Removal Of Contaminants In Water Research Articles

WS2-Assisted Electrochemical Activation of Peroxymonosulfate for Eliminating Organic Pollutant in Water

Advanced oxidation process based on heterogeneous activation of peroxymonosulfate (PMS) has received significant attention in wastewater remediation. Herein, a facile and effective electrochemical method was introduced in a tungsten sulfide (WS2)-activated PMS process for the removal of a typical azo dye Acid Orange 7 (AO7) in aqueous solution. It was found that the electrochemical activation could remarkably promote the removal of organic pollutants by coupling with WS2/PMS system. The elimination of AO7 in the electro-assisted WS2-activated PMS (E/WS2/PMS) system achieved 95.8% of AO7 removal in 30 min, with the optimal conditions of 1.0 g/L WS2, 1.0 mM PMS, current density of 1.0 mA/cm2 and initial pH of 6.5. Based on quenching experiments and EPR techniques, mechanistic studies confirmed that hydroxyl radical (•OH) and singlet oxygen (1O2) are the primary reactive oxygen species for the oxidation of pollutants. In addition, the influences of pH, WS2 dosage, PMS concentration, current density, common anions and humic acid on the AO7 removal are also investigated in detail. Furthermore, the system exhibited resistance to aqueous matrices, verifying the accepted applicability in real water (i.e., Yangtze River water and Shahu Lake water). In summary, this study demonstrates a green system for the effective removal of contaminants in water, holding significant implications for practical application.

Evaluation of adsorption isotherms and kinetics of anionic pollutant in water using biochar derived from locally available agro-waste

The uses of agricultural byproduct solid wastes to develop low cost sorbents are advantageous and promising for the removal of water contaminants. It serves the purposes of both environmental remediation and appropriate management of agricultural waste generated during agricultural processing. In this study, locally available apricot seed shell and Salix Alba leaves were utilized as agro-waste for the preparation of adsorbents. The biochar was prepared at 300-370oC via pyrolysis and 80 mesh particle sizes were modified by 1N HCl. The unmodified and acid modified local Salix Alba leaves and Apricot seed shell biochar were used to study the adsorption of chloride ion in water, which can damages appliances of industries and also poses health issues at elevated concentration. Adsorption kinetics and equilibrium studies were conducted at pH 7. The adsorption efficiency of modified biochar was much higher than the unmodified biochar due to induce surface positive charge. The Langmuir maximum adsorption of modified Salix Alba leaves sorbent was found to 22.98 mg/g, while modified Apricot seed shell biochar was found 25.83 mg/g. The experimental data were simulated and applied to fit Langmuir, Freundlich isotherm, pseudo 1st and 2nd order kinetics models and found a better compliance with Freundlich isotherm model and pseudo 2nd order kinetics model.

Dual-capable spinel cobalt oxide nanoparticles for electrocatalytic oxygen evolution and water contaminant removal.

This study investigates the synthesis and electrocatalytic performance of cobalt oxide (Co3O4) nanoparticles for the oxygen evolution reaction (OER) and their role in water treatment as contaminant removal agents. Cobalt oxide nanoparticles are recognized as promising materials in electrocatalysis due to their tunable properties and nanoscale engineering potential. Here, fine cobalt oxide nanoparticles are synthesized using the sol-gel method followed by various sintering temperatures to achieve precise control over surface morphology, size, and shape. Characterization via high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM) elucidates the impact of sintering temperature on nanoparticle properties. Thin film electrodes of cobalt oxide are fabricated using the doctor blade method and evaluated using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Among the tested sintering temperatures, cobalt oxide electrodes sintered at 600°C exhibit superior catalytic activity, demonstrating an overpotential of 258mV (vs RHE) at 10mAcm-2 current density and a Tafel slope of 17.33mV dec-1. Furthermore, these electrodes demonstrate excellent stability, maintaining OER performance for 10h in 1M NaOH electrolyte. Additionally, the role of cobalt oxide nanoparticles in water treatment is explored using inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental results reveal that lower sintering temperatures enhance the electrocatalytic properties of cobalt oxide nanoparticles, highlighting their potential contribution to sustainable energy and water treatment technologies. This work underscores the significance of cobalt oxide nanoparticles as dual-functional materials for advancing electrocatalysis and water purification applications, thus paving the way for the development of efficient and environmentally friendly technologies.

