Deep insights into kinetics, optimization and thermodynamic estimates of methylene blue adsorption from aqueous solution onto coffee husk (Coffee arabica) activated carbon.

In the current study, an attempt was made to synthesize coffee husk (CH) activated carbon by chemical modification approach (sulphuric acid-activated CH (SACH) activated carbon) and was used as a valuable and economical sorbent for plausible remediation of Methylene blue (MB) dye. Batch mode trials were carried out by carefully varying the batch experimental variables: SACH activated carbon (SACH AC) dosage, pH, initial dye concentration, temperature, and contact time. The optimum equilibrium time for adsorption by SACH activated carbon was obtained as 60 min, and the maximum adsorption took place at 30 °C. Morphological and elemental composition, crystallinity behaviour, functional groups, and thermal stability were examined using SEM with EDX, XRD, FTIR, BET, TGA, and DTA and these tests showed successful production of activated carbon. The outcomes showed that chemical activation enhanced the number of pores and roughness which possibly maximized the adsorptive potential of coffee husk. The Box-Benken design (BBD) was used to optimize the MB dye adsorption studies and 99.48% MB dye removed at SACH AC dosage of 4.83 g/L at 30 °C for 60 min and pH 8.12, and the maximum adsorption was yielded for sulphuric acid-activated coffee husk carbon carbon with 88.1 mg/g maximum MB adsorption capacity. Langmuir- Freundlich model deliberately provided a better fit to the equilibrium data. The SACH AC-MB dye system kinetics showed a high goodness-of-fit with pseudo second order model, compared to other studied models. Change in Gibbs's free energy (ΔGo) of the system indicated spontaneity whereas low entropy value (ΔSo) suggested that the removal of MB dye on the SACH activated carbon was an enthalpy-driven process. The exothermic nature of the sorption cycle was affirmed by the negative enthalpy value (ΔHo). The adsorptive-desorptive studies reveal that SACH AC could be restored with the maximum adsorption efficiency being conserved after the fifth cycles. Overall, the outcomes revealed that sulphuric acid-activated coffee husk activated carbon (SACH AC) can be used as prompt alternative for low-cost sorbent for treating dye-laden synthetic wastewaters.

Progress and Prospective of the Industrial Development and Applications of Eco-Friendly Colorants: An Insight into Environmental Impact and Sustainability Issues.

Color is the prime feature directly associated with the consumer's attraction and choice of their food. The flavor, safety, and nutritional value of any food product are directly associated with the food color. Natural and synthetic colorants (dyes and pigments) have diversified applications in various sectors such as food, feed, pharmaceutical, textiles, cosmetics, and others. Concerning the food industry, different types of natural and synthetic colorants are available in the market. Synthetic food colorants have gained popularity as they are highly stable and cheaply available. Consumers worldwide prefer delightful foodstuffs but are more concerned about the safety of the food. After its disposal, the colloidal particles present in the synthetic colorants do not allow sunlight to penetrate aquatic bodies. This causes a foul smell and turbidity formation and gives a bad appearance. Furthermore, different studies carried out previously have presented the toxicological, carcinogenic effects, hypersensitivity reactions, and behavioral changes linked to the usage of synthetic colorants. Natural food colorings, however, have nutraceutical qualities that are valuable to human health such as curcumin extracted from turmeric and beta-carotene extracted from carrots. In addition, natural colorants have beneficial properties such as excellent antioxidant properties, antimutagenic, anti-inflammatory, antineoplastic, and antiarthritic effects. This review summarizes the sources of natural and synthetic colorants, their production rate, demand, extraction, and characterization of food colorants, their industrial applications, environmental impact, challenges in the sustainable utilization of natural colorants, and their prospects.

Agricultural waste biomass for sustainable bioenergy production: Feedstock, characterization and pre-treatment methodologies.

The worldwide trend in energy production is moving toward circular economy systems and sustainable availability of sources. Some advanced methods support the economic development of energy production by the utilization of waste biomass, while limiting ecological effects. The use of agro waste biomass is viewed as a major alternative energy source that expressively lowers greenhouse gas emissions. Agricultural residues produced as wastes after each step of agricultural production are used as sustainable biomass assets for bioenergy production. Nevertheless, agro waste biomass needs to go through a few cyclic changes, among which biomass pre-treatment contributes to the removal of lignin and has a significant role in the efficiency and yield of bioenergy production. As a result of rapid innovation in the utilization of agro waste for biomass-derived bioenergy, a comprehensive overview of the thrilling highlights and necessary advancements, in addition to a detailed analysis of feedstock, characterization, bioconversion, and contemporary pre-treatment procedures, appear to be vital. To this end, the current status in the generation of bioenergy from agro biomass through various pre-treatment procedures was examined in this study, along with presenting relevant challenges and a perspective for future investigations.

Persistent organic pollutants in water resources: Fate, occurrence, characterization and risk analysis.

Persistent organic pollutants (POPs) are organic chemicals that can persist in the environment for a longer period due to their non-biodegradability. The pervasive and bio-accumulative behavior of POPs makes them highly toxic to the environmental species including plants, animals, and humans. The present review specifies the POP along with their fate, persistence, occurrence, and risk analysis towards humans. The different biological POPs degradation methods, especially the microbial degradation using bacteria, fungi, algae, and actinomycetes, and their mechanisms were described. Moreover, the source, transport of POPs to the environmental sources, and the toxic nature of POPs were discussed in detail. Agricultural and industrial activities are distinguished as the primary source of these toxic compounds, which are delivered to air, soil, and water, affecting on the social and economic advancement of society at a worldwide scale. This review also demonstrated the microbial degradation of POPs and outlines the potential for an eco-accommodating and cost-effective approach for the biological remediation of POPs using microbes. The direction for future research in eliminating POPs from the environmental sources through various microbial processes was emphasized.

