Sulfuric acid h2so4

Raw bentonite (R-Bent)
was collected from Pacitan, East Java, Indonesia.
It was pulverized to fine particles (100–150 μm) before
being subjected to organic impurities’ removal by soaking the
particles in a 30% (w/w) hydrogen peroxide solution for 3 h at room
temperature. The treated R-Bent was subsequently washed with deionized
water, dried overnight at 110 °C to remove the excess water,
and repulverized to particles with a size of 100–150 μm.
Meanwhile, CPO was obtained from the local industry in Gresik, Indonesia.
Prior use, CPO was degummed using 0.1% (w/w) phosphoric acid (85%
purity) to dissociate the phospholipids and gums into phosphatidic
acid, which can be easily removed during the bleaching process. The
degumming process was performed at a temperature of 90 °C for
2 h. Several important characteristics of CPO, e.g., FFA, PV, and
β-carotene content, were analyzed in accordance with the standard
methods of AOCS Ca 5a-40, AOCS Cd 8b-90, and Speek et al.,^{34 (link)} respectively; the CEC of R-Bent was measured
using ASTM C837-99. The characteristics of both raw materials are
presented in Table 3. CTAB as the intercalating agent, sulfuric acid (H₂SO₄, 95–98% purity), and methylene blue were purchased
from Merck (Merck, Germany). All chemicals and reagents used in the
analysis were of analytical grade and required no further purification.