In natural water bodies, humic acid (HA), generated during the chlorination disinfection process at water treatment plants, can produce halogenated disinfection by-products, increasing the risk to drinking water safety and posing a threat to human health. Effectively removing HA from natural waters is a critical focus of environmental research. This study established a synergistic ultraviolet/peroxymonosulfate (UV/PMS) system to remove HA from water. It compared the efficacy of various UV/advanced oxidation processes (AOPs) on HA degradation, and assessed the influence of different water sources, initial pH, oxidant concentration, and anions (HCO₃ ⁻, Cl⁻, NO₃ ⁻) on HA degradation. The degradation mechanism of HA by the UV/PMS process was also investigated. Results showed that under the conditions of 3 mmol L⁻¹ PMS concentration, 10 mg L⁻¹ HA concentration, initial solution pH of 7, and a reaction time of 240 minutes, the mineralization rate of HA by UV/PMS reached 94.15%. The pseudo-first-order kinetic constant (k_obs) was 0.01034 and the single-electric energy (EE/O) was 0.0157 kW h m⁻³, indicating superior HA removal efficiency compared to other systems. Common anions (HCO₃ ⁻, Cl⁻, NO₃ ⁻) in water were found to inhibit the degradation of HA, and acidic conditions were more conducive to HA removal, with the optimal pH being 3. Free radical quenching experiments showed that both sulfate radical (SO₄ ⁻˙) and hydroxyl radical (˙OH) radicals were involved in HA degradation, with SO₄ ⁻˙ being the primary oxidant and ˙OH as the auxiliary species. Analyses using 3D-excitation-emission matrix (EEM), parallel factor analysis (PARAFAC), specific fluorescence index, and absorbance demonstrated that UV/PMS technology could effectively degrade HA in water. This study provides theoretical references for further research on the removal of HA and other organic substances using UV/PMS technology.

Using graphite powder, chitosan, and diatomite as raw materials, graphene oxide was first prepared by Hummer’s method and GO was carboxylated and modified into hydroxylated graphene oxide (GOH). It was then modified into GOH via carboxylation, and then diatomite (DE) and the prepared magnetic chitosan (MCS) were supported on GOH by blending to generate the magnetic graphene oxide composite GOH/DMCS. This novel composite was then studied to determine its methylene blue wastewater adsorption capability. Results showed that at 45 °C, a dosage of adsorbent of 1 g L⁻¹, and a pH of 12, the adsorption of methylene blue dye by GOH/DMCS reached equilibrium after 120 min, and the maximum adsorption amount was 205.34 mg·g⁻¹. The adsorbent was then cycled eight times to test its reusability, and the adsorption efficiency remained greater than 86%. The adsorption process of methylene blue by GOH/DMCS fit well to a pseudo second-order kinetic model. These results showed that the adsorption rate was more sensitive to the initial concentration of methylene blue dye, which implies a chemical adsorption process. The adsorption process conformed to the Langmuir isotherm adsorption model, indicating that the adsorption was monolayer surface adsorption.

Antibiotic-related environmental contamination directly threatens ecosystems and human health. Adsorption is an efficient and simple treatment process for removing antibiotics from water environments. Attapulgite (ATP) is a natural clay mineral extensively researched as a promising adsorbent material in the food industry, pharmaceutical sanitation, and organic wastewater treatment. Graphene oxide (GO) is widely employed in the treatment of organic wastewater due to its superior physicochemical properties. Here, using high temperature and HCl, ATP was activated (a-ATP), and a GO/a-ATP composite was prepared via hydrothermal synthesis. Using an adsorbent dosage of 0.75 g L⁻¹, pH = 5, reaction time of 120 min, initial temperature = 35 °C, and initial TC concentration of 50 mg L⁻¹, the adsorption capacity of GO/a-ATP for TC was 38.8 mg g⁻¹. The pseudo-first-order model (PFO) and pseudo-second-order (PSO) model were fitted to the kinetic data, and yielded an R²-value of PSO (0.99991) > PFO (0.9389), indicating that the adsorption process is related to chemisorption. Adsorption was also well described by the mixed-order (MO) model (R² = 0.9827), demonstrating that two rate-limiting adsorption reaction steps, diffusion and adsorption, occur; the former exerting greater influence. Equilibrium data was fitted to Langmuir, Freundlich, and Temkin isotherm models; the Langmuir model gave the best fit, suggesting the adsorption process is a homogeneous and monolayer adsorption process. Various thermodynamic parameters such as standard Gibbs free energy (ΔG⁰) and standard enthalpy (ΔH⁰) were also calculated, these results indicate the adsorption reaction is an endothermic process. Our study shows that GO/a-ATP is a promising adsorbent material for use in the adsorption of tetracycline in aquatic environments.

To improve the adsorption and separation efficiency of lead-containing wastewater by graphene oxide (GO), attapulgite (ATP) was used through a simple hydrothermal reaction. The prepared GO was characterized by SEM, TEM, FTIR, and XPS. The adsorption properties of the prepared GO were investigated. The maximum adsorption capacity of Pb²⁺ on as-prepared GO at pH 5 and 25 °C was 450.9 mg/g. It is concluded that the as-prepared GO can be used as a high-efficiency adsorbent for lead-containing wastewater.

For continuous and efficient oil/water separation and adsorption of dyes, coconut shell powder was grafted onto the surface of quartz sand by dip-coating method to make coconut shell powder-covered quartz sand filter media (CSQS) with superhydrophilic and underwater superoleophobic properties and superoleophilic and underoil highly hydrophobic properties. The contact angles of the underwater oil and underoil water with CSQS were more than 151.2° and 134.2°, respectively. A continuous oil/water separation device was designed. The separation device filled with CSQS can separate oil/water mixture (whether heavy or light oil) into water and oil at the same time with a separation efficiency of above 99.92%. The filter layer can be recovered through reverse extrusion even after lyophobic liquid penetrated the filter layer; hence, the separation efficiency of the filter layer was still above 99.99% for diesel and water mixture. Simultaneously, CSQS can effectively adsorb methylene blue with the highest removal rate as 98.94%. CSQS can maintain stable wettability under harsh environment conditions. This paper provides a new idea on continuous and efficient oil/water separation and simultaneous dye adsorption.