Adsorption of ciprofloxacin from aqueous solution using surface improved tamarind shell as an economical and effective adsorbent.

Antibiotics in water bodies are emerging as an alarming new pollutant because of its persistent and recombinant nature. In recent period of human lifestyle, pharmaceutical products play a vital role in many perspectives. Due to this unpredictable usage of products, the unreacted components release into waterbodies in trace quantities. Eventhough these trace quantities initiate a crisis of developing resistant antibacterial strains which pose health risks to humans and animals. This work reports the batch adsorption of a fluoroquinolone, a fourth-generation antibiotic compound by a biosorbent made by acid-treated tamarind shells. The shells were treated with zinc chloride and hydrochloric acid. The characterization of biosorbent was performed by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The optimized adsorption parameters of time, pH and temperature were 30 minutes, 6 and 60 °C. The adsorbent can be reused up to seven times with negligible loss in its adsorption capacity. Adsorption followed by Langmuir, Freundlich and Tempkin model where used to determine the correlation coefficient. Pseudo first-order, second-order and intra-particle kinetic model were used to fit the experimental data. The results are best described by pseudo second-order denoting chemisorption and Freundlich isotherm model describing multilayer adsorption.Novelty StatementThe proposed work is to investigate about improved tamarind shell as biomass used in the removal unreacted PPCP components that have been released into aquatic environment.The novelty of this paper lies in that it puts forward a better resource utilization method for treating PPCP component wastewater, and studies the method theoretically from the perspective of mechanism and proves its feasibility.Identifying the maximum adsorption of antibiotic component from wastewater under different conditions and finding the optimum range.In addition to the existing literatures, this study has compared the adsorption efficiency of raw and treated adsorbent material prepared using Tamarind shell.

Facile synthesis of nitrogen-doped porous carbon materials using waste biomass for energy storage applications.

A simple, low-cost, and green route for the preparation of lotus carbon (LC) materials using lotus parts including leaves, flowers, fruits (seed pods), and stems as a renewable precursor is reported. Different porous carbons, leaf-carbon (LF-carbon), flower-carbon (FL-carbon), fruit-carbon (FR-carbon), and stem-carbon (ST-carbon) were synthesized from different parts of the lotus plant by simple carbonization method. The as-synthesized LC materials were well-characterized by many techniques such as electron microscopy and spectroscopy techniques, X-ray diffraction, and BET-surface area analysis. These techniques confirmed the porous structure of LC materials and the existence of heteroatoms in the prepared LC materials. The mesoporous structure of LC materials suggested employing it for the supercapacitor applications. The obtained FR-Carbon exhibits a high specific capacitance of 160 F/g in a three-electrode system in an aqueous 1 M H2SO4 electrolyte with a high rate performance of 52% retention from 0.5 to 5.0 A/g with good cycling stability of 95%. These results indicate that the porous carbon derived from lotus fruits is a potential electrode material for high-performance supercapacitors.

Adsorption behavior of fluoroquinolone(ciprofloxacin) using zinc oxide impregnated activated carbon prepared from jack fruit peel: Kinetics and isotherm studies.

Ciprofloxacin is a pharmaceutical component used for treating various tract infections. This is considered as an emerging contaminant due to the release of unreacted components getting disposed into the water bodies. This component is effectively treated using renewable biomass, which is converted into a useful renewable low-cost adsorbent material. Discarded Jack Fruit Peel (JFP) is used as an activated carbon incorporated with zinc oxide nanocomposite. The prepared activated carbon in this experiment was characterized by determining their functional groups, morphological characters, and nature of the adsorbent material by analyzing the Fourier Transform InfraRed (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and X-ray Diffraction (XRD) characterization. Further, the prepared composite's correlation coefficients and equilibrium sorption of the adsorption process were calculated using Ultra Violet (UV)-Visible Spectroscopy and analyzed with isotherm models (Langmuir model, Freundlich model, and Temkin model) and kinetic models (Pseudo-first-order kinetics, Pseudo-second-order kinetics, Intraparticle diffusion model, and Elovich model). Among the different models, the Zinc oxide impregnated activated carbon show Freundlich Isotherm and Pseudo Second order equation having a maximum correlation with experimental studies indicating double-layer adsorption, which suggests that the process is chemisorption. The operational parameters, including the effect of pH, dosage of activated carbon, and contact time of adsorption was calculated to identify the optimal condition for maximum adsorption.

Effective removal of malachite green dye from aqueous solution in hybrid system utilizing agricultural waste as particle electrodes.

A comparison study of an electrolytic, adsorption, and a novel hybrid method towards the removal of malachite green (MGD) dye from the aquatic environment utilizing agricultural biomass, Eucalyptus globulus seeds was examined. The synthesized material has been characterized by thermogravimetric analysis, SEM, FTIR, and XRD. The acid-modified biosorbent developed a microporous structure suggesting a suitable removal process of MDG. The hybrid method was carried in an indigenously designed three-phase three-dimensional electrolytic reactor with varying applied voltage (6, 9, and 12 V) with biosorbent serving as particle electrode. The hybrid method gave the highest removal rate at a voltage of 12 V, compared to other methods. Moreover, the dye removal capacity increased with increased voltage, and contact time was optimized at 15 min. The adsorption isotherm was well fitted with Freundlich isotherm and kinetic data represented pseudo-second-order. Intra particle diffusion studies suggested no interference with gradual adsorption from macropores to micropores. The removal efficiency of particles electrodes for 6, 9, and 12 V were 95, 97, and 99.8%, respectively. The higher removal of MDG towards the hybrid system may be assigned to the synergistic effect of electrolytic and adsorption systems. Regeneration studies indicated that the biosorbent can be reused up to ten times without appreciable loss of efficiency.