Using molasses wastewater as partial acidifying agent, a new Fenton-like catalyst (ACRMsm) was prepared through a simple process of acidification and calcination using red mud as main material. With molasses wastewater, both the free alkali and the chemically bonded alkali in red mud were effectively removed under the action of H2SO4 and molasses wastewater, and the prepared ACRMsm was a near-neutral catalyst. The ACRMsm preparation conditions were as follows: for 3 g of red mud, 9 mL of 0.7 mol/L H2SO4 plus 2 g of molasses wastewater as the acidifying agent, calcination temperature 573 K, and calcination time 1 h. Iron phase of ACRMsm was mainly α-Fe2O3 and trace amount of carbon existed in ACRMsm. The addition of molasses wastewater not only effectively reduced the consumption of H2SO4 in acidification of red mud but also resulted in the generation of carbon and significantly improved the distribution of macropore in prepared ACRMsm. It was found that near-neutral pH of catalyst, generated carbon, and wide distribution of macropore were the main reasons for the high catalytic activity of ACRMsm. The generated carbon and wide distribution of macropore were entirely due to the molasses wastewater added. In degradation of orange II, ACRMsm retained most of its catalytic stability and activity after five recycling times, indicating ACRMsm had an excellent long-term stability in the Fenton-like process. Furthermore, the performance test of settling showed ACRMsm had an excellent settleability. ACRMsm was a safe and green catalytic material used in Fenton-like oxidation for wastewater treatment.

Leaching of zinc from indium-bearing zinc ferrite (IBZF) under microwave heating (MH) has been investigated. The result showed microwave intensified the leaching reaction of IBZF in the MH process. Microwave had a great nonthermal effect on the leaching reaction. The effective collision and the H2SO4 activation under the action of microwave belonged to the nonthermal microwave effect. Particle size of IBZF in the range from 45 to 150 μm almost had no effect on the zinc leaching in the MH process. Leaching temperature and leaching time had important effects on the zinc leaching. Zinc leaching in the MH process obeyed the unreacted shrinking core model very well, and the activation energy was 73.747 kJ/mol. The kinetic equation was \(1 - (1 - x)^{1/3} = 8.82 \times 10^8 e^{ - 73.747 \times 10^3 /RT} t\). The ratio of frequency factor of K0(In)/K0(Zn) was up to 4.69, indicating the effect of microwave intensification on the indium leaching was greater than that on the zinc leaching.

The adsorption behaviors of methylene blue (MB) by a thermo-sensitive colloid composed of sodium alginate and methylcellulose (TSC-SA/MC) have been investigated. The results showed that the dosage of SA had an important effect on the adsorption capability of TSC-SA/MC. The maximum of adsorption capability appeared at mSA/mMC of 0.3:1, and among all the differences in adsorption capability between 30 and 60 °C, 61 mg·g−1 was the maximum adsorption difference appeared at mSA/mMC of 0.3:1. The adsorption capability of TSC-SA/MC increased with pH from 2 to 11, decreased with temperature from 30 to 70 °C. The adsorption data were not well fitted by Langmuir, Freundlich, Temkin, or Dubinin-Radushkevich model, suggesting the adsorption of MB on TSC-SA/MC did not belong to a single adsorption style. The maximum adsorption capacity of adsorption isotherm data was 1098.5 mg·g−1. The adsorption of MB by TSC-SA/MC fitted the pseudo-second-order model, and the main resistances for MB adsorption by TSC-SA/MC involved the external mass transfer, intraparticle mass transfer, and sorption on active site. The ΔH of MB adsorption by TSC-SA/MC was −48.26 kJ·mol−1, and the ΔS was −143.00 J·K−1·mol−1. The ΔG indicated that the adsorption could change from a spontaneous process to a nonspontaneous process with temperature increase. Both physical and chemical adsorption took place in the MB adsorption process. Fourier transform infrared spectroscopy (FTIR) spectra of filter cakes of TSC-SA/MC before and after adsorption of MB showed that the adsorption process for MB by TSC-SA/MC had a quite complicated mechanism, and the successful adsorption involved many chemical groups.