Using modified fish scale waste from Sardinella brasiliensis as a low-cost adsorbent to remove dyes from textile effluents

Ultra-efficient adsorption of diclofenac sodium on fish-scale biochar functionalized with H3PO4 via synergistic mechanisms

Developing safe and efficient diclofenac sodium (DS) removal technology has become a critical issue. This study synthesized the fish-scale biochar by co-pyrolysis of fish scale and phosphoric acid (H₃PO₄). In addition to increasing the specific surface area and pore volume of fish-scale biochar, H₃PO₄ assisted in the formation of Graphitic N and sp² C, as well as reacting with C═O groups to form a significant number of phosphorus-containing groups. All these functional groups could act as major active sites for DS adsorption. Adsorption data could well fit pseudo-second-order and Langmuir models. The maximum adsorption capacity of FSB_600-15 for DS was 967.1 mg g^-1, which was much better than that reported in the literature. Under the synergistic effect of various mechanisms (pore-filling effect, electrostatic attraction, H-bonding, π-π, and n-π electron donor-acceptor interactions), the DS ultra-efficient adsorption on FSB_600-15 was realized. Meanwhile, the DS adsorption by FSB_600-15 was an endothermic, spontaneous, and entropy-increasing process. Furthermore, the DS adsorption capacity was more than 426.5 mg g^-1 in the actual water, which was sufficient for practical applications.

In vivo toxicity assessment of Remazol Gelb-GR (RG-GR) textile dye in zebrafish embryos/larvae (Danio rerio): Teratogenic effects, biochemical changes, immunohistochemical changes

Dyes, which are very important for various industries, have very adverse effects on the aquatic environment and aquatic life. However, there are limited studies on the toxic properties of dyes on living things. This research elucidated the sublethal toxicity of acute exposure of the textile dye remazol gelb-GR (RG-GR) using zebrafish embryos and larvae for 96 h. The 96 h-LC₅₀ for RG-GR in zebrafish embryos/larvae was determined to be 151.92 mg/L. Sublethal 96 hpf exposure was performed in RG-GR concentrations (0.5; 1.0; 10.0; 100.0 mg/L) to determine the development of toxicity in zebrafish embryos/larvae. RG-GR dye affected morphological development, and decreased heart rate, hatching, blood flow, and survival rates in zebrafish embryos/larvae. The immunopositivity of 8-hydroxy 2 deoxyguanosine (8-OHdG) in larvae exposed to RG-GR at high concentrations was found to be intense. Depending on the RG-GR dose increase, some biochemical parameters such as glutathione peroxidase (GSH) level, acetylcholinesterase (AChE) activity, catalase (CAT) activities, superoxide dismutase (SOD), and nuclear factor erythroid 2 (Nrf-2) levels were detected to be decreased in larvae, while malondialdehyde (MDA) content, nuclear factor kappa (NF-kB), tumor necrosis factor-α (TNF-α), DNA damage (8-OHdG level), interleukin-6 (IL-6) and apoptosis (Caspase-3) levels were found to be increased. The experimental results revealed that RG-GR dye has high acute toxicity on zebrafish embryo/larvae.

Recent advances in biodecolorization and biodegradation of environmental threatening textile finishing dyes

Organic nature of dyes and their commercially made products are widely utilized in many industries including paper, cosmetics, pharmaceuticals, photography, petroleum as well as in textile manufacturing. The textile industry being the top most consumer of a large variety of dyes during various unit processes operation generates substantial amount of wastewater; hence, nominated as "Major Polluter of Potable Water". The direct discharge of such effluents into environment poses serious threats to the functioning of biotic communities of natural ecosystems. The detection of these synthetic dyes is considered as relatively easy, however, it is extremely difficult to completely eliminate them from wastewater and freshwater ecosystems. Aromatic chemical structure seems to be the main reason behind low biodegradability of these dyes. Currently, various physiochemical and biological methods are employed for their remediation. Among them, microbial degradation has attracted greater attention due to its sustainability, high efficiency, cost effectiveness, and eco-friendly nature. The current review presents recent advances in biodegradation of industrial dyes towards a sustainable and tangible technological innovative solutions as an alternative to existing conventional physicochemical treatment processes.

Adsorption behavior of Congo red on a carbon material based on humic acid

Humic acid is used as an inexpensive starting material to prepare a strong adsorbent for the removal of Congo red from water.

Using basic parameters to evaluate adsorption potential of alternative materials: example of amoxicillin adsorption by activated carbon produced from termite bio-waste

The minimum set of parameters that can be used to assess the adsorption capacity of activated carbon (AC) produced from termite bio-waste was determined. Three types of AC were prepared: AC600 at 600 °C, MAC600 at the same temperature and impregnated with FeCl₃, and AC800 at 800 °C. The influence of the solution pH on the adsorption, adsorption kinetics, isotherms and thermodynamic parameters was considered to characterize the amoxicillin (AMX) adsorption process. The AC materials had surface areas (m² g^-1) of approximately 248.8 for AC600, 501.6 for AC800 and 269.5 for MAC600, with point of zero charge (pH_PZC) values of 8.3, 7.5 and 1.7, respectively. A time period of 30 min was chosen for the adsorption kinetics, which was best represented by the pseudo-first-order model for AC600, the intraparticle diffusion model for AC800 and the pseudo-second-order model for MAC600. Regarding the isotherms, a maximum adsorption of 23.4 mg g^-1 was found for AC800. In general, the thermodynamic parameters demonstrated a non-spontaneous process. It seems that the medium conditions, the adsorbate and adsorbent characteristics, and the Gibbs free energy are the most important parameters to be considered in a preliminary assessment of the adsorption efficiency of specific adsorbent/adsorbate pairs.