Waste to catalyst: Role of agricultural waste in water and wastewater treatment

Zeolites in wastewater treatment: A comprehensive review on scientometric analysis, adsorption mechanisms, and future prospects

Zeolites possess a microporous crystalline structure, a large surface area, and a uniform pore size. Natural or synthetic zeolites are commonly utilized for adsorbing organic and inorganic compounds from wastewater because of their unique physicochemical properties and cost-effectiveness. The present review work comprehensively revealed the application of zeolites in removing a diverse range of wastewater contaminates, such as dyes, heavy metal ions, and phenolic compounds, within the framework of contemporary research. The present review work offers a summary of the existing literature about the chemical composition of zeolites and their synthesis by different methods. Subsequently, the article provides a wide range of factors to examine the adsorption mechanisms of both inorganic and organic pollutants using natural zeolites and modified zeolites. This review explores the different mechanisms through which zeolites effectively eliminate pollutants from aquatic matrices. Additionally, this review explores that the Langmuir and pseudo-second-order models are the predominant models used in investigating isothermal and kinetic adsorption and also evaluates the research gap on zeolite through scientometric analysis. The prospective efficacy of zeolite materials in future wastewater treatment may be assessed by a comparative analysis of their capacity to adsorb toxic inorganic and organic contaminates from wastewater, with other adsorbents.

Ultrasmall copper-metal organic framework (Cu-MOF) quantum dots decorated on waste derived biochar for enhanced removal of emerging contaminants: Synergistic effect and mechanistic insight

This study proposes a novel one-pot hydrothermal impregnation strategy for surface decoration of waste derived pisum sativum biochar with zero‒dimensional Cu‒MOF Quantum dots (PBC‒HK), with an average particle size of 5.67 nm, for synergistic removal of an emerging sulfur containing drug pantoprazole (PTZ) and Basic Blue 26 (VB) dye within 80 min and 50 min of visible-light exposure, respectively. The designed Integrated Photocatalytic Adsorbent (IPA) presented an enhanced PTZ removal efficiency of 95.23% with a catalyst loading of 0.24 g/L and initial PTZ conc. 30 mg/L at pH 7, within 80 min via synergistic adsorption and photodegradation under visible-light exposure. While, on the other hand, 96.31% VB removal efficiency was obtained in 50 min with a catalyst dosage of 0.20 g/L, initial VB conc. 60 mg/L at pH 7 under similar irradiation conditions. An in-depth analysis of the synergistic adsorption and photocatalysis mechanism resulting in the shortened time for the removal of contaminants in the synergistic integrated model has been performed by outlining the various advantageous attributes of this strategy. The first-order degradation rate constant for PTZ was found to be 0.04846 min-1 and 0.04370 min-1 for PTZ and VB, respectively. Adsorption of contaminant molecules on the biochar (PS‒BC) surface can facilitate photodegradation by accelerating the kinetics, and photodegradation promotes regeneration of adsorption sites, contributing to an overall reduction in operation time for removal of contaminants. Besides enhancing the adsorption of targeted pollutants, the carbon matrix of IPAs serves as a surface for adsorption of intermediates of degradation, thereby minimizing the risk of secondary pollution. The photogenerated holes present in the VB is responsible for the generation of •OH radicals. While, the photogenerated electrons present in the CB are captured by Cu2+ of the MOF metal center, reducing it to Cu+, which is subsequently oxidized to produce additional •OH species in the aqueous medium. This process leads to effective charge separation of the photogenerated charge carriers and minimizes the probability of charge recombination as evident from photoluminescence (PL) analysis. Meanwhile, PL studies, EPR and radical trapping experiments indicate the predominant role of •OH radicals in the removal mechanism of PTZ and VB. The investigation of the degradation reaction intermediates was confirmed by HR‒LCMS, on the basis of which the plausible degradation pathway was elucidated in detail. Moreover, effects of pH, inorganic salts, other organic compounds and humic acid concentration have been investigated in detail. The environmental impact of the proposed method was comprehensively evaluated by ICP-OES analysis and TOC and COD removal studies. Furthermore, the economic feasibility and the cost-effectiveness of the catalyst was assessed to address the potential for large scale commercialization. Notably, this research not only demonstrates a rational design strategy for the utilization of solid waste into treasure via the fabrication of IPAs based on MOF Quantum dots (QDs) and waste-derived biochar, but also provides a practical solution for real wastewater treatment systems for broader industrial applications.

