Biodegradation Behavior of Starch in Simulated White Water System of Old Corrugated Cardboard Pulping Process

Considering the serious barriers/issues induced by the accumulated starch generated in white water system of old corrugated cardboard(OCC)pulping process,large amounts of accumulated starch in white water would be decomposed by microorganisms and could not be utilized,thereby resulting in severe resource wastage and environmental pollution.This study mainly explored the effects of biodegradation/hydrolysis conditions of the two types of starch substrates(native starch and enzymatically(α-amylase)hydrolyzed starch),which were treated via microorganism degradation within the simulated white water from OCC pulping system and their biodegradation products on the key properties were characterized via X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FT-IR),and gel permeation chromatography(GPC)technologies.The effects of system temperature,pH value,starch concentration,and biodegradation time on starch biodegradation ratio and the characteristics of obtained biodegradated products from the two types of starches were studied.In addition,the effect ofα-amylase dosage on the biodegradation ratio of enzymatically hydrolyzed starch and its properties was investigated.It was found that the native starch presented a maximal degradation ratio at a system temperature of 55℃and pH value range of 5-7,respectively,the corresponding starch concentration within simulated white water system was 200 mg/L.Whereas the enzymatically hydrolyzed starch exhibited a highest degradation ratio at a system temperature of 50℃and pH value of 5.5,respectively,and the corresponding starch concentration within simulated white water system was 100 mg/L.It was verified that native starch is more readily bio-hydrolyzed and biodegradation-susceptive by microorganisms in simulated white water system of OCC pulping process,while the enzymatically hydrolyzed starch exhibits better biodegradation/hydrolysis resistance to the microbial degradation than that of native starch.This study provides a practical and interesting approach to investigate the starch hydrolysis or biodegradation behaviors in white water system of OCC pulping process,which would greatly contribute to the full recycling and valorized application of starch as a versatile additive during paperboard production.

Starch-based Surface-sizing Agents in Paper Industry:An Overview

Natural starch is an abundant and inexpensive polysaccharide biopolymer that is widely used as a surface-sizing agent in the paper industry.The surface sizing of paper improves its water and abrasion resistance,as well as its physical strength and printing adaptability.However,natural starch presents some disadvantages,such as high viscosity,poor fluidity,poor filmforming properties,and easy coagulation.Therefore,starch is usually modified and blended with various components to achieve better sizing performance.This article reviews approaches for the surface sizing of paper and modification of starch using enzymes or chemical methods,such as oxidation,cationization,and graft copolymerization.This article also discusses the application of starch-based multiphase systems(obtained by blending starch with various components)as surface-sizing agents.

Recent progress on the pretreatment and fractionation of lignocelluloses for biorefinery at QIBEBT

Pretreatment and fractionation are amongst the key steps for the conversion of lignocelluloses to sustainable biofuels,biomaterials or biochemicals,as pretreatment/fractionation can break the natural recalcitrance of lignocelluloses,improving the conversion efficiency of downstream processes.This paper reviews the recent progress on the pretreatment and fractionation of lignocelluloses for biorefinery at the Chinese Academy of Sciences-Qingdao Institute of Bioenergy and Bioprocess Technology(QIBEBT).The main technologies developed at the QIBEBT in recent years include alkaline twin-screw extrusion pretreatment,modified alkali pretreatment,hydrogen peroxide-assisted sodium carbonate pretreatment,fractionation with formic acid,as well as the two-step fractionation by hot water treatment coupling ammonium sulfite treatment.With the development of these technologies,a pilot scale platform for the pretreatment and saccharification of biomass has been established in the pilot plant of QIBEBT.