Equilibrium, kinetic and thermodynamic studies of acid soluble lignin adsorption from rice straw hydrolysate by a self-synthesized macro/mesoporous resin

Abstract

A self-synthesized HQ-8 resin was prepared using a O/W suspension polymerization technique and employed as a potential adsorbent for the removal of acid soluble lignin (ASL) from rice straw hydrolysate (RSH). The structure and morphology of the HQ-8 resin before and after the adsorption of ASL were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and nitrogen adsorption-desorption isotherms. A series of adsorption conditions such as pH value, adsorbent dose, initial concentration, and temperature were systematically investigated to obtain the optimum process parameters. Within the studied range of ASL concentrations, the adsorption equilibrium was found to follow the Freundlich isotherm model well, with R 2 > 0.988. The rate of ASL adsorption onto the HQ-8 resin was very quick, and equilibrium was reached within 50 min of contact.Furthermore, the maximum adsorption capacity of ASL on the HQ-8 resin was 64.61 mg g À1 at 298 K at an initial solution pH of 1. The regression results revealed that the ASL adsorption kinetics was represented accurately by a pseudo-second-order model. The efficiency of the HQ-8 resin for the spontaneous and exothermic adsorption of ASL is attributed to the hydrophobic interaction between the cross-linked benzene ring of the HQ-8 resin and the aromatic ring of ASL. In addition, the activation energy of ASL adsorption onto the HQ-8 resin was 35.99 kJ mol À1 . In summary, the present adsorption studies of ASL from RSH revealed the potential of a self-synthesized HQ-8 resin to be applied as an alternative adsorbent for lignocellulose hydrolysate detoxification.

Controllable synthesis of monoacrylate‐modified adsorption resins and enhancing adsorption toward fermentation inhibitors from rice straw hydrolysate

“…The preparation of spherical monoacrylate modified St‐DVB adsorption resins was similar to a previous study with minor modification . Briefly, the polymerization process took place in a 500 mL three‐necked round‐bottomed flask equipped with a mechanical stirrer, a thermometer, and a reflux condenser.…”

“…The adsorption performances of the resins with different amounts of ester groups toward fermentation inhibitors were investigated. In this section, ASL, low molar mass phenolic compounds, were selected as target inhibitor because of their stronger detrimental effects on microorganisms than other inhibitors present in the hydrolysate . It is interesting to observe in Fig.…”

“…In this section, ASL, low molar mass phenolic compounds, were selected as target inhibitor because of their stronger detrimental effects on microorganisms than other inhibitors present in the hydrolysate. 21,34 It is interesting to observe in Fig. 2 that the adsorption capacity of ASL by monoacrylate modified resins was improved.…”

“…The preparation of spherical monoacrylate modified St-DVB adsorption resins was similar to a previous study with minor modification. 21 Briefly, the polymerization process took place in a 500 mL three-necked round-bottomed flask equipped with a mechanical stirrer, a thermometer, and a reflux condenser. 240 g of 0.75 wt% PVA aqueous solution and a few drops of 1 wt% methylene blue were added to the flask, which was then heated to 323 K. Organic solution containing 20 g monomers (St and monoacrylate), 20 g crosslinker (DVB), 0.4 g initiator (BPO) and 40 g porogens (toluene and n-heptane, w/w = 1:1) was transferred into the reactor, and then nitrogen was bubbled through the mixture for about 5 min to get rid of oxygen.…”

Novel poly(aniline-co-3-amino-4-methoxybenzoic acid) copolymer for the separation and recovery of Pd(ii) from the leaching liquor of automotive catalysts

“…9). 49 The Langmuir isotherm model clearly exhibited the best correlation for the adsorption of Pd(II) on the PANI-AMB copolymer. The theoretical maximum sorption capacity (Q m ) obtained from the Langmuir isotherm model was 278.5 mg g À1 .…”