In this article, we report results of experiments on covalent immobilization of Candidia rugosa lipase enzyme on modified multiwall carbon nanotubes (MW-CNTs) for oily wastewater treatment application. MWCNTs were produced using chemical vapor deposition (CVD) and surface-modified by nitric acid and organic cross-linkers. Successful attachment and high enzyme loading up to 30 wt % was confirmed via FTIR and TGA analysis. Enzymatic activity and loading, which are dependent on the oxidized MWCNT surfaces, cross-linker types and concentrations, resulted with high thermal and operational stability in the microenvironment conditions. This demonstrates the potential for improved resistance to the severe conditions in industrial applications. Furthermore, the CNTs-immobilized enzyme yielded a catalytic activity about 93 times higher than those immobilized on other reported support materials. Up to 98% biological activity retention was also achieved, marking a significant improvement over literature-reported activities (1-20%). Titrimetric analysis of hydrolyzed samples using MWCNT-Lipase (after 1 hr reaction time at 378C) resulted in an enzymatic activity increase of about five times over those from lyophilized lipase.
Chemical vapor deposition (CVD) method has proven its benchmark, over other methods, for the production of different types of carbon nanotubes (CNT) on commercial and lab scale. In this study, an injection vertical CVD reactor fitted with an ultrasonic atomization head was used in a pilot-plant scale (height 274 cm, radius 25 cm) for semicontinuous production of multiwall carbon nanotubes (MWCNTs). p-Xylene was used as a hydrocarbon precursor in which ferrocene was dissolved and provided the cracking catalyst. Atomization of the feed solution resulted in full and even dispersion of the catalytic solution. This dispersion led to the production of high aspect ratio MWCNTs (ranging from 8,000 to 12,000) at 850°C. Different experimental parameters affecting the quality and quantity of the produced CNTs were investigated. These included temperature, reaction time, and flow rate of the reaction and carrier gases. Different properties of the produced CNTs were characterized using SEM and TEM, while TGA was used to evaluate their purity. Specific surface area of selected samples was calculated by BET.
Objective: Leaves methanol extract of Jacaranda acutifolia Humb. and Bonpl. (JA) family Bignoniaceae was subjected to phytochemical investigation as well as antioxidant, hepatoprotective, cytotoxic and antihyperglycemic activities evaluation.Key findings: Eight compounds were identified: luteolin-7-O-β-D-glucuronide, luteolin-7-O-β-D-glucoside, aesculetin, luteolin, verbascoside, luteolin-7-O-β-D-glucuronide methyl ester, apigenin-7-O-β-D-glucuronide methyl ester and apigenin. JA revealed a potent antioxidant activity in vitro superior to vitamin E (DPPH assay; EC 50 of 0.43 mg/mL). A potential cytotoxic activity was produced against hepatocellular (HepG2) and cervical (HeLa) carcinoma cells with IC 50 of 6.05 and 16.7 µg, respectively. Treatment with JA extract inhibited the rise in alanine aminotransferase and aspartate aminotransferase by 33.6% and 36.8% respectively, reduced thiobarbituric acid by 35.7% and decreased the tamoxifen-induced elevation in tumor necrosis factor alpha (TNF-α) level by 42.86%. JA extract elicited a significant decrease in fasting blood glucose by -59.26%. Conclusions:Jacaranda acutifolia could be a natural source for antioxidant, hepatoprotective supplements and could provide a basis for a potential cytotoxic agent. The compounds isolated are responsible at least in part for the observed effects.
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