Vinasse-based biochar magnetic composites: adsorptive removal of tetracycline in aqueous solutions

Magnetic biochar serves as adsorbents and catalyst supports for the removal of antibiotics from wastewater: A review

Numerous antibiotics are being released into the natural environment through wastewater. As antibiotic usage increases annually, its detrimental impact on the environment is escalating. Addressing environmental sustainability and human health requires significant attention towards antibiotic removal. In recent years, magnetic biochar (MBC) has gained widespread application in water treatment due to its exceptional adsorption and catalytic degradation capabilities. Antibiotics such as sulfamethoxazole (SMX), tetracycline (TC), ciprofloxacin (CIP), and others commonly exhibit an adsorption capacity by MBC ranging from 5 mg/g to 900 mg/g. Moreover, MBC typically removes over 90% of these antibiotics within 60 min. The effectiveness of antibiotic removal is significantly influenced by various preparation and modification methods. Furthermore, the incorporation of magnetism enables the material to be recycled and reused multiple times, thereby reducing consumption costs. This article discusses recent studies on antibiotic removal using MBC. It has been observed that variations in the selection of raw material and preparation procedures significantly affect antibiotic removal, while the mechanisms involved in antibiotic removal remain ambiguous. Additionally, it has been noted that the removal process may lead to secondary pollution and high preparation costs. Therefore, this review comprehensively outlines the utilization of MBC in the removal of antibiotics from wastewater, including aspects such as modification, preparation, removal mechanism, and factors influencing removal, and providing recommendations for antibiotic development. The aim is to offer researchers a clear understanding to advance the field of MBC materials.

Soil microbial improvement using enriched vinasse as a new abundant waste

This study proposes the use of vinasse, an inexpensive and readily available waste biopolymer, as a fundamental component of a waste culture medium that can enhance the effectiveness and cost-efficiency of the microbial-induced calcite precipitation (MICP) method for sustainable soil improvement. Vinasse enriched with urea, sodium caseinate, or whey protein concentrate is employed to optimize bacterial growth and urease activity of Sporosarcina pasteurii (S. pasteurii) bacterium. The best culture medium is analyzed using Taguchi design of experiments (TDOE) and statistical analysis, considering the concentration of vinasse and urea as effective parameters during growth time. To test the best culture medium for bio-treated soil, direct shear tests were performed on loose and bio-treated sand. The results demonstrate a substantial cost reduction from $0.455 to $0.005 per liter when using the new culture medium (vinasse and urea) compared to the conventional Nutrient Broth (NB) culture medium. Additionally, the new medium enhances soil shear strength, increasing the friction angle by 2.5 degrees and cohesion to 20.7 kPa compared to the conventional medium. Furthermore, the recycling of vinasse as a waste product can promote the progress of a circular economy and reduce environmental pollution. As ground improvement is essential for many construction projects, especially those that require high shear strength or are built on loose soil, this study provides a promising approach to achieving cost-effective and sustainable soil microbial improvement using enriched vinasse.

Effect of water-washing pretreatment on the enhancement of tetracycline adsorption by biogas residue biochar

Biochar preparation was a feasible strategy for realizing the reduction, harmlessness, and resource utilization of biogas residue (BR) simultaneously. How to enhance the adsorption performance of biogas residue biochar through simple, friendly, and effective way still needs to be investigated. In this study, water-washing pretreatment of BR was adopted before biochar preparation (BRBC-W), and pristine biochar (BRBC) was also produced to serve as control. The adsorption behavior and possible adsorption mechanisms of tetracycline (TC) onto biochars were comprehensively studied. The results showed that water-washing pretreatment could increase the surface area and mesoporous volume of biochar from 358.63 to 391.98 cm³∙g^-1, and 0.459 to 0.488 cm³∙g^-1, respectively. More graphitic structure was observed in BRBC-W. In addition, the surface morphology, element content, minerals composition, and surface functional groups also changed in biochar after water-washing pretreatment. The pseudo-second-order and Redlich-Peterson models better descried the adsorption behavior of TC on BCRBC-W. The maximum adsorption capacity of BRBC and BRBC-W for TC based on Langmuir isotherm was 224.93 and 306.94 mg·g^-1, respectively. The adsorption affinity of BRBC-W toward TC was greater than that of BRBC. BRBC and BRBC-W can effectively remove TC in water within a wide pH range and under the interference of co-existing ions. The adsorption mechanism of TC onto BRBC and BRBC-W included ore filling, π-π interaction, and hydrogen bonding. The enhancement of TC on BRBC-W by water-washing pretreatment was attributable to the strengthening of pore diffusion and π-π interaction. Therefore, water-washing pretreatment effectively enhanced the adsorption performance of BRB, and BRBC-W was an effective eco-friendly adsorbent for the removal of TC from aquatic environment.

Biochar Derived from Chinese Herb Medicine Residues for Rhodamine B Dye Adsorption

In this study, one well-known CHM residue (Atropa belladonna L., ABL) was used to prepare biochar capable of adsorbing rhodamine B (RhB) with an ultrahigh surface area for the first time. Three micropore-rich ABL biochars including ABL@ZnCl₂ (1866 m²/g), ABL@H₃PO₄ (1488 m²/g), and ABL@KOH (590 m²/g) were obtained using the one-step carbonization method with activation agents (ZnCl₂, H₃PO₄, and KOH) via chemical activation and carbonization at 500 °C, and their adsorption performance for RhB was systematically studied with adsorption kinetics, isotherms, and thermodynamics. Through pore diffusion, π-π interaction, and hydrogen bonding, ABL biochar had excellent adsorption performance for RhB. Moreover, when C ₀ was 200 mg/L, biochar dosage was 1 g/L, and the contact time was 120 min; the maximum RhB adsorption capacity and removal efficiency on ABL@ZnCl₂ and ABL@H₃PO₄ were 190.63 mg/g, 95% and 184.70 mg/g, 92%, respectively, indicating that it was feasible to prepare biochar from the ABL residue for RhB adsorption. The theoretical maximum adsorption capacities of ABL@ZnCl₂ and ABL@H₃PO₄ for RhB were 263.19 mg/g and 309.11 mg/g at 25 °C, respectively. Furthermore, the prepared biochar showed good economic applicability, with pay back of USD 972/t (ABL@ZnCl₂) and USD 987/t (ABL@H₃PO₄), respectively. More importantly, even after five cycles, ABL@H₃PO₄ biochar still showed great RhB removal efficiency, suggesting that it had a good application prospect and provided a new method for the resource utilization of traditional CHM residues. Additionally, pore diffusion, π-π interactions, and hydrogen bonding all play roles in the physical adsorption of RhB on ABL biochar. π-π interactions dominated in the early stage of RhB adsorption on ABL@H₃PO₄, while pore diffusion played a crucial role in the whole adsorption process on both adsorbents.