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As a key organic impurity in Bayer process, sodium oxalate seriously affects the quality of alumina products, thereby threatening the effective utilization of aluminum resources. Specifically, sodium oxalate continues to accumulate in the recovery solution and can eventually co-precipitate with aluminum trihydroxide. This is detrimental to the quality of the alumina, refines the trihydroxide particle size, and also causes the precipitated particles to become embrittled and therefore need to be removed. Herein, this review first outlines the sources of sodium oxalate in the Bayer process, then clearly summarizes the hazards of sodium oxalate, highlights on the existing disposal routes for sodium oxalate, and finally focuses on the opportunities and challenges faced by this area. The results of the literature review show that the existing sodium oxalate treatment process still has the problems of lower removal rate, higher usage cost and greater energy consumption. Advanced oxidation processes (AOPs) in chemical reaction methods is a promising technology for removing sodium oxalate. Furthermore, combining outfield with various sodium oxalate removal pathways can effectively increase the reaction rate and reduce disposal costs.

Triglycerides is a kind of natural oil widely existing in animals and plants, and it is also an ideal raw material for preparing biomass liquid fuel. Selectively hydrotreatment of unsaturated glyceride is an important strategy for the production of fuels and chemical feedstocks. In this work, catalytic hydrotreatment of triglycerides over Ni-based catalysts was investigated. Thus, an array of metal–organic frameworks derived Ni@C catalysts synthesized under different temperatures (350 °C, 400 °C, 450 °C) were prepared and applied for hydrotreatment of triglycerides. The highest conversion of triglycerides was 98.9% and the cracking rate could achieve 4.61% over the optimal Ni@C-BTC-400 catalyst in cyclohexane at 320 °C. The physicochemical characterizations were carried out by means of powder X-ray diffraction, scanning electronic microscopy, thermo gravimetric analyzer, N2adsorption–desorption, and Raman. Based on the optimal reaction condition (320 °C, 3 h, 3.0 MPa H2), five typical vegetable oils and gutter oils were selected for the hydrotreatment study to investigate the adaptability of Ni@C-BTC-400 catalyst. The result indicated that Ni@C-BTC-400 catalyst performed good universality, and could transform oil raw materials with different fatty acid carbon chain structure to desired alkanes. Furthermore, the optimal Ni@C-BTC-400 catalyst could be carried out in next two consecutive recycling runs and could also be regenerated by H2for the following experiments.

Alkali lignin, which is derived from the pulping and paper-making process, has been recognized to have great potential in the preparation of chemicals and value-added renewable biofuels. In this report, saturated steam was applied simultaneously, a novelty procedure, to assist in lower-temperature pyrolysis (from 275 to 350 °C) of alkali lignin and selective production of guaiacol components in a fixed-bed reactor. The results indicated that the lower-temperature pyrolysis displayed a positive effect on the breaking of aliphatic C–O bonds of lignin (β-O-4 bond) and helped to increase the intensity of oxygenated aromatic carbons and aromatic C═C structures. The guaiacol components were successfully removed from alkali lignin and extracted by saturated steam. This method displayed a useful effect on pyrolysis of lignin and on higher selectivity of guaiacol components. A relatively higher yield of stable solid carbon (from 68.45 to 88.67 wt %) and relative selectivity of guaiacol components (from 79 to 90.7%) were obtained. This novel method is quite a promising technique for simultaneous pretreatment of lignin and selective production of guaiacol components.

The objective of this study was to determine whether nutrient digestibility and reproductive performance of pregnant mink (Neovison vison) were affected by different dietary protein levels. One hundred and twenty female mink were randomly assigned to four groups, receiving diets of fresh material with different protein levels. The dietary protein levels, expressed as percentage of dry matter (DM), were 32, 36, 40 and 44% respectively. These values corresponded to average 320, 360, 400 and 440 g protein/kg DM, respectively. Results were as follows. All of crude protein digestibility, nitrogen (N) intake, N retention increased along with dietary protein level increasing. Low protein level (32%) significantly reduced the above indicators (P < 0.05). DM digestibility and ether extract digestibility were not affected by dietary protein level. Results of mated females, barren females, kids per litter, live born kids per mated female, birth survival rate, and birth weight showed that mink achieved optimal reproductive performance when dietary protein level was 36%. In conclusion, dietary protein was anticipated to significantly influence some nutrients' utilization. Adopting the appropriate dietary protein level allow better reproduction performance. The most preferable reproductive performance was achieved when diet contained 275.5 g digestible protein per kg DM for female mink in gestation.