Camel Dung-Derived Biochar for the Removal of Copper(II) and Chromium(III) Ions from Aqueous Solutions: Adsorption and Kinetics Studies

This study explores an innovative approach to tackle the critical issue of heavy metal ion contamination in aqueous solutions through the utilization of camel dung-derived biochar. In the context of global environmental concerns and the adverse impacts of heavy metal pollution on ecosystems and human health, the investigation focuses on copper(II) and chromium(III) ions, which are among the most pervasive pollutants originating from industrial activities. The research revealed that camel dung-derived biochar exhibits exceptional potential for the removal of copper(II) and chromium(III) ions, with removal efficiencies of more than 90% and adsorption capacities of 23.20 and 23.36 mg/g, respectively. The adsorption processes followed second-order kinetics, and the data fitted both the Langmuir and Freundlich adsorption models. The underlying mechanisms governing this adsorption phenomenon seem to be grounded in complexation reactions, cation exchange, and cation-π interactions, underscoring the multifaceted nature of the interactions between the biochar and heavy metal ions. This research not only advances our understanding of sustainable materials for water purification but also harnesses the underutilized potential of camel dung as a valuable resource for environmental remediation, offering a promising avenue for addressing global water pollution challenges.

Metal Oxide-Impregnated Biochar for Azo Dye Remediation as Revealed through Kinetics, Thermodynamics, and Response Surface Methodology

This study reports for the first time the adsorption capacity of a novel adsorbent Croton bonplandianus Baill. biochar. Its adsorption capacity was further enhanced by loading magnetic composites on it, which makes it an efficient medium for the adsorption of dyes. Two azo dyes, Basic Brown 1 (BB1) and Basic Orange 2 (BO2), were studied for their effective adsorption from aqueous media. A comprehensive characterization was performed by using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to study the properties of Fe2O3-loaded C. bonplandianus Baill. biochar (FO-CBPBB). A series of batch experiments were conducted to optimize various parameters (pH, contact time, adsorbent amount, initial BB1 and BO2 concentrations, and temperature) for the maximum adsorption of BB1 and BO2 on the FO-CBPBB adsorbent. The percentage of BB1 and BO2 dyes that adsorb to FO-CBPBB under the best experimental circumstances (pH of solution 7, contact time 80 min, temperature of solution 40 °C, initial BB1 and BO2 dye concentrations 80 mg L-1, and adsorbent dose 1 g L-1) was 93 and 95%, respectively. The best adsorption of BB1 and BO2 was accomplished by optimizing the effects of several factors, including the starting dye concentration, contact time, and temperature, based on the central composite design. The Freundlich and Langmuir isotherm models were used to examine the equilibrium data. The Langmuir isotherm with the greatest adsorption capacity and R2 value effectively captured the experimental results. When kinetic parameters were investigated, it was found that pseudo-second-order was appropriate, reflecting the fact that the dye-adsorbent interaction was the rate-controlling factor in this study. The sorption process was endothermic and spontaneous, as shown by the thermodynamic variables. Based on the interaction between the adsorbent and azo dyes, it was concluded that the adsorption process was electrostatic in nature. Adsorbents that have been synthesized can effectively remove azo dyes from wastewater. Excellent regeneration efficiency was exhibited by FO-CBPBB, which makes it an eco-friendly and cost-effective alternative to other costly techniques applied for water purification.

Efficient removal of purine compounds from solutions via biomass carbons derived from pomelo peel

The high purine diet could result in the increase of the level of blood uric acid, causing serious health problems such as hyperuricemia, gout, nephropathy and cardiovascular diseases. To find out a safe, cheap and super adsorption material for removing purines in stomach or pretreating high-purine beverages, we used different tissues of pomelo peel to prepare biomass carbon by drying, chemical modification and carbonization and then applied it to remove purine compounds in strong acidic solution, beer and soybean milk. The characteristic analysis of pomelo-peel-derived carbons (PPCs) indicated that the preparation methods significantly affected the structures and adsorption capacities of PPCs. Compared with the biomass carbon derived from bamboo, PPCs exhibited higher adsorption capabilities for purine compounds in strong acidic solution (adsorption rates > 99% in 15 min) and soybean milk (adsorption rates > 56% in 30 min) but slightly lower adsorption capabilities in beer (adsorption rates > 52% in 30 min). In addition, the adsorption capabilities of PPCs for purine compounds in beer and soybean milk were not obviously affected by temperatures. Therefore, PPCs are promising absorbents for applications in removing purine compounds from beverages to produce low-purine, healthier products for treating hyperuricemia. The strong adsorption capabilities of PPCs on purine compounds in strong acidic environment also provides a possibility of using the PPCs as food additives for removing purines in stomach for healthcare applications such as gout prevention after confirming their biosafety.

Adsorption characteristics of magnetized biochar derived from Citrus limetta peels

Agro-industrial waste is an alarming issue that needs to be addressed. Waste valorization is an effective technique to deal with such effectively. Synthesis of biochar from fruit waste is one of the emerging approaches for adsorption, energy storage, air purification, catalysis, and biogas production trending these days. Magnetized Citrus limetta biochar (MCLB) was synthesized from Citrus limetta peels and was magnetized using iron oxide. Magnetization of biochar increases its functionalities as well as makes its separation easy. The removal of Methylene Blue (MB) dye from an aqueous solution is achieved through the use of MCLB. Methylene Blue is a prominent and widely used cationic-azo dye in the textile and printing industries. The accumulation of MB in wastewater is the major problem as MB is reported as a carcinogenic agent. The removal of MB dye with MCLB was analyzed by adsorption studies, wherein the effect of factors influencing adsorption such as initial concentration of MB dye, MCLB dosage, the effect of pH, contact time, and adsorption isotherms were studied. Characterization of MCLB was carried out using various techniques, such as FTIR, VSM, XRD, SEM, RAMAN, and Zeta potential. The adsorption isotherm mechanism was well explained with the non-linear Langmuir isotherm model resulting in a good adsorption capacity (q e  = 41.57 mg/g) of MCLB when MB (co = 60 mg/L, pH ~ 6.8, T = 273K). The thermodynamics analysis revealed that MB's spontaneous and endothermic adsorption onto the MCLB surface followed pseudo-second-order kinetics. The results obtained from this study suggest that the magnetized biochar derived from Citrus limetta peels has a wide range of potential applications in the treatment of dyeing wastewater.

Magnetic Hydrogel Composite for Wastewater Treatment

Nanocomposite hydrogels are highly porous colloidal structures with a high adsorption capacity, making them promising materials for wastewater treatment. In particular, magnetic nanoparticle (MNP) incorporated hydrogels are an excellent adsorbent for aquatic pollutants. An added advantage is that, with the application of an external magnetic field, magnetic hydrogels can be collected back from the wastewater system. However, magnetic hydrogels are quite brittle and structurally unstable under compact conditions such as in fixed-bed adsorption columns. To address this issue, this study demonstrates a unique hydrogel composite bead structure, providing a good adsorption capacity and superior compressive stress tolerance due to the presence of hollow cores within the beads. The gel beads contain alginate polymer as the matrix and MNP-decorated cellulose nanofibres (CNF) as the reinforcing agent. The MNPs within the gel provide active adsorption functionality, while CNF provide a good stress transfer phenomenon when the beads are under compressive stress. Their adsorption performance is evaluated in a red mud solution for pollutant adsorption. Composite gel beads have shown high performance in adsorbing metal (aluminium, potassium, selenium, sodium, and vanadium) and non-metal (sulphur) contaminations. This novel hybrid hydrogel could be a promising alternative to the conventionally used toxic adsorbent, providing environmentally friendly operational benefits.

An Insight into a Sustainable Removal of Bisphenol A from Aqueous Solution by Novel Palm Kernel Shell Magnetically Induced Biochar: Synthesis, Characterization, Kinetic, and Thermodynamic Studies

Recently Bisphenol A (BPA) is one of the persistent trace hazardous estrogenic contaminants in the environment, that can trigger a severe threat to humans and environment even at minuscule concentrations. Thus, this work focused on the synthesis of neat and magnetic biochar (BC) as a sustainable and inexpensive adsorbent to remove BPA from aqueous environment. Novel magnetic biochar was efficiently synthesized by utilizing palm kernel shell, using ferric chloride and ferrous chloride as magnetic medium via chemical co-precipitation technique. In this experimental study, the influence of operating factors comprising contact time (20-240 min), pH (3.0-12.0), adsorbent dose (0.2-0.8 g), and starting concentrations of BPA (8.0-150 ppm) were studied in removing BPA during batch adsorption system using neat biochar and magnetic biochar. It was observed that the magnetically loaded BC demonstrates superior maximum removal efficiency of BPA with 94.2%, over the neat biochar. The functional groups (FTIR), Zeta potential, vibrating sample magnetometer (VSM), surface and textural properties (BET), surface morphology, and mineral constituents (FESEM/EDX), and chemical composition (XRD) of the adsorbents were examined. The experimental results demonstrated that the sorption isotherm and kinetics were suitably described by pseudo-second-order model and Freundlich model, respectively. By studying the adsorption mechanism, it was concluded that π-π electron acceptor-donor interaction (EAD), hydrophobic interaction, and hydrogen bond were the principal drives for the adsorption of BPA onto the neat BC and magnetic BC.