Photodegradation and Photoelectrodegradation of Methyl Orange and Methyl Violet Dyes using Graphite/PbTiO3 Composite under Visible Light Irradiation

The composite of Graphite/PbTiO3 has been synthesized for photocatalyst and photo-electrocatalyst of Methyl Orange (MO) and Methyl Violet (MV) degradation using a visible light source. The aims of the research were to study the influence of pH of the solution, iradiation time and kinetics study of MO and MV photodegradation, voltage of photoelectrodegradation of MO and MV. Composite of Graphite/PbTiO3 was synthesized by the sol-gel process with Titanium Tetraisopropoxide (TTIP) solution and Pb(NO3)2 powder as the precursors. Graphite/PbTiO3 composite was characterized using X-ray difractometer and FTIR spectrometer. The diffractogram of Graphite/PbTiO3 composite showed peaks at 2θ = 26.507o as a characteristic diffraction of Graphite, and at 2θ = 31.838o and 39.294o as those of PbTiO3. FTIR spectrum of Graphite/PbTiO3 composite exhibits vibration peaks of TiO2 at 609.5 – 420.5 cm-1 and those of Pb-O at 1337.66 cm-1 until 1395.56 cm-1. The photodegradation results showed that Graphite/PbTiO3 composite can degrade MO and MV optimally at a pH = 3. The photodegradation levels of MO and MV were 90.33% and 88.26% for 30 min of visible light radiation, respectively. The photodegradation of MO and MV were following the first-order reaction with a reaction rate constant of 0.4445 min-1 and 0.4244 min-1, respectively. Meanwhile, the photoelectrodegradation of MO was 96.50% at 10 volts and at pH 11, while the photoelectrodegradation of MV was 95.14% at 10 volts and at pH 7. When compared previous research, this result also shows excellent degradation MO and MV using Graphite/PbTiO3 under visible light irradiation. So that the use of visible lights provides an advantage over the use of UV light.

The enhancement of dye filtration performance and antifouling properties in amino-functionalized bentonite/polyvinylidene fluoride mixed matrix membranes

Trade-off issue and membrane fouling remain two major issues in the utilization of membrane technology for the water treatment due to reduced membrane permeability and lifetime. In our study, we employed 3-aminopropyltriethoxysilane modified bentonite (BNTAPS) as an anti-fouling modifier to prepare polyvinylidene fluoride (PVDF)-based membranes via the phase inversion method. The effects of BNTAPS concentration on the physical, mechanical, morphological, and filtration performance of the hybrid membranes have been investigated. It was found that the addition of BNTAPS improved the hydrophilicity of the membrane revealed by the decreased water contact angle. Consequently, the pure water flux of PVDF membrane containing 0.5% BNTAPS (PVDF/BNTAPS0.5%) increased to 35.5 L m^-2 h^-1. Moreover, the PVDF/BNTAPS membrane showed a smaller pore diameter and porosity compared to pristine PVDF. The membrane performance evaluation was carried out using cationic and anionic dyes, i.e., methylene blue (MB) and acid yellow (AY17), respectively. Our study revealed that the rejection of each dye was slightly increased for the PVDF/BNTAPS0.5%. However, the flux recovery rate of the PVDF/BNTAPS membrane significantly improved, which directly prolonged the membrane lifetime.

Silylated-montmorillonite as co-adsorbent of chitosan composites for methylene blue dye removal in aqueous solution

Industrialization plays important role in the economy of developing countries, including increasing community welfare. However, the presence of poorly industries waste disposal system has negative impact to the environment. Therefore, it is necessary to overcome this problem with low-cost technology, called adsorption. In this research, silylated-montmorillonite (sMMt) has been successfully prepared as supporting material for adsorption of methylene blue by chitosan. The sMMt was characterized by FTIR, XRD, and elemental mapping techniques. The chitosan/sMMt composites were prepared through dissolution-precipitation method and produced rod-like morphology as observed by SEM. The adsorption process was carried out in a batch method by studying the pH and the adsorption contact time. The adsorption kinetic mechanism of the chitosan/sMMt nanocomposite followed pseudo-second order rather than Lagergren model indicating chemisorption predominant. The addition of silylated-montmorillonite into chitosan enhanced the methylene blue dye removal performance, which evidenced by improving Qe values by 10% compared to chitosan.