Characteristics and aqueous dye removal ability of novel biosorbents derived from acidic and alkaline one-step ball milling of hickory wood

Characterization and potential usage of selected eggshell species

Today's awareness of environmental pollution and the idea of creating a reuse area for waste is one of the trend topics. The base opinion, regarding the reuse of any material is that all resources are inherently limited in the world. In the ethical approach, it is a moral issue that people take responsibility for future generations to protect nature. Eggshells are one of the most used natural biomasses. And natural harmless eggshells deserve to be researched to reveal their potential. The aim of this study, blending the characterization processes with the research published until now, finding criteria for the unique structures and application capacities of eggshell species, ensures choosing the right type as biomass in the industry, and directing the eggshell usage to the appropriate applications and industries. In many industries, finding benchmarks of eggshell types in their unique structures and application capacity gives a clue to selecting the right type and directing the eggshells to a suitable place. In this study, different species of eggshell (Coturnix Coturnix Japonica, Anser Anser, Denizli Hen, Alectoris Chukar, and Struthio Camelus) were characterized by XRD, FTIR, AFM, Stereo Microscope, SEM, XRF, and TGA analysis. Calcined forms of eggshell samples were characterized by XRD, FTIR, and XRF analysis. TGA analysis results are used as a precursor to determine the temperature of calcination (800-900°). XRD results show that the CaCO3 peak is 2Ɵ=29.58° for all eggshells. The reason why this peak is not observed after the calcination process is that the entire CaCO3 structure is converted to CaO. In FTIR results, the C-O stretching band which is observed at 1424 cm- 1 is the main characteristic band of selected eggshell species. When AFM images are examined, it is seen that the surface of small eggshells is rougher, while the surface of the eggshell becomes smoother as the egg size increases. SEM and stereo microscope images show that the shell thickness increases as the egg size increases.

Efficient removal of aqueous ciprofloxacin antibiotic by ZnO/CuO-bentonite composites synthesized via carbon-bed pyrolysis of bentonite and metal co-precipitation

Antibiotics are of emerging concern due to their widespread use, lack of adequate treatment, and for their potential to threaten human health and the environment. Here, a facile fabrication approach for synthesizing ZnO/CuO-bentonite composites was investigated via carbon-bed pyrolysis of bentonite followed by ZnO/CuO co-precipitation. Sorbents were synthesized using a range of bentonite pyrolysis temperatures, metal oxide contents, and ZnO:CuO mass ratios. The ZnO/CuO-bentonite composites exhibited diverse functional groups, excellent mesoporosity, and high specific surface area (135.0 m2 g-1, four times that of pyrolyzed bentonite-only control). Ciprofloxacin removal was maximized at a bentonite pyrolysis temperature of 450 °C, a total metal oxide content of 25 %, and a Zn/Cu ratio between 95:5 and 93:7, and this material had an observed experimental CIP adsorption of 451 mg g-1 and a calculated maximum adsorption capacity of 1249.3 mg g-1. This excellent CIP sorption ability was attributed to its abundant surface active sites and multiple sorption mechanisms, including hydrogen-bond interaction, ion exchange, and electrostatic interaction. These results illustrate that ZnO/CuO-bentonite composite sorbents have excellent potential for use in environmental remediation and water treatment applications.

Sulfuric acid-assisted ball milling for the preparation of Si-O-enriched straw biochar: removal efficiency of rhodamine B and adsorption mechanism

Traditional pyrolysis biochar has been widely employed to treat dye wastewater. However, there are some problems in the pyrolysis process, such as the generation of harmful gases and the low content of silico-oxygen functional groups to promote adsorption. Straw biochar (Ac-BCbm) was prepared by sulfuric acid co-ball milling method. The adsorption performance and adsorption mechanism of rhodamine B (RhB) under different preparation conditions and factors were investigated. The results showed that the adsorption rate of Ac-BCbm on RhB was up to 94.9%, which was 60.5% and 55.8% higher than that of ball-milling straw (STbm) and biochar prepared by pyrolysis (STBC600), respectively. The Ac-BCbm had better adaptability under different pH and common interfering ions for remove RhB. Characterization and DFT simulation analysis revealed that the sulfuric acid co-ball milling process promoted the formation of Si-OH and Si-O-CH3 oxygen-containing functional groups of Si component in straw, which enhanced the hydrogen bonding interactions and effectively improved the adsorption efficiency. This study investigated a new strategy for biochar preparation by sulfuric acid co-ball milling, which provides an additional development direction for the efficient resource utilization of straw.

