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This work explores the bio-activation of zeolitic imidazolate framework (ZIF-L) by laccase encapsulation for enhanced performance of emerging pollutant removal from wastewater. ZIF-L exhibits high surface area, porosity, and selective adsorption characteristics, which contribute to its effective adsorption of ibuprofen. Under the same conditions, the ibuprofen removal increased from 50% using bare ZIF-L to 83% using bio-activated ZIF-L. The Kinetics and thermodynamics of ibuprofen adsorption on ZIF-L were studied and mathematically modeled. The effect of laccase encapsulation inside the ZIF-L crystals was thoroughly investigated using a diffusion-reaction model, which was solved numerically using a finite difference explicit scheme. The results showed deep ibuprofen penetration within the ZIF-L crystal containing encapsulated laccase. The bio-activated ZIF-L was used in a fixed-bed column to study the continuous removal of ibuprofen. The dynamic behavior of the continuous fixed-bed system was mathematically modeled to predict the concentration profiles and breakthrough curves at various initial ibuprofen concentrations. This study presents a novel approach demonstrating the positive effect of laccase catalytic activity in enhancing the performance of ZIF-L as an adsorbent for ibuprofen removal. The approach offers an effective, economical, and environmentally friendly method to remove emerging pollutants from wastewater.

This study investigated the development of poly(vinylidene fluoride) (PVDF) hybrid ultrafiltration membranes, where ZIF-8 nanocrystals are synthesized in situ within the membrane pores. These ZIF-8 embedded membranes are specifically designed for the treatment of emerging pollutants, such as ibuprofen. The optimized membrane, characterized by a higher concentration of ZIF-8 and greater surface coverage, exhibited significantly enhanced performance and improved properties, including increased hydrophobicity and mechanical strength. By increasing the zinc concentration from 0.2 to 0.3 M during the preparation of the ZIF-8 coated membrane, hydrophobicity was enhanced, as indicated by an increase in the contact angle from 60.3° to 87.2°, along with improved porosity from 41.3% to 60.5%. Further performance enhancements were achieved by encapsulating enzymes, specifically laccase and peroxidase, within the ZIF-8 coated membrane. A comparison of ibuprofen removal by these enzymes showed that peroxidase was slightly more effective, reaching a maximum removal efficiency of approximately 45% within 2 h. The biocatalytic membranes demonstrated a high stability and reusability, underscoring their potential for efficient ibuprofen removal. These findings highlight the efficacy of ZIF-8-coated PVDF membranes as advanced tools for water purification, offering significant improvements in both purification efficiency and membrane stability.

Hydrogenating carbon dioxide to formate using formate dehydrogenase (FDH) is a sustainable approach for CO2 mitigation. Herein, we developed a biocatalytic system with cofactor regeneration by immobilizing multiple enzymes, namely FDH, carbonic anhydrase (CA), and glutamate dehydrogenase (GDH), on a hydrophobic surface modified MOF, SA-HKUST-1. The adsorption kinetics of the multiple enzymes on the SA-HKUST-1 surface were described using pseudo second-order model, while the equilibrium followed Freundlich isotherm. Formate production by the enzymes immobilized on SA-HKUST-1 was 3.75 times higher than that achieved by free enzymes and 8.4 times higher than that of FDH immobilized alone on SA-HKUST-1. The hydrophobic interaction between the enzymes and the support altered the secondary structure of enzymes, and the immobilized enzymes retained 94% of their activity after four reuse cycles. This study provides novel insights into the combined effect of hydrophobic support and multiple enzymes on the catalytic efficiency and stability of FDH. These findings can provide a basis for developing a highly stable biocatalytic system with cofactor regeneration for continuous hydrogenation of CO2 to formate at the industrial level.

Post synthetic modification of a hydrophilic metal–organic framework (MOF), HKUST-1, with stearic acid (SA) was carried out to enhance the stability of HKUST-1 in aqueous solution to be used as a support for formate dehydrogenase (FDH) used for CO2 conversion to formate. SA modification improved the hydrophobicity without affecting the morphology and crystal structure of MOF. Adsorption of FDH on the modified MOF (SA@HKUST-1) was compared to that of the native HKUST-1 and ZIF-L. The adsorption kinetics on all MOFs was found to follow pseudo-second order kinetics and the isotherm was best described by Freundlich model. The high stability of SA@HKUST-1 and enhanced hydrophobic interaction between support and CO2 resulted in high catalytic efficiency and stability of FDH@SA@HKUST-1. The immobilized enzyme retained 95.1% of its initial activity after 4 cycles of repeated use. It was also shown that FDH@SA@HKUST-1 retained morphology and crystal structure after repeated use. Results of the present work provide novel insight into the influence of hydrophobic MOFs on the activity and stability of immobilized FDH. These findings are expected to assist in developing highly active and stable biocatalysts for CO2 hydrogenation at commercial level.

The utilization of agricultural waste to produce energy is considered a promising solution that combines waste minimization with energy diversification. This study investigated the full utilization of date seeds (DSs) for the combined production of biodiesel, bioethanol, and bio-oil. To optimize this process, the efficacy of oil extraction as a pretreatment method to enhance enzymatic hydrolysis was explored. Oil extraction was not only proved to be a good pretreatment method, it was also shown that it is superior to the conventional alkaline-pretreated under optimum operating conditions. Using post oil extraction samples, with 7% oil yield, the total sugars production by enzymatic hydrolysis increased by an impressive 75%, as compared to alkaline pretreatment, with 30% lignin removal. Subjecting the leftover DSs, after oil extraction and enzymatic hydrolysis, to pyrolysis at a temperature, heating rate, and residence time of 500 °C, 10 °C/min, and 10 min, respectively, resulted in bio-oil yield of 33.3%. This work demonstrated the potential of fully utilizing DSs for producing various biofuels, by providing a promising alternative for managing agricultural waste.