Role of biochar in superoxide-dominated dye degradation in catalyst-activated peroxymonosulphate process

In recent times, the application of biochar (BC) as an upcoming catalyst for the elimination of recalcitrant pollutants has been widely explored. Here, an iron loaded bamboo biochar activated peroxymonosulphate (PMS) process was tested for removing Congo red (CR) dye from water medium. The catalyst was synthesized using a green synthesis method using neem extracts and characterized using SEM, FTIR, and XRD. The effects of various operating parameters, including solution pH, catalyst dosage, and pollutant dosage, on dye degradation efficiency were examined. The results showed that at the optimized conditions of 300 mg L-1 PMS concentration, 200 mg L-1 catalyst dosage, and pH 6, about 89.7% of CR dye (initial concentration 10 ppm) was removed at 60 min of operation. Scavenging experiments revealed the significant contribution of O2•-, •OH, and 1O2 for dye degradation, with a major contribution of O2•-. The activation of PMS was mainly done by biochar rather than iron (loaded on biochar). The catalyst was highly active even after four cycles.

Conversion of locally available materials to biochar and activated carbon for drinking water treatment

For environmental sustainability and to achieve sustainable development goals (SDGs), drinking water treatment must be done at a reasonable cost with minimal environmental impact. Therefore, treating contaminated drinking water requires materials and approaches that are inexpensive, produced locally, and effortlessly. Hence, locally available materials and their derivatives, such as biochar (BC) and activated carbon (AC) were investigated thoroughly. Several researchers and their findings show that the application of locally accessible materials and their derivatives are capable of the adsorptive removal of organic and inorganic contaminants from drinking water. The application of locally available materials such as lignocellulosic materials/waste and its thermo-chemically derived products, including BC and AC were found effective in the treatment of contaminated drinking water. Thus, this review aims to thoroughly examine the latest developments in the use of locally accessible feedstocks for tailoring BC and AC, as well as their features and applications in the treatment of drinking water. We attempted to explain facts related to the potential mechanisms of BC and AC, such as complexation, co-precipitation, electrostatic interaction, and ion exchange to treat water, thereby achieving a risk-free remediation approach to polluted water. Additionally, this research offers guidance on creating efficient household treatment units based on the health risks associated with customized adsorbents and cost-benefit analyses. Lastly, this review work discusses the current obstacles for using locally accessible materials and their thermo-chemically produced by-products to purify drinking water, as well as the necessity for technological interventions.

Competitive heavy metal adsorption on pinecone shells: Mathematical modelling of fixed-bed column and surface interaction insights

Pinecone shells are assessed as a cost-effective biosorbent for the removal of metal ions Pb(II), Cu(II), Cd(II), Ni(II), and Cr(VI) in a fixed-bed column. Influent concentration, bed height, and flowrate are studied to improve efficiency. The breakthrough data is well fitted by the Sips adsorption model, suggesting a surface complexation mechanism, with maximum adsorption capacities of 11.1 mg/g for Cu(II) and 66 mg/g for Pb(II). In multimetal solutions, the uptake sequence at breakthrough and saturation is Pb(II) > Cu(II) > Cd(II). Characterization via FTIR and XRD reveals carboxyl and hydroxyl functional groups interacting with metal ions. Ca(II) does not compete with Pb(II), Cu(II), and Cd(II) adsorption, highlighting the ability of pinecone to adsorb heavy metals via surface complexation. Its application in the treatment of industrial effluents containing Cu(II), Ni(II), and Cr(VI) is explored. The study investigates bed media regeneration via eluting adsorbed metal ions with hydrochloric acid solutions. The potential of pinecone shells as an efficient biosorbent for removing toxic metal ions from industrial wastewater is emphasized. These findings enhance our understanding of the adsorption mechanism and underscore the fixed-bed column system's applicability in real-world scenarios, addressing environmental concerns related to heavy metal contamination of industrial effluents.

A novel porous lignocellulosic standing hierarchical hydroxyapatite for enhanced aqueous copper(II) removal

Potentially toxic metal-polluted water resources are a heavily discussed topic the pollution by potentially toxic metals can cause significant health risks. Nanomaterials are actively developed towards providing high specific surface area and creating active adsorption sites for the treatment and remediation of these polluted waters. In an effort to tackle the limitations of conventional type adsorbents, nano-hydroxyapatite (HAp) was developed in this study by in situ generation onto wood powder, resulting in the formation of uniform hybrid powder (HAp@wood composite) structure consisting of HAp nanoparticles that showed the removal efficiency up to 80 % after 10 min; the maximum adsorption capacity for Cu(II) ions (98.95 mg/g-HAp) was higher compared to agglomerated nano-HAp (72.85 mg/g-HAp). The adsorption capacity of Cu(II) remained stable (89.85-107.66 mg/g-HAp) during the four adsorption-desorption cycles in multi-component system, thereby demonstrating high selectivity for Cu(II). This approach of using nanoparticle is relatively simple yet effective in improving the adsorption of potentially toxic metals and the developed approach can be used to develop advanced nanocomposites in commercial wastewater treatment.