Nanocellulose-Based Materials for Water Pollutant Removal: A Review.

Cellulose in the nano regime, defined as nanocellulose, has been intensively used for water treatment. Nanocellulose can be produced in various forms, including colloidal, water redispersible powders, films, membranes, papers, hydrogels/aerogels, and three-dimensional (3D) objects. They were reported for the removal of water contaminants, e.g., heavy metals, dyes, drugs, pesticides, pharmaceuticals, microbial cells, and other pollutants from water systems. This review summarized the recent technologies for water treatment using nanocellulose-based materials. A scientometric analysis of the topic was also included. Cellulose-based materials enable the removal of water contaminants, and salts offer advanced technologies for water desalination. They are widely used as substrates, adsorbents, and catalysts. They were applied for pollutant removal via several methods such as adsorption, filtration, disinfection, coagulation/flocculation, chemical precipitation, sedimentation, filtration (e.g., ultrafiltration (UF), nanofiltration (NF)), electrofiltration (electrodialysis), ion-exchange, chelation, catalysis, and photocatalysis. Processing cellulose into commercial products enables the wide use of nanocellulose-based materials as adsorbents and catalysts.

Persulfate activation by biochar and iron: Effect of chloride on formation of reactive species and transformation of N,N-diethyl-m-toluamide (DEET)

Fenton-like processes using persulfate for oxidative water treatment and contaminant removal can be enhanced by the addition of redox-active biochar, which accelerates the reduction of Fe(III) to Fe(II) and increases the yield of reactive species that react with organic contaminants. However, available data on the formation of non-radical or radical species in the biochar/Fe(III)/persulfate system are inconsistent, which limits the evaluation of treatment efficiency and applicability in different water matrices. Based on competition kinetics calculations, we employed different scavengers and probe compounds to systematically evaluate the effect of chloride in presence of organic matter on the formation of major reactive species in the biochar/Fe(III)/persulfate system for the transformation of the model compound N,N‑diethyl-m-toluamide (DEET) at pH 2.5. We show that the transformation of methyl phenyl sulfoxide (PMSO) to methyl phenyl sulfone (PMSO2) cannot serve as a reliable indicator for Fe(IV), as previously suggested, because sulfate radicals also induce PMSO2 formation. Although the formation of Fe(IV) cannot be completely excluded, sulfate radicals were identified as the major reactive species in the biochar/Fe(III)/persulfate system in pure water. In the presence of dissolved organic matter, low chloride concentrations (0.1 mM) shifted the major reactive species likely to hydroxyl radicals. Higher chloride concentrations (1 mM), as present in a mining-impacted acidic surface water, resulted in the formation of another reactive species, possibly Cl2•−, and efficient DEET degradation. To tailor the application of this oxidation process, the water matrix must be considered as a decisive factor for reactive species formation and contaminant removal.

Recent Progress in MOF-Aerogel Fabrication and Applications.

Recent advancements in metal-organic frameworks (MOFs) underscore their significant potential in chemical and materials research, owing to their remarkable properties and diverse structures. Despite challenges like intrinsic brittleness, powdered crystalline nature, and limited stability impedingdirect applications, MOF-based aerogels have shown superior performance in various areas, particularly in water treatment and contaminant removal. This review highlights the latest progress in MOF-based aerogels, with a focus on hybrid systems incorporating materials like graphene, carbon nanotube, silica, and cellulose in MOF aerogels, which enhance their functional properties. The manifold advantages of MOF-based aerogels in energy storage, adsorption, and catalysis are discussed, with an emphasizing on their improved stability, processability, and ease of handling. This review aims to unlock the potential of MOF-based aerogels and their real-world applications. Aerogels are expected to reshape the technological landscape of MOFs through enhanced stability, adaptability, and efficiency.

