Controlling water and air pollution by photocatalysts is an advanced technique and has aroused great interest. TiO₂/hydroxyapatite (HAP) composites were successfully prepared via a one-step hydrothermal route that add a certain weight of tetrabutyl titanate to a mixed solution of Ca(NO₃)₂ and (NH₄)₂HPO₄, and then put into a Teflon-lined autoclave for hydrothermal reaction. The surface morphology, chemical composition, crystalline structure, and optical property of the TiO₂/HAP composites were characterized. The field emission-scanning electron microscopy (FE-SEM) observed the cube-like structure of crystal with the size of 10–20 μm. Energy dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD) demonstrated that Ti ₓ Ca₅₋ₓ (PO₄)₃(OH) was a unit of the crystal. UV–visible diffuse reflectance spectra show that the optical absorbance edge appeared at long wavelength (∼400 nm). Both higher temperature and longer time could contribute to the complete crystallization. Photocatalytic activity was evaluated by the degradation of rhodamine B (RhB) under visible light irradiation and found that the TiO₂/HAP composites exhibited excellent photocatalytic activity. Therefore, these TiO₂/HAP composites were expected to become one of advanced materials removing dyes from water.

Separating organic pollutants from oil-based drill cuttings (OBDC) is the current trend for its safe disposal. In this study, pressurized hot water extraction (PHWE) was adapted to decontaminate OBDC for the first time. Two typical OBDC samples, i.e., diesel-based drill cuttings (OBDC-A) and white oil-based drill cuttings (OBDC-B), were statically extracted in a homemade batch autoclave. Response surface methodology (RSM) with a central composite design (CCD) was applied to investigate the effects and interactive effects of three independent operating parameters (temperature, extraction time, and water volume) and to ultimately optimize the PHWE process. The results suggested that temperature is the dominant parameter, followed by water volume and extraction time. Interactive effects among the three parameters are present in the PHWE of OBDC-A but absent in the PHWE of OBDC-B. The suitable conditions for the effective PHWE of OBDC-A were found to be a temperature of 284–300 °C, water volume of 15–35 ml, and extraction time of 20–60 min. The corresponding conditions were 237–300 °C, 15–35 ml, and 20–60 min for the PHWE of OBDC-B. These different phenomena are caused by the different characteristics of the two OBDC samples. All of the polynomial models obtained from the RSM experiments are very valid and can adequately describe the relationship among the three independent operating parameters and responses. The experimental results also confirmed that PHWE is a more efficient separation technique for decontaminating OBDC than single organic solvent extraction or low-temperature thermal desorption because PHWE integrates the advantages of both these processes.

Phthalate esters (PAEs) are mainly used as plasticizers, and their release in the environment during the manufacturing, use, and disposal has caused serious environmental health concerns, since some of them are suspected to be mutagens, hepatotoxic agents, and carcinogens. In the present study, leaching of PAEs from different drinking stuffs (water cooler, mineral water bottles) exposed to sunlight and baby feeders subjected to different heating treatments (boiling, autoclave and oven) was studied. Results showed that a total of 10 PAEs were leached and identified. Among them, dimethyl phthalate, bis(2-methoxyethyl) phthalate, diethyl phthalate, and dibutyl phthalate were the major leached PAEs found in the range 9–112.50 μg L⁻¹. Boiling treatment was found safer for baby feeders as PAE leaching was ~26–54% less as compared to other two treatments. The leached PAEs in water samples were then subjected to biodegradation experiment with Bacillus thuringiensis strain at optimized conditions (time 72 h and 30 °C). Hence, leaching of hazardous PAEs from different water stuffs is alarming and needs immediate attention. Moreover, B. thuringiensis strain was found effective for PAE remediation (75–96% degradation) at neutral pH. Graphical abstract ᅟ

The increasing use of antibiotics, especially tetracycline, in livestock feed adversely affects animal health and ecological integrity. Therefore, approaches to decrease this risk are urgently needed. High temperatures facilitate antibiotic degradation; whether this reduces transmission risk and transfer of tetracycline-resistant bacteria (TRBs) and tetracycline resistance genes (TRGs) in soil remains unknown. Successive experiments with soil columns evaluated the effects of autoclaving pig manure (APM) on soil TRB populations and TRGs over time at different soil depths. The data showed sharp increases in TRB populations and TRGs in each subsoil layer of PM (non-APM) and APM treatments within 30 days, indicating that TRBs and TRGs transferred rapidly. The level of TRBs in the upper soil layers was approximately 15-fold higher than in subsoils. TRBs were not dependent on PM and APM levels, especially in the late phase. Nevertheless, higher levels of APM led to rapid expansion of TRBs as compared to PM. Moreover, temporal changes in TRB frequencies in total culturable bacteria (TCBs) were similar to TRBs, indicating that the impact of PM or APM on TRBs was more obvious than for TCBs. TRBs were hypothesized to depend on the numbers of TRGs and indigenous recipient bacteria. In the plough layer, five TRGs (tetB, tetG, tetM, tetW, and tetB/P) existed in each treatment within 150 days. Selective pressure of TC may not be a necessary condition for the transfer and persistence of TRGs in soil. High temperatures might reduce TRBs in PM, which had minimal impact on the transmission and transfer of TRGs in soil. Identifying alternatives to decrease TRG transmission remains a major challenge.