Proficient sonophotocatalytic degradation of organic pollutants using Co3O4/TiO2 nanocomposite immobilized on zeolite: Optimization, and artificial neural network modeling

The health of all living organisms is greatly influenced by the quality of the water. Therefore, developing cost-effective, eco-friendly, and easily accessible methods is desperately needed to meet the high global demand for clean water. Recently, nanozyme-based dye degradation methods have been promising for the remediation of water pollution. In this work, peroxidase-mimic Co3O4/TiO2 nanocomposite was synthesized and characterized for its size, morphology, and crystalline structure. Colorimetric assay results showed that the peroxidase-like activity of the Co3O4/TiO2 nanocomposite was considerably enhanced compared to the pure Co3O4 NPs and TiO2 NPs. Besides excellent enzyme-mimic activity, the higher sonophotocatalytic dye degradation capability of the nanocomposite after immobilization on zeolite (Co3O4/TiO2@Ze) was also demonstrated. Under optimal conditions (pH = 5.0, 25 °C), 0.1 g/L of catalyst was able to degrade 100 % of methylene blue (MB) with 600 μM in the presence of 30 μM H2O2 within 12 min. GC/MS analysis and toxicity studies revealed less toxic metabolite production after treatment of MB with sonophotocatalytic Co3O4/TiO2@Ze. Modeling of MB degradation using artificial neural networks (ANN) with a 5:6:1 topology was successfully performed, and the results confirmed the fitness of theoretical and experimental outputs according to the calculated correlation coefficient values. The prepared nanocomposite could thus be used as a promising and highly effective catalyst for the removal of organic dyes from polluted water.

Natural waste-derived nano photocatalysts for azo dye degradation

Due to their widespread application in water purification, there is a significant interest in synthesising nanoscale photocatalysts. Nanophotocatalysts are primarily manufactured through chemical methods, which can lead to side effects like pollution, high-energy usage, and even health issues. To address these issues, "green synthesis" was developed, which involves using plant extracts as reductants or capping agents rather than industrial chemical agents. Green fabrication has the benefits of costs less, pollution reduction, environmental protection and human health safety, compared to the traditional methods. This article summarises recent advances in the environmentally friendly synthesis of various nanophotocatalysts employed in the degradation of azo dyes. This study compiles critical findings on natural and artificial methods to achieve the goal. Green synthesis is constrained by the time and place of production and issues with low purity and poor yield, reflecting the complexity of plants' geographical and seasonal distributions and their compositions. However, green photocatalyst synthesis provides additional growth opportunities and potential uses.

Ultrasonic processing of WO3 nanosheets integrated Ti3C2 MXene 2D-2D based heterojunctions with synergistic effects for enhanced water splitting and environmental remediation

This article describes a straightforward chemical procedure that involves hydrothermal and ultrasonic treatments to create a new 2D/2D ultrathin WO3/Ti3C2 heterojunctions. The features of the fabricated heterojunctions were characterized and examined by field emission electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), optical absorption spectroscopy (UV-Vis). By photodegrading an organic dye under the influence of visible light, the photocatalytic degradation capabilities of the heterojunctions were also investigated. The performance of WO3/Ti3C2 was superior to that of bare WO3, with a removal rate of 94% and a kinetic rate constant (k) that was approximately 3 times that of WO3. The creation of 2D/2D heterojunction was observed to encourage the spatial charge separation and increase the surface reactive sites, to result with the increased photocatalytic activity in WO3/Ti3C2 heterojunction. The photocurrent values discovered through photoelectrochemical studies further indicated Ti3C2's active function in enhancing water-splitting performance. The impedance analysis examined by an electrochemical method revealed that heterojunctions might be helpful in accelerating the migration of charges quickly to get the outcomes seen.