Investigation of La-BiVO4/g-C3N4 photocatalytic system for efficient removal of hazardous water contaminants

The application of semiconductor photocatalysis powered by renewable energy sources for environmental remediation of emerging contaminants has gained significant research interest in recent years. Lanthanum-substituted bismuth vanadate (La-BiVO4)/graphitic carbon nitride (g-C3N4) heterojunctions were synthesized for the photocatalytic degradation of emerging water contaminants. Significantly, La³+ substitution serves as a model system for exploring the broader concept of cationic substitutions on BiVO4. By strategically replacing a portion of Bi(III) with various cations, we can potentially tailor the electronic structure of BiVO4 for enhanced photocatalytic performance. Photoelectrochemical analysis confirmed rapid charge separation and reduced resistance, leading to effective contaminant degradation. The La-BiVO4/g-C3N4 nanocomposite exhibited exceptional photocatalytic performance under simulated solar light irradiation (Xe-350W, AM 1.5 G), achieving 87.66% photooxidation of roxarsone within 150 min, surpassing g-C3N4, BiVO4, LaVO4, La-BiVO4, BiVO4/g-C3N4, and LaVO4/g-C3N4 by factors of 1.94, 1.26, 2.25, 1.39, 1.13, and 2.51, respectively. Moreover, it demonstrated 99.61% degradation of Cr(VI) after 60 min, outperforming g-C3N4, BiVO4, LaVO4, La-BiVO4, BiVO4/g-C3N4, and LaVO4/g-C3N4 by factors of 1.11, 1.81, 1.62, 1.67, 1.20, and 1.13, respectively. These findings underscore the superior photocatalytic efficacy of the La-BiVO4/g-C3N4 nanocomposite. The efficient photocatalytic activity of La-BiVO4/g-C3N4 type-II heterojunctions demonstrates its potential for real-world environmental remediation. This material offers a promising strategy for removing harmful water contaminants, thereby mitigating risks associated with water consumption.

Efficient removal of Cd2+ ions and methylene blue from aqueous solutions by polyanionic sodium alginate-derived hydrogel

Considering the purification technology based on the fabrication of efficient adsorbents for the effective removal of water contaminants, we developed a polyanionic superabsorbent hydrogel for its application in the adsorption of cadmium ions (Cd2+) and methylene blue (MB). The hydrogel was prepared by graft copolymerization of methacrylic acid, acrylamide, and 2-acrylamido-2-methyl-1-propanesulfonic acid onto sodium alginate. The hydrogel structure, thermal stability, surface morphology, and surface area were studied using FT-IR, SEM, EDX, TGA, and BET techniques.The hydrogel capacity to remove Cd2+ MB from aqueous solutions was investigated at different contact times, pH, sorbent dosage, contaminant concentrations, temperature salinity, and ion selectivity. To understand the hydrogel sorption behavior, different adsorption kinetics and isotherms models were employed. The hydrogel exhibited impressive efficacy in the removal of Cd2+ and MB ions, achieving removal efficiencies of up to 87% and 97.5%, respectively, under a sorbent dosage of 0.15 g/100 mL and a temperature of 25°C. Utilizing the Langmuir isotherm model, the maximum sorption capacities were determined to be 526 mg/g for cadmium ions and 131.5 mg/g for methylene blue. Regeneration experiments confirmed the reusability of the hydrogel, highlighting its potential as an effective adsorbent for Cd²⁺ and MB dye.

A superhydrophilic composite membrane with excellent photo-Fenton antifouling performance for efficient removal of diverse contaminants

The development of multifunctional composite membranes with integrating membrane separation and catalytic degradation processes is of great significance for effectively eliminating diverse contaminants from water. Herein, a superhydrophilic PANI/Fe1.02Zr-MOF/PVDF composite membrane was designed and prepared via nonsolvent induced phase separation (NIPS) method followed by in situ polymerization to coat a polyaniline (PANI) layer. The introduction of Fe-doped Zr-MOF (Fe1.02Zr-MOF) imparts an excellent self-cleaning ability to the membrane due to in situ photo-Fenton reaction. The surface modification with a PANI layer enhances the membrane’s hydrophilicity and provides abundant active sites for contaminant enrichment. The composite membrane demonstrated remarkable removal efficiency towards a wide range of contaminants, including antibiotics, hexavalent chromium, and oil, as well as excellent antifouling ability. Moreover, continuous and rapid sewage purification was achieved by combining multiple membranes in a cascade configuration under a small additional pressure. The potential toxicities of intermediate products generated from the degradation of antibiotics were analyzed. The mechanisms involved in photo-Fenton degradation of antibiotic and photocatalytic reduction of Cr(VI) were studied. This work highlights a novel strategy to develop composite membranes with excellent photo-Fenton self-cleaning ability for efficient removal of diverse water contaminants.

Efficient and easily recyclable photocatalytic reduction of Se(IV) from wastewater using stable TiO2/BiOBr/cloth: Mechanism insight and machine learning modeling

Photocatalytic technology is extensively employed for the reductive removal of water contaminants; however, it contends with low catalytic efficiency and challenges in catalyst recovery. In this study, we propose integrating experimental procedures with artificial intelligence modeling to enhance the purification of Se(IV)-contaminated wastewater. We present an efficient, easily recyclable, and cost-effective strategy for photocatalyst fabrication. Specifically, we develop a novel method for Se(IV) removal by immobilizing TiO2/BiOBr onto glass fiber cloth surfaces using chitosan for Se(IV) reduction in aqueous solutions. The TiO2/BiOBr/cloth (TB-4/cloth) catalyst achieves a remarkable 99.2 % Se(IV) removal within 2 h under visible light and maintains excellent Se(IV) reduction photocatalytic activity (86.4 %) even after eight cycles, remaining easily reusable. Additionally, we develop two machine learning models, namely artificial neural network (ANN) and long short-term memory (LSTM), to validate the anticipated experimental outcomes. Both models exhibit high accuracy and predictive capability (R2 > 0.99, RMSE < 0.03). This study introduces a novel approach that combines experimentation with artificial intelligence modeling, paving the way for future advancements in Se(IV)-contaminated wastewater purification methods.

Removal of Contaminants in Water with Scallop Shell Waste

Currently, the cultivation and harvesting of mollusks is a crucial activity worldwide. However, this industry generates a large amount of mollusk shell waste disposed of in landfills, causing environmental pollution. In addition, the companies linked to this item allocate large sums of money to depositing the shells in authorized landfills. In South America, Chile is one of the leading producers worldwide of scallop shell (Argopecten purpuratus) waste, creating a growing environmental and financial problem in the country, especially considering that there has yet to be progress in the development of new technologies that may reuse this waste in Chile. This study used different techniques to completely characterize the northern Chile scallop shell waste’s physical and chemical properties for the first time. The XRD result corresponded with calcite crystal structures (CaCO3), and the XFR showed 97.68% purity. Three particle sizes were obtained: BS (595–100 µm), MS (250–595 µm), and SS (&lt;250 µm). In addition, the potential use of these wastes to remove contaminants present in water from the wine industry (caffeic acid) and some drinking water (arsenic(III)) was evaluated. The powder with the smallest particle size (SS), which has a surface area of 1 m2/g, 0.0050 m3/g of pore volume and pore diameter of 18.0 nm, removed 100.0% of CA and 23.0% As(III) in a pH condition of 4.6. The results show that scallop shell waste can be used to treat water and reinforce polymeric matrix composite materials to improve mechanical properties.

Carbon Nanotubes as Adsorbents for Heavy Metals: Focus on Arsenic and Hydrargyrum Removal from Water

Water is the most common and indissoluble substance in the ecosystem. It is really sad that the development of cities, people, and industries has side effects on water resources, as they are getting worse. Heavy metals are mostly found in industries; their toxicity levels are a big challenge. The work details the latest methods employed in the removal of water contaminants with heavy metals, absorption being the technique used. Following the completeness of the literature review for various sorbents that are used to remove heavy metals from wastewater, this article details one of the possible sorbents that can play this role, using carbon nanotubes as a sorbent. Through the test, it has been demonstrated that CNTs have high efficiency, yet some shortcomings have also been shown. It should, additionally, be known that further improvement of desulfurizing agents to make them better at removing heavy metals is needed. This work demonstrates that, in comparison to IL's, which must be supplied by producers, DES's, as an alternative approach, are cheaper, more accessible to use, and much safer for the environment. In other words, the method of adsorption with functionalized CNTs + DESs proved to be the most suitable. The practical diagnostics and conclusions generated from this research should prove valuable to engineers and environmental scientists involved in carbon nanotube applications in environmental remediation.

Humic acid-nanoceria composite as a sustainable adsorbent for simultaneous removal of uranium(VI), chromium(VI), and fluoride ions from aqueous solutions.

In this article, the multifunctional behavior of novel, efficient, and cost-effective humic acid-coated nanoceria (HA@CeO2 NPs) was utilized for the sorptive removal of U(VI), Cr(VI), and F- ions at different conditions. The production cost of HA@CeO2 was $19.28/kg and was well characterized by DLS, FESEM, HRTEM, FTIR, XRD, XPS, and TGA. Batch adsorption study for U(VI) (at pH ~ 8), Cr(VI) (at pH ~ 1), and F- (at pH ~ 2) revealed that the maximum percentage of sorption was > 80% for all the cases. From the contact time experiment, it was concluded that pseudo-second-order kinetics followed, and hence, the process should be a chemisorption. The adsorption study revealed that U(VI) and Cr(VI) followed the Freundlich isotherm, whereas F- followed the Langmuir isotherm. Maximum adsorption capacity for F- was 96mgg-1. Experiments in real water suggest that adsorption is decreased in Kaljani River water (~ 12% for Cr(VI) and ~ 11% for F-) and Kochbihar Lake water (25.04% for Cr(VI) and 20.5% for F-) because of competing ion effect. Mechanism was well established by the kinetic study as well as XPS analysis. Because of high adsorption efficiency, HA@CeO2 NPs can be used for the removal of other harmful water contaminants to make healthy aquatic life as well as purified drinking water.

Low-cost, manual centrifuge for separation of particles from water

Water separation is a critical process with far-reaching implications for the environment, public health, and various industries. Traditional water filtration methods are often limited to commercial use, posing challenges for individuals lacking access to clean water, or the equipment to separate particles suspended in water. In this study, we developed a spinning device for water separation through centrifugal and rotation force. Our goal was to create a device that could provide a low-cost alternative for removing contaminants from water. During the testing, we found that the device had a theoretical efficiency of 67% and longer separation times consistently produced significantly lower absorbance values in the visible range, indicating more effective particle removal. A computational model was also used to simulate the movement of particles under the influence of rotational forces, and showed that the smallest particle in this experiment (microplastics) can be theoretically moved by the rotational forces. This study underscores the promise of a manually powered spinning toy as an innovative and efficient tool for water separation and contaminant removal, holding the potential to address global water quality challenges.

High performance of reduced graphene oxide and g-C3N4 co-doped CuFe2O4 for peroxymonosulfate activation under visible light: Degradation process of sulfamethazine via a singlet oxygen dominated pathway

Peroxymonosulfate (PMS) activation by heterogeneous metal-based catalysts has been extensively applied for the degradation of organic pollutants in water. However, the catalysts suffer from the low oxidant utilization efficiency, pH limitations and severe matrix interference. Here, a reduced graphene oxide and g-C3N4 co-doped copper ferrite (rGO-CNCF) was synthesized and its performance for PMS activation under visible light was evaluated for removal of sulfamethazine. In the condition of rGO-CNCF (0.2 g/L) and PMS (0.1 g/L), the vis/rGO-CNCF/PMS system could degrade 99.9 % of sulfamethazine (SMT, 10 mg/L) within 30 min at pH 7.0, and the system also showed high degrading abilty of SMT over a wide pH range (0–14), along with a good adaptability to common coexisting ions in water solution. The introduction of rGO not only enhanced the stability of rGO-CNCF but also changed the binding sites between PMS and rGO-CNCF which reduced the adsorption energy. Singlet oxygen (1O2) was unveiled to be the major reactive oxygen species (ROS), which was produced by the transformation between negatively charged PMS (HSO5−) and water,along with the self-degradation of PMS. SMT was decomposed through four degradation pathways in this system, and quantitative structure–activity relationship (QSAR) predictions indicated a significant decrease in its toxicity. Results of this study indicated that the material can efficiently activate persulfate for the removal of organic pollutants from water under visible light conditions and it provided a novel catalytic system for removal of organic contaminants in water.

Sustainable Zeolite–Silver Nanocomposites via Green Methods for Water Contaminant Mitigation and Modeling Approaches

This study explores cutting-edge and sustainable green methodologies and technologies for the synthesis of functional nanomaterials, with a specific focus on the removal of water contaminants and the application of kinetic adsorption models. Our research adopts a conscientious approach to environmental stewardship by synergistically employing eco-friendly silver nanoparticles, synthesized using Justicia spicigera extract as a biogenic reducing agent, in conjunction with Mexican zeolite to enhance contaminant remediation, particularly targeting Cu2+ ions. Structural analysis, utilizing X-ray diffraction (XRD) and high-resolution scanning and transmission electron microscopy (TEM and SEM), yields crucial insights into nanocomposite structure and morphology. Rigorous linear and non-linear kinetic models, encompassing pseudo-first order, pseudo-second order, Freundlich, and Langmuir, are employed to elucidate the kinetics and equilibrium behaviors of adsorption. The results underscore the remarkable efficiency of the Zeolite–Ag composite in Cu2+ ion removal, surpassing traditional materials and achieving an impressive adsorption rate of 98% for Cu. Furthermore, the Zeolite–Ag composite exhibits maximum adsorption times of 480 min. In the computational analysis, an initial mechanism for Cu2+ adsorption on zeolites is identified. The process involves rapid adsorption onto the surface of the Zeolite–Ag NP composite, followed by a gradual diffusion of ions into the cavities within the zeolite structure. Upon reaching equilibrium, a substantial reduction in copper ion concentration in the solution signifies successful removal. This research represents a noteworthy stride in sustainable contaminant removal, aligning with eco-friendly practices and supporting the potential integration of this technology into environmental applications. Consequently, it presents a promising solution for eco-conscious contaminant remediation, emphasizing the utilization of green methodologies and sustainable technologies in the development of functional nanomaterials.

Engineering Magnetic Biochar from Polyphenol-Functionalized Biomass for the Removal of Broad-Spectrum Water Contaminants

Engineering Magnetic Biochar from Polyphenol-Functionalized Biomass for the Removal of Broad-Spectrum Water Contaminants

Theory-guided unraveling of the mechanism underlying Cu1.0/Mn1.0-ZnO with dual reaction centers for enhanced peroxymonosulfate activation

Developing efficient catalytic systems for water contamination removal is a topic of great interest. However, the use of heterogeneous catalysts faces challenges due to insufficient active sites and electron cycling. In this study, results from first-principles calculations demonstrate that dual reaction centers (DRCs) are produced around the Cu and Mn sites in Cu1.0/Mn1.0-ZnO due to the electronegativity difference. Experimental results reveal the material with DRCs greatly enhances electron transfer efficiency and significantly impacts the oxidation and reduction of peroxymonosulfate (PMS). In addition, the self-consistent potential correction (SCPC) method was introduced to correct the energy and charge of charged periodic systems simulating a catalytic process, resulting in more precise catalytic results. Specifically, the material exhibits a preference for adsorbing negatively charged PMS anions at electron-deficient Mn sites, facilitating PMS oxidation for the generation of 1O2, and PMS reduction around the electron-rich Cu for the formation of •OH and SO4•−. The major reactive oxygen species is 1O2, showcasing effective performance in various degradation systems. Overall, our work provides novel insights into the persulfate-based heterogeneous catalytic oxidation process, paving the way for the development of high-performance catalytic systems for water purification.

Baked hydrogel from palm starch and modified chitosan for water contaminant removal

Baked hydrogel from palm starch and modified chitosan for water contaminant removal

BIOCHAR FROM LIGNOCELLULOSIC BIOMASS: A SUSTAINABLE CIRCULAR ECONOMY APPROACH FOR REMOVING ORGANIC AND INORGANIC CONTAMINANTS

Metals, pharmaceuticals, personal care products, pesticides, and dyes constitute contaminants widely detected in aquatic ecosystems. Adsorption is an important technology for addressing these noxious contaminants in water systems. Its widespread employment stems from its uncomplicated design, environmentally benign nature, heightened sensitivity to contaminants, and mechanical robustness. These inherent advantages render it a highly promising solution for such challenges. Within this framework, biochar embodies key physicochemical properties akin to activated carbon, the foremost adsorbent globally recognized for its efficacy in water contaminant removal. Moreover, biochar derives from the repurposing of biomass waste, thereby presenting an opportunity to enhance the value chain of numerous agricultural byproducts across Brazil. Therefore, this review article aims to present the most commonly studied lignocellulosic residues from Brazil as adsorbents, the methods used to convert them into biochar, the factors influencing the adsorption of contaminants on biochar, and their environmental applications. The main results related to lignocellulosic biomass were presented, including sugarcane, soybean, corn, rice, cotton, coffee, açaí, tucumã, coconut, Brazil nut, cupuaçu, nuts, murumuru, orange, cassava, banana, malt, macaúba, and guava. It was concluded that chemical activation is more common than physical activation, especially using ZnCl2. Finally, the materials have been employed for the removal of metals and a few organic contaminants, mainly dyes, from synthetic solutions.