Michael Kidane Ghide,Kai Li,Jianhua Wang,Saadiah A. Abdulmalek,Yunjun Yan
Nowadays, breast milk is considered as the ideal food for infants owing to the most common oleic acid-palmitic acid-oleic acid (OA-PA-OA) fatty acid distribution of the human milk fat (HMF). This study reports the synthesis of 1,3-dioleoyl-2-palmotoylglycerol (OPO)-rich human milk fat substitutes in a two-step enzymatic acidolysis reaction with Rhizomucor miehei lipase (RML) immobilized on magnetic multi-walled carbon nanotubes(mMWCNTs). The immobilized RML (RML-mMWCNTs) showed better thermal and pH stability, convenient recovery and reusability than the free soluble form. Under optimized reaction conditions (1:8 tripalmitin (PPP)/OA, 10%wt. enzyme, 50 °C, 5 h), PA content at the sn- 2 position and OA incorporation at the sn -1,3 positions reached 93.46% and 59.54%, respectively. Comparison tests have also showed that RML-mMWCNTs has better catalytic activity and reusability than the commercial lipase Lipozyme RM IM. The results suggest that RML-mMWCNTs is a promising biocatalyst for the synthesis of OPO-rich TAGs with potential use in infant formulas.
Dongping Song,Tao Huang,Kai Chen,Jialin Cui,Qingyang Xu,Chengyu Yan,Chengzhe Yang,Shaohang Wan,Minfeng Tao
In this study, the magnesium phosphate cement (MPC) coupling with graphene nanosheets (GNP) was employed to solidify municipal solid waste incineration fly ashes (MSWI-FA) and stabilize the contaminants of heavy metals (HMs) and chloride salts in the matrix. The maximum compressive strength of 45.62 MPa and the minimum leaching concentration of 0.012, 0.0064, 0.00079, 0.0045, and 0.048 mg/L for Zn, Cu, Cd, Pb, and total Cr and 0.86 g/L for chloride were obtained from the GNP-MPC-MSWI-FA-cemented matrix in the orthogonal tests and toxicity-leaching experiments, respectively. MSWI-FA significantly changed the MPC hydration process. The influence of MPC on the speciation transformation of HMs was more prominent than that of GNP. Fick's theory model was appropriate in fitting the whole leaching process of HMs and dissolvable chloride species from the matrix under acid-immersion conditions. Both K-struvite and Phase-5 were formed in the matrix in mineral analysis, verifying the formation of both MPC and magnesium oxychloride cement (MOC). The chloride salts in the MSWI-FA facilitated the self-cementation of MOC from light-burnt magnesia in MPC. The mechanisms including the formation of phosphate precipitation, gelation encapsulation, and chemical hydration brought by MPC attributed to effective solidification/stabilization of HMs and chloride in the MSWI-FA.
The aging mechanisms of modified biochar for arsenic (As) immobilization at micro/nano-interfacial scales in diverse soils remain poorly understood. Herein, we employed three aging treatments, including natural aging (NA), freeze–thaw cycles (FT), and dry–wet alternation (DW), to simulate the aging behavior of cerium-manganese modified biochar (CMBC) in two As-contaminated field soils. Results indicated that CMBC amendment significantly reduced soil pH by 7.5–16.7%, while simultaneously increasing dissolved organic carbon contents by 10–45%, available phosphorus levels by 11–43%, and the activities of four soil enzymes by 30–320% in comparison to unamended soils. These improvements proved to be most effective under FT-aging, followed by DW-aging and NA-aging. FT-aging also led to the most pronounced reduction in water-soluble As concentrations ranging from 94 to 99%, as well as a decrease in As mobilization coefficients of 38% to 59% in CMBC-amended soils when compared to DW-aging and NA-aging. The superior As immobilization under FT-aging can be attributed to adhesion mediated by Ce–Si crystal nano-bridge between soil microparticles and CMBC matrix, whereas such adhesion was not observed in NA/DW-aged samples. This unique interfacial configuration promoted Ca/Fe-oxide intercalation and amorphous Ce-oxides formation within CMBC, which facilitated the development of As–Fe/Ce crystalline phases. Meanwhile, the synergistic enrichment of metallic and oxygen-containing groups on FT-aged CMBC surface induced the formation of stable As–Ce/Fe–O species and triggered dual redox transformations: (1) Ce/Mn reduction drove bulk As(III) oxidation to As(V), and (2) Fe(0) oxidation mediated partial reduction of As(V)/As(III) to inert As(0). Notably, CMBC-amended red soil exhibited preferential As immobilization during aging due to the tighter adhesion between nano-CMBC and soil colloids. This enhanced adhesion strengthened the bonding of Ce/Fe-oxides with As and intensified the oxidation of As(III) to As(V) through increased Ce/Mn reduction. This study provides innovative microscale mechanistic insights into the aging behavior of modified biochar for remediating diverse soils contaminated with potentially toxic elements. Graphical
危险品化学品经营许可证（带存储）