Straw-derived biochar for the removal of antibiotics from water: Adsorption and degradation mechanisms, recent advancements and challenges

Antibiotics, a kind of containments with the properties of widely distributed and difficult to degrade, has aroused extensive attention in the world. As a prevalent agricultural waste, straws can be utilized to prepare biochar (straw-derived biochar, SBC) to remove antibiotics from aquatic environment. To date, although a number of review papers have summarized and discussed research on biochar application in wastewater treatment and soil remediation, there are few reviews on SBC for antibiotic removal. Due to the limitations of poor adsorption and degradation performance of the pristine SBC, it is necessary to modify SBC to improve its applications for antibiotics removal. The maximum antibiotic removal capacity of modified SBC could reach 1346.55 mg/g. Moreover, the adsorption mechanisms between modified SBC and antibiotics mainly involve π-π interactions, electrostatic interactions, hydrophobic interactions, and charge dipole interactions. In addition, the modified SBC could completely degrade antibiotics within 6 min by activating oxidants, such as PS, PDS, H2O2, and O3. The mechanisms of antibiotic degradation by SBC activated oxidants mainly include free radicals (including SO4•-, •OH, and O2•-) and non-free radical pathway (such as, 1O2, electrons transfer, and surface-confined reaction). Although SBC and modified SBC have demonstrated excellent performance in removing antibiotics, they still face some challenges in practical applications, such as poor stability, high cost, and difficulties in recycling. Therefore, the further research directions and trends for the development of SBC and biochar-based materials should be taken into consideration.

Pharmaceutical and personal care products (PPCPs) degradation and microbial characteristics of low-temperature operation combined with constructed wetlands

Emerging contaminants (ECs), which are present in water bodies, could cause global environmental and human health problems. These contaminants originate from various sources such as hospitals, clinics, households, and industries. Additionally, they can also indirectly enter the water supply through runoff from agriculture and leachate from landfills. ECs, specifically Pharmaceutical and personal care products (PPCPs), are causing widespread concern due to their contribution to persistent water pollution. Traditional approaches often involve expensive chemicals and energy or result in the creation of by-products. This study developed a practical and environmentally-friendly method for removing PPCPs, which involved combining and integrating various techniques. To implement this method, it was necessary to establish and used a field simulator based on the real-life scenario. Based on the data analysis, the average removal rates of COD, TP, TN, and NH4+-N were 57%, 59%, 63%, and 73%, respectively. the removal rate of PPCPs by CCWs was found to be 82.7% after comparing samples that were not treated by constructed wetlands and those that were treated. Combined constructed wetlands (CCWs) were found to effectively remove PPCPs from water. This is due to the combined action of plant absorption, absorption, and biodegradation by microorganisms living in the wetlands. Interestingly, the wetland plant reed had been shown to play an important role in removing these pollutants. Microbial degradation was the most important pathway for PPCPs removal in CCWs. Carbamazepine was selected as a typical PPCP for analysis. In addition, the microbial community structure of the composite filler was also investigated. High-throughput sequencing confirmed that the dominant bacteria had good adaptability to PPCPs. This technique not only reduced the potential environmental impact but also served as a foundation for further research on the use of constructed wetlands for the treatment of PPCPs contaminated water bodies and its large-scale implementation.

A review on the lignocellulosic derived biochar-based catalyst in wastewater remediation: Advanced treatment technologies and machine learning tools

Wastewater disposal in the ecosystem affects aquatic and human life, which necessitates the removal of the contaminants. Eliminating wastewater contaminants using biochar produced through the thermal decomposition of lignocellulosic biomass (LCB) is sustainable. Due to its high specific surface area, porous structure, oxygen functional groups, and low cost, biochar has emerged as an alternate contender in catalysis. Various innovative advanced technologies were combined with biochar for effective wastewater treatment. This review examines the use of LCB for the synthesis of biochar along with its activation methods. It also elaborates on using advanced biochar-based technologies in wastewater treatment and the mechanism for forming oxidizing species. The research also highlights the use of machine learning in pollutant removal and identifies the obstacles of biochar-based catalysts in both real-time and cutting-edge technologies. Probable and restrictions for further exploration are discussed.

Nano-bioremediation: an eco-friendly and effective step towards petroleum hydrocarbon removal from environment

Global concern about petroleum hydrocarbon pollution has intensified and gained scientific interest due to its noxious nature, high persistence in environmental matrices, and low degradability. One way to address this is by combining remediation techniques that could overcome the constraints of traditional physio-chemical and biological remediation strategies. The upgraded concept of bioremediation to nano-bioremediation in this direction offers an efficient, economical, and eco-friendly approach to mitigate petroleum contaminants. Here, we review the unique attributes of different types of nanoparticles and their synthesis procedures in remediating various petroleum pollutants. This review also highlights the microbial interaction with different metallic nanoparticles and their consequential alteration in microbial as well as enzymatic activity which expedites the remediating process. Besides, the latter part of the review explores the application of petroleum hydrocarbon degradation and the application of nano supports as immobilizing agents for microbes and enzymes. Further, the challenges and the future prospects of nano-bioremediation have also been discussed.

Characteristics of Adsorption/Desorption Process on Dolomite Adsorbent in the Copper(II) Removal from Aqueous Solutions

The removal of hazardous heavy metals that have been released into the environment due to industrial activities has become an important issue in recent years. The presented study concerned the removal of copper(II) ions from aqueous solutions using dolomites. Dolomite is a very attractive adsorbent due to its wide availability, low cost, good adsorption, and environmental compatibility. The paper describes the properties of D-I and D-II dolomites from two different open-cast mines in Poland. The properties of natural adsorbents were determined based on point of zero charges (PZC), elemental analysis of the adsorbent composition, FT-IR, XRD, and SEM spectra analysis. Depending on the initial concentration of the solution used, the adsorption efficiency of copper(II) ions was 58-80% for D-I and 80-97% for D-II. The adsorption mechanism in the case of D-II dolomite was mainly based on ion exchange, while chemisorption dominated the D-I dolomite surface. Considering the possibility of the regeneration and reuse of the adsorbent, dolomite D-II is a better material (the desorption efficiency of copper(II) ions was 58-80%). The adsorption behavior of dolomites has been described using six adsorption isotherms. The best fit was obtained for the Redlich-Peterson, Jovanović, and Langmuir isotherms, indicating that monolayer adsorption occurred. The maximum adsorption capacity for copper(II) was 378 mg/g of D-I and 308 mg/g of D-II.

Bio-inspired sustainable synthesis of novel SnS2/biochar nanocomposite for adsorption coupled photodegradation of amoxicillin and congo red: Effects of reaction parameters, and water matrices

This study aims to fabricate a novel integrated photocatalytic adsorbent (IPA) via a green solvothermal process employing tea (Camellia sinensis var. assamica) leaf extract as a stabilizing and capping agent for the removal of organic pollutants from wastewater. An n-type semiconductor photocatalyst, SnS_2, was chosen as a photocatalyst due to its remarkable photocatalytic activity supported over areca nut (Areca catechu) biochar for the adsorption of pollutants. The adsorption and photocatalytic properties of fabricated IPA were examined by taking amoxicillin (AM) and congo red (CR) as two emerging pollutants found in wastewater. Investigating synergistic adsorption and photocatalytic properties under varying reaction conditions mimicking actual wastewater conditions marks the novelty of the present research. The support of biochar for the SnS₂ thin films induced a reduction in charge recombination rate, which enhanced the photocatalytic activity of the material. The adsorption data were in accordance with the Langmuir nonlinear isotherm model, indicating monolayer chemosorption with the pseudo-second-order rate kinetics. The photodegradation process follows pseudo-first-order kinetics with the highest rate constant of 0.0450 min^-1 for AM and 0.0454 min^-1 for CR. The overall removal efficiency of 93.72 ± 1.19% and 98.43 ± 1.53% could be achieved within 90 min for AM and CR via simultaneous adsorption and photodegradation model. A plausible mechanism of synergistic adsorption and photodegradation of pollutants is also presented. The effect of pH, Humic acid (HA) concentration, inorganic salts and water matrices have also been included.The photodegradation activity of SnS₂ under visible light coupled with the adsorption capability of the biochar results in the excellent removal of the contaminants from the liquid phase.

Photocatalytic Degradation of Methylene Blue Using N-Doped ZnO/Carbon Dot (N-ZnO/CD) Nanocomposites Derived from Organic Soybean

This study reports on successful synthesis of carbon dots (CDs), nitrogen-doped zinc oxide (N-ZnO), and N-ZnO/CD nanocomposites as photocatalysts for degradation of methylene blue. The first part was the synthesis of CDs utilizing a precursor from soybean and ethylenediamine as a dopant by a hydrothermal method. The second part was the synthesis of N-ZnO with urea as the nitrogen dopant carried out by a calcination method in a furnace at 500 °C for 2 h in an N2 atmosphere (5 °C min-1). The third part was the synthesis of N-ZnO/CD nanocomposites. The characteristics of CDs, N-ZnO, and N-ZnO/CD nanocomposites were analyzed through Fourier transform infrared (FTIR), UV-vis absorbance, photoluminescence (PL), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), thermal gravimetry analysis (TGA), field-emission scanning electron microscopy energy-dispersive spectroscopy (FESEM EDS), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) analysis. Based on the HR-TEM analysis, the CDs had a spherical shape with an average particle size of 4.249 nm. Meanwhile, based on the XRD and HR-TEM characterization, the N-ZnO and N-ZnO/CD nanocomposites have wurtzite hexagonal structures. The materials of N-ZnO and N-ZnO/CD show increased adsorption in the visible light region and low energy gap E g. The E g values of N-ZnO and N-ZnO/CDs were found to be 2.95 and 2.81 eV, respectively, whereas the surface area (S BET) values 3.827 m2 g-1 (N-ZnO) and 3.757 m2 g-1(N-ZnO/CDs) belonged to the microporous structure. In the last part, the photocatalysts of CDs, N-ZnO, and N-ZnO/CD nanocomposites were used for degradation of MB (10 ppm) under UV-B light irradiation pH = 7.04 (neutral) for 60 min at room temperature. The N-ZnO/CD nanocomposites showed a photodegradation efficiency of 83.4% with a kinetic rate of 0.0299 min-1 higher than N-ZnO and CDs. The XRD analysis and FESEM EDS of the N-ZnO/CDs before and after three cycles confirm the stability of the photocatalyst with an MB degradation of 58.2%. These results have clearly shown that the N-ZnO/CD nanocomposites could be used as an ideal photocatalytic material for the decolorization of organic compounds in wastewater.

Ciprofloxacin degradation performances and mechanisms by the heterogeneous electro-Fenton with flocculated fermentation biochar

Antibiotic fermentation residue flocculated by polymeric ferric sulfate (PFS) has been classified as a "hazardous waste" in China. In this study, it was recycled into antibiotic fermentation residue biochar (AFRB) by pyrolysis and used as a heterogeneous electro-Fenton (EF) catalyst for ciprofloxacin (CIP) degradation. The results show that PFS was reduced to Fe⁰ and FeS during pyrolysis, which was beneficial for the EF process. The AFRB with mesoporous structures exhibited soft magnetic features, which were convenient for separation. CIP was completely degraded within 10 min by the AFRB-EF process at an initial concentration of 20 mg/L. Increasing the working current and catalyst dosage within a certain range could improve the degradation rate. ·OH and O₂^·- were the dominant reactive oxygen species that played critical roles for CIP degradation. The antibacterial groups of CIP have been destroyed by the heterogeneous electro-Fenton process and its toxicity was negligible. The AFRB showed satisfactory performance, even though it was recycled five times. This study provide new insights into the resourceful treatment of antibiotic fermentation residues.

Solar light-based advanced oxidation processes for degradation of methylene blue dye using novel Zn-modified CeO2@biochar

Herein, a novel nanocomposite, namely, Zn-modified CeO₂@biochar (Zn/CeO₂@BC), is synthesized via facile one-step sol-precipitation to study its photocatalytic activity towards the removal of methylene blue dye. Firstly, Zn/Ce(OH)₄@biochar was precipitated by adding sodium hydroxide to cerium salt precursor; then, the composite was calcined in a muffle furnace to convert Ce(OH)₄ into CeO₂. The crystallite structure, topographical and morphological properties, chemical compositions, and specific surface area of the synthesized nanocomposite are characterized by XRD, SEM, TEM, XPS, EDS, and BET analysis. The nearly spherical Zn/CeO₂@BC nanocomposite has an average particle size of 27.05 nm and a specific surface area of 141.59 m²/g. All the tests showed the agglomeration of Zn nanoparticles over the CeO₂@biochar matrix. The synthesized nanocomposite showed remarkable photocatalytic activity towards removing methylene blue, an organic dye commonly found in industrial effluents. The kinetics and mechanism of Fenton-activated dye degradation were studied. The nanocomposite exhibited the highest degradation efficiency of 98.24% under direct solar irradiation of 90 min, at an optimum dosage of 0.2 g l^-1 catalyst and 10 ppm dye concentration, in the presence of 25% (V/V) 0.2 ml (4 µl/ml) hydrogen peroxide. The hydroxyl radical generated from H₂O₂ during the photo-Fenton reaction process was attributed to the nanocomposite's improved photodegradation performance. The degradation process followed pseudo-first-order kinetics having a rate constant (k) value of 0.0274 min^-1.