Fabrication of Iron-Containing Biochar by One-Step Ball Milling for Cr(VI) and Tetracycline Removal from Wastewater

Simple ball milling technology can simultaneously improve the adsorption performance of adsorbents for heavy metals and organic pollutants and has attracted increasing attention. Iron-modified biochar (Fe@MBC) was prepared by one-step ball milling, and the characterization results proved that FeCl3 was successfully loaded on biochar. The removal rates of Cr(VI) and tetracycline hydrochloride (TC) by Fe@MBC were increased by 88.27% and 82.64% compared with BC. The average pore size, oxygen-containing functional groups and graphitization degree of Fe@MBC are higher than those of BC, which is more conducive to promoting adsorption. The adsorption isotherms show that the adsorption of Cr(VI) and TC on the Fe@MBC surface conforms to the Langmuir type of single-layer adsorption and the Freundlich model of multilayer adsorption, respectively. The maximum adsorption capacities of Cr(VI) and TC are 25.46 and 66.91 mg·g-1, respectively. Kinetic experiments show that the adsorption process is more consistent with the pseudo-second-order model of chemical adsorption. The adsorption process of Cr(VI) and TC on the Fe@MBC surface is a spontaneous endothermic process that becomes more obvious as the temperature increases. The increase in solution pH has a significant impact on the removal rate of Fe@MBC. When the pH value increased from 3 to 11, the adsorption rates decreased by 53.74% and 17.16%, respectively. The presence of PO43-, CO32-, K+, and Cu2+ significantly affects the adsorption of TC by Fe@MBC, and PO43- and CO32- also affect the adsorption of Cr(VI). Mechanistic studies show that ion exchange, electrostatic interaction, pore filling, and hydrogen bonding contribute to the removal of Cr(VI) and TC by Fe@MBC. The removal mechanism of Cr(VI) also involves complexation and redox reactions, and the removal mechanism of TC involves π-π bonds and van der Waals forces. The results show that Fe@MBC is a green and efficient adsorbent.

Durable superhydrophobic/superoleophilic melamine foam based on biomass-derived porous carbon and multi-walled carbon nanotube for oil/water separation

In the present study, fabrications of two eco-friendly superhydrophobic/superoleophilic recyclable foamy-based adsorbents for oil/water mixture separation were developed. Hierarchically biomass (celery)-derived porous carbon (PC) and multi-walled carbon nanotube (MWCNT) were firstly synthesized and loaded on pristine melamine foam (MF) by the simple dip-coating approach by combining silicone adhesive to create superhydrophobic/superoleophilic, recyclable, and reusable three-dimensional porous structure. The prepared samples have a large specific surface area of 240 m²/g (MWCNT), 1126 m²/g (PC), and good micro-mesoporous frameworks. The water contact angle (WCA) values of the as-prepared foams, PC/MF and MWCNT/MF, not only were 159.34° ± 1.9° and 156.42° ± 1.6°, respectively but also had oil contact angle (OCA) of equal to 0° for a wide range of oils and organic solvents. Therefore, PC/MF and MWCNT/MF exhibited superhydrophobicity and superoleophilicity properties, which can be considered effective adsorbents in oil/water mixture separations. In this context, superhydrophobic/superoleophilic prepared foams for kind of different oils and organic solvents were shown to have superior separation performance ranges of 54-143 g/g and 46-137 g/g for PC/MF and MWCNT/MF, respectively, suggesting a new effective porous material for separating oil spills. Also, outstanding recyclability and reusability of these structures in the ten adsorption-squeezing cycles indicated that the WCA and sorption capacity has not appreciably changed after soaking into acidic (pH = 2) and alkaline (pH = 12) as well as saline (3.5% NaCl) solutions. More importantly, the reusability and chemical durability of the superhydrophobic samples made them good opportunities for use in different harsh conditions for oil-spill cleanup.

A Comprehensive Review on Adsorption, Photocatalytic and Chemical Degradation of Dyes and Nitro-Compounds over Different Kinds of Porous and Composite Materials

Dye and nitro-compound pollution has become a significant issue worldwide. The adsorption and degradation of dyes and nitro-compounds have recently become important areas of study. Different methods, such as precipitation, flocculation, ultra-filtration, ion exchange, coagulation, and electro-catalytic degradation have been adopted for the adsorption and degradation of these organic pollutants. Apart from these methods, adsorption, photocatalytic degradation, and chemical degradation are considered the most economical and efficient to control water pollution from dyes and nitro-compounds. In this review, different kinds of dyes and nitro-compounds, and their adverse effects on aquatic organisms and human beings, were summarized in depth. This review article covers the comprehensive analysis of the adsorption of dyes over different materials (porous polymer, carbon-based materials, clay-based materials, layer double hydroxides, metal-organic frameworks, and biosorbents). The mechanism and kinetics of dye adsorption were the central parts of this study. The structures of all the materials mentioned above were discussed, along with their main functional groups responsible for dye adsorption. Removal and degradation methods, such as adsorption, photocatalytic degradation, and chemical degradation of dyes and nitro-compounds were also the main aim of this review article, as well as the materials used for such degradation. The mechanisms of photocatalytic and chemical degradation were also explained comprehensively. Different factors responsible for adsorption, photocatalytic degradation, and chemical degradation were also highlighted. Advantages and disadvantages, as well as economic cost, were also discussed briefly. This review will be beneficial for the reader as it covers all aspects of dye adsorption and the degradation of dyes and nitro-compounds. Future aspects and shortcomings were also part of this review article. There are several review articles on all these topics, but such a comprehensive study has not been performed so far in the literature.