area (478.5 m² g⁻¹) and pore size (about 3.4 nm) are calculated from the adsorption N₂equation. The adsorption mechanism of activated carbon is evaluated and follows a pseudo-first-order kinetic model (large single adsorption) and the Langmuir isotherm model (physical interaction). The factors affecting ciprofloxacin adsorption using activated carbon derived from Burmese grapes are also evaluated and optimized by the response surface method model based on influencing factors including the contact time, the solution pH, the antibiotic concentration, and the material dosage. The optimal parameters are as follows: pH = 6.26, concentration = 58.9 mg L⁻¹, content = 0.15 g L⁻¹, time = 54 min. Under optimal conditions, the adsorption capacity predicted from the model is 191.33 mg g⁻¹with an efficiency of 41.35%.

In this study, we investigated the adsorption process of organic Congo red (CR) by M/Fe-MOF (M=Co, Ni) materials. The results of the study show that the optimal adsorption capacity of the materials under the optimal conditions is as follows: Adsorbent weight 0.1 g/L and pH8 for all 3 materials. At the concentration of colorant CR 75 mg/L, the adsorption capacity reached 530 mg/g for Co/Fe- MOF materials; for Ni/Fe-MOF materials, the adsorption capacity reached 560 mg/g, at the colorant concentration CR 140 mg/L; for Fe-MOF materials, the adsorption capacity reached 523 mg/g, at the colorant concentration CR 120 mg/L. The experimental data are consistent with Langmuir and PSO models for both M/Fe-MOF materials (M=Co, Ni). Research results on the reuse process of M/Fe-MOF (M=Co, Ni) materials show that the material is reused 4 times. With this result, it can be considered as the first step to improve the efficiency of pigment adsorption in the current water pollution treatment problem.

The catalytic effect of red mud on Vietnam anthracite’s combustion characteristics was investigated. The mineralogical composition of the red mud includes CaCO₃, Fe₂O₃, FeO(OH), FeTiO₃, and Al(OH)₃. This red mud is rich in Na, Ca, Al, Fe, and Ti. The combustion characteristics were analyzed by the thermogravimetry method. The combustion effectiveness was assessed by thermogravimetric analysis. The results were derived from a combination of several parameters, such as the ignition temperature, the burnout efficiency, and the amount of heat release. The combustion characteristics of pulverized coal were improved by the introduction of red mud, and the greatest catalytic performance was achieved when the content reached 6%. With the optimal addition, the ignition temperature of anthracite was reduced by 12 °C, and the burnout efficiencies were increased by 2.59% compared to raw anthracite. The amount of heat released by anthracite was increased to 6.93 kJ/g by adding red mud.