Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2025Scopus SJRQ2/r/munzur/1344
  Chromium removal with walnut shells and oak branches, adsorption studies, and kinetics

  Fırat, Tülay

  This study investigates the chromium sorption properties of walnut shells (WS) and oak branches (OB), both of which were modified using NaOH and lactic acid treatments. The characterization of these adsorbents was carried out using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), point of zero charge (pHpzc) analysis, and Brunauer–Emmett–Teller (BET) surface area measurements. According to BET results, WS exhibited higher surface area values compared to OB. The pH and pHpzc measurements revealed that acidic functional groups are more prevalent than basic ones on both adsorbents. Batch experiments were conducted to evaluate the chromium ion sorption capacities of WS and OB. To further understand the adsorption mechanism, the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models were analyzed, with the Langmuir and Freundlich models being widely recognized for describing adsorption in single-solute systems. The equilibrium data aligned best with the Langmuir isotherm, while the kinetic data were modeled using pseudo-first-order and pseudo-second-order kinetics. The maximum chromium sorption capacity for WS was determined to be 30.51 mg/g. The energy values calculated from the D-R equation for chromium adsorption onto WS and OB were 13.49 kJ/mol and 15.71 kJ/mol, respectively, indicating that the adsorption process is primarily driven by physical adsorption.

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• MakaleAçık Erişim2025Scopus SJRQ2/r/munzur/1013
  A novel additive for enhancing biomass energy production from agro-industrial wastes: synthesis of hydrophobic nanoporous silica aerogel and its effect on methane production

  Gulsen Akbay, Habibe Elif; Basgoz, Oykum; Guler, Omer

  Anaerobic digestion (AD) is one of the most preferred processes for the treatment of organic waste. However, additional processes such as co-digestion, pretreatment, and additive addition continue to be explored to remove the limits on the applicability of AD. This study investigated the effects of hydrophobic nanoporous silica aerogel (NpSA) synthesized from waste rice husks on the anaerobic co-digestion (AnCD) of the mixture consisting of sewage sludge and fruit processing industry wastes. All bioreactors containing NpSA-free, 0.1 g, 0.2 g, 0.5 g, and 1 g NpSA (0.03–0.3 gNpSA/gVSadded) were operated in a mesophilic-batch process. Biogas and methane yields increased from 346 mL/gVS (NpSA-free) to 387 mL/gVS and from 231 mL/gVS (NpSA-free) to 288 mL/gVS, respectively, with 0.1 g NpSA addition. NpSA additive increased biogas production in all bioreactors compared to the blank. However, biogas production rate and methane content increased faster at lower doses of NpSA. Maximum soluble chemical oxygen demand (sCOD), protein, carbohydrate, and volatile solid (VS) reductions were between 45–71%, 35–54%, 44–65%, and 34–91% for NpSA added mixtures, respectively. The hydrophobic NpSA additive was effective in improving the AnCD performance and biogas/methane production. Experimental results fit the kinetic models frequently preferred in such AD processes. In addition, the possible energy and financial potential of the produced methane were also discussed, and it was determined that the direct sale of methane gas produced by the addition of NpSA in the global market could provide 1.4 $/Lmixture more financial gain than the mixture NpSA-free.

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