ABSTRACT
A novel polyaniline (PANI) coupled CuBi2O4 photocatalyst was successfully synthesized via in situ polymerization of aniline with pre-synthesized CuBi2O4 composites. The structure and morphology of the synthesized CuBi2O4/PANI composite photocatalyst were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) and the photocatalytic performance were evaluated through degradation process of ammonia in water under visible light irradiation. The resultant CuBi2O4/PANI composite showed exceptional stability as its structure and morphology persisted even after being immersed in water for 2 days. The composite photocatalyst exhibited improved charge transport properties due to the electrical conductivity of the PANI protective layer, leading to enhanced photoelectrochemical activity in water and removal of ammonia. PANI with CuBi2O4 (10% wt) heterostructure was applied for photodegradation of ammonia and exhibited a 96% ammonia removal efficiency (30 mg/l with 0.1 g photocatalyst and 180 min), as compared to PANI (78%) and CuBi2O4 (70%). The degradation was attributed to the efficient charge transfer (e- and h+) and formation of reactive oxygen species upon simulated sunlight exposure. The present work suggests that the CuBi2O4/PANI photocatalyst can be synthesized in a simple process and provides an excellent adsorption capacity, high photocatalytic activity, long term stability, and reusability making it a promising alternative for ammonia removal from wastewater.
ABSTRACT
This review compiles recent advances and challenges on photocatalytic treatment of wastewater using nanoparticles, nanocomposites, and polymer nanocomposites as photocatalyst. The review provides an overview of the fundamental principles of photocatalytic treatment along the recent advances on photocatalytic treatment, especially on the modification strategies and operational conditions to enhance treatment efficiency and removal of recalcitrant organic contaminants. The different types of photocatalysts along the key factors influencing their performance are also critically discussed and recommendations for future research are provided.
ABSTRACT
Heavy metal/metalloids (HMs) and polycyclic aromatic hydrocarbons (PAHs) in soil have caused serious environmental problems, compromised agriculture quality, and have detrimental effects on all forms of life including humans. There is a need to develop appropriate and effective remediation methods to resolve combined contaminated problems. Although conventional technologies exist to tackle contaminated soils, application of biochar as an effective renewable adsorbent for enhanced bioremediation is considered by many scientific researchers as a promising strategy to mitigate HM/PAH co-contaminated soils. This review aims to: (i) provide an overview of biochar preparation and its application, and (ii) critically discuss and examine the prospects of (bio)engineered biochar for enhancing HMs/PAHs co-remediation efficacy by reducing their mobility and bioavailability. The adsorption effectiveness of a biochar largely depends on the type of biomass material, carbonisation method and pyrolysis conditions. Biochar induced soil immobilise and remove metal ions via various mechanisms including electrostatic attractions, ion exchange, complexation and precipitation. PAHs remediation mechanisms are achieved via pore filling, hydrophobic effect, electrostatic attraction, hydrogen bond and partitioning. During last decade, biochar engineering (modification) via biological and chemical approaches to enhance contaminant removal efficiency has garnered greater interests. Hence, the development and application of (bio)engineered biochars in risk management, contaminant management associated with HM/PAH co-contaminated soil. In terms of (bio)engineered biochar, we review the prospects of amalgamating biochar with hydrogel, digestate and bioaugmentation to produce biochar composites.