In order to reduce the enzyme cost for lignocellulosic enzymatic hydrolysis, the upper critical solution temperature (UCST) additives are used to recover and reuse cellulase by regulating the temperature. A...

That recovering and recycling cellulase at room temperature by adding recyclable thermoresponsive zwitterionic surfactant is more significant for reducing the cost of the production of cellulosic ethanol. Sulfobetaines can...

Enzymatic conversion of lignocelluloses into fermentable sugar is a key step in the production of cellulosic ethanol. In this work, enzymatic hydrolysis lignin (EHL)-grafted phosphobetaine (EHLPB) was prepared, and the phosphobetaine intermediate, 3-chloro-2-hydroxypropyl­(2-(trimethylammonio)­ethyl)­phosphate, was synthesized from phosphocholine chloride calcium salt and epichlorohydrin. EHLPB showed a pH-sensitive response. When pH ≥ 5.0, it was completely dissolved in the buffer solution, whereas 95.5% of EHLPPB was precipitated when pH ≤ 3.0. Adding 1.2 wt % EHLPB-210 can increase the high-solid enzymatic digestibility of Eu-SPORL (sulfite pretreatment to overcome recalcitrance of eucalyptus) and CCR (corncob residue) from 33.6% and 52.6% to 71.5% and 73.6%, respectively. After the enzymatic hydrolysis of Eu-SPORL, 95% of EHLPB-210 was recovered by adjusting the slurry pH from 5 to 3. The recovered EHLPB-210 still kept the ability to enhance enzymatic hydrolysis of lignocelluloses. Adding 1.2 wt % recovered EHLPB-210 can increase the enzymatic digestibility of Eu-SPORL from 33.6% to 75.1%. Investigation of the adsorption of cellulase on lignin by sodium dodecyl sulfate–polyacylamide gel electrophoresis (SDS-PAGE) showed that EHLPB can significantly reduce the nonproductive absorption of cellulase on lignin and therefore enhance the enzymatic hydrolysis of lignocelluloses. By adding recoverable pH-responsive EHLPB, the enzymatic hydrolysis efficiency of lignocelluloses improved and the value-added utilization of enzymatic hydrolysis lignin was realized.