：The feasibility of utilizing an abundant agricultural waste (desert date seed shell) as an alternative lowcost adsorbent for the removal of hazardous basic dyes [crystal violet (CV) and malachite green (MG)] and hexavalent chromium [Cr(VI)] from synthetic industrial effluent was investigated. Five different adsorbents including the raw, carbonized and chemically activated carbons were prepared and screened with respect to adsorption efficiency of the chosen adsorbates. The prepared adsorbents were characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and pH of zero point charge (pHzpc) analyses. The effects of operational variables such as solution pH, contact time and temperature on adsorption have been investigated. The removal of the adsorbates was found to be highly pH-dependent and the optimum pH was determined as 8.0 for the dyes and 2.0 for hexavalent chromium. The screening results revealed that the NaOH activated carbon (NAC) has the best adsorption characteristics with removal efficiencies of 91.10, 99.15 and 91.5 % for CV, MG and Cr(VI), respectively. The process dynamics was evaluated by pseudo-first-order and pseudosecond-order kinetic models. Experimental data have been found to be well in line with the pseudo-second-order model, suggesting therefore, a chemically-based sorption process. Negative Gibbs free energy change (∆G) values obtained from thermodynamic analysis indicated that the adsorption process was spontaneous and had a high feasibility. Positive values for enthalpy change (∆H) showed that the removal process was endothermic, implying that the amount of adsorbate adsorbed increased with increasing reaction temperatures. Additionally, positive values of entropy change (∆S) reflect the high affinity of the adsorbent material to the adsorbates. On the basis of results and their analyses, it has been established that adsorbent derived from desert date seed shell has a promising potential in environmental applications such as removing hazardous substances from industrial effluents. Through this work, it is believed that contributions are provided to the scientific investigations about the decontamination of precious water resources.

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Activated carbon derived from Balanites aegyptiaca seed shell (ACBS) was employed to remove crystal violet (CV) from aqueous medium. The characterization of this ACBS has been conducted using analytical techniques such as SEM, EDS, and Brunauer-Emmett-Teller (BET) surface area analysis. The adsorption parameters investigated were as follows: contact time (5-120 min), temperature (303-333 K) and initial concentration (100-500 mg/L). The adsorption data were interpreted by using kinetic, isotherms and thermodynamic equations. The kinetic data matched the pseudo-second-order model well, and both external diffusion and internal diffusion influenced the adsorption of the dye onto the adsorbent. The isotherm data was in concurrence with the Freundlich model intimating the multilayer coverage of CV on the heterogeneous surface of the ACBS. The thermodynamic quantities like ∆S°, ∆H° and ∆G° were computed using Gibbs plot. The results implicated the practicability and endothermicity of the dye adsorption process. Regeneration studies show the effectiveness of CH3COOH solution in CV recovery from ACBS than distilled water, H2SO4, HCl, HNO3, and NaOH solutions. The regenerated ACBS was recycled five times and sustained an adsorption efficiency of 92.08%.

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The corrosion inhibition behaviour of Henna leaves on Tin in 1.0 M HCl and 1.0 M NaOH was investigated using weight loss technique at temperatures ranges, 25-50°C. The maximum inhibition efficiency was found to be 95.45 at optimum inhibitor concentration. The presence of the compound adsorbed on the tin coupons was verified by spectroscopic measurements of the surface before and after corrosion tests. The leaves extract of Lawsonia inermis was found to be more effective in alkaline solution. It also confirmed that the inhibition efficiency decreased with increased in temperature but increased with increasing inhibitor concentrations. The Activation energy, Gibbs free energy were found to be 28.131, 29.589 kJmol-1 ;-3.280,-3.245 kJmol-1 in acidic and alkaline media respectively. The adsorption was found to obey Freundlich isotherm with linear coefficient (R 2) and equilibrium parameter K ads to be 0.972, 0.957; 0.06, 0.05 for both systems in acidic and alkaline media respectively. Physical adsorption mechanism is proposed from the trend of ∆G ads. The negative values of ∆G ads shows the spontaneity of the inhibition process. The increase in the activation energy of the inhibition processes with values of 80kJ/mol support the mechanism of physical adsorption process. Lawsonia inermis leaves extract has proved to be more excellent inhibitor for tin in NaOH alkaline.