Removal of Pb(Ⅱ) from aqueous solutions using waste textiles/poly(acrylic acid) composite synthesized by radical polymerization technique

Waste textiles（WTs） are the inevitable outcome of human activity and should be separated and recycled in view of sustainable development. In this work, WT was modified through grafting with acrylic acid（AA） via radical polymerization process using ceric ammonium nitrate（CAN） as an initiator and microwave and/or UV irradiation as energy supply. The acrylic acid-grafted waste textiles（WT-g-AA） thus obtained was then used as an adsorbent to remove Pb（Ⅱ） from Pb（Ⅱ）-containing wastewater. The effects of p H, initial concentrations of Pb（Ⅱ） and adsorbent dose were investigated, and around 95% Pb（Ⅱ） can be removed from the aqueous solution containing 10 mg/L at p H 6.0–8.0. The experimental adsorption isotherm data was fitted to the Langmuir model with maximum adsorption capacity of35.7 mg Pb/g WT-g-AA. The Pb-absorbed WT-g-AA was stripped using dilute nitric acid solution and the adsorption capacity of Pb-free material decreased from 95.4%（cycle 1） to91.1%（cycle 3）. It was considered that the WT-g-AA adsorption for Pb（Ⅱ） may be realized through the ion-exchange mechanism between ／COOH and Pb（Ⅱ）. The promising results manifested that WT-g-AA powder was an efficient, eco-friendly and reusable adsorbent for the removal of Pb（Ⅱ） from wastewater.

Waste Textile Reutilization Via a Scalable Dyeing Technology: A Strategy to Enhance Dyestuffs Degradation Efficiency

The rapid expansion of the fast fashion industry brings about environmental concerns such as dyestuffs-related water pollutions and waste textiles.Conventional wastewater-disposal strategies emphasize the optimization of photocatalytic activity to improve pollutant degradation efficiency,while the absorptivity,recyclability and sustainability of photocatalysts are always ignored.The overproduced textiles are still in urgent of being recycled and reutilized in eco-friendly approaches.In this work,a scalable dyeing technology is employed to achieve green and sustainable reutilization of waste textiles.The functionalized TiO2/reduced graphene oxide wool fabrics show excellent sustainability,remarkable adsorbing capacity and enhanced photocatalytic performance.By taking advantage of these properties,we develop an integrated strategy of nighttime adsorption and day-time photodegradation which could significantly optimize the dyestuffs degradation efficiency.The concept of waste textiles reutilization and wastewater treatment in this work provides practical potential for efficient and sustainable environmental remediation.

The addition of microbes for treating textile wastewater

Some strains and culture of bacteria which are able to decolorize dyes and degrade polyvinyl alcohol(PVA) were isolated and selected. A pilot scale facultative anaerobic-aerobic biological process was applied for treatment of textile wastewater containing dyes and PVA. Activated carbon adsorption was used as a tertiary treatment stage, and residual sludge from clarifier returned to the anaerobic reactor again. The pilot test were carried out with two systems. One was inoculated by acclimated sludge, and the another was adding the mixed culture of dye-decoloring and PVA-degrading bacteria for forming biological films, the latter was observed to be more effective than the former. The test has run normally for ten months with a COD loading of 2.13 kg/m3/day, a BOD5 loading of 0.34 kg/m3/day in anaerobic reactor; a COD loading of 1.71 kg/m3/day, a BOD5 loading 0.44 kg/m3/day in aerobic reactor. The pollutants removal efficiency by adding microbes was about 20% higher than that by acclimated sludge. The average removal efficiency of COD stood about 92%, BOD5 97%, PVA 90% and decolorization 80%. The other parameters of effluent quality are also satisfactory.

Study on textile waste generation in the undifferentiated municipal solid waste stream in Guimarães,Portugal

Guimarães is a middle sized city and municipality located in northern Portugal.The municipality has committed to reducing the annual amount of undifferentiated municipal solid waste(MSW)from 371 kg/capita in 2021 to 120 kg/capita by 2030 under the Zero Waste Cities Certification process.In the municipality of Guimarães,one of the constant fractions of MSW composition is textile waste(TW),which the revised EU Waste Framework Directive requires separate collection by 1 January 2025.Therefore,two indicators of TW generation were analysed to identify waste collection routes with a high level of textile waste generation for the priority implementation of separate collection:TW composition in the undifferentiated MSW stream and TW generation per capita.Basic statistical analysis methods were used to process the source data of TW composition in the undifferentiated MSW stream.Cluster analysis was applied to the data set on TW generation per capita,considering the area typology(urban,rural or mixed)of collection routes.It was considered that 39%of the industrial sector of Guimarães consists of textile and clothing production and represents small-and medium-sized enterprises,which can affect TW generation in the undifferentiated MSW stream.Causal-comparative research was used to define the correlation between TW generation per capita and the economic activity of the textile and clothing industry in the municipality.As a result,applying a multi-disciplinary approach,a project of the Textile Waste Generation Map was presented.

Converting textile waste into value-added chemicals:An integrated bio-refinery process

The rate of textile waste generation worldwide has increased dramatically due to a rise in clothing consumption and production.Here,conversion of cotton-based,colored cotton-based,and blended cotton-polyethylene terephthalate(PET)textile waste materials into value-added chemicals(bioethanol,sorbitol,lactic acid,terephthalic acid(TPA),and ethylene glycol(EG))via enzymatic hydrolysis and fermentation was investigated.In order to enhance the efficiency of enzymatic saccharification,effective pretreatment methods for each type of textile waste were developed,respectively.A high glucose yield of 99.1%was obtained from white cotton-based textile waste after NaOH pretreatment.Furthermore,the digestibility of the cellulose in colored cotton-based textile wastes was increased 1.38e1.75 times because of the removal of dye materials by HPAC-NaOH pretreatment.The blended cotton
PET samples showed good hydrolysis efficiency following PET removal via NaOHeethanol pretreatment,with a glucose yield of 92.49%.The sugar content produced via enzymatic hydrolysis was then converted into key platform chemicals(bioethanol,sorbitol,and lactic acid)via fermentation or hydrogenation.The maximum ethanol yield was achieved with the white T-shirt sample(537 mL/kg substrate),which was 3.2,2.1,and 2.6 times higher than those obtained with rice straw,pine wood,and oak wood,respectively.Glucose was selectively converted into sorbitol and LA at a yield of 70%and 83.67%,respectively.TPA and EG were produced from blended cotton
PET via NaOHeethanol pretreatment.The integrated biorefinery process proposed here demonstrates significant potential for valorization of textile waste.

Textile waste-an opportunity as well as a threat

Clothing and textiles are very challenging to recycle due to the fact that they are nearly always a blend of fibres from different types of polymers.There are some promising early indications that new green solvents including CyreneTM and TMO as well as some simple ionic liquids can be used to aid recycling of complex fabrics by selective dissolution of one of the component polymers.A viable process for the future valorisation of many waste fabrics should be designed to maximise the creation of valuable product streams while also minimising any waste.