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Coating of zeolite nanoparticles, previously dispersed in Polycarboxylic acid (PCA) solution, on cellulose textile surface has several advanced technological applications. One of the possible usages is for the Durable Press finishing enabling simultaneous enhanced antimicrobial or flame retardant properties. In this study, one of the polycarboxylic acid crosslinking agents, Citric acid (CA) is used to coat cotton fabric in the presence of synthesized zeolite applied as a catalyst. Cotton fabric samples were padded with a suspension containing zeolite powder in aqueous solution of CA crosslinking agent. Drying and curing of coated samples was performed at different curing conditions, either in a microwave oven or in conventional dryer. Scanning electron microscope (SEM) is used to characterize the surface morphology and confirm bonding of zeolite particles to cellulose fibers. Further characterization of coated surface is performed by attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy while the effects of microwave irradiation on zeolite nanoparticles bonding is estimated by thermogravimetric analysis.

Wood specimens of fir (Abies alba Mill) and beech (Fagus sylvatica L.) were chemically modified using polycarboxylic acids (PCA), cured by convection heating or microwave treatment and analyzed by HPLC. A new non-formaldehyde cross-linking system was composed of citric acid (CA) and 1,2,3,4-butanetetracarboxylic acid (BTCA), which are representative polycarboxylic acids (PCAs). These reagents require phosphono-based catalysts, so a sodium hypophosphite (SHP) catalyst was used in this study. The effects of PCA treatment were compared with a previously introduced 1,3-dimethylol 4,5-dihydroxy ethylene urea (DMDHEU) treatment. The dimensional stability of the modified wood was determined in terms of the anti-swelling efficiency (ASE) using the water soak/oven dry method. The results revealed an improvement in ASE for wood modified with PCA compared to modification with DMDHEU. Qualitative and quantitative determinations of bound acids were performed by HPLC. Further intensification of the wood modification process and an increase in the quality of wood-based materials were achieved using microwave treatment. Among other benefits, the formation of cross-links between the wood and the reagent components led to an improvement in the tensile strength retention, particularly in combination with the microwave treatment.

Biocomposites were prepared by reinforcing polylactic acid (PLA) with randomly oriented, short Spartium junceum L. fibres. Prior to the composite production, the fibres were treated with montmorillonite nanoclay (MMT) in order to increase biocomposites resistance to the fire. Characterizations of the biocomposites in the presence and absence of MMT and Citric acid (CA) were performed by Thermogravimetric Analysis (TGA) and Microscale Combustion Calorimetry (MCC). The results indicated that biocomposites reinforced with fibres modified with MMT enhanced some of its thermal properties. Degradation level of residual fibres (char) after the TGA treatment at 800 °C was observed by Scanning Electron Microscope (SEM). The work provided us with the idea of using MMT in the presence of CA as a crosslinker in biocomposites for possible applications.

Polycarboxylic acids BTCA (1, 2, 3, 4-butanetetracarboxylic acid) and CA (citric acid) are used as non-formaldehyde durable press finishing agents instead of the formaldehyde-releasing N-methylol compounds, such as DMDHEU. Isocratic HPLC is applied in an attempt to quantify the PCA that have reacted with the cellulosic material dyed with C.I. Reactive Red 195, C.I. Reactive Yellow 145 and C.I. Reactive Blue 221. Subsequently, the fabrics are cured with formulations containing 60 g/L BTCA or 60 g/L CA and a combination of 15 g/L BTCA and 45 g/L CA. The chromatographic determination reveals that an increase in the shade depth results in the decrease of the amount of BTCA, except in the case when the cotton sample is dyed with C.I. Reactive Blue 221, a copper formazan complex-based dyestuff. The evaluation of the color measurements indicates that the  E* values decrease in order of C.I. Reactive Yellow 145, C.I. Reactive Red 195 and C.I. Reactive Blue 221.

Aim To study the antimicrobial activity of citric acid (CA) and sodium hypophosphite monohydrate (SHP) against gram-positive and gram-negative bacteria, and to determine the influence of conventional and microwave thermal treatments on the effectiveness of antimicrobial treatment of cotton textiles. Method Textile material was impregnated with CA and SHP solution and thermally treated by either conventional or microwave drying/curing treatment. Antibacterial effectiveness was tested according to the ISO 20743:2009 standard, using absorption method. The surfaces were morphologically observed by scanning electron microscopy, while physical characteristics were determined by wrinkle recovery angles method (DIN 53 891), tensile strength (DIN 53 837), and whiteness degree method (AATCC 110-2000). Results Cotton fabric treated with CA and SHP showed significant antibacterial activity against MRSA (6.38 log10 treated by conventional drying and 6.46 log10 treated by microwave drying before washing, and 6.90 log10 and 7.86 log10, respectively, after 1 cycle of home domestic laundering washing [HDLW]). Antibacterial activity was also remarkable against S. aureus (4.25 log10 by conventional drying, 4.58 log10 by microwave drying) and against P. aeruginosa (1.93 log10 by conventional and 4.66 log10 by microwave drying). Antibacterial activity against P. aeruginosa was higher in samples subjected to microwave drying/curing than in those subjected to conventional drying/curing. As expected, antibacterial activity was reduced after 10 HDLW cycles but the compound was still effective. The surface of the untreated cotton polymer was smooth, while minor erosion stripes appeared on the surfaces treated with antimicrobial agent, and long and deep stripes were found on the surface of the washed sample. Conclusion CA can be used both for the disposable (non-durable) materials (gowns, masks, and cuffs for blood pressure measurement) and the materials that require durability to laundering. The current protocols and initiatives in infection control could be improved by the use of antimicrobial agents applied on cotton carbohydrate polymer.

In this study the esterification of cotton fabrics with citric acid (CA) in the presence of zeolite as a catalyst is presented. Ester crosslinking of cellulose chains imparts wrinkle resistance, shrinkage resistance and smooth drying properties to cotton fabrics. The goal was obtaining an eco-sustainable esterification system consisting of an environmentally friendly agent and catalyst. The result was the improved flame retarding properties of cotton in view of the fact that a considerable amount of zeolite remains strongly bonded to cellulose. Several techniques such as FTIR spectroscopy, thermogravimetry and scanning electron microscopy were used to verify the degree of esterification.