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Nickel-based catalysts promoted by Mo-oxo species have been proven to be quite promising for transformation of triglycerides into green diesel. The selection of the support for such catalysts is crucial. In the present study, pyrolyzed rice husk subjected to acid and/or alkaline post-treatment was studied as support for the aforementioned catalysts. Biochar produced by slow pyrolysis of raw material at 850 °C for 5 h under limited-oxygen conditions exhibited the most promising textural characteristics. These were substantially improved by alkaline post-treatment. Thus, the corresponding MoNi catalysts proved the most efficient for upgrading used cooking oil (UCO) to green diesel via a solvent-free hydrotreatment process, performed in a semi-batch reactor (at 310 °C, 40 bar, 100 mL/min H2, 100 mL UCO and 1 g of catalyst). The enhanced catalytic performance (complete conversion of UCO and 32 wt.% green diesel yield) of MoNi catalysts supported on biochar subjected at least to an alkaline post-treatment step has been attributed to their high SSA, suitable pore size distribution (enhanced mesoporosity), and acidity (enhanced population of acid sites with moderate strength), as well as to the high dispersion of the active phase. [ABSTRACT FROM AUTHOR]

Perfluorooctanesulfonic (PFOS) acid is a persistent anthropogenic organic fluorinated compound ubiquitous in industrial applications and is resistant to conventional wastewater treatment methods. Human exposure to PFOS can cause adverse health effects. In this study, a low‐content titanium dioxide (TiO2) photocatalyst coated on glass beads was synthesized through a simple method and showed improved activity and durability. This material exhibited easy recovery and potential for large‐scale applications. The efficacy of the TiO2 nanoparticle‐deposited glass beads' (TiO2@GBs) photocatalyst in treating PFOS contaminants in wastewater was explored, demonstrating its ability to promote photocatalytic reactions to break down PFOS into shorter chain byproducts. The study employed the response surface method (RSM) using the Box–Behnken design (BBD) to optimize treatment conditions at a PFOS concentration of 0.1 mg/L. Investigated factors included pH (4–9), TiO2 dosage (0.11–0.53 g/L), and irradiation time (4–8 h). Design‐Expert 12 software was used to plan and optimize the experiments. Fifteen experiments were conducted, and triplicate runs occurred at the center points of the experimental plan. ANOVA and Fisher's test yielded an F value of 73.88 (p < 0.0001) which demonstrated the model's statistical significance with over 99% confidence regression prediction. The optimized treatment conditions that achieved 100% degradation of PFOS included a pH of 4.55, TiO2 dosage of 0.396 mg/L, and irradiation time of 6.59 hours. After the photocatalytic treatment, PFOS was transformed into intermediate products such as PFPeA, PFHpA, L‐PFBS, and L‐PFHxS. [ABSTRACT FROM AUTHOR]

This study aims to utilize biochars derived from residual biomass as supports for Ni-based catalysts. For the preparation of the biochars, byproducts of agro-industrial activities were used, such as espresso coffee residue (C) and rice husks (R). Sufficient quantities of the respective biochars (BioC and BioR) were prepared via pyrolysis at 850 °C of the aforementioned materials under limited oxygen conditions. The biochars were further treated with hot water (WBioC, WBioR), H3PO4 or H2SO4 solution (BioC-P, BioC-S, BioR-P, BioR-S), and NaOH solution (BioC-A and BioR-A), and the obtained solids were characterized using various physicochemical techniques. The biochars produced were microporous with high surface areas (367–938 m2g−1). The most promising biochars were selected as supports for the preparation of nickel catalysts (10 wt.% Ni) with high Ni dispersion (mean crystal size: 8.2–9.8 nm) and suitable acidity. The catalysts were evaluated in a high-pressure semi-batch reactor for the transformation of waste cooking oil (WCO) into green diesel. The 10Ni_BioC-P catalyst exhibited the best performance, resulting in a complete conversion of the WCO but a low hydrocarbon yield (7.5%). Yield improvement was achieved by promoting this catalyst with molybdenum. The addition of Mo increased the hydrocarbon yield by almost three times (19.5%). [ABSTRACT FROM AUTHOR]

The efficiency of Ni/TiO2 catalysts for renewable diesel production was evaluated in the present study. Two series of catalysts were synthesized and characterized using various physicochemical techniques (N2 physisorption, XRD, SEM, XPS, H2-TPR, and NH3–TPD). In the first series of catalysts, successive dry impregnations (SDI) were used for depositing 10, 20, 30, 50, and 60 wt.% Ni. The yield towards renewable diesel is maximized over the catalyst with 50 wt.% Ni loading. Selecting this optimum loading, a second series of catalysts were synthesized via three additional preparation methods: wet impregnation (WI) and deposition–precipitation using either ammonia (DP-NH3) or urea (DP-Urea) as the precipitation agent. The catalysts' efficiency in the production of green diesel is influenced by the preparation method following the order: DP-Urea > DP-NH3 > WI ≈ SDI. The metallic surface area and the balanced acidity mainly determine the performance of the catalysts. [ABSTRACT FROM AUTHOR]

A novel methodology, called the potentiometric mass titration (PMT) technique, for determining the point of zero charge (pzc) of mineral hydr(oxides) immersed in electrolytic solutions. The comparison of the pzc values determined by PMT, with the corresponding ones determined using the traditional methodologies, and strongly suggested that the PMT technique can be used to determine the pzc of oxides.