Search

Hydroxyapatite (HA) had the effect of maintaining the pH balance of the reaction system and promoting enzyme activity. In this work, hydroxyapatite was synthesized by coprecipitation and characterized for biohydrogen (bioH 2 ) production from glucose. The highest bioH 2 yield obtained was 182.33 ± 2.41 mL/g glucose, amended with an optimal dosage of 400 mg/L HA, which was a 55.80% higher bioH 2 yield compared with the control group without any addition. The results indicated that HA facilitated the deterioration of organic substances and increased the concentration of soluble microbial products (SMPs). Microbial community analysis revealed that HA significantly increased the abundance of Firmicutes from 35.27% (0 mg/L, HA) to 76.41% (400 mg/L, HA), which played an essential role in bioH 2 generation. In particular, the abundance of Clostridium sensu stricto 1 increased from 15.33% (0 mg/L HA) to 45.17% (400 mg/L HA) and became the dominant bacteria. The results also indicated that HA likely improves bioH 2 production from organic wastewater in practice., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

High phosphorus concentrations mainly result in environmental problems such as agricultural pollution and eutrophication, which have great negative influence on many natural water bodies. In this work, calcium lignosulfonate was employed to produce calcium-doped char at 400 and 800 °C. To compare the phosphorus adsorption behaviors of the two carbon materials, batch adsorption experiments were conducted in a phosphorus microenvironment. The factors including the initial solution pH, phosphorus concentration, and adsorbent amount were considered, and the main characteristics of calcium-doped chars before and after adsorption were assessed. The results revealed that the phosphorus removal processes fitted both the Freundlich and pseudo-second-order-kinetic models. According to the Langmuir model, the maximum adsorption capacities of the two adsorbents obtained at 400 and 800 °C toward phosphorus (50 °C) were 53.22 and 17.77 mg/g adsorbent, respectively. The former was rich in calcium carbonate (CaCO 3 ) and hydroxyl and carboxyl groups, and it mainly served as a precipitant and a chelating agent, while the latter with a high surface area was dominant in P adsorption., Competing Interests: The authors declare no competing financial interest., (© 2020 The Authors. Published by American Chemical Society.)

Wheat straw was pretreated with either CaO 2 or CaO to improve biohydrogen production. Both CaO and CaO 2 pretreatments improved the biodegradability of the wheat straw. CaO pretreatment raised the H 2 yield by between 48.8 and 163.9% at CaO contents ranging from 2 to 4%. The highest H 2 yield [144 mL/g total solid (TS)] was obtained at 121 °C and 6% CaO. In addition, the highest H 2 yield from wheat straw pretreated at the same temperature and dosage of CaO 2 was 71.8 mL/g TS, which was higher than that of the control group (43.2 mL/g TS), with hot water (121 °C) treatment. Considering pretreatment costs and H 2 production potential, CaO was a better pretreatment agent than CaO 2 ., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)