Search

In this study, alkaline catalyst (NaOH)-aided sulfolane organosolv pretreatment was firstly developed to reduce the recalcitrance of willow (Salix matsudana cv. Zhuliu) for effective saccharificatio...

The separation of toluene/pyridine by distillation still remains an obstacle in industry because of not only the formation of a minimum-boiling azeotrope but also their relative volatilities, whose ratio is close to unity throughout the whole composition range. Extractive distillation is still not feasible because it is hard to find suitable entrainers. Heterogeneous azeotropic distillation might require high energy consumption to obtain both purified products. Conventional pressure-swing distillation is also not feasible. In this work, we apply entrainer-assisted pressure-swing distillation to separate toluene/pyridine (95 mol %/5 mol %) by introducing n-propanol as an entrainer. Based on the different compositions of the recycling stream sent back to the azeotropic column, a two-column sequence and a three-column sequence are established. Both sequences are partially heat-integrated. The steady-state designs of both sequences are optimized based on the total annual cost (TAC). The results reveal that th...

The heterogeneous azeotropic dividing-wall column (ADWC) features significant reduction of capital investment and energy consumption. Conventional azeotropic distillation sequences can be thermally coupled into two types of configurations of ADWCs, namely, the original ADWC with simple azeotropic–recovery section and the other with recovery section also serving as preconcentrator. The ADWC with a combined recovery–preconcentrator section has been investigated in both steady-state design and dynamic controllability. However, the original ADWC has only been proven to be more energy efficient than the conventional azeotropic–recovery column sequence, not compared with the conventional azeotropic–stripper column sequence. Furthermore, the dynamic performance of this ADWC are still unclear. Note that all the benefits of the ADWC are reasonable only under good dynamic controllability. Thus, in this work, we develop a comparative study of optimal design and dynamic performance of the ADWC with two conventional s...

The steady-state multiplicity in azeotropic distillation processes has been theoretically predicted and verified experimentally for decades. However, it is a tough task to detect all the steady-state solutions. The purpose of this article is 2-fold: first, it provides a systematical study on the multiplicity in homogeneous azeotropic distillation with intermediate entrainer and a novel strategy is proposed to find all the steady-state solutions using “Design Specs/Vary” in Aspen Plus. Operating on the unstable steady-state branch benefits both energy saving and reducing capital investment with the product quality specified. Because of the great benefits that operating on the unstable steady-state branch offers, the second purpose is to present suitable control schemes to stabilize the operating point on the unstable steady-state branch to achieve robust control.

In the present study, magnetic cellulose/graphene oxide composite (MCGO) was prepared as a novel adsorbent to dispose of dye wastewater. The morphology and chemical structure of the MCGO composite were characterized by the Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), and scanning electronic microscope (SEM). The adsorption of methylene blue (MB) onto MCGO was studied in relation to initial concentration of MB, contact time, adsorbent dose, and pH value of solution. Adsorption kinetics and the equilibrium adsorption isotherm were fitted by a pseudo-second-order kinetic model and Langmuir isotherm, respectively. The thermodynamic parameters indicated that the adsorption was spontaneous, favorable, and exothermic in nature. Furthermore, MCGO was very stable and can easily be recycled. The adsorption efficiency of MCGO was still over 89% after recycling for five times.