Valorization of Camellia oleifera oil processing byproducts to value-added chemicals and biobased materials: A critical review

The C.oleifera oil processing industry generates large amounts of solid wastes,including C.oleifera shell(COS)and C.oleifera cake(COC).Distinct from generally acknowledged lignocellulosic biomass(corn stover,bamboo,birch,etc.),Camellia wastes contain diverse bioactive substances in addition to the abundant lignocellulosic components,and thus,the biorefinery utilization of C.oleifera processing byproducts involves complicated processing technologies.This reviewfirst summarizes various technologies for extracting and converting the main components in C.oleifera oil processing byproducts into value-added chemicals and biobased materials,as well as their potential applications.Microwave,ultrasound,and Soxhlet extractions are compared for the extraction of functional bioactive components(tannin,flavonoid,saponin,etc.),while solvothermal conversion and pyrolysis are discussed for the conversion of lignocellulosic components into value-added chemicals.The application areas of these chemicals according to their properties are introduced in detail,including utilizing antioxidant and anti-in-flammatory properties of the bioactive substances for the specific application,as well as drop-in chemicals for the substitution of unrenewable fossil fuel-derived products.In addition to chemical production,biochar fabricated from COS and its applications in thefields of adsorption,supercapacitor,soil remediation and wood composites are comprehensively reviewed and discussed.Finally,based on the compositions and structural characteristics of C.oleifera byproducts,the development of full-component valorization strategies and the expansion of the appli-cationfields are proposed.

Coating of Mineral Acids with Niobic Solid Acid for Preparing Furfural from Nut Shell of Camellia oleifera Abel

Nut shell of Camellia oleifera Abel which has large scale of plantation in mountainous region of southern China is abundant renewable resource. The nut shell is suitable for preparation of furfural, as the content of which is as much as 16% (based the dried nut shell). In early time, mineral acids were employed as typically catalyst for preparing of furfural from the nut shells. These mineral acids could pollute water and corrode equipment. In this paper we used various mineral acids coating with niobic acid as catalysts to investigate reactions for preparation of furfural. Among these catalysts, the catalyst of sulfuric acid coating with niobic acid was found to be very effective, which had higher hammett acidity and better effect of hydrolysis of the nut shells;The catalysts of sulfuric acid coating with niobic acid was characterized, and the conditions of preparation of the catalyst were investigated. The optimum conditions were: sulfuric acid as coating acid, the concentration of sulfuric 1.1 mol/L, impregnation time 8 h, calcination time 8 h and calcination temperature 450°C. Then hydrolysis of the nut shells was explored, the optimum conditions were as follows: dose of catalyst 20%, ratio of solid to liquid 1:15, reaction temperature 100°C, reaction time 4 h;Under this condition, the yield of furfural was 8.7%.

Fabrication of supported acid catalytic composite fibers by a simple and low-cost method and their application on the synthesis of liquid biofuel 5-ethoxymethylfurfural

In this paper,sulfonic groups functionalized annealed bio-based carbon microspheres loaded polytetrafluoroethylene(A-BCMSs-SO_(3)H@PTFE)fibers with high activity,high stability,and easy regeneration were successfully fabricated by a simple method using low-cost raw materials.The characterization results showed that the annealed biomass carbon microspheres derived from waste Camellia oleifera shells were evenly distributed on the polytetrafluoroethylene fibers and the sulfonic groups can be successfully loaded on the surface of annealed biomass carbon microspheres by room temperature sulfonation.Subsequently,the as-prepared A-BCMSs-SO_(3)H@PTFE fibers were applied to the acidcatalyzed synthesis of liquid biofuel 5-ethoxymethylfurfural.The catalytic experiment results indicated that the annealing temperature and time during catalyst preparation have a significant effect on the activity and selectivity of A-BCMSs-SO_(3)H@PTFE fibers.The results of catalytic reaction kinetics showed that the yield of 5-ethoxymethylfurfural can reach more than 60%after 72 h of acid-catalyzed reaction.The stability test showed that the as-prepared A-BCMSs-SO_(3)H@PTFE fibers still maintained a stable acid catalytic activity after four recycles.

Biorefinery process for production of bioactive compounds and bio-oil from Camellia oleifera shell

A biorefinery process was developed in this study to obtain bioactive compounds and bio-oil from Camellia oleifera shells.Four different extraction techniques(water,ethanol,ultrasound-assisted deionized water,and ultrasound-assisted ethanol)were utilized to extract tea saponin and tannin from C.oleifera shells.Results showed that ethanol had better extraction capacity than did deionized water,and ultrasound could promote the dissolution of tannin and tea saponin in solution.The thermogravimetric curves of the samples treated under the four conditions moved toward high temperatures.This phenomenon indicated the thermal stability of the residue was significantly improved.The pretreatment showed a slight effect on the chemical compositions of bio-oil.Specifically,the samples treated with ethanol and ultrasound-assisted deionized water contained higher phenol contents(81.07%and 81.52%,respectively)than the other samples.The content of organic acid decreased with an increase in the phenol content.