Synthesis of graphitic carbon nitride modified kaolin-carboxyl graphene for the degradation of pharmaceutical waste under sunlight.

Graphitic carbon nitride modified with kaolin-carboxyl graphene (g-C3N4/KG) was successfully synthesized using urea as the precursor and was applied for the photocatalytic degradation of pharmaceutical compound, "cefepime." Structural and optical characteristics of g-C3N4/KG were analyzed using various characterization techniques such as FT-IR, XRD, TEM, SEM, EDX, TG, BET, DRS, and PL. The PL studies confirmed that g-C3N4/KG catalyst exhibits strong charge separation and electron flow, and enhanced visible light absorption capacity was revealed by DRS studies. Studies on the active radical species demonstrate that superoxide and hydroxy radicals play a major role in the photocatalytic degradation of cefepime and dye pollutants. g-C3N4/KG showed the complete removal MB and 85% of degradation of cefepime under solar light irradiation time of 75 min and 135 min, respectively. Additionally, possible mechanism for the breakdown of the antibiotic cefepime was presented, along with identification of the intermediates produced during the degradation process. The study demonstrates that this novel photocatalyst could be utilized to remove dyes as well as medical wastes from water under solar light.

Zeolite Y-supported carbon-doped TiO2 nanocomposites: Efficient solar photocatalysts for the purification of medicinal wastewater.

The existence of antibiotics in aquatic streams destroys water quality and thereby poses serious ecological hitches. Photocatalysis involving nanosemiconductors is an environmentally benign technique for the mineralization of antibiotics. Herein, we prepared a new visible light-sensitive photocatalyst, zeolite Y-supported carbon-doped TiO2 nanocomposite (zeolite Y-c-TiO2), for the elimination of cefazolin antibiotic in wastewater systems. The structural and optical properties of the synthesized nanocomposites were investigated by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller surface area analysis (BET) as well as diffuse reflectance spectroscopy (UV-DRS) and photoluminescence spectroscopy (PL). The UV-Vis absorbance spectrum of zeolite Y-c-TiO2 exhibited a red shift towards longer wavelength with an increase in visible light absorption as compared to pure TiO2 nanoparticles and zeolite Y-supported TiO2 nanocomposites (zeolite Y-TiO2). Accordingly, the photocatalytic action of the zeolite Y-c-TiO2 for the degradation of methylene blue was evaluated under solar simulator, and it turned out to be highly efficient (100%) mineralization as compared to TiO2-nanoparticles (42%) and zeolite Y-TiO2 (62%) after 70 min irradiation for a 50mg L-1 methylene blue solution. Radical scavenging experiments revealed the involvement of hydroxyl radicals, superoxide radicals, and photogenerated holes in the degradation process. Consequently, zeolite Y-c-TiO2 was applied for the photocatalytic degradation of the cefazolin antibiotic in water, and complete degradation of cefazolin (50 mg L-1) was observed within 6 h of solar light irradiation on zeolite Y-c-TiO2. The degradation pathway of cefazolin was proposed by considering various intermediates detected via LC-MS analysis. The study points to the significant potential of zeolite Y-c-TiO2 photocatalyst for the purification of medicinal wastewater under sunlight.

Kaolin-graphene carboxyl incorporated TiO2 as efficient visible light active photocatalyst for the degradation of cefuroxime sodium.

A novel solar light active photocatalyst, TiO2/kaolin-graphene carboxyl nanocomposite was synthesized by hydrothermal method for the degradation of cephalosporin antibiotic, cefuroxime sodium. The synthesized photocatalyst was characterized by various analytical and spectroscopic techniques, including Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) thermogravimetry (TG), UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL). The prepared TiO2/kaolin-graphene carboxyl nanocomposite exhibited efficient photocatalytic degradation of methylene blue (MB) upon illumination with the solar simulator as compared to unmodified TiO2. The incorporation of both kaolin and graphene carboxyl was found to immobilize TiO2, enhancing the visible light absorption range of TiO2. Scavenger study revealed that hydroxyl radicals act as the main active species in the photocatalytic degradation process. The hydroxyl group present on kaolin surface reacts with photo-generated holes to increase the amount of hydroxyl radical, and further the graphene carboxyl plays a role to impede the recombination of photo-generated electron-hole pairs. Furthermore, the synthesized photocatalyst was found to degrade cefuroxime sodium within 90 min of sunlight illumination, indicating that TiO2/kaolin-graphene carboxyl nanocomposites would be very beneficial for pharmaceutical waste management through the advanced oxidation process. Mass spectral analysis was also carried out for elucidating the photocatalytic degradation pathway of cefuroxime sodium.

Carbon nitride-based photocatalysts for the mitigation of water pollution engendered by pharmaceutical compounds.

In recent decades, the destructive impact of active pharmaceutical ingredients (API) present in surface and drinking water on aquatic and terrestrial life forms becomes a major concern of researchers. API like diclofenac (DCF), carbamazepine (CBZ), tetracycline (TC), and sulfamethoxazole (SME) found in water bodies cause antimicrobial resistance and are potent carcinogens and endocrine disruptors. Conventional wastewater treatment methods possess some drawbacks and were found to be insufficient for the effective removal of APIs. Visible light-assisted semiconductor photocatalysis has become an alternative choice for tackling this worse scenario. Graphitic carbon nitride, a metal-free visible light active semiconductor photocatalyst is an emerging hotspot nanomaterial whose practical utility in water purification is widely recognized. This review comes up with an insightful outlook on the panorama of recent progress in the field of g-C3N4-assisted photocatalytic systems for the eradication of APIs. In addition, the review summarizes various strategies adopted for the broad-spectrum utilization of visible light and the enhancement of charge separation of pristine g-C3N4. The mechanistic pathways followed by different pharmaceuticals during their photocatalytic degradation process were also briefly discussed.