A biomorphic MgO nanomaterial was fabricated via a facile and low-cost immersion method using cotton as the template.

In this work, bentonite‐supported Cu(II) complex (B@Cu(II)L) was prepared by a one‐pot method and used as a heterogeneous catalyst for evaluating its catalytic activity in oxidation degradation of hydroxypropyl guar gum (HPGG) in oilfield wastewater. All of the reaction parameters effected degradation efficiency, such as Na2S2O8 concentration, catalyst amount, reaction temperature, and pH value, were investigated in detail. The results showed that the absolute viscosity of HPGG solution can be decreased from 15 to 1.48 mm2/s in presence of 15% Na2S2O8 (mass ratio to HPGG) and 1.5 g/L B@Cu(II)L at 45°C and pH = 10. It was also found that the chemical oxygen demand of HPGG solution catalyzed by B@Cu(II)L decreased from 4,080 to 584 mg/L after 240 min under the optimum experimental conditions. The catalytic activity of supported bivalent copper complexes over bentonite was gradually decreased due to the loss of the active copper.

To seek for efficient Fenton-like oxidation processing for treatment of waste fracturing fluid containing hydroxypropyl guar gum (HPGG), in heterogeneous reaction, five bentonite-supported zero-valent metal catalysts were prepared by liquid-phase reduction. The results showed that the bentonite-supported zero-valent copper exhibited best catalytic performance, attributed to the high dispersion of active sites of zero-valent copper. The effects of the most relevant operating factors (H2O2 concentration, catalyst dosage, temperature and pH) were evaluated in detail. Moreover, the chemical oxygen demand removal rate of HPGG can achieve 76% when the reaction time was selected at 45 min under optimal experimental conditions. The stability evaluation showed that the catalytic performance was almost unaffected after the catalyst was recycled and used once more showing the good stability of the bentonite-supported zero-valent copper in the application process.

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