This report deals with converting the agriculture waste (rice straw) to environmental cleaner materials (biochar) using airless pyrolysis followed by eco-friendly activation. The biochar (p-Biochar) obtained after pyrolysis step (poorly active material) was activated using wet attrition method to give m-Biochar (highly active materials). The both p-Biochar and m-Biochar were characterized in detail and utilized for MB and CV dye removal from aqueous solution. Various parameters affecting the adsorption process such as dye concentration, adsorbent dose, contact time, temperature, NaCl dose and pH were investigated. The adsorption isotherm was well fitted using Langmuir isotherm, and the maximum adsorption capacity is 90.91 and 44.64 mg/g, for MB and CV dyes, respectively. The contact time data obtained showed that the two dyes were poorly adsorbed over p-Biochar. The equilibrium was reached quickly in 15 min for MB dye and 20 min for CV dye using the m-Biochar, and removal percent was 94.45 and 92.70% for MB and CV dyes, respectively. Moreover, the kinetic isotherm presented very well fitted by pseudo-second-order model. In addition, the adsorption percent increases with further increasing the pH value. Finally, we observed that m-Biochar highly adsorbs the MB dye compared with the CV dye over all experimental conditions.

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Mechanical alloying is a simple and useful processing technique that is now being employed in the production of nanocrystals and/or nanoparticles from all material classes. In the present work, preparation of silica nanoparticles (SiO 2 NPs) by wet mechanical attrition of white and yellow sand using a lab scaled ball mill was investigated. The different experimental parameters affecting the milling process were thoroughly studied such as the milling period, water volume and the initial size of sand particles. Analysis of the results obtained revealed that SiO 2 NPs with particle size 22-33 nm and 38-48 nm could successfully be prepared from original white and yellow sand, respectively. The optimum experimental parameters to obtain these SiO 2 NPs are 25 g original sand particle, 50 ml water, 113 g media weight and 8 hr milling period at 400 rpm mill speed. The SiO 2 NPs obtained were characterized by SEM, XRD, EDS and FTIR. The results obtained showed high homogeneity of the produced spherical SiO 2 NPs. These SiO 2 NPs have good potentials for use in industry such as their use as additive materials in ultrahigh performance concrete for the next development. Based on economic value, the produced SiO 2 NPs have excellent potential to be developed.SiO 2 NPs are used in many industries such as semiconductor technology, optical communication, removal of heavy metals and dyes from water, catalysts, pigments and pharmacy industry.SiO 2 NPs have been prepared by several techniques sol -gel process [6][7][8][9][10][11][12], microemulsion [13][14][15][16], oxidation of tetraethyl-orthosilicate TEOS in the bench-scale diffusion flame reactor [17], an interdigital micromixer and a batch reactor, have been used to prepare silica nanoparticles [18]. Recently, encapsulation of water insoluble drugs in mesoporous silica nanoparticles using supercritical carbon dioxide has been described [19].A literature survey revealed that little information is available regarding the preparation of SiO 2 NPs by wet mechanical attrition of white and yellow sand. The aim of the present study is to throw light on the preparation and characterization SiO 2 NPs by wet mechanical attrition white and yellow sand based on their following peculiar properties: 1) they have mechanic strength to enhance the usable life.2) The SiO 2 NPs possess nano-scaled size larger specific surface area allowing the easy adsorption of different environmental pollutants 3) the raw materials are low-cost and the synthetic approach is simple, which make these nanoparticles potentially commercializable. factors affecting the milling process were thoroughly investigated. The proposed method is particularly suitable for large quantity production, relatively simple with a few operation parameters, high homogenous product and low cost.

Cotton fiber–graphene oxide (C–GO) composite with high adsorptive properties towards the cationic dye, crystal violet (CV), was successfully fabricated by simple mixing of cotton fiber and GO in aqueous solution using a homogenizer.

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