The effective reduction of hazardous organic pollutants in wastewater is a pressing global concern, necessitating the development of advanced treatment technologies. Pollutants such as nitrophenols and dyes, which pose significant risks to both human and aquatic health, making their reduction particularly crucial. Despite the existence of various methods to eliminate these pollutants, they are not without limitations. The utilization of nanomaterials as catalysts for chemical reduction exhibits a promising alternative owing to their distinguished catalytic activity and substantial surface area. For catalytically reducing the pollutants NaBH4 has been utilized as a useful source for it because it reduces the pollutants quiet efficiently and it also releases hydrogen gas as well which can be used as a source of energy. This paper provides a comprehensive review of recent research on different types of nanomaterials that function as catalysts to reduce organic pollutants and also generating hydrogen from NaBH4 methanolysis while also evaluating the positive and negative aspects of nanocatalyst. Additionally, this paper examines the features effecting the process and the mechanism of catalysis. The comparison of different catalysts is based on size of catalyst, reaction time, rate of reaction, hydrogen generation rate, activation energy, and durability. The information obtained from this paper can be used to steer the development of new catalysts for reducing organic pollutants and generation hydrogen by NaBH4 methanolysis.
This work reports silver nanoparticles (AgNPs) supported on biopolymer carboxymethyl cellulose beads (Ag-CMC) serves as an efficient catalyst in the reduction process of p-nitrophenol (p-NP) and methyl orange (MO). For Ag-CMC synthesis, first CMC beads were prepared by crosslinking the CMC solution in aluminium nitrate solution and then the CMC beads were introduced into AgNO3 solution to adsorb Ag ions. Field emission scanning electron microscopy (FE-SEM) analysis suggests the uniform distribution of Ag nanoparticles on the CMC beads. The X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis revealed the metallic and fcc planes of AgNPs, respectively, in the Ag-CMC catalyst. The Ag-CMC catalyst exhibits remarkable reduction activity for the p-NP and MO dyes with the highest rate constant (kapp) of a chemical reaction is 0.519 and 0.697 min-1, respectively. Comparative reduction studies of Ag-CMC with CMC, Fe-CMC and Co-CMC disclosed that Ag-CMC containing AgNPs is an important factore in reducing the organic pollutants like p-NP and MO dyes. During the recyclability tests, the Ag-CMC also maintained high reduction activity, which suggests that CMC protects the AgNPs from leaching during dye reduction reactions.
To maintain human health and purity of drinking water, it is crucial to eliminate harmful chemicals such as nitrophenols and azo dyes, considering their natural presence in the surroundings. In this particular research study, the application of machine learning techniques was employed in order to make an estimation of the performance of reduction catalysis in the context of ecologically detrimental nitrophenols and azo dyes contaminants. The catalyst utilized in the experiment was Ag@CMC, which proved to be highly effective in eliminating various contaminants found in water, like 4-nitrophenol (4-NP). The experiments were carefully conducted at various time intervals, and the machine learning procedures used in this study were all employed to forecast catalytic performance. The evaluation of the performance of such algorithms were done by means of Mean Absolute Error. The noteworthy findings of this research indicated that the ADAM and LSTM algorithm exhibited the most favourable performance in the case of toxic compounds i.e. 4-NP. Moreover, the Ag@CMC catalyst demonstrated an impressive reduction efficiency of 98 % against nitrophenol in just 8 min. Thus, based on these compelling results, it can be concluded that Ag@CMC works as a highly effective catalyst for practical applications in real-world scenarios.
A catalytic system has been developed, utilizing metal nanoparticles confined within a chitosan‑carbon black composite hydrogel (M-CH/CB), aimed at improving ease of use and recovery in catalytic processes. The M-CH/CBs were characterized by XPS, XRD, SEM, and EDX, the M-CH/CB system demonstrated exceptional catalytic activity in producing hydrogen gas (H2) from water and methanol, and in reducing several hazardous materials including 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), 2,6-dinitrophenol (2,6-DNP), acridine orange (ArO), methyl orange (MO), congo red (CR), methylene blue (MB), and potassium ferricyanide (PFC). Among the tested nanocatalysts, CH/CB showed the highest efficiency for H₂ production, while Fe0-CH/CB excelled in contaminant reduction (7.0 min). In addition to the synthesis and characterization of the catalytic system, various factors, such as NaBH₄ amount, catalyst quantity, pollutant concentration, and reaction temperature were optimized to maximize its overall efficacy and efficiency. Fe0-CH/CB achieved the best reaction rate of 0.850 min-1 for 4-NP reduction, while CH/CB had a hydrogen generation rate (HGR) of 3500 ml.g-1.min-1. The Fe0-CH/CB was able to achieve the 4-NP reduction percentage of >95 % over 5 times during the recyclability tests. However, a slight decrease in reduction time was observed as the reaction rate dropped to 0.716 min-1 after 5 cycles, but the catalyst remained effective, underscoring its practical potential for environmental remediation, water treatment, and sustainable energy production.
This review article provides a thorough examination of an interaction between linear alkylbenzenes (LABs) and ecosystems. The review covers various aspects of LABs' impact on ecosystems, focusing on detection and treatment strategies to mitigate ecological consequences. It delves into LABs' role as molecular markers for sewage pollution, their physicochemical properties contributing to persistence, and their effects on aquatic and terrestrial organisms, including disruptions to endocrine systems. The diverse sources of LABs, including domestic wastewater and industrial effluents, are explored, along with their ratios in different matrices for assessing contamination origins. Biodegradation pathways of LABs, both aerobic and anaerobic, are scrutinized, considering their interaction with microbes. Distribution patterns in aquatic environments are discussed, encompassing sediment, water, sewage, and soils. An investigation is conducted on the relationship between LABs and total organic carbon (TOC) as a means of evaluating sewage pollution. It is assessed how sewage treatment facilities (STPs) contribute to biodegradation.