Biomass-derived carbons are emerging materials with a wide range of catalytic properties, such as large surface area and porosity, which make them ideal candidates to be used as heterogeneous catalysts and catalytic supports. Their unique physical and chemical properties, such as their tunable surface, chemical inertness, and hydrophobicity, along with being environmentally friendly and cost effective, give them an edge over other catalysts. The biomass-derived carbon materials are compatible with a wide range of reactions including organic transformations, electrocatalytic reactions, and photocatalytic reactions. This review discusses the uses of materials produced from biomass in the realm of heterogeneous catalysis, highlighting the different types of carbon materials derived from biomass that are potential catalysts, and the importance and unique properties of heterogeneous catalysts with different preparation methods are summarized. Furthermore, this review article presents the relevant work carried out in recent years where unique biomass-derived materials are used as heterogeneous catalysts and their contribution to the field of catalysis. The challenges and potential prospects of heterogeneous catalysis are also discussed.

Silver nanoparticles (AgNPs) have received a lot of interest for their several applications, including their remarkable potential as photocatalysts for organic dye degradation. This research thoroughly investigates the efficacy of ecologically friendly, green-synthesized AgNPs in the treatment of synthetic dye-contaminated wastewater. The synthesis of AgNPs from various biological substrates is investigated, emphasizing their economic viability, significant conductivity, and considerable biocompatibility. The improper disposal of synthetic dyes in wastewater poses severe environmental and health risks due to their non-biodegradable nature and persistent chemical features. In response to this challenge, this review paper investigates the capability of AgNPs to serve as effective photocatalysts for degrading a range of organic dyes commonly found in industrial effluents. Specific dyes, including methyl orange, congo red, nitrophenol, methylene blue, and malachite green, are studied in the context of wastewater treatment, providing insights into the efficacy of AgNPs synthesized from diverse biological sources. The review sheds light on the photocatalytic degradation methods used by green-synthesized AgNPs, shedding light on the transition of these synthetic dyes into less hazardous compounds. It also delves into the toxicity aspect of the AgNPs and its possible remediation from the environment. The ecologically friendly synthesis procedures investigated in this work provide an alternative to traditional methods, highlighting the importance of sustainable technologies in solving modern environmental concerns. Furthermore, a comparative examination of various biological substrates for AgNPs synthesis is presented, evaluating their respective dye degradation efficiencies. This not only helps researchers understand the environmental impact of synthetic dyes, but it also directs them in choosing the best substrates for the production of AgNPs with enhanced photocatalytic activities.

The ongoing discharge of hazardous dyes from industrial processes has intensified global water pollution, posing serious threats to aquatic ecosystems and human health. Addressing this challenge, our study explores the potential of bio-based carbon nanomaterials (CNM), synthesized from onion peel biowaste and designated as ON11, as effective agents in dye removal. These CNMs were incorporated into a mixed matrix membrane (MMM), using polysulfone (PSU) as the membrane substrate, to enhance dye adsorption. The CNM synthesis was achieved through a simple, eco-friendly process. We examined their impact on adsorption efficiency by introducing ON11 nanoparticles at varying concentrations into the PSU membrane (ON11@PSU). This CNM-embedded membrane structure offers a solution to challenges associated with the large-scale application of nanomaterials, particularly by minimizing leaching into water and improving durability. The ON11 and ON11@PSU membranes were characterized using various techniques, including SEM, Raman spectroscopy, XRD, optical profilometer, and FTIR, to confirm their behavior, morphology, and structural integrity. The surface area of ON11 was 423.26 m² g⁻¹, with BJH average pore diameter of 4.5 nm and BET pore volume of 0.26 cm³ g⁻¹. ON11 nanoparticles were adsorptive in nature, and their utility in membrane adsorption is explored. The influence of parameters, including contact time, dye concentration, membrane thickness, pH, and adsorbent dosage, was systematically evaluated to optimize the dye adsorption efficiency of the ON11@PSU membrane pad. It was observed that the thickness of the 60 μm membrane (S_a = 2.170 μm and S_q = 2.75 μm) showed higher removal efficiency for all the selected dyes than the other thicknesses at the native pH itself. The MMM demonstrated its effectiveness as an adsorbent membrane, achieving maximum removal efficiencies of approximately 98% for MG dye, 92% for RhB dye, and 67% for MB dye. The negative zeta potential of adsorptive membranes enabled the electrostatic attraction of positively charged dyes, enhancing adsorption capacity. The findings contribute to developing sustainable and effective membrane utility as adsorbents, opening avenues for the effective use of agricultural waste products in environmental remediation applications.

Arachis hypogaea skin-derived carbon nanospheres as an efficient adsorbent for the rapid removal of cationic dyes from aqueous solutions up to 98% removal efficiency within